aviation lounge

Mind-blowing Engineering

2009-06-14T15:32:00.000-07:00

This video is not aviation related but worth watching I hope every one would like it.

This incredible machine was built as a collaborative effort between The Robert M. Trammell Music Conservatory and the Sharon Wick School of Engineering at the University of Iowa . Amazingly, 97% of the machine's components came from John Deere Industries who make tractors, and Irrigation Equipment of Bancroft, Iowa, manufacturers of farm equipment. For sceptics who think this is computer animation, It took the team a combined 13,029 hours of set-up, alignment, calibration, and tuning before filming this video. The machine is now on display in Iowa in the Matthew Gerhard Alumni Hall at the University and is already slated to be donated to the Smithsonian.

Ten Worst airplanes

2009-06-14T14:48:00.000-07:00

By Chuck Squatriglia
July 7, 2008

In the 105 years since the Wright Brothers took to the air, dreamers, engineers and aviation buffs have designed every kind of airplane imaginable in a never-ending quest to fly higher, faster or further. Some were innovative, some were beautiful and some even made history. Others, well, let's just say they must have looked good on paper.

Here's a tribute to the 10 worst ever that surely looked better on paper. (Photos below).

Tupolev TU- 144

1.The Concorde gets all the love, but Russia's Tupolev TU-144 was the first supersonic transport and the only commercial plane to exceed Mach 2. The "Concordski" was fast but plagued by bad luck. Three crashes -- including a dramatic mid-air breakup during the 1973 Paris Air Show -- relegated it largely to a lifetime delivering mail. It was mothballed in 1985 but briefly brought back a few years later as a research plane.

B.O.A.C de Havilland Comet

2.The Comet was the premiere commercial jet airliner and a landmark in British aeronautics when it first flew in 1949. Today it's better known for its atrocious safety record. Of the 114 Comets built, 13 were involved in fatal accidents, most of them attributed to design flaws and metal fatigue.

Hughes H-4 Hercules

3.The “Spruce Goose” was either a brilliant aircraft years ahead of its time or the biggest government boondoggle ever. By far the largest aircraft ever conceived -- its wingspan was 319 feet -- the Spruce Goose was intended to be a military transport plane. But it wasn't finished until well after World War II ended, rendering it both obsolete and irrelevant. It only flew once.

LWS-4 Zubr

4.The Polish Zubr was as useless as it was ugly. Not only was it incapable of flying with the landing gear retracted, the airframe was so highly stressed the plane could disintegrate without warning. If that wasn't enough, it couldn't take off with a payload much heavier than a few cartons of cigarettes. The Polish Air Force had a few in its fleet during World War II, but none of them saw combat.

Christmas Bullet

5.Cool name, lousy plane. Dr. William Christmas didn't know the first thing about planes when he designed one for the U.S. Army Signal Corps, and it showed. He didn't think the plane needed wing struts, so of course they fell off during the plane's maiden flight in 1918.

Beechcraft Starship

6.With its carbon-composite construction, unique design and rearward-facing turboprop engines, the Starship was a groundbreaking aircraft. But it was slow, difficult to fly and a bear to maintain. It took to the air in 1989, but Beechcraft only sold a few of the 53 it built.

Hiller VZ-1

7.The Hiller VZ-1 hovercraft must have looked good on paper, because it sure didn't look good in the air. The idea was simple -- a fan provides lift and the pilot steers by shifting his weight. The Defense Department loved it until it saw the Pawnee in flight. It was good for just 16 mph and it tended to be uncontrollable. The project was killed in the late 1950s.

A-12 Avenger II

8.Defense Department projects are famous for cost overruns, and General Dynamic’s flying wing bomber was a doozy. The Flying Dorito was the most troubled of the stealth aircraft projects the Pentagon embraced during the 1980s, experiencing problems with its radar systems and use of composite materials. When the projected cost of each plane ballooned to $165 million, a Secretary of Defense named Dick Cheney killed it in 1991.

Royal Aircraft B.E.2

9.With its anemic engine, poor maneuverability and gunner blocking the pilot's view, the British B.E. 2 was doomed from the start. German pilots had no problem shooting them down during the First World War, making it just about useless as a fighter. It had no problems against German Zeppelins, though, so the plane lived out its days attacking them instead.

Boeing XB 15

10.The XB 15 was the largest plane ever built in the United States until the Spruce Goose came along. The heavy bomber was so massive it had passageways in the wings and bunks for the crew. But big planes need big engines and no one made one big enough to give the XB any kind of speed for its maiden flight in 1937. The plane maxed out at 200 mph, and the U.S. Army Air Corps killed the project. The only XB ever built saw duty as a cargo plane in the Caribbean during World War II.

Future Technology and Aircraft Types

2009-06-12T12:45:00.000-07:00

The following discussion is based on a presentation by Ilan Kroo entitled, Reinventing the

Airplane: New Concepts for Flight in the 21st Century.

When we think about what may appear in future aircraft designs, we might look at recent history. The look may be frightening. From first appearances, anyway, nothing has happened in the last 40 years!
There are many causes of this apparent stagnation. The first is the enormous economic risk involved. Along with the investment risk, there is a liability risk which is of especially great concern to U.S. manufacturers of small aircraft. One might also argue that the commercial aircraft manufacturers are not doing too badly, so why argue with success and do something new? These issues are discussed in the previous section on the origins of aircraft.Because of the development of new technologies or processes, or because new roles and missions appear for aircraft, we expect that aircraft will indeed change. Most new aircraft will change in evolutionary ways, but more revolutionary ideas are possible too.This section will discuss several aspects of future aircraft including the following:

1.Improving the modern airplane
2.New configurations
3.New roles and requirements

Improving the Modern Airplane
Breakthroughs in many fields have provided evolutionary improvements in performance. Although the aircraft configuration looks similar, reductions in cost by nearly a factor of 3 since the 707 have been achieved through improvements in aerodynamics, structures and materials, control systems, and (primarily) propulsion technology. Some of these areas are described in the following sections.

Active Controls

Active flight control can be used in many ways, ranging from the relatively simple angle of attack limiting found on airplanes such as the Boeing 727, to maneuver and gust load control investigated early with L-1011 aircraft, to more recent applications on the Airbus and 777 aircraft for stability augmentation.
Reduced structural loads permit larger spans for a given structural weight and thus a lower induced drag. As we will see, a 10% reduction in maneuver bending load can be translated into a 3% span increase without increasing wing weight. This produces about a 6% reduction in induced drag.Reduced stability requirements permit smaller tail surfaces or reduced trim loads which often provide both drag and weight reductions.
Such systems may also enable new configuration concepts, although even when applied to conventional designs, improvements in performance are achievable. In addition to performance advantages the use of these systems may be suggested for reasons of reliability, improved safety or ride quality, and reduced pilot workload, although some of the advantages are arguable.

New Airfoil Concepts
Airfoil design has improved dramatically in the past 40 years, from the transonic "peaky" sections used on aircraft in the 60's and 70's to the more aggressive supercritical sections used on today's aircraft.
Continuing progress in airfoil design is likely in the next few years, due in part to advances in viscous computational capabilities. One example of an emerging area in airfoil design is the constructive use of separation. The examples below show the divergent trailing edge section developed for the MD-11 and a cross-section of the Aerobie, a flying ring toy that uses this unusual section to enhance the ring's stability.
Flow Near Trailing Edge of DTE Airfoil and Aerobie Cross-Section

Flow Control
Subtle manipulation of aircraft aerodynamics, principally the wing and fuselage boundary layers, can be used to increase performance and provide control. From laminar flow control, which seeks to reduce drag by maintaining extensive runs of laminar flow, to vortex flow control (through blowing or small vortex generators), and more recent concepts using MEMS devices or synthetic jets, the concept of controlling aerodynamic flows by making small changes in the right way is a major area of aerodynamic research. Although some of the more unusual concepts (including active control of turbulence) are far from practical realization, vortex control and hybrid laminar flow control are more likely possibilities.

Structures
Structural materials and design concepts are evolving rapidly. Despite the conservative approach taken by commercial airlines, composite materials are finally finding their way into a larger fraction of the aircraft structure. At the moment composite materials are used in empennage primary structure on commercial transports and on the small ATR-72 outer wing boxes, but it is expected that in the next 10-20 years the airlines and the FAA will be more ready to adopt this technology.
New materials and processes are critical for high speed aircraft, UAV's, and military aircraft, but even for subsonic applications concepts such as stitched resin film infusion (RFI) are beginning to make cost-competitive composite applications more believable.

Propulsion
Propulsion is the area in which most evolutionary progress has been made in the last few decades and which will continue to improve the economics of aircraft. Very high efficiency, unbelievably large turbines are continuing to evolve, while low cost small turbine engines may well revolutionize small aircraft design in the next 20 years. Interest in very clean, low noise engines is growing for aircraft ranging from commuters and regional jets to supersonic transports.

Multidisciplinary Optimization
In addition to advances in disciplinary technologies, improved methods for integrating discipline-based design into a better system are being developed. The field of multidisciplinary optimization permits detailed analyses and design methods in several disciplines to be combined to best advantage for the system as a whole.
The figure here shows the problem with sequential optimization of a design in individual disciplines. If the aerodynamics group assumes a certain structural design and optimizes the design with respect to aerodynamic design variables (corresponding to horizontal motion in the conceptual plot shown on the right), then the structures group finds the best design (in the vertical degree of freedom), and this process is repeated, we arrive at a converged solution, but one that is not the best solution. Conventional trade studies in 1 or 2 or several parameters are fine, but when hundreds or thousands of design degrees of freedom are available, the use of more formal optimization methods are necessary.
Although a specific technology may provide a certain drag savings, the advantages may be amplified by exploiting these savings in a re-optimized design. The figure to the right shows how an aircraft was redesigned to incorporate active control technologies. While the reduced static margin provides small performance gains, the re-designed aircraft provides many times that advantage. Some typical estimates for fuel savings associated with "advanced" technologies are given below. Note that these are sometimes optimistic, and cannot be simply added together.

1.Active Control .............10%

2.Composites ..................20%

3.Laminar Flow ..............10%

4.Improved Wing ...........10%

5.Propulsion ...................20%

Total ..............................70%

New Configuration Concepts
Apart from evolutionary improvements in conventional aircraft, revolutionary changes are possible when the "rules" are changed. This is possible when the configuration concept iteself is changed and when new roles or requirements are introduced.
The following images give some idea of the range of concepts that have been studied over the past few years, some of which are currently being pursued by NASA and industry.

Blended Wing Body

The BWB design is intended to improve airplane efficiency through a major change in the airframe configuration. The thick centerbody accommodates passengers and cargo without the extra wetted area and weight of a fuselage. Orginally designed as a very large aircraft with as many as 800 passengers, versions of the BWB has been designed with as few as 250 passengers

and more conventional twin, podded engines.

Joined Wing

The joined wing design was developed principally by Dr. Julian Wolkovitch in the 1980's as an efficient structural arrangement in which the horizontal tail was used as a sturcural support for the main wing as well as a stabilizing surface. It is currently being considered for application to high altitiude long endurance UAVs.

Oblique Flying Wing

One of the most unusual concepts for passenger flight is the oblique wing, studied by Robert T. Jones at NASA from 1945 through the 1990s. Theoretical considerations suggest that the concept is well suited to low drag supersonic flight, while providing a structurally efficient means of achieving variable geometry.

New Roles and Requirements
In addition to new configuration ideas, new roles and requirements for aircrafrt may lead to new aircraft concepts. Some of these are summarized below.
Pacific Rim Travel
As global commerce continues to increase, the need for passenger and cargo transportation grows as well. Many have speculated that growth in pacific rim travel may be the impetus for high speed aircraft development. The figure above suggests how the time required for flight from Los Angeles to Tokyo varies with cruise Mach number. (The somewhat facetious Mach 8 aircraft requires extra time to cool off before passengers can deplane.)

Supersonic transportation (Boeing High Speed Civil Transport Concept)

Ground Effect Cargo Tranport Concept

Vehicles designed for missions other than carrying passengers include military aircraft with new constraints on radar detection (low observables), very high altitude aircraft, such as the Helios solar powered aircraft intended for atmospheric science and earth observation studies, and vehicles such as the Proteus, designed as a communications platform.

Low Observables (B2 Bomber)

Autonomous Air Vehicles (Pathfinder: a prototype for Helios solar UAV)

Halo Autonomous Air Vehicle for Communications Services (an AeroSat)

Finally a new class of air vehicles intended to provide lower cost access to space is under study. The near-term future of such designs depends on the economic health of the commercial space enterprise and it presently appears that these concepts are not likely to be seen soon.

Access to Space

Conclusions

1. Improved understanding and analysis capabilities permit continued improvement in aircraft designs
2. Exploiting new technologies can change the rules of thegame,permitting very different solution
3. New objectives and constraints may require unconventional configurations
4. Future progress requires unprecedented communication among aircraft designers, scientists, and computational specialists

Unusual aircraft (part 1)

2009-06-12T11:12:00.000-07:00

Airbus, Shell begin alternate fuel research

2009-06-12T05:14:00.000-07:00

Airbus, Shell begin alternate fuel research
By: Thierry Dubois

Airbus and Shell recently made the first ever commercial flight using liquid fuel processed from gas when an A380 airliner flew from Filton in the UK to the airframer’s Toulouse, France headquarters. The flight marked the start of a program to evaluate the environmental impact of alternative fuels in the airline market.One of the A380’s four Rolls-Royce Trent 900 engines was powered by a blend of Shell’s gas-to-liquid (GTL) fuel and standard jet-A. The other three engines burned jet-A. The aircraft’s segregated fuel tanks made it well suited for engine shutdown and relight tests.For Airbus, the three-hour flight was the first step in its efforts to evaluate viable and sustainable alternative fuels. It believes that GTL fuel–which promises less impact on air quality and more efficient fuel burn–could be available at certain locations to make it a practical alternative fuel for commercial aviation in the short term. The manufacturer believes that development of GTL will support future second generation bio-fuels, which are not presently available in sufficient commercial quantities. Airbus has committed itself to studying viable second generation bio-fuels when they become available.With global prices of petroleum on the rise, scientists are striving to bring second-generation biofuels from the research stage to full production. First-generation biofuels–which airlines together with aircraft and engine manufacturers are close to flight-testing–cut overall carbon dioxide emissions because their feedstock plants absorb CO2, but they still have major environmental drawbacks. First-generation fuels can be seen as wasteful in that they use only part of the plant (cereal grains or beetroot, for example).By contrast, second-generation biofuels are created using plants in their entirety, including straw, wood and so on. Also, the range of raw materials available to create second-generation fuels is larger and more types of plants can be used, as well as waste such as wood chips.The greater efficiency of second-generation biofuels is seen as an answer to at least one major concern. Green groups have been challenging the use of huge land surfaces to produce fuel rather than food, which has already raised the price of some basic food, such as corn. Using the entire plant is viewed as much better from the perspective of those who believe the primary role of agriculture as a food source for humans shouldn’t be compromised. Using vegetable waste is one way to solve the problem, but collecting waste–such as wood chips and straw– can be challenging. Forestry and farm waste is highly scattered, and building big plants to transform large quantities of waste would involve a lot of transportation to collect and consolidate it. Another alternative would have the biofuels process relying instead on small, local units. The first generation of biofuels also has raised concerns about biodiversity. “Is it reasonable to replace rain forest with sugar cane or cereal fields?” a senior executive at a major U.S. airline recently asked rhetorically. Environmental experts see retaining biodiversity–the living fabric that covers the earth–as urgent an issue as global warming. Second-generation biofuels, if made from waste, do not affect biodiversity, but the problem remains if they are made from purpose-grown plants.Three kinds of processes are under development. The first–biochemical–yields sugar and then ethanol but it is not well suited to aviation, according to Xavier Montagne, deputy scientific director of IFP, a French research institute on oil and energy. “Ethanol contains 33 percent less energy than today’s jet fuel,” Montagne, explained to AIN. Energy density is critical in aviation, where weight and volume are enemies of efficiency. In addition, ethanol’s flash point is too low. While jet fuel has a specification for 100 degrees F, the flash point for ethanol is just 59 to 64 degrees F.The second process, called biomass to liquid (BtL), is thermochemical. Biomass is first transformed into a synthetic gas, then the Fischer-Tropsch (F-T) process converts the gas into liquid hydrocarbons. The final product can be used to make a fuel that is very close to (and, in some respects, even better than) current jet fuel.“The first part of the process is the most challenging,” Montagne said. The second part, the F-T process, is well known now. However, further performance improvement is needed in F-T facilities, Montagne added.In terms of greenhouse emissions, second-generation biofuels would perform appreciably better than those further along in development. First-gen biofuels can save up to 70 percent of CO2 emissions over oil-based fuels (measured through the so-called well-to-wheel approach), but savings of 90 percent can be achieved with BtL, according to Montagne.Another second-gen biofuel is hydrotreated vegetable oil (HVO). For example, vegetable oil made from lipid algae, if hydrotreated, yields a fuel that is close to that obtained with BtL. Their main characteristics, including flash point, are consistent with aviation requirements. Their energy content is a bit lower than today’s jet-A fuel if measured per volume, but it is greater if measured per weight.Last June, engine maker CFM International said it was evaluating alternative fuels made using biomass. But some still speculate whether the benefits of the second-generation biofuels are enough. “Should we spend millions on biofuel research and production, while IATA has assigned the industry the challenge to be carbon-free in 2050?” asked the same skeptical U.S. airline executive

The World's First Flying Hotel

2009-06-11T14:32:00.000-07:00

"The Hotelicopter features 18 luxuriously-appointed rooms for adrenaline junkies seeking a truly unique and memorable travel experience. Each soundproofed room is equipped with a queen-sized bed, fine linens, a mini-bar, coffee machine, wireless internet access, and all the luxurious appointments you'd expect from a flying five star hotel. Room service is available one hour after liftoff and prior to landing." The Hotelicopter is due to fly maiden journey this summer(June 26th) with an undisclosed price....If you have interesting? There is three fly tour.

Dimensions Length: 42 m (137 ft)

Height: 28m (91 ft)

Maximum Takeoff Weight: 105850 kg (232,870 lb)

Maximum speed: 255 km/h (137 kt) (158 miles/h)

Cruising speed: 237 km/h (127 kt) (147 miles/h)

Original Mi Range: 515 km (320 mi)

Our augmented Mi Range - 1,296 km (700 mi)

2009-06-10T12:41:00.000-07:00

Good News: 747 Supertanker Ready to Be Deployed

A tip from an anonymous commenter points us to this announcement from Evergreen Aviation."EVERGREEN SUPERTANKER READY TO FIGHT WILDFIRES The B747 Supertanker is certified to fly by Interagency Air Tanker BoardMcMinnville, Ore.—Evergreen International Aviation’s B747 Supertanker won certification for operation this season after receiving its interim approval letter from the Interagency Air Tanker Board. The aircraft also received its Supplemental Type Certificate from the Federal Aviation Administration (FAA) in November 2008. It is now available to assist world firefighting agencies during the 2009 season and beyond. The award is unique because the Supertanker has an 8:1 drop ratio compared to that of all other current firefighting aircraft, meaning the Supertanker will forever change the way wildland fires are fought. The plane is the first of a fleet designed to accommodate the needs of U.S. and International private and public agencies.The Supertanker showed impressive results during the U.S. Forest Service administered grid tests. From high, medium and low coverage levels, the Supertanker showed it provides quality, consistent retardant line construction. The cutting-edge aircraft proved it belongs on the front line, from the onset, to fight wildfire day and night. The uniformed pattern of the Supertanker drops, and its ability, in a single flight, for split loads at multiple coverage levels, gives agencies an incredibly versatile firefighting tool.The multi-role B747 Supertanker is the largest tanker aircraft available today. With a payload of more than 20,000 gallons and a response time of 600 mph, it has more than eight times the drop capability and twice the speed of any other federal air tanker currently fighting fires. The Supertanker’s patented pressurized system has the capability to disperse product at high pressure for an overwhelming response, or disperse at the speed of falling rain in a single or several segmented drops. This pressurized system will also allow for drops at higher altitudes, creating a significant safety buffer and enabling the Supertanker to fight fires during the day and at night, when they are most vulnerable. It also offers a significant value for saving homes, natural resources, and most importantly, lives. When employed properly, the Supertanker has the capability to save the governments billions of dollars in fire suppression, natural resource losses, tourism, and rehabilitation costs every year.Evergreen International Aviation, which has more than 70 years of firefighting experience and more than one million hours of large aircraft operating experience, has invested five years and $50 million of its own funding to develop this next generation of firefighting aircraft.The Supertanker program will continue to grow and advance its capabilities. On the firefighting front, operations of the Supertanker will expand to Western Europe, Australia and Brazil. The aircraft will be available to provide service to international governments, as well as private industry. The next endeavor is to prove the vehicle as a solution for oil spills, decontamination of biological/chemical poisoning and radiation knock down. With this diverse range of qualifications, the Supertanker will go on protecting valuable resources for generations to come.

Narrowest escape in VTOL fighter

2009-06-10T11:11:00.000-07:00

The US Navy pilot of this VTOL fighter kept his cool amazingly when his thrust vectoring
nozzle fired uncommanded. He worked his way out of the almost fatal situation - with
some good luck of course...

Aero Medical Facts (part 3of 3)

2009-06-09T14:14:00.000-07:00

Spatial Disorientation:
Various complex motions and forces and certain visual scenes encountered in flight can create illusions of motion and position. Spatial disorientation from these illusions can be prevented only by visual reference to reliable, fixed points on the ground or to flight instruments. Spatial disorientation is mainly associated with flight in instrument conditions, but they can happen in visual flying
ILLUSIONS IN FLIGHT
Runway Width Illusion:
A narrower-than-usual runway can create the illusion that the aircraft is at a higher altitude than it actually is. If you don't recognize this illusion, you may have a tendency to fly a low approach, risking a short landing. A wider-than-usual runway can have the opposite effect, with the risk of leveling out high or overshooting the runway. What is usual? Usual is what you are used to, so when you make your first landing at a new airfield, think about this illusion and deal with it.
Runway and Terrain Slopes:
IllusionAn up sloping runway, up sloping terrain, or both can create the illusion that the aircraft is at a higher altitude than it actually is. A low approach can result if the pilot allows this illusion to convince him/her that the aircraft is high. A down-sloping runway will have the opposite effect causing the pilot to flare or round out too high.
Featureless Terrain Illusion:
A pilot landing in a featureless area such as a dry lake bed or desert, will tend to fly a lower than normal approach, thinking he/she is to high.
Atmospheric Illusions:
Rain on the canopy will give the illusion of greater height. Haze will give the illusion of being a greater distance from the runway.
VISION IN FLIGHT

Excessive Illumination:
Light from the low sun levels, reflecting off the canopy or other surfaces can create a hazard when it obstructs other aircraft from you view. This is the perfect excuse to convince your significant other that a new pair of good sunglasses are needed. Sunglasses for protection from glare should absorb at least 85 percent of visible light (15 percent transmittance) and all colors equally (neutral transmittance), with negligible image distortion from refractive and prismatic errors. In other words, you need the good ones.
Scanning for Other Aircraft:
Scanning is the key factor in collision avoidance. In order to scan, your eyes have to be looking out of the cockpit. We have more and more sophisticated equipment in our aircraft and each piece of electronic wizardry demands a certain amount of attention. It doesn't make a bit of difference if you are perfectly on course when you're on a collision course with a twin engine airplane.While the eyes can observe an approximate 200 degree arc of the horizon at one glance, only a very small center area called the fovea, in the rear of the eye, has the ability to send a clear image to the brain. The rest of the area will be of less detail, in fact, an aircraft at a distance of 7 miles which appears in sharp focus within the center of vision would have to be as close as 7/10 of a mile in order to be recognized. Because of this physical limitation, one must scan a series of regularly spaced horizontal movements that bring successive areas of the sky into the central visual field. Break the scanning area up into 10-degree segments and stop and observe a few seconds at each area. When you stop to observe the area, look out and then back toward the aircraft. A successful scanning pattern is a very personal thing, and with practice, it will become a positive habit that will keep you safe as well as increase your flying enjoyment.
Empty-feild Myopia is a condition that occurs when flying on hazy days. The haze provides nothing specific to focus on and this causes the eye to focus 10 to 30 feet in front of your aircraft. So while you are looking, you are not seeing. An effective scan will help you avoid Empty-field Myopia. Look out in front of the aircraft and focus on something on the ground, then raise your eyes up to and above the horizon. This will force your eyes to focus beyond the 10-to-30 foot distance.
JUDGMENT ASPECTS OF COLLISION AVOIDANCE

Determining Relative Altitude:
Use the horizon as a reference point. If an approaching aircraft is above the horizon it is probably above you, if it is below the horizon it should be below you.Taking Appropriate ActionBe familiar with the rules on right of way.
Collision Course Targets:
Any aircraft that appears to have no relative motion and stays in one scan quadrant is likely to be on a collision course. If the target shows no lateral or vertical motion, but increases in size, take immediate evasive action.
Recognize High Hazard:
AreasAirways, especially near navigation radio stations like a Very High Frequency Omnirange Station (VOR), and instrument approach courses at airports are areas to avoid. Knowing the locations of instrument approach courses at your local flying field and avoiding them is a must. Having a radio to monitor the common traffic advisory frequency (CTAF) is a must for aircraft operations and especially on an airport with different types of traffic. Take time to talk with the locals when first flying at a new field. Get the lay of the land and any particular traffic procedures for that field.

Canopy Conditions:
Keep it clean. This is often overlooked; however, a dirty canopy or wind screen can greatly reduce a pilot's ability to avoid other aircraft.
Visibility Conditions:
Be aware that smoke, haze, dust, rain and flying into the sun can greatly reduce your ability to avoid other aircraft.
Visual Obstructions in the Cockpit:
Become aware of blind spots in different aircraft. Always move your head and look around potential blind spots. You may even need to drop or raise a wing or maneuver the aircraft to clear your flight path.

Aero Medical Facts (part 2of 3)

2009-06-09T14:10:00.000-07:00

Smoking and Carbon Monoxide:
Hemoglobin in red blood cells transports oxygen to body tissue. Anything that adheres to hemoglobin takes up space on the cell and limits the amount of oxygen that gets to body tissue. Smoking deposits carbon monoxide on the hemoglobin and literally takes up space that should be carrying oxygen. If you smoke, realize your susceptibility to Hypoxia is heightened. A leaky exhaust system can certainly raise carbon monoxide levels in the cockpit to dangerous levels.
Ear Block:
As the glider cockpit pressure decreases during ascent, the expanding air in the middle ear pushes the Eustachian tube open, allowing the air to escape down the nasal passages, equalizing the middle ear chamber pressure with the outside pressure. However, on descent the pilot must periodically open the Eustachian tube to equalize pressure. This can be done by swallowing, yawning, tensing muscles in the throat or by doing the Valsalva Maneuver. The Valsalva Maneuver is done by closing your month, pinching your nose shut and attempting to blow through your nostrils. An ear block can produce severe pain and loss of hearing that can last for several hours. If an ear block does not clear shortly after landing, a physician should be consulted.
Sinus Block:
A sinus block can produce the same excruciating pain as an ear block. Again, don't fly with a cold, sinusitis, or a nasal allergic condition.
Decompression Sickness After Scuba Diving:
Pilots should allow their body to rid itself of excess nitrogen absorbed during diving. The recommended waiting time before going to flight altitudes of up to 8,000 feet is at least 12 hours after diving which has not required controlled ascent, and at least 24 hours after diving which has required controlled ascent. The waiting time for flights above 8,000 feet is 24 hours. Flying too soon after scuba diving could allow nitrogen gas bubbles to form around joints and muscles causing severe pain.
Hyperventilation in Flight:
It is an abnormal increase in the volume of air breathed in and out of the lungs. This can occur during a stressful situation. During hyperventilation, the pilot blows off excessive carbon dioxide from his body. This can cause lightheadedness, suffocation, drowsiness, and tingling in the extremities. Incapacitation can result from disorientation and painful muscle spasms. A pilot can stop hyperventilation by breathing into a paper bag or simply recognizing the symptoms and making a conscious effort to slow down his/her breathing. Do you carry a paper bag, I don't. But singing works well also. Singing forces you to breath normally. It might not be audibly pleasant for your passengers, but you passing out might make them a little more uncomfortable.

Engine Malfunctions

2009-06-09T13:53:00.000-07:00

http://www.youtube.com/watch?v=E4DLzL0lBW0

Contributed by FO Faruqui

Aero Medical Facts (part 1 of 3)

2009-06-09T01:25:00.000-07:00

Medications:

Pilot performance can be seriously degraded by both prescribed and over-the-counter medications, as well as the medical conditions for which they are taken. Many medications such as tranquilizers, sedatives, strong pain relievers, cough suppressant preparations, antihistamines, blood pressure drugs, muscle relaxants, agents to control diarrhea and motion sickness have side effects that may impair judgment, memory alertness, coordination, vision, and the ability to make calculations. Medications to especially watch are antihistamines. Many over-the-counter cold formulas and inhalers have antihistamines. A stuffy nose might just be a reason not to fly.

Alcohol:

As little as 1 ounce of liquor, 1 bottle of beer, or 4 ounces of wine can impair flying skills, alcohol consumed in these small amounts is detectable on the breath and in the blood for 3 hours. Don't discount the hangover. Flying under the influence or with the effects of alcohol is stupid as well as illegal. Since a pilot may be under the influence 8 hours after drinking moderate amounts of alcohol, a good rule of thumb is "12 hours between the bottle and the throttle." This is obviously only a rule of thumb, heavy drinking might call for a 24-hour rest prior to flying. You have to be the judge.FatigueThe Aeronautical Manual (AIM) describes fatigue as either acute (short term) or chronic (long term). Acute fatigue occurs daily due to strenuous muscular effort, mental strain, etc. Adequate rest along with proper diet and exercise is the best prevention. Chronic fatigue occurs when one does not fully recover from acute fatigue. With chronic fatigue, judgment becomes impaired and recovery requires prolonged rest. Fatigue is an insidious killer. One may become fatigued slowly over a period of time and not be aware of his/her condition If you think you are fatigued and if possible fly another day because fatigue can impair you decision making to a great extent.

Stress:

Stress from everyday life can have a devastating effect on pilot performance. The fact is it's a rare person that can leave their difficulties on the ground. Stress like fatigue is insidious and when both are present, you are in an extremely dangerous situation.

Emotion:

Severe emotionally upsetting events including family troubles, death of a family member, loss of a job, or financial troubles can affect your ability to fly safely. Give yourself some healing time before your next flight

EFFECTS OF ALTITUDE

Hypoxia:

Hypoxia is a state of oxygen deficiency in the body sufficient to impair functions of the brain and other organs. When you increase altitude, the level of oxygen remains the same as ground level; however, the pressure needed to get the oxygen into your lungs just isn't there. Therefore, at altitudes above 5,000 feet your night vision is impaired and above 12,000 feet of altitude you may start suffering the effects of hypoxia. Hypoxia causes problems with judgment, memory, alertness, coordination, and the ability to make calculations. Physical effects you might notice are headache, drowsiness, dizziness and most serious of all, a profound sense of well being or perhaps belligerence. As altitude is increased the period of time before the onset of symptoms is shortened.
5,000 feet

Night vision impairment.

12,000 to 15,000 feet

Hypoxic symptoms begin.

15,000feetandabove

Serious performance deteriorate within 15 min.Periphery

vision narrows causing a tunnel vision effect.Fingernails and lips turn blue

18,000 feet

Twenty to 30 minutes of useful consciousness. After that

pilot will be unable to take corrective action

20,000 feet

The pilot has 5 to 12 minutes until he/she is

totally unconsciousness

To prevent hypoxia above 10,000 feet during the day and 5,000 feet at night, pilots are encouraged to use supplemental oxygen.According to Federal Aviation Regulations (FARs) require that the flight crew use supplemental oxygen after 30 minutes of exposure to pressure altitudes between 12,500 and 14,000 feet. Above 15,000 feet, crew and passengers have to use supplemental oxygen.

Useful Information about Hypoxia

2009-06-08T13:51:00.000-07:00

How the Human Body Uses Oxygen

Let's start our discussion of the effects of altitude on our bodies by first discussing how the body normally acquires, transports and uses oxygen. The importance of all those gas laws should become clearer. We're all aware that oxygen is necessary to sustain combustion or oxidation. It is necessary in the human body for the same reasons -- to support the oxidation of fuels needed to provide energy for life.

Very little of the oxygen carried by the blood is carried in dissolved form in the plasma. Most of the oxygen -- almost 98% -- is transported by the hemoglobin molecules in the red blood cells. The ability of hemoglobin to combine with and transport oxygen is dependent upon the pressure of oxygen in the surrounding environment. Higher pressures of oxygen enable the hemoglobin to take up larger quantities of oxygen. Lower oxygen pressures will result in an increasing tendency by the hemoglobin to give up oxygen. This variable combining characteristic is what allows the blood to acquire oxygen in the lungs and transport it to the tissues where it is used in metabolism. This characteristic of the hemoglobin also results in what is known as the oxygen dissociation curve (see graph below). While we've seen that oxygen pressure decreases a bit less than linearly with altitude, the ability of the hemoglobin to hold oxygen follows a much different curve. There is a big change for the worse in the hemoglobin's ability to combine with oxygen that occurs in the low twenties.

Air entering the lungs at sea level enters at a pressure of 760 mm Hg. This results in a partial pressure of oxygen in sea level air of about 160 mm Hg. (that's about 21% of 760 mm). The blood flowing through the lungs isn't exposed to atmospheric air though. Blood comes in contact with alveolar air -- the air mixture contained in the tiny air sacks of the lungs -- which is only 14% oxygen. (This is because of the addition of water vapor to the air you breath in plus the carbon dioxide that has diffused from the blood returning from the tissues.) The partial pressure of oxygen in alveolar air is about 14% of 760 mm Hg or 106.4 mm Hg. Carbon dioxide, which is 5.5% of alveolar air (as contrasted to less than 1% in the atmosphere) exerts a pressure of 41.8 mm Hg.

The hemoglobin in the blood returning from the tissues carries oxygen at a pressure of about 40 mm Hg. Graham's Law governs the diffusion of oxygen from the higher pressure of the alveolar air to the blood and the diffusion of carbon dioxide from the blood to the alveolar sacks. The opposite transfer takes place when the oxygen rich blood reaches the tissues which carry oxygen at an average pressure of 20 mm Hg. This lower pressure will allow the hemoglobin to release oxygen which will then diffuse into the tissues. At the same time, carbon dioxide is diffusing from the tissues into the blood. (An average pressure for CO in the tissues is 50 mm Hg.; however, this is dependent upon the activity level of the tissue.) Getting hypoxic yet from all this high altitude discussion??

In a normal, healthy individual, sea level pressure is sufficient to cause the blood leaving the lungs to be almost totally (97%) saturated with oxygen. At 10,000 feet the saturation has dropped to almost 90% -- still sufficient for nearly all usual life functions. An oxygen saturation of 93% is considered by medical folks to be the low limit of normal functioning. On top of Pike's Peak (about 14,500 feet and 438 mm Hg atmospheric pressure) the oxygen saturation has dropped to about 80%. Many people, if left in this rarefied air for some period, will develop mountain or altitude sickness: vertigo, nausea, weakness, hyperpnea (increased breathing), incoordination, slowed thinking, dimmed vision and increased heart rate. At 25,000 feet the oxygen saturation is only 55% and consciousness is lost. (Note that the partial pressure of oxygen in alveolar air at 25,000 feet is 14% of 281.8 mm Hg or 39.5 mm Hg -- slightly less than that normally found in venous blood returning from the tissues. Which way do you think the oxygen will diffuse at altitudes above 25,000 feet?)

Nowadays, altitude-savvy pilots are starting to carry a tiny instrument called a pulse oximeter that clips on the finger and, by passing a light beam through the vascular bed of the fingertip, measures the oxygen saturation of the blood and displays it on a digital readout. Think of it as a "hypoxia meter" that allows you to see precisely how hypoxic you are at any given time.

Types of Hypoxia
The effects of hypoxia upon flying skills and the symptoms of its onset are the same no matter what the cause of the hypoxia. It is useful, however, to look at some varying causes of this condition so we can be alert to its possible onset when of one or more of these factors is present.

Hypoxic hypoxia: is also referred to by aviators as "altitude hypoxia." This is the hypoxia that results when there is a lack of available oxygen or partial pressure of oxygen in the breathing air. This is the type hypoxia experienced when flying in an unpressurized cabin or when flying at altitude in a jet with a cabin pressurized to a cabin altitude above 5000 feet. Although strictly speaking, we are somewhat hypoxic when operating even a few hundred feet above the altitude of acclimatization, this becomes most evident when flying unpressurized aircraft. In reality, the symptoms of hypoxic hypoxia do not, in the absence of other contributing factors, become significant until about 5000 feet.

Hypoxic hypoxia occurs because there is a smaller and smaller pressure differential between the pressure of oxygen in the inspired air in the lungs and the pressure of the oxygen in the blood and tissues. Remember that the combining power of hemoglobin and oxygen is influenced by this pressure differential. The greater the differential, the more efficient the hemoglobin becomes. As this pressure differential lessens, it becomes harder and harder for the hemoglobin to pick up and transport the oxygen.

Hypemic hypoxia: (also called anemic hypoxia) occurs whenever the blood's ability to carry oxygen is reduced although there is sufficient oxygen at a sufficient pressure in the inspired air. There are a variety of conditions that can cause this to happen.
Any condition that would cause a reduction in the number of healthy, functioning red blood cells (anemia or reduced production of red blood cells, blood loss, deformed blood cells, disease, etc.) will impair the blood's ability to supply the tissues with oxygen. Remember the old advertisements warning about "iron poor blood?" Iron is the functional part of the hemoglobin molecule and it is the iron which renders the hemoglobin absolutely indispensable for life. In addition to a reduction in the number of red blood cells available, anything that would interfere with the ability of hemoglobin to transport oxygen or anything that would displace the oxygen that is bound to the hemoglobin will affect the oxygen available to the cells.
The most common impairment to oxygen transport by the hemoglobin is carbon monoxide. Carbon monoxide combines with hemoglobin 200-300 times more readily than does oxygen and once bound is extremely hard to eliminate. Smokers will find that the carbon monoxide bound to their hemoglobin will lower their altitude for onset of hypoxic symptoms by 2000-3000 feet. This effect is not limited to smokers, however. Anyone exposed to a smoky atmosphere will suffer somewhat. (Remember this next time you volunteer to go along as a designated driver for a group of drinkers. Just sitting in that smoky bar for several hours is going to affect your performance the next day, even without alcohol and fatigue!) Other chemicals, among them sulfa drugs and nitrites (found in food preservatives) can have an adverse effect on the ability of hemoglobin to combine with and transport oxygen.

Histotoxic hypoxia: is a disruption of cellular respiration. There may well be sufficient oxygen of sufficient pressure in the inspired air to fully saturate the blood and hemoglobin, but the cells expecting and needing the oxygen are unable to use it due to the presence or absorption of cell toxins. The most common toxin found at the cellular level that can cause this effect is alcohol. Although other toxins, notably cyanide and some narcotics, also can cause this disruption of cellular respiration, alcohol is by far the most common culprit.
Now, we are all aware of the hazards associated with alcohol and flying and I'm not suggesting that any true professional would knowingly violate these rules and guidelines. Many pilots, however, may be impaired by alcohol at the cellular level and not be aware of the problem -- or its cause. Remember the iron poor blood mentioned earlier? Be cautious of the "tonics" or "elixirs" offered as remedies. Carefully read the labels on any over-the-counter medications or nutritional supplements you propose to ingest. Although many more manufacturers are eliminating or reducing the alcohol content of the liquid medications, you may be surprised at the percentage of alcohol some still contain. One popular vitamin supplement for "iron poor blood" contains 12% alcohol!

Development of a Jet engine

2009-06-08T05:13:00.000-07:00

Jet engines

A simplified view of how a jet engine works.

Before World War II, in 1939, jet engines existed only as laboratory items for test. But at the end of the war, in 1945, it was clear that the future of aviation lay with jets. The new engines gave great power and thrust, but were compact in size. They also were simple in their overall layout.
A jet engine, down to the present day, pulls in air by using a compressor. It looks like a short length of an ear of corn, but instead of corn kernels, the compressor is studded with numerous small blades. The compressor rotates rapidly, compressing the air.
The compressed air flows into a combustor. Here fuel is injected, mixed with this air, and burned. This heats the air to a high temperature. The hot, high-pressure air then passes through a turbine, forcing it to spin rapidly. The turbine draws power from this hot airflow. A long shaft connects the turbine and compressor; the spinning turbine uses its power to turn the compressor.
The jet-engine principle was known early in the twentieth century. However, jet engines work well only at speeds of at least several hundred miles per hour. Racing planes were the first to reach such speeds, with a British seaplane setting a record of 407 miles per hour (655 kilometres per hour) in 1931 and an Italian aircraft raising this record to 440 miles per hour (708 kilometres per hour) in 1934.
A young German physicist, Hans von Ohain, was in the forefront. He started by working on his own at Gottingen University. He then went to work for Ernst Heinkel, a plane builder who had a strong interest in advanced engines. Together they crafted the world's first jet plane, the experimental Heinkel He 178, which first flew on August 27, 1939.

The Jumo 004 jet engine of World War II. Its main features carried over to later engines.
Building on this work, the German engine designer Anselm Franz developed an engine suitable for use in a jet fighter. This airplane, the Me 262, was built by the firm of Messerschmitt. It was the only jet fighter to fly in combat during World War II. But the Me 262 spent most of its time on the ground because it used too much fuel. It was a sitting duck for Allied attacks.
Two Jumo 004 engines powered the Me 262. This was the first jet fighter to fly in combat and probably broke the sound barrier first. Because the Germans had not secured a source of chromium, the blades would stretch after a few hours making engine life very short indeed.
In England, Frank Whittle had no knowledge of Ohain's ideas but invented a jet engine completely on his own. The British drew on his work and developed a successful engine for another early jet fighter—the Gloster Meteor. Britain used it for homeland defence but it did not see combat over Germany because it lacked high speed. The W.1 turbojet engine used to power the Gloster E28/39 aircraft. It was designed to produce a static thrust of 1,240 lbs at 17,750 rpm. This engine was also the basis of the design of the General Electric I-14 turbojet engine used to power the Bell XP-59A twin engine experimental fighter.

The British shared Whittle's technology with the United States, enabling the engine-builder General Electric (GE) to build jet engines for America's first jet fighter, the Bell XP-59. The aircraft company Lockheed then used a British engine in the initial version of its Lockheed P-80, America's first operational jet fighter, which entered service soon after the war's end. The British continued to develop new jet engines that used Whittle's designs, with Rolls-Royce initiating work on the Nene engine during 1944. Rolls sold Nenes to the Soviets, and a Soviet-built version of the engine subsequently powered the MiG-15 jet fighter that fought U.S. fighters and bombers during the Korean War.
The surrender of Germany, in 1945, unlocked a treasure trove of wartime discoveries and inventions. General Electric and Pratt & Whitney, another American engine-builder, added German lessons to those of Whittle and other British designers. Early jet engines, such as those of the Me 262, gulped fuel rapidly. Thus, an initial challenge involved building an engine that could give high thrust with less fuel consumption.

The J-31 (also known by its company designation, I-16) was the first turbojet engine produced in quantity in the United States. It was developed from the original American-built jet engine, the General Electric I-A, which was a copy of the highly secret British "Whittle" engine.
Pratt & Whitney solved this problem in 1948 with its "dual spool" concept. This combined two engines into one. The engine had two compressors—each rotated independently, with the inner one giving high compression for good performance. Each compressor drew power from its own turbine; hence there were two turbines, one behind the other. This approach led to the J-57 engine, which entered service with the U.S. Air Force in 1953.

The turboprop used power from a jet engine to drive a propeller. Additional turbines, placed near the exhaust, tapped this power and spun rapidly. An attached shaft delivered this power to a gearbox. Turboprops drew attention between 1945 and 1960 but lost out because jet aircraft were faster.
This was one of the outstanding post-war engines. It powered U.S. Air Force fighters, including the F-100, the first to break the sound barrier without going into a dive. Eight such engines powered the B-52 bomber. Commercial airliners—the Boeing 707, the Douglas DC-8—flew with it. This engine also saw use in the U-2 spy plane, which flew over the Soviet Union and photographed its military secrets.
Twin-spool jet engine (top) compared with a conventional design (below). Note that the twin-spool version has two compressors, each driven by its own turbine. This arrangement gave more thrust with better fuel economy.
The dual-spool engine represented an important step forward, but engine designers soon wanted more. As they reached for increasing performance, they ran into the problem of "compressor stall." This meant that at certain speeds while in flight, the compressor would pull in more air than the rest of the engine could swallow. Compressor stall produced a sudden blast of air that rushed forward within the engine. The engine lost all its thrust, while this air blast sometimes caused severe damage by breaking off compressor blades.
During the early 1950s, Pratt & Whitney rode merrily along with its J-57. Its competitor, GE, had a good engine of its own: the J-47, which powered the F-86 fighter and B-47 bomber. Still, GE's managers wanted something better. They got it from the engineer Gerhard Neumann, who found a way to eliminate compressor stall. Neumann introduced the "variable stator." This was a set of small vanes that protruded into the airflow within the compressor. Each such vane was like your hand that you stick into the outside air when you ride in a car. Like your hand, each vane could turn as if mounted to a wrist. When the vanes faced the airflow with their edges forward, they allowed the flow to pass them freely. But when the vanes were turned to present their broad faces to the flow, they partially blocked it. These vanes then reduced the amount of flow that was passing through the compressor, and kept it from gulping too much air.

Jet fighters gained speed by burning fuel within an afterburner. This was a tube fitted to the end of the jet engine. Exhaust from that engine contained a great deal of hot air and allowed fuel to burn within the afterburner, for more thrust.
This invention led to an important GE engine, the J-79. It became the first true engine for supersonic flight. With it, the Lockheed F-104 fighter flew at twice the speed of sound. In May 1958, U.S. Air Force pilots used this airplane to set a world speed record of 1,404 miles per hour (2,260 kilometres per hour) and an altitude record of 91,249 feet (27,813 meters). With supersonic flight in hand, the next frontier in jet-engine progress called for engines of very great power, suitable for aircraft of the largest possible size. The key concept proved to be the "turbofan," also called the "fanjet."

General layout of a turbofan engine. Note that a separate set of turbines drives the front fan, as in a turboprop. The term "high-bypass" means that most of the air in the exhaust comes from the fan and flows past the rest of the engine, rather than flowing through it.
The "jet" of a jet engine is the hot stream of exhaust that blasts out the back to produce thrust. However, that exhaust carries power as well as thrust, which the turbines use to run the compressor. By using a larger set of turbines, it is possible to tap off still more of this power. The big turbine then turns a fan, which somewhat resembles an airplane propeller but has many long blades set closely together. The fan adds its thrust to that of the jet. This arrangement yielded the turbofan. It more than doubled the thrust of earlier engines. It also further improved fuel economy. In addition, turbofan engines were relatively quiet, in contrast to earlier jets that produced loud shrieks and screams. GE and Pratt & Whitney both built turbofans after 1965, with Rolls-Royce, offering versions of its own. All truly large airliners have used them, starting with the Boeing 747. These engines have also powered large U.S. Air Force cargo planes, including the C-5A and C-17.
The first aircraft to use these large engines was the Lockheed C-5, which entered development in 1965 and first flew in 1968. A key to its design was the engine—the GE TF-39 turbofan. It had a dual-spool layout as well as a variable stator, with its big fan providing 85 percent of the thrust. The dual-spool arrangement gave the fan its own turbine for power, separate from the rest of the engine. The compressor had 16 stages, or rows of blades.
These three design principles—dual-spool layout, variable stators, and the turbofan—remain in use to this day. All three can even appear in the same engine, as with the TF-39. The dual-spool design gives high thrust with good fuel economy. Variable stators allow efficient operation at all flight speeds. The big forward fan reduces noise, further improves fuel economy, and produces much of the thrust. In turn, the thrust of engines continues to increase. Germany's engine for the wartime Me 262, the Jumo 004, delivered 2,000 pounds (8,900 Newtons) of thrust. The J-57 was rated at 13,500 pounds (60,000 Newtons) of thrust. The J-57 was similar in thrust but weighed considerably less, which made it much speedier. Early turbofans, around 1970, came in around 40,000 pounds (180,000 Newtons) of thrust. But GE's new GE 90 turbofan is rated at close to 90,000 pounds (400,000 Newtons) of thrust! That is why today's planes fly fast and are very large.

In the early 1990s, GE developed the GE90 turbofan engine to power the large, twin-engine Boeing 777. The GE90 family, with the baseline engine certified on the 777 in 1995, has produced a world's record thrust of 110,300 pounds in ground testing, has the world's largest fan at 123 inches in diameter, composite fan blades, and the highest engine bypass ratio (9:1) to produce the greatest propulsive efficiency of any commercial transport engine.
In this engine, air is sucked in from the right by the compressor. The compressor is basically a cone-shaped cylinder with small fan blades attached in rows (eight rows of blades are represented here). Assuming the light blue represents air at normal air pressure, then as the air is forced through the compression stage its pressure rises significantly. In some engines, the pressure of the air can rise by a factor of 30. The high-pressure air produced by the compressor is shown in dark blue.

Development of piston engine

2009-06-08T00:13:00.000-07:00

Piston Engine development

Picture a tube or cylinder that holds a snugly fitting plug. The plug is free to move back and forth within this tube, pushed by pressure from hot gases. A rod is mounted to the moving plug; it connects to a crankshaft, causing this shaft to rotate rapidly. A propeller sits at the end of this shaft, spinning within the air. Here, in outline, is the piston engine, which powered all airplanes until the advent of jet engines.
Pistons in cylinders first saw use in steam engines. Scotland's James Watt crafted the first good ones during the 1770s. A century later, the German inventors Nicolaus Otto and Gottlieb Daimler introduced gasoline as the fuel, burned directly within the cylinders. Such motors powered the earliest automobiles. They were lighter and more mobile than steam engines, more reliable, and easier to start.
Some single-piston gasoline engines entered service, but for use with airplanes, most such engines had a number of pistons, each shuttling back and forth within its own cylinder. Each piston also had a connecting rod, which pushed on a crank that was part of a crankshaft. This crankshaft drove the propeller.
Cutaway view of a piston engine built by Germany's Gottlieb Daimler. Though dating to the 19th century, the main features of this motor appear in modern engines.
Engines built for airplanes had to produce plenty of power while remaining light in weight. The first American planebuilders—Wilbur and Orville Wright, Glenn Curtiss—used motors that resembled those of automobiles. They were heavy and complex because they used water-filled plumbing to stay cool.
A French engine of 1908, the "Gnome," introduced air cooling as a way to eliminate the plumbing and lighten the weight. It was known as a rotary engine. The Wright and Curtiss motors had been mounted firmly in supports, with the shaft and propeller spinning. Rotary engines reversed that, with the shaft being held tightly—and the engine spinning! The propeller was mounted to the rotating engine, which stayed cool by having its cylinders whirl within the open air.

Numerous types of Gnome engines were designed and built, one of the most famous being the 165-hp 9-N "Monosoupape" (one valve). It was used during WWI primarily in the Nieuport 28. The engine had one valve per cylinder. Having no intake valves, its fuel mixture entered the cylinders through circular holes or "ports" cut in the cylinder walls. The propeller was bolted firmly to the engine and it, along with the cylinders, turned as a single unit around a stationary crankshaft rigidly mounted to the fuselage of the airplane. The rotary engine used castor oil for lubrication.
During World War I, rotaries attained tremendous popularity. They were less complex and easier to make than the water-cooled type. They powered such outstanding fighter planes as German's Fokker DR-1 and Britain's Sopwith Camel. They used castor oil for lubrication because it did not dissolve in gasoline. However, they tended to spray this oil all over, making a smelly mess. Worse, they were limited in power. The best of them reached 260 to 280 horsepower (190 to 210 kilowatts).

America's greatest technological contribution during WWI was the Liberty 12-cylinder water-cooled engine. Rated at 410 hp. , it weighed only two pounds per horsepower, far surpassing similar types of engines mass-produced by England, France, Italy, and Germany at that time.
Thus, in 1917 a group of American engine builders returned to water cooling as they sought a 400-horsepower (300-kilowatt) engine. The engine that resulted, the Liberty, was the most powerful aircraft engine of its day, with the U.S. auto industry building more than 20,000 of them. Water-cooled engines built in Europe also outperformed the air-cooled rotaries, and lasted longer. With the war continuing until late in 1918, the rotaries lost favor.
In this fashion, designers returned to water-cooled motors that again were fixed in position. They stayed cool by having water or antifreeze flow in channels through the engine to carry away the heat. A radiator cooled the heated water. In addition to offering plenty of power, such motors could be completely enclosed within a streamlined housing, to reduce drag and thus produce higher speeds in flight. Rolls Royce, Great Britain's leading engine-builder, built only water-cooled motors.
Air-cooled rotaries were largely out of the picture after 1920. Even so, air-cooled engines offered tempting advantages. They dispensed with radiators that leaked, hoses that burst, cooling jackets that corroded, and water pumps that failed.
Thus, the air-cooled "radial engine" emerged. This type of air-cooled engine arranged its cylinders to extend radially outward from its hub, like spokes of a wheel. The U.S. Navy became an early supporter of radials, which offered reliability along with light weight. This was an important feature if planes were to take off successfully from an aircraft carrier's flight deck.
With financial support from the Navy, two American firms, Wright Aeronautical and Pratt & Whitney, began building air-cooled radials. The Wright Whirlwind, in 1924, delivered 220 horsepower (164 kilowatts). A year later, the Pratt & Whitney Wasp was tested at 410 horsepower (306 kilowatts).
Aircraft designers wanted to build planes that could fly at high altitudes. High-flying planes could swoop down on their enemies and also were harder to shoot down. Bombers and passenger aircraft flying at high altitudes could fly faster because air is thin at high altitudes and there is less drag in the thinner air. These planes also could fly farther on a tank of fuel.

The supercharger, spinning within a closely fitted housing (not shown), pumped additional air into aircraft piston engines.
But because the air was thinner, aircraft engines produced much less power. They needed air to operate, and they couldn't produce power unless they had more air. Designers responded by fitting the engine with a "supercharger." This was a pump that took in air and compressed it. The extra air, fed into an engine, enabled it to continue to put out full power even at high altitude.

A supercharger needed power to operate. This power came from the engine itself. The supercharger, also called a centrifugal compressor, drew air through an inlet. It compressed this air and sent it into the engine. Similar compressors later found use in early jet engines.
Early superchargers underwent tests before the end of World War I, but they were heavy and offered little advantage. The development of superchargers proved to be technically demanding, but by 1930, the best British and American engines installed such units routinely. In the United States, the Army funded work on superchargers at another engine-builder, General Electric. After 1935, engines fitted with GE's superchargers gave full power at heights above 30,000 feet (9,000 meters).
Fuels for aviation also demanded attention. When engine designers tried to build motors with greater power, they ran into the problem of "knock." This had to do with the way fuel burned within them. An airplane engine had a carburettor that took in fuel and air, producing a highly flammable mixture of gasoline vapour with air, which went into the cylinders. There, this mix was supposed to burn very rapidly, but in a controlled manner. Unfortunately, the mixture tended to explode, which damaged engines. The motor then was said to knock.
Poor-grade fuels avoided knock but produced little power. Soon after World War I, an American chemist, Thomas Midgely, determined that small quantities of a suitable chemical added to high-grade gasoline might help it burn without knock. He tried a number of additives and found that the best was tetraethyl lead. The U.S. Army began experiments with leaded aviation fuel as early as 1922; the Navy adopted it for its carrier-based aircraft in 1926. Leaded gasoline became standard as a high-test fuel, used widely in automobiles as well as in aircraft.

The Pratt and Whitney R-1830 Twin Wasp engine was one of the most efficient and reliable engines of the 1930s. It was a "twin-row" engine. Twin-row engines powered the warplanes of World War II.
Leaded gas improved an aircraft engine's performance by enabling it to use a supercharger more effectively while using less fuel. The results were spectacular. The best engine of World War I, the Liberty, developed 400 horsepower (300 kilowatts). In World War II, Britain's Merlin engine was about the same size—and put out 2,200 horsepower (1,640 kilowatts). Samuel Heron, a long-time leader in the development of aircraft engines and fuels, writes that "it is probably true that about half the gain in power was due to fuel."
The V-1650 liquid-cooled engine was the U.S. version of the famous British Rolls-Royce "Merlin" engine which powered the "Spitfire" and "Hurricane" fighters during the Battle of Britain in 1940.

During World War II, the best piston engines used a turbocharger. This was a supercharger that drew its power from the engine' hot exhaust gases. This exhaust had plenty of power, which otherwise would have gone to waste. A turbine tapped this power and drove the supercharger. Similar turbines later appeared in jet engines.
These advances in supercharging and knock-resistant fuels laid the groundwork for the engines of World War II. In 1939, the German test pilot Fritz Wendel flew a piston-powered fighter to a speed record of 469 miles per hour (755 kilometres per hour). U.S. bombers used superchargers to carry heavy bomb loads at 34,000 feet (10,000 meters). They also achieved long range, the B-29 bomber had the range to fly non-stop from Miami to Seattle. Fighters routinely topped 400 miles per hour (640 kilometers per hour). Airliners, led by the Lockheed Constellation, showed that they could fly non-stop from coast to coast.

The Wasp Major engine was developed during World War II though it only saw service late in the war on some B-29 and B-50 aircraft and after the war. It represented the most technically advanced and complex reciprocating engine produced in large numbers in the United States. It was a four-row engine, meaning it had four circumferential rows of cylinders.
By 1945, the jet engine was drawing both attention and excitement. Jet fighters came quickly to the forefront. However, while early jet engines gave dramatic increases in speed, they showed poor fuel economy. It took time before engine builders learned to build jets that could sip fuel rather than gulp it. Until that happened, the piston engine retained its advantage for use in bombers and airliners, which needed to be able to fly a great distance without refuelling.
Pratt & Whitney was the first to achieve high thrust with good fuel economy. Its J-57 engine, which did these things, first ran on a test stand in 1950. Eight such engines powered the B-52, a jet bomber with intercontinental range that entered service in 1954. Civilian versions of this engine powered the Boeing 707 and Douglas DC-8, jet airliners that began carrying passengers in 1958 and 1959, respectively. In this fashion, jet engines conquered nearly the whole of aviation.

More on cross wind landing

2009-06-07T15:07:00.000-07:00

WINDY WEATHER PLANES

By Clay Ramskill

All too often, on an otherwise nice, but windy day, folks just don't fly. Obviously, for a beginner, that's just common sense - but for someone who has some experience, the wind should just be another challenge to add some spice to their flying.

While its easy to see that experience level has a lot to do with how much wind is too much, it may not be quite as apparent that the type of plane you're flying also can have a great effect on your ability to handle winds. Let's go through a bunch of airplane design features and see which ones give us the best flying characteristics to handle winds and the resulting turbulence.

Size: In general, the larger the plane, everything else being equal, the better it will handle winds of all kinds; they just don't "flop around as much!
Dihedral: The more dihedral in a planes wing, the more it is going to be affected by cross-wind gusts; it is hard to keep the wings reasonably level, and therefore lineup to the runway is difficult in a cross-wind situation.

Wing Loading: The higher the wing loading, the less a plane will be affected when hit with a gust.

Aspect Ratio: Lower aspect ratio (stubby) wings will be less bothered by gusts; there is less leverage for side forces to upset the plane, and the lower aspect ratio wing has a greater tolerance to changes in angle of attack caused by gusts.

Power: Pretty obvious - having the power to overcome the forces provided by the wind is a must. The same goes when you get into a sticky situation.
Lateral Control: Ailerons are very beneficial in a cross-wind, in landing and takeoff phases. The ability to dip a wing into a cross-wind without changing heading is essential, as is the ability to rudder the plane parallel to the runway heading while keeping wings level with aileron while landing.

Landing Gear: tri gear planes are easier to land and take off in a cross-wind than tail-draggers. And the wider the spread on the main gear, the better.
Maneuverability: This ones a bit harder to quantify. You want a plane with stability, yet you do need good maneuverability to cope with gusts. So you want a plane that is stable, yet responsive.

Wing Mounting: Generally, a low wing plane will handle crosswinds better. This is because the CG of the plane is nearer, in a vertical sense, to the aerodynamic center of the wing. So the low wing plane is not as easily rolled by a side gust. And by mounting the main landing gear on that low wing, we can spread them out wider.

It's unfortunate that almost every item above is in direct opposition to the characteristics found in a lot of popular trainers, the main exception being the requirement for tricycle landing gear. But even with trainers, there are differences; compare a Seniorita with the Cadet Mk2. While the Seniorita may be a bit slower and a bit easier to fly, the Cadet, with its ailerons, higher wing loading, lower aspect ratio, and lower dihedral, is a far better plane flying in windy conditions.
Going a step further with the same kit manufacturer, their Cougar(.40)/Cobra(.60 size) kits embody ALL the right characteristics for windy flying.
And in closing, I offer Confucius' only known saying about R/C flying – "To learn to fly in wind, one must fly in wind!.
When Your Plane Tries To Tell You
By Clay Ramskill
Once upon a time your author had a new pattern plane. On the first few days of flying it, everything was fine. But one day, on the first flight, it required several clicks of down trim (odd...) after take off -- and after each turn or maneuver, the pitch trim would be off again (VERY odd...). Only when it took full down stick to fly inverted (JEEPERS!) was your author smart enough to realize something was wrong. After landing, the problem was obvious: I had not bolted the wing to the fuselage!
But the plane DID "try to tell me"; I just wasn't listening. Only new, tight-fitting wing dowels had saved the plane from destruction – it certainly wasn't the pilot! Recapping later, I thought of a number of things that would have caused similar symptoms: servo or servo tray loose, bad servo centering, broken elevator hinges, loose control horn, et cetera. The point is, ALL of those things are BAD! And with the plane not behaving properly, WHY did I keep flying?
Just suppose you're getting an occasional glitch from your radio; something that doesn't normally happen. This could be an antenna problem; it could be metal-to-metal vibration causing home-grown interference, or a loose crystal.
Will any of these get better while you keep flying? And speaking of vibration, what if you start hearing it in the air? It's your plane talking to you -- loose muffler, engine mount, worn wing dowel holes, loose cowl mounting. Again, such problems don't get better, only worse.
One more example -- this has happened to all but the most careful pilots. Your engine goes lean and sags at the top of a loop. It's TELLING you that the mixture is too lean. But you don't listen and keep flying; a minute later, while doing another loop, you're suddenly dead stick!
The sky gods know -- we have enough problems that pop up suddenly, and we don't have any opportunity to prevent them. Other times the plane "tells you" that there is, or will be, a problem. Unless you really enjoy repairing or rebuilding -- LISTEN! Cutting a hop short to check out a possible problem is much quicker (and vastly cheaper) than building another plane!
DUAL RATES - the Good, Bad, and Ugly
by Clay Ramskill
Usually found on radios with 6 or more channels, dual rates allow you, with a flip of a handy switch, to change how much servo response you get from a movement of your control stick. There is a switch for each channel involved, and an adjustment for each which allows you to "dial in" how much less response you'll get with the dual rate "on".
Dual rate use is fairly simple - with the dual rate "off" you get normal response; that is, full servo rotation with full stick deflection. Turning dual rate "on" you get only a certain percentage of the servo rotation you would normally have had at any stick deflection. That percentage is what you control with the adjustment on the transmitter.
This is a nice capability - your plane can be set to be wildly responsive for aerobatics, yet with dual rates on, you can still fly very smoothly, for landing, for instance. Pattern fliers use this a lot.
THE GOOD. You could set your plane up such that with dual rate on, the elevator travel isn't enough to stall the plane, allowing smooth, stall-free flight. Turning the rate back up then would allow such maneuvers as snaps and spins. Some folks use dual rates for landing only, to stop over controlling at slow speeds. Dual rate capability is super for test flying a new plane, when you're unsure of just how responsive the plane will be. The possibilities are near endless.
THE BAD. The radios with dual rates cost extra bucks. You have more switches to twiddle with, and to check before flight. And in dual rate, you're not using all your servo travel - they will not be as accurate as they are using full travel, nor as powerful.
THE UGLY. The problem is, that you get used to having a certain response from your plane, and expect that response all the time. With dual rates in use, you must remember whether you're "in" or "out" at all times so you know what responses your plane is capable of. A BUNCH of planes have been crashed that way; the pilot wondering why his plane wouldn't pull out of a loop like it normally did! Or on dual rates, the plane couldn't respond quick enough to overcome some turbulence on landing.
The Bottom Line. If you have dual rates and use them, you've got to know at all times where those little switches are set. If you don't use them, set them such that if the switch is turned on, you still have 100% travel; that way, it doesn't matter where the switch is. NEVER set the rate such that the plane is un-flyable or only marginally controllable with dual rate "on". You all know how Murphy's Law works, right?

Cross wind landing Techniques

2009-06-07T14:59:00.000-07:00

Crosswind Techniques

By Jim VanNamee

It’s summer in the mountains now, and distant afternoon thunderstorms often produce blustery wind speeds above what is usual. The inevitable hangar discussion ensues around crosswind take off and landing techniques. Some questions asked are:• Does one operate where crosswinds exceed the demonstrated limit found in the POH?• Should I use the slip or "kick out" method of landing?• How much flaps does one use in a crosswind?Let’s investigate some of these questions and determine for ourselves our own answers to the above questions based upon our own skill level. But first, how do we derive the crosswind component? "Use the crosswind component chart," says the student to the examiner. Yeah, well, it’s been a long time since you’ve even seen that chart, right? Of course, it’s been a long time since you’ve reviewed the POH, either. That’s where it can be found for some airplanes, but, hey, since we aren’t in doubt, we don’t read the book, do we? So, great aviators that we are, we estimate:
Wind off the Nose 30 degrees50 degrees 70 degrees
Crosswind ComponentHalf the wind speedApprox. 75% of the windApprox. 90% of the wind
Does one fly in crosswinds in excess of the demonstrated limit in the POH? The POH figures were set during certification trials by test pilots flying the airplane in a manner akin to how you might fly. In other words, they try to take into account how the average GA pilot would fly the plane, and not how experienced, high time engineering test pilots take to the air. Federal Aviation Regulation (FAR 23.233) requires that all airplanes certificated after 1962 must be safely handled in a 90-degree crosswind at .2 Vso. This means that if your C-182 has a stall speed of 49 knots it should be able to handle a direct crosswind of 10 knots, or your Turbo-Bonanza with a stall speed of 57 knots must be safe in a 11.5 knot direct crosswind. We know that the POH records higher demonstrated values than 10 or 11.5 knots, respectively. How’d that happen? The figures derived are not the limit’s the plane’s controls can handle in a crosswind, but a conservative value that keeps you out of trouble, and keeps the manufacturer out of court. There is a rule of thumb articulated by an unknown "they" that says "If wind gusts surpass 65 percent of Vs1, don’t take off or land." For a C-182 with a Vs1 of 50 knots, and a Turbo-Bonanza of 64 knots, this means a direct crosswind of 32.5 and 41.6 knots respectively should keep you from operating that day. Most pilots should cower at these crosswind numbers, and rightly so. It’s possible the aforementioned test pilots can handle these crosswinds with great vim and vigor, but the rest of us should probably opt out at a much lower figure. Practice should show you what your limit is. Another rule of thumb – if the local "Vulture’s Row" crowd suddenly appears on the ramp with coat hangers and marshmallows as you taxi out, you may want to return to the tie-down area.Can you fly in higher crosswinds than the airplane’s certification minimums? I would hope so. Can you fly in winds up to the demonstrated limits in the POH? I hope so. Can you fly in higher winds? Maybe. However, I would couch all of these replies with three precautions:1. Wet or snow covered runways change everything. Unless you want to demonstrate your best Olympic skating techniques, it would be best to stay in bed that day. Besides, the French judge won’t appreciate your larking about on the runway, anyway.2. Practice, practice, practice. And, oh, by the way, practice with an instructor who has the skills to handle and demonstrate crosswind landings in these type of conditions, in the airplane you fly. The time to find out that your expertise isn’t up to even certification minimums is not on take off run or in the flare.3. FAR 91.13 (Careless or Reckless Operation) can be used against you if you operate your aerospace vehicle in excess of the POH demonstrated crosswind component. The FAA can violate you and/or a civil suit can be filed should an unpleasant event occur as a result of your actions in a high wind environment.Does one use the slip or "kick out" method of landing in a crosswind? At the moment of touchdown in a crosswind, the airplanes’ fuselage must be heading parallel to its direction of travel, preferably down the center of the runway, with drift under control as well as no lateral movement. Most pilots probably use a slip to accomplish crosswind landings. This is a tactic where a crab on final is established, then at some point (about there looks right) the fuselage is aligned to the runway centerline with rudder, and the upwind wing lowered into the wind to negate drift. The airplane is landed on the upwind wheel. Keep the plane over, and aligned with, the runway centerline and allow the raised (downwind) wing to lower itself to the ground aerodynamically. Continue to maintain rudder and aileron in a cross-controlled condition until coming to a stop. Making a perfect landing on the upwind wheel and then encountering a roll over situation doesn’t make for the best of days. If you can imagine a line drawn from the axle of your main wheels to the axle of your nose wheel, this is the "roll over axis" of a tricycle landing gear airplane. Any more than about ten degrees of cornering angle (angular difference between the heading of the tire and the path it is actually taking – skidding) and your little aerospace vehicle can begin to roll about its roll over axis. Maintain cross-controlled rudder and ailerons to keep the fuselage over and aligned with the runway centerline and drift under control. Even after taxiing off the runway, utilize the POH recommended techniques for taxiing. Rollout and taxiing in high wind conditions can be a precarious period during your flight. Yes "flight." You aren’t through, and shouldn’t relax, until the engine is shut down, gust locks in place, and the airplane tied down.There are some disadvantages to the slip method of landing. You must determine when to set up the airplane for this type of approach. Too early, and your passengers become uncomfortable; too late, and you may not have set up the plane for a safe and successful landing. Because the wind can vary at differing altitudes, even on final, you are constantly making adjustments with aileron and rudder to keep the plane aligned with the centerline of the runway. Since it is a cross-control technique, the rate of descent increases. This, along with an adjustment for gust factor, entails a higher approach speed than normal.Another method of crosswind landing is the "kick out" technique. This was used by pilots of early jet passenger planes because the jet didn’t slip well. This method advocates crabbing the plane on final until in the flare. Just prior to touchdown, the upwind wing is lowered and that tire is "planted" on the runway. The remaining wheels are allowed to lower themselves aerodynamically. Roll out is accomplished the same as the slip method of landing. This technique, also, has disadvantages. If the crab is taken out too early, the pilot must either go around or establish a crosswind slip to landing. If the crab is taken out too late, upon touchdown the airplane can start skidding athwart the pavement and the hapless pilot may soon discover how to enlighten his or her friendly NTSB envoy about the topic of roll over axis. Also, one must be very proficient in this type of modus operandi. Much practice is required for mastery. Notice I didn’t discuss this method very intensely. I’m not ready to spend a successful 3.0 hours of PIC X/C flight time and then exchange that for about 5 seconds of wishful thinking. There are advocates for this type of crosswind landing technique, and I respect their opinion. However, I’m not comfortable with it, and it’s definitely not for weekend warriors.Does one use flaps in a crosswind? This is one question that has a lot of answers – many with stanch opinions. Visit the Google web site, under the group rec.aviation.student, where you will find a plethora of panaceas, opinions, and solutions to this oft-asked query.Flaps allow a pilot to fly a steeper rate of descent without an increase in airspeed. This means flaps are both a lift and drag-producing device. Stall speeds are reduced by the addition of flaps. Up to a point, flaps produce more lift than drag. Ever notice the droop created by the first setting of flaps almost mirrors aileron droop with full throw of the yoke? That setting approximates the flap angle that creates the most lift without the negative consequences of drag. Go beyond that flap setting and drag begins to have a more noticeable affect. This is the area where you get the ability to increase your rate of descent without increasing airspeed.Flaps allow for a slower groundspeed on touchdown. If, for example, full-flap final approach airspeed in your trusty C-182 is 60 knots and the headwind component is 10 knots, then you can still touch down with the same groundspeed – even if you’ve increased your final approach speed for zero flaps and the gust factor. At this point, flaps become a personal preference. Yes, I know stall speed is increased with no flaps extended, but since you fly an airspeed several knots higher than full flap final approach airspeed, you have about the same buffer between Vso and Vs1. More flaps also offer a better opportunity for the airplane to weathervane immediately after touchdown; in a high wing airplane, the upwind wing can be more easily lifted by a gust. My personal preference with a headwind down the runway is 20 degrees of flaps if the wind is 10 knots or less, and 10 degrees of flaps if the wind is 11 to 20 knots. I don’t use full flaps unless I am performing a short or soft field landing. At high density altitudes found in the mountains, most rental and training airplanes available here may not climb during a go around if the flaps fail and we are "heavy, hot, high, and humid." The Turbo-Bonanza? It’s a rock on final with 30 knots of headwind and full flaps – goes around, too. Jim Van Namee lives in Angel Fire, New Mexico, and is a CFI at Taos Aviation Services, Taos Regional Airport, Taos, New Mexico. If you have questions about flying in the Taos or Angel Fire area, he can be reached at jimvn@aol.com

If trapped how to fly out of thunderstorm

2009-06-07T12:03:00.000-07:00

STORMSCOPE

An instrument known as a stormscope, installed in the airplane, can help a pilot avoid thunderstorms. The stormscope detects the electromagnetic discharges associated with vertical air currents. All thunderstorms contain strong updrafts and downdrafts. These opposing ascending and descending air currents rub against each other, generating static electricity. The electrons tend to accumulate in positive and negative charges and when they have built up sufficiently, the potential difference will cause a current discharge. This discharge manifests itself not only as lightning but also in the radio spectrum. The stormscope picks up the radio frequencies from these discharges, a computer processes the signals, plots them by range and azimuth and presents them on a small, circular, radar like screen. The static electrical discharges picked up by the stormscope may or may not be associated with lightning. The stormscope receives these signals through 360 degrees around the airplane and from as far away as 200 nautical miles.
Each static discharge is represented by a bright green dot on the cathode ray tube display. Clusters of dots indicate areas of thunderstorm activity. The display can be programmed to 3 different range settings, 40, 100 and 200 miles. It is most accurate on the 40 mile range. On the 200 mile range, the stormscope sees everything but range is not so accurate. Generally, the display is more accurate and easier to read as the storm intensifies. In heavy electrical activity, the system has a problem called radial spread. The dots tend to spread over the display screening the areas between major clumps of storm caused dots.
The stormscope has some advantages over weather radar. Radar measures rainfall intensity. The stormscope is capable of detecting turbulence in clouds that have little or no precipitation. It is also able to see through areas of heavy precipitation to detect turbulent areas beyond. A stormscope does not, however, see rain. Recognizing the advantages of having both a stormscope and a weather radar, a recent model of stormscope interfaces with radar, displaying information from both systems on the same screen. The stormscope is not dependent on line of sight. It will see, for example, the weather behind mountains. The system can. Therefore, be used on the ground to determine weather for a 200 mile radius and is a useful flight planning tool.

WEATHER RADAR
Airborne weather radar is one of the best instrument aids that a pilot can have in locating and avoiding thunderstorms. It is able to detect and display on the cockpit radar screen any significant weather that lies ahead on the flight route. The radar equipment does this by measuring precisely rainfall density of targets under observation. The antenna of the weather radar radiates a very narrow and highly directional beam, in the X band of the radio spectrum, straight ahead of the aircraft. The beam is cone-shaped and from 3 to 10 degrees in diameter. (Beam width is a function of antenna size and type.) The antenna scans left and right to cover a sector of about 120 degrees.
Although, weather radar is not able to detect turbulence itself, the intensity of precipitation within a storm is a reliable indication of the amount of turbulence within a storm since strong drafts and gusts are necessary to produce water drops of significant size and quantity. Radar sees only water drops that are large enough to be affected by gravity and tall as rain. Because of the characteristics of X band radio waves and water, raindrops reflect the radiated beam back to the radar receiver. The sum of the reflections from all the raindrops appears on the screen as a target.
The computerized receiver measures the rainfall rate and grades the targets into levels which are represented on the screen by colors, green for level 1 which is light rain, yellow for level 2 which is medium rain and red for level 3 which is heavy rain. Areas of steep rain gradients are easy to see because of the color coding. A precipitation rate that changes from minimum to maximum over a short distance is known as a steep rain gradient and usually is associated with a shear zone. Any target that is showing red, said to be contouring, is considered to be a storm and must be avoided and detoured. Areas of no precipitation between targets remain black and are called corridors.
The airborne display is gradated into mileage rings. Distance to the storm as well as its bearing with respect to the airplane's heading are therefore displayed. As a result, the pilot is able to select a safe and smooth flight path through thunderstorm areas. It is wise to give all contouring targets at least a ten mile clearance. A corridor between 2 targets should be at least 20 miles wide before considering it a safe passage. Most weather radar systems manufactured today present a digital display that does not fade between sweeps. Some equipment incorporates automatic tilt to compensate for the altitude of the airplane. When an airplane, while flying at a level where the temperature is at or below freezing, strikes a supercooled water droplet, the droplet will freeze and adhere to the airplane. Dangerous icing can occur in clouds, freezing rain, or freezing drizzle.
The cloud in which icing most frequently occurs in winter is stratocumulus, but the heaviest deposits are encountered in cumulus and cumulonimbus. Clouds composed of ice crystals (such as cirrus) do not present an icing hazard. (The ice crystals do not adhere to the wing.) The more dangerous types of icing are encountered in dense clouds, composed of heavy accumulations of large supercooled drops, and in freezing rain. The seriousness of icing depends on the air temperature, the temperature of the aircraft skin and the amount of water striking the aircraft.
A supercooled water droplet freezes if disturbed. When struck by an aircraft, the drop begins to freeze immediately, but as it freezes, it releases heat to raise its temperature to 0°C. Freezing by impact then ceases and the remaining liquid in the drop begins to freeze more slowly as a result of cold surroundings. At very low temperatures, a large part of the drop freezes by impact. At higher temperatures, a smaller part of the drop freezes by impact leaving a greater amount to freeze more slowly. How fast this liquid part of the drop freezes depends on the temperature of the aircraft skin. The higher the temperature, the more the drop will spread from the point of impact before freezing is complete.
Whether or not a drop freezes completely before another drop strikes the same spot is another factor affecting the character of icing. The amount of water intercepted by an aircraft in a given time is called its rate of catch. This rate varies with the liquid water content of the cloud, the size of the water droplets, the airspeed and the type of wing of the aircraft. The liquid water content varies from level to level within the cloud. Generally, the amount of supercooled water in a cloud increases with height when the temperature is just a little below 0°C but decreases with height when the temperature is well below freezing, since at such low temperatures, more drops will freeze into ice crystals reducing the liquid content.
On some models, tilt is handled manually. Since the weather radar only can display targets illuminated by the radar beam, tilt management of the radar antenna is essential. The tilt feature controls the up and down angle of the antenna and consequently the plane of scan of the antenna. This feature is important in evaluating weather. The antenna beam does not see the whole storm, but only a 3 to 10 degree slice of it. By seeing the tilt higher, the beam scans the upper region of the cell. By setting it lower, the beam scans the lower region of the cell. Since rain is most concentrated in the middle and lower regions of a thunderstorm, the best part of a storm to scan is this middle/lower area that gives the best indication of size and intensity.
It does take skill and training to use airborne weather radar most effectively. Interpreting the display is not an exact science but depends on the pilot's general knowledge of thunderstorms, the quality of the pre-flight briefing that he has received, and his familiarity with the limitations of the radar equipment in his airplane. There are some limitations to weather radar. Moisture in relatively close proximity to the airplane can scatter the radar beams. This problem called attenuatlon, means that heavy rain areas can block out a radar return from significant weather that lies beyond. Moisture and ice on the radar dome (the radome) installation on the nose of the airplane can diminish the radar signal. Useful range of the weather radar is only about 90 to 100 miles.

ICING
The size of droplets also affects the rate of catch. Small drops tend to follow the airflow and are carried around the wing. Large, heavy drops tend to strike the wing. When a small drop does hit, it will spread back over the wing only a small distance. The large drop spreads farther. As for airspeed, the number of droplets struck by the aircraft in a certain time increases as the airspeed increases. The curvature of the leading edge of the wing also has an effect on the rate of catch. Thin wings catch more droplets than do thick wings. The rate of catch is, therefore, greatest for an aircraft with thin wings flying at high speed through a cloud with large droplets and a high liquid water content.

HOW ICING AFFECTS THE AIRPLANE
Ice collects on and seriously hampers the function of not only wings and control surfaces and propellers, but also windscreens and canopies, radio antennas, pilot tubes and static vents, carburetors and air intakes. Turbine engines are especially vulnerable. Ice forming on the intake cowling constricts the air intake. Ice on the rotor and starter blades affects their performance and efficiency and may result in flame out. Chunks of ice breaking off may be sucked into the engine and cause structural damage. The first structures to accumulate ice are the surfaces with thin leading edges: antennas, propeller blades, horizontal stabilizers, rudder, and landing gear struts. Usually the pencil-thin outside air temperature gauge is the first place where ice forms on an airplane. The wings are normally the last structural component to collect ice. Sometimes, a thin coating of ice will form on the windshield, preceded in some instances by frosting. This can occur on take-off and landing and with sufficient rapidity to obscure the runway and other landmarks during a critical time in flight.
Icing of the propeller generally makes itself known by a slow loss of power and a gradual onset of engine roughness. The ice first forms on the spinner or propeller dome and then spreads to the blades themselves. Ice customarily accumulates unevenly on the blades, throwing them out of balance. The resulting vibration places undue stress on the blades and on the engine mounts, leading to their possible failure. If the propeller is building up ice, it is almost certain that the same thing is happening on the wings, tail surfaces and other projections. The weight of the accumulated ice is less serious than the disruption of the airflow around the wings and tail surfaces. The ice changes the airfoil cross section and destroys lift, increases drag and raises the stalling speed. At the same time, thrust is degraded because of ice on the propeller blades and the pilot finds himself having to use full power and a high angle of attack just to maintain altitude. With the high angle of attack, ice will start to form on the underside of the wing adding still more weight and drag. Landing approaches and landing itself can be particularly hazardous under icing conditions. Pilots should use more power and speed than usual when landing an ice-laden airplane.
If ice builds up on the pilot tube and static pressure ports, flight instruments may cease operating. The altimeter, airspeed and rate of climb would be affected. Gyroscopic instruments powered by a venturi would be affected by ice building up on the venturi throat. Ice on radio antennas can impede VOR reception and destroy all communications with the ground. Whip antennas may break off under the weight of the accumulating ice.

TYPES OF ICING
The three main types of ice accretion, in order of their hazard to flying, are as follows:

CLEAR ICE
A heavy coating of glassy ice which forms when flying in dense cloud or freezing rain is known as clear ice or glaze ice. It spreads, often unevenly, over wing and tail surfaces, propeller blades, antennas, etc. Clear ice forms when only a small part of the supercooled water droplet freezes on impact. The temperature of the aircraft skin rises to 0°C with the heat released during that initial freezing by impact of the part of the droplet. A large portion of the droplet is left to spread out, mingle with other droplets before slowly and finally freezing. A solid sheet of clear ice thus forms with no embedded air bubbles to weaken its structure. As more ice accumulates, the ice builds up into a single or double horn shape that projects ahead of the wing, tail surface, antenna, etc. on which it is collecting. This unique ice formation severely disrupts the airflow and is responsible for an increase in drag that may be as much as 300 to 500%.
The danger of clear ice is great owing to
(1) the loss of lift, because of the altered wing camber and the disruption of the smooth flow of air over the wing and tail surfaces,
(2) the increase in drag on account of the enlarged profile area of the wings.
(3) the weight of the large mass of ice which may accumulate in a short time, and finally
(4) the vibration caused by the unequal loading on the wings and on the blades of the propeller(5) When large blocks break off, the vibration may become severe enough to seriously impair the structure of the airplane. When mixed with snow or sleet, clear ice may have a whitish appearance. (This was once classified as rime-glazed but it is now considered to be a form of clear ice).

RIME ICE
An opaque, or milky white, deposit of ice is known as rime. It accumulates on the leading edges of wings and on antennas, pilot heads, etc. For rime to form, the aircraft skin must be at a temperature below 0°C. The drop will then freeze completely and quickly without spreading from the point of impact. It is also dependent on a low rate of catch of small supercooled water droplets.
Rime forms when the airplane is flying though filmy clouds. The deposit has no great weight, but its danger lies in the aerodynamic alteration of the wing camber and in the choking of the orifices of the carburetor and instruments. Rime is usually brittle and can easily be dislodged by de-icing equipment. Occasionally, both rime and clear ice will form concurrently. This is called mixed icing and has the bad features of both types.

FROST
A white semi-crystalline frost which covers the surface of the airplane forms in clear air by the process of sublimation. This has little or no effect on flying but may obscure vision by coating the windshield. It may also interfere with radio by coating the antenna with ice. It generally forms in clear air when a cold aircraft enters warmer and damper air during a steep descent. . Aircraft parked outside on clear cold nights are likely to be coated with frost by morning. The upper surfaces of the aircraft cool by radiation to a temperature below that of the surrounding air.
Frost which forms on wings, tail and control surfaces must be removed before take-off. Frost alters the aerodynamic characteristics of the wing sufficiently to interfere with take-off by increasing stall speed and reducing lift. Frozen dew may also form on aircraft parked outside on a night when temperatures are just below freezing. Dew first condenses on the aircraft skin and then freezes as the surface of the aircraft cools. Frozen dew is usually clear and somewhat crystalline, whereas frost is white and feathery. Frozen dew, like frost, must be removed before take-off. In fact, any snow or moisture of any kind should be removed since these may freeze to the surface while the airplane is taxiing out for take-off. The heat loss due to the forward speed of the airplane may be sufficient to cause congelation.

INTENSITY OF ICING
Icing may be described as light, moderate, and severe (or heavy). In severe icing conditions, the rate of accretion is such that anti-icing and de-icing may fail to reduce or control the hazard. A change in heading and altitude is considered essential. In moderate icing, a diversion may be essential since the rate of accretion is such that there is potential for a hazardous situation. Light icing is usually not a problem unless the aircraft is exposed for a lengthy period. Clear ice is considered more serious than rime ice since the rate of catch must be high to precipitate the formation of clear ice. The seriousness of an icing situation is, of course, dependent on the type of aircraft and the type of de-icing or anti-icing equipment with which the aircraft is equipped or the lack of such equipment.

ICING IN CLOUDS AND PRECIPITATION
Cumulus. Severe icing is likely to occur in the upper half of heavy cumulus clouds approaching the mature cumulonimbus stage especially when the temperatures are between -25°C and 0°C. The horizontal extent of such cloud is, however, limited so that the aircraft is exposed for only a short time.
Stratus. Icing is usually less severe in layer cloud than in cumulus type clouds but it can be serious if the cloud has a high water content. Since stratus cloud is widespread in the horizontal, exposure to the icing condition can be prolonged. Icing is more severe if cumulus clouds are embedded in the stratus layer.
Freezing Rain is common ahead of warm fronts in winter.
Serious icing occurs when the aircraft is flying near the top of the cold air mass beneath a deep layer of warm air. Rain drops are much larger than cloud droplets and therefore give a very high rate of catch. In freezing temperatures, they form clear ice.
Freezing Drizzle. Drizzle falls from stratus clouds with a high water content. As the droplets fall through the clear air , prompt action on the radio is important when icing starts. Information about the latest weather for altitudes above and below will help the pilot to make the decision on what action to take. The final alternative would be to turn back, or, if the accumulation of ice has already become serious, to make a precautionary landing immediately. In any event, the decision must be made rapidly since once ice has started to form, the condition may become critical in a matter of approximately six minutes.
Pilots flying in light airplanes which are not fitted with an outside air temperature gauge will be well advised to have one installed as this instrument will warn of temperatures that are conducive to icing conditions. To avoid icing problems, here are a few rules to follow:
Avoid flight into an area where icing conditions are known to exist. Do not fly through rain showers or wet snow when the temperature is near 0°C. Do not fly into cumulus clouds when the temperature is low.
Always consult a weather office or flight service station to obtain a forecast about expected icing conditions before taking off on any flight in fall or winter. Icing in freezing drizzle is usually maximum just below the cloud base where the drops are largest. Icing is of the clear ice type.
Snow and Ice Crystals do not adhere to cold aircraft and do not usually constitute an icing problem. However, if the aircraft is warm, the snow may melt as it strikes the warm surface and ice accretion may result. If supercooled water droplets are also present with the snow, a rapid build up of rough ice can occur.

PROTECTION FROM ICING
Many modern airplanes that are designed for personal and corporate use, as well as the larger transport type airplanes, are fitted with various systems designed to prevent ice from forming (anti-icers) or to remove ice after it has formed (de-icers).
1. Fluids. There are fluids which are released through slinger rings or porous leading edge members to flow over the blades of the propellers and the surfaces of the wings. A fluid is an anti-icing device since it makes it difficult for ice to form.
2. Rubber Boots. Membranes of rubber are attached to the leading edges. They can be made to pulsate in such a way that ice is cracked and broken off after it has already formed. This is a de-icing device.
3. Heating Devices. Heating vulnerable areas is a method for preventing the buildup of ice. Hot air from the engine or special heaters is ducted to the leading edges of wings, empennages, etc. Electrically heated coils protect pilot tubes, propellers, etc.

ICING AVOIDANCE
Few single engine airplanes, or even light twin-engine types incorporate any means of ice prevention. A few tips for pilots flying airplanes in this category will therefore be in order.
When ice formation is observed in flight, there is only one certain method of avoiding its hazards and that is to get out of the ice-forming layer as quickly as possible. This may be done by climbing above the ice forming zone. This alternative would obviously require an airplane that has good performance and is fitted with radio and proper instruments for flying over the top. The next alternative would be to descend and fly contact below the ice forming zone. The advisability of this course would depend on the ceiling and visibility along the route at the lower level concerned.
Do not remain in icing conditions any longer than necessary. For that reason, during climbs or descents through a layer in which icing conditions exist, plan your ascent or descent to be in the layer for as short a time as possible. However, keep your speed as slow as possible consistent with safety. Speed of an airplane affects accretion of ice. The faster an airplane moves through an area of supercooled water drops, the more moisture it encounters and the faster will be the accumulation of ice.
If ice has started to build up on the airplane, do not make steep turns or climb too fast since stalling speed is affected by ice accumulation. Fuel consumption is greater due to increased drag and the additional power required. Land with more speed and power than usual. Do not land with power off. With the advent of the jet age, the problem of icing has taken on some surprising new aspects. At one time, the pilots of airplanes flying through high cirrus clouds did not worry about ice forming on the airplane as cirrus clouds are composed of ice crystals rather than water droplets. With the increased speeds of which jet airplanes are capable, the heat of friction is sufficient to turn the ice crystals in the cloud to liquid droplets which subsequently freeze to the airplane.

TURBULENCE
Turbulence is one of the most unpredictable of all the weather phenomena that are of significance to pilots. Turbulence is an irregular motion of the air resulting from eddies and vertical currents. It may be as insignificant as a few annoying bumps or severe enough to momentarily throw an airplane out of control or to cause structural damage. Most of the causes of turbulence have been mentioned in other sections of this chapter since turbulence is associated with fronts, wind shear, thunderstorms, etc.
In reporting turbulence, it is usually classed as light, moderate, severe or extreme. The degree is determined by the nature of the initiating agency and by the degree of stability of the air.
Light turbulence momentarily causes slight changes in altitude and/or attitude or a slight bumpiness. Occupants of the airplane may feel a slight strain against their seat belts.
Moderate turbulence is similar to light turbulence but somewhat more intense. There is, however, no loss of control of the airplane. Occupants will feel a definite strain against their seat belts and unsecured objects will be dislodged.
Severe turbulence causes large and abrupt changes in altitude and/or attitude and, usually, large variations in indicated airspeed. The airplane may momentarily be out of control. Occupants of the airplane will be forced violently against their seat belts. In extreme turbulence, the airplane is tossed violently about and is impossible to control. It may cause structural damage. Whether turbulence will be light or more severe is determined by the nature of the initiating agency and by the degree of stability of the air.
There are four causes of turbulence.

1. Mechanical Turbulence. Friction between the air and the ground, especially irregular terrain and man-made obstacles, causes eddies and therefore turbulence in the lower levels. The intensity of this eddy motion depends on the strength of the surface wind, the nature of the surface and the stability of the air. The stronger the wind speed, the rougher the terrain and the more unstable the air, the greater will be the turbulence. Of these factors that affect the formation of turbulence, stability is the most important. If the air is being heated from below, the vertical motion will be more vigorous and extensive and the choppiness more pronounced. In unstable air, eddies tend to grow in size; in stable air, they tend not to grow in size but do dissipate more slowly.
Turbulence can be expected on the windward side and over the crests of mountains and hills if the air is unstable. There is less turbulence on the leeward side since subsidence stabilizes the air. Mountain waves produce some of the most severe turbulence associated with mechanical agencies. In strong winds, even hangars and large buildings cause eddies that can be carried some distance downwind. Strong winds are usually quite gusty; that is, they fluctuate rapidly in speed. Sudden increases in speed that last several minutes are known as squalls and they are responsible for quite severe turbulence.

2. Thermal Turbulence. Turbulence can also be expected on warm summer days when the sun heats the earth's surface unevenly. Certain surfaces, such as barren ground, rocky and sandy areas, are heated more rapidly than are grass covered fields and much more rapidly than is water. Isolated convective currents are therefore set in motion which are responsible for bumpy conditions as an airplane flies in and out of them. This kind of turbulence is uncomfortable for pilot and passengers. In weather conditions when thermal activity can be expected, many pilots prefer to fly in the early morning or in the evening when the thermal activity is not as severe.
Convective currents are often strong enough to produce air mass thunderstorms with which severe turbulence is associated. Turbulence can also be expected in the lower levels of a cold air mass that is moving over a warm surface. Heating from below creates unstable conditions, gusty winds and bumpy flying conditions.
Thermal turbulence will have a pronounced-effect on the flight path of an airplane approaching a landing area. The airplane is subject to convective currents of varying intensity set in motion over the ground along the approach path. These thermals may displace the airplane from its normal glide path with the result that it will either overshoot or undershoot the runway.

3. Frontal Turbulence. The lifting of the warm air by the sloping frontal surface and friction between the two opposing air masses produce turbulence in the frontal zone. This turbulence is most marked when the warm air is moist and unstable and will be extremely severe if thunderstorms develop. Turbulence is more commonly associated with cold fronts but can be present, to a lesser degree, in a warm front as well.

4. Wind Shear. Any marked changes in wind with height produce local areas of turbulence. When the change in wind speed and direction is pronounced, quite severe turbulence can be expected. Clear air turbulence is associated at high altitudes with the jet stream.

Do"s and Dont"s of a Thunderstorm Flying

2009-06-07T09:54:00.000-07:00

Flight Environment
THUNDERSTORM HAZARDS

The dangers of flying in or close to a thunderstorm are:

1. Turbulence. Turbulence, associated with thunderstorms, can be extremely hazardous, having the potential to cause overstressing of the aircraft or loss of control. Thunderstorm vertical currents may be strong enough to displace an aircraft up or down vertically as much as 2000 to 6000 feet. The greatest turbulence occurs in the vicinity of adjacent rising and descending drafts. Gust loads can be severe enough to stall an aircraft flying at rough air (maneuvering) speed or to cripple it at design cruising speed. Maximum turbulence usually occurs near the mid-level of the storm, between 12,000 and 20,000 feet and is most severe in clouds of the greatest vertical development.
Severe turbulence is present not just within the cloud. It can be expected up to 20 miles from severe thunderstorms and will be greater downwind than into wind. Severe turbulence and strong out-flowing winds may also be present beneath a thunderstorm. Microbursts can be especially hazardous because of the severe wind shear associated with them.

2. Lightning. Static electricity may build up in the airframe, interfering with operation of the radio and affecting the behaviour of the compass. Trailing antennas should be wound in. Lightning blindness. may affect the crew's vision for 30 to 50 seconds at a time, making instrument reading impossible during that brief period. Lightning strikes of aircraft are not uncommon. The probability of a lightning strike is greatest when the temperature is between -5ºC and 5°C. If the airplane is in close proximity to a thunderstorm, a lightning strike can happen even though the aircraft is flying in clear air. Lightning strikes pose special hazards. Structural damage is possible. The solid state circuitry of modem avionics is particularly vulnerable to lightning strikes. Electrical circuits may be disrupted. The possibility of lightning igniting the fuel vapor in the fuel cells is also considered a potential hazard.

3. Hail. Hailstones are capable of inflicting serious damage to an airplane. Hail is encountered at levels between 10 and 30 thousand feet. It is, on occasion, also encountered in clear air outside the cloud as it is thrown upward and outward by especially active cells.

4. Icing. Heaviest icing conditions occur above the freezing level where the water droplets are supercooled. Icing is most severe during the mature stage of the thunderstorm.

5. Pressure. Rapid changes in barometric pressure associated with the storm cause altimeter readings to become very unreliable.

6. Wind. Abrupt changes in wind speed and direction advance of a thunderstorm present a hazard during take-off and landing. Gusts in excess of 80 knots have been observed.
Very violent thunderstorms draw air into their cloud bases with great intensity. Sometimes the rising air forms an extremely concentrated vortex from the surface of the ground well into the cloud with vortex speeds of 200 knots or more and very low pressure in its center. Such a vortex is known as a tornado.

7. Rain. The thunderstorm contains vast amounts of liquid water droplets suspended or carried aloft by the updrafts. This water can be as damaging as hail to an aircraft penetrating the thunderstorm at high speed. The heavy rain showers associated with thunderstorms encountered during approach and landing can reduce visibility and cause retraction on the windscreen of the aircraft, producing an illusion that the runway threshold is lower than it actually is. Water lying on the runway can cause hydroplaning which destroys the braking action needed to bring the aircraft to a stop within the confines of the airport runway. Hydroplaning can also lead to loss of control during take-off.

ST. ELMO'S FIRE
If an airplane flies through clouds in which positive charges have been separated from negative charges, it may pick up some of the cloud's overload of positive charges. Weird flames may appear along the wings and around the propeller tips. These are called St. Elmo's Fire. They are awe-inspiring but harmless. It the airplane flies in the vicinity of a cloud where negative charges are concentrated, its positive overload may discharge into the cloud. In this case, it is the airplane which strikes the cloud with lightning! The electricity discharges cause a noisy disturbance in the lower frequency radio bands but do not interfere with the very high frequencies. This precipitation static, as it is called, tends to be most severe near the freezing level and where turbulence and up and down drafts occur.

THUNDERSTORM AVOIDANCE

Because of the severe hazards enumerated above, attempting to penetrate a thunderstorm is asking for trouble. In the case of flight, airplane pilots, the best advice on how to fly through a thunderstorm is summed up in one word—DON'T.
Detour around storms as early as possible when encountering them enroute. Stay at least 5 miles away from a thunderstorm with large overhanging areas because of the danger of encountering hail. Stay even farther away from a thunderstorm identified as very severe as turbulence may be encountered as much as 15 or more nautical miles away. Vivid and frequent lightning indicates the probability of a severe thunderstorm. Any thunderstorm with tops at 35,000 feet or higher should be regarded as extremely hazardous. Avoid landing or taking off at any airport in close proximity to an approaching thunderstorm or squall line.
Microbursts occur from cell activity and are especially hazardous if encountered during landing or take-off since severe wind shear is associated with microburst activity. Dry microbursts can sometimes be detected by a ring of dust on the surface. Virga falling and evaporating from high based storms can cause violent downdrafts.

The gust front, another zone of hazardous wind shear, can be identified by a line of dust and debris blowing along the earth's surface.
Swirls of dust or ragged clouds hanging from the base of the storm can indicate tornado activity. If one tornado is seen, expect others since they tend to occur in groups.
Do not fly under a thunderstorm even if you can see through to the other side, since turbulence may be severe. Especially, do not attempt to fly underneath a thunderstorm formed by orographic lift. The wind flow that is responsible for the formation of the thunderstorm is likely to create dangerous up and down drafts and turbulence between the mountain peaks.
Reduce airspeed to maneuvering speed when in the vicinity of a thunderstorm or at the first indication of turbulence.

Do not fly into a cloud mass containing scattered embedded thunderstorms unless you have airborne radar.

Do not attempt to go through a narrow clear space between two thunderstorms. The turbulence there may be more severe than through the storms themselves. If the clear space is several miles in width, however, it may be safe to attempt to fly through the center, but always go through at the highest possible altitude. When flying around a thunderstorm, it is better to fly around the right side of it. The wind circulates anti-clockwise and you will get more favorable winds. If circumstances are such that you must penetrate a thunderstorm, the following few simple rules may help you to survive the ordeal:

1.~ Go straight through a front, not across it, so that you will get through the storm in the minimum amount of time.

2.~ Hold a reasonably constant heading that will get you through the storm cell in the shortest possible time.

3.~ Before entering the storm, reduce the airspeed to the airplane's maneuvering airspeed to minimize structural stresses.

4.~ Turn the cockpit lights full bright. (This helps to minimize the risk of lightning blindness.) Check the pitot head. Fasten seat belts. Secure loose objects in the cabin.

5.~ Try to maintain a constant attitude and power setting. (Vertical drafts past the pitot head and clogging by rain cause erratic airspeed readings.)

6.~ Avoid unnecessary maneuvering (to prevent adding maneuver loads to those already imposed by turbulence).

7.~ Determine the freezing level and avoid the icing zone. Avoid dark areas of the cell and, at night, those areas of heavy lightning.

8.~ Do not use the autopilot. It is a constant altitude device and will dive the airplane to compensate for updrafts, causing excessive airspeed, or will cause the plane to climb in a downdraft creating the risk of a stall.

The best ever pilotage i have seen (miraclous Save)

2009-06-06T10:01:00.000-07:00

This is one of the best video of a pilot i have seen a salaute to the pilot

Trent 900 destruction test

2009-06-06T09:48:00.000-07:00

A nice test video of trent 900

Carrier landing

2009-06-06T08:38:00.000-07:00

Three helicopter pilots you would never like to fly with

2009-06-06T05:11:00.000-07:00

2009-06-06T04:33:00.000-07:00

A Plane i love for speed and beauty

SR 71

Best Portable Gps

2009-06-05T12:44:00.000-07:00

Here you can see portable GPS i think top the ranking, keeping in view the features they offer.

1. GARMIN GPSMAP 696:-

The GPSMAP 696 is one of the latest and most modren gps garmin offer its a gps a pilot could want in a portable GPS unit for the airplane. A huge 7” screen and full featured GPS is bundled with the ability to view FAA/NACO approach plate’s giving this unit Class 1/Class 2 electronic flight bag (EFB) capability, for more details check garmin website.

2. Bendix/King AV80R GPS

Bendix/King AV8OR is a feature packed GPS unit at an affordable price. It features a large 4.3” color touch screen that can be used both in the air and your car. For the air, the unit features an upgradable Jeppesen database of terrain, airspace boundaries and waypoints. The unit features WAAS capable gps technology with accuracy down to five meters and is upgradable to include XM Satellite weather. It also features the flexibility to take it in the car and use it as a full featured 3D automotive GPS with voice prompts. Bluetooth capability allows you to sync up with headsets and other Bluetooth products. For more details visit Bendix/King website

3. Garmin 496:-

The Garmin 496 packs all the power of a full multi-function display in one compact unit. The Garmin includes the ability to show XM Satellite weather including real time text and NEXRAD radar imaging as well as terrain and airspace alerts. Despite its small size the unit features a high resolution database that boasts ten times as much data as other portable units as well as an update rate that is five times faster than other portable units producing a very smooth and detailed picture. The unit comes preloaded with over 850 taxiway diagrams helping pilots navigate unfamiliar airports and taxiways on the ground. Pilots who want take it out of the airplane completely can add optional MapSource and use it in car or in sea. For details vist garmin website.

4. AvMap EKP IV

AvMap EKP IV is perfect for anyone looking for a great aviation GPS who does not want to pay the monthly subscription for XM Satellite weather service. At the heart of unit is a gigantic 7” screen that is bright and easy to read in the cockpit. The screen can be rotated to display in either landscape or portrait layout. The updatable database includes a topographic base map, instrument waypoints such as victor airways, and airport information. In addition to all of this, the unit is able to integrate with onboard avionics such as autopilots and external antennae’s. overall a nice choice

Alternate fuel

2009-06-05T04:48:00.000-07:00

Jatropha Oil Biofuel Update

Air New Zealand is coming out in strong support of alternative fuel, saying that more than 3,000 pounds of fuel can be saved on a 12-hour flight if that flight is flown on a jatropha-seed-oil biofuel blend instead of straight Jet A. The airline makes the claim after flying the plant's seed oil in a 50:50 blend with Jet A during December 2008 flight tests, pumping the fuel to one Rolls-Royce RB2111 engine aboard a Boeing 747-400. Though the tests consisted of only a few hours, more than a dozen tests were conducted at various altitudes and under a variety of conditions. From that experience the airline believes it has found potential significant savings for the airline industry in fuel and, therefore, carbon footprint that would result in a 60-percent reduction in greenhouse gas emissions. Air New Zealand aims to fulfill 10 percent of its fuel requirements with alternative sources by 2013, but the airline did not work alone on alternative fuel tests. Boeing Continental, Japan Airlines, Air New Zealand and Virgin Atlantic are among those who have conducted tests over the past year and a half. And it appears there is not necessarily agreement on which alternative source would be best, which may complicate fast-tracked certification.

Boeing supports the use of camelina over jatropha and in the long term is more optimistic about algae-based biofuels. Both jatropha and camelina have short-term appeal for their ability to grow well on marginal lands, but camelina may be better-suited to grow in U.S. climates without competing with other crops. It is currently grown in Washington, Montana, Idaho, and the Dakotas. Aircraft are thought to account for about 3 percent of the U.S.'s carbon dioxide emissions, but lowering emissions and fuel burn will depend on the availability of a certified fuel alternative and there is not yet agreement on even the source of the alternative fuel oil.

courtesy: AVweb

Cross wind landings (Amazing clip)

2009-06-05T04:18:00.000-07:00

Talk about interiors have a look at these

2009-06-05T02:55:00.000-07:00

Nice pictures of contrails and other

2009-06-05T00:39:00.000-07:00

Gibraltar....Traffic waits for aircraft wait for traffic... amazing

2009-06-04T23:59:00.000-07:00

2009-06-04T15:00:00.000-07:00

Custer Channelwing

The saga of the Custer Channelwing is probably the most interesting of all V/STOL aircraft. It is without doubt, the oldest ongoing saga in aviation. This is the story of a single minded man on a single minded mission to change the path of aviation. Years of research, tests by every conceivable variety of agency, and stunning flying examples, didn't add up to commercial production of the Channelwing. It isn't that the Custer wouldn't perform, it was rather, that maybe it performed unbelievably well, with the accent on unbelievable. Willard Custer made many claims for the Channelwing, including the discovery of new lift principles, which he called, "aerophysics". Most engineers, cynics and parents, know you can't get something, for nothing. So when Custer claimed 8.2 pounds of static lift per horsepower, with a simple fixed wing aircraft, critics scoffed and tended to look the other way. But, Custer was persistent to say the least. In time, he was back, claiming 13.8 pounds lift per horsepower, vertical capabilities, fighter like speed, simple construction, and heavy load capacity, beyond anything built to date. He also hinted that the university academia and manufacturers didn't know what they were talking about when they criticized the Channelwing, and needed to be re-trained to understand his new theories of lift. It was obvious by this time that he was a crackpot inventor, untrained in the aeronautical world, and tiresome to listen to.Custer was dumped into the dustbin of aviation history for obvious reasons. So obvious, in fact, that no one stopped to notice that, for the most part, he was right.

CCW5 - five seconds into takeoff run. This aircraft can be seen at the Mid Atlantic Air Museum, in Reading, Pennsylvania.
The idea of the channelwing pre-dates most of those who are reading this site. It all began in the 1920s, when Willard Custer took shelter in a barn during a near hurricane velocity storm. Much to his surprise and fascination, the roof of the barn suddenly lifted off, and soared through the air. He wondered why an airplane had to gather speed on a runway, while a barn roof, a poor airfoil by any reckoning, could fly from a standing start. He soon came to the realization that it was ,the speed of the air, over the surface, not the speed of the surface through the air that created lift. Bernoulli principle in both cases, but an application that had eluded aviation up to that time. He settled on the idea of pulling the air through channels that were, in fact, the lower half of a venturi. He was reversing the normal method of powered flight. Instead of using the engines to move the airfoil through the air, he used the engine to move the air through the airfoil. His channel had the effect of going several hundred miles per hour, due to the induced air flow, while standing still. The airflow over the surface of the channel created conventional lift, and a lot of it. It was at this point that Custer settled on," It's the speed of the air, not the airspeed", which became his mantra of, "aerophysics". Many experiments followed with all nature of devices. The first real aircraft to which he applied his principle, was the CCW-1, or Custer Channelwing number one, which now hangs at the Garber facility of the Smithsonian. It is still strangely modern, even after all these years, with a smoothly rounded fuselage, and a wrap around Plexiglas canopy. But, close inspection reveals the channels appended with two by four struts. Two 75 HP engines were fitted into the two six foot diameter half-barrel like channels, and the tests were started. First flight was November 12, 1942. The CCW-1 was used for test purposes only, to prove the concept. More than 300 hours of flight tests did prove that the Custer not only flew, but was capable of flight without wings. After the first flights proved stability, the wings were progressively cut off or had spoilers attached to the point of having no lift from the wings at all. The test pilot noticed no difference because the channels furnished all the lift needed! Most of these tests were low, straight ahead hops. A demonstration took place in Beltsville Maryland for Brigadier General W. E. Gilmore. Gilmore was noted for his gruff temperament, but after seeing the demonstration, was excited enough to place a call to Orville Wright, asking that he come out to witness the Custer phenomenon. Orville didn't make it, but the plane was placed in a military test program. The results of these tests proved to be typical of the many government tests the Channel wing received over the years. The Army Air Force technical report concluded that the lift generated by the channels was similar to normal induced lift created by other wing /propeller arrangements. Although this was a complete falsification, the damage was done, and Custer was on the defensive. What they forgot to mention, was that the channelwing created more static lift than the weight of the test vehicle, and was, in fact, capable of vertical takeoff! The report stated that the channelwing was inferior to the helicopter in creating static lift and did not show sufficient promise of military value to warrant further testing. This was at a time when every conceivable concept from flying wings to rocket ships was being tried. The conclusion, both then and now, seems incomprehensible to say the least. To Custer, it was obvious that the tests had been too good, and consequently helicopter interests were pushing him out of the picture. That seems to be the most likely scenario, as later tests proved the channelwing to outlift helicopters of the day, with 13.8 pounds of lift per horsepower recorded. Custer was a good inventor, but a little naive about politics and government contracts. He also felt that the engineering staff and theorists just didn't understand the Custer phenomenon, as they didn't understand "aero physics". But, if faith in the government was dimmed, faith in himself wasn't. Over the next forty years, he obtained financial backing for a series of aircraft from CCW-2 to CCW-5. He had enough data and tests to convince enough investors to bring him near full production on at least two occasions.In 1951, he co-operated with the Baumann Aircraft Company, and modified one of their twin pusher aircraft to a Custer configuration. This was the CCW-5, and had two 225 HP engines, and weighed en excess of 4300 pounds. Walker Davidson made the first flight of the CCW-5 in July of 1953. As usual, the aircraft was highly successful. Demonstrations repeatedly showed hair raising maximum performance takeoffs, nose high climbs at speeds so low it seemed obvious that the Custer would fall out of the sky. Three second takeoffs, with nose high steep turns of 45 to 60 degrees bank, at speeds below 30MPH gave the CCW-5 the ability to take off and do a 180 before most planes could lift off. Video of these flights still confound experienced pilots. Although I have personally logged 20,000+ hours, in all nature of aircraft, I was absolutely stunned the first time I saw the videos of the Custer doing a 150 foot takeoff, roll into a steep bank at speeds that would have insured a stall - spin - crash, in any other plane, and leave town going the other way, while staying within what appeared to be about a 250' square area. Slow flight was a specialty, and the CCW-5 flew at a measured 22 MPH and on August 27, 1954 hovered against an 11 MPH wind, although it was not modified to use maximum lift potential. Cruise speed remained a normal 170 mph.These tests attracted more investors, and it seemed that Custer and Noordyun Aircraft Ltd. of Canada were going to do a production run of at least 100 aircraft. On the strength of this proposal, a production version of the CCW-5 was built and rolled out on July 4 of 1964. Although it looked like the original Baumann conversion, the second model was built from scratch, rather than modified from an existing aircraft. Now came the securities and exchange commission who claimed the stock was not issued correctly, and the deal fell through, in a manner reminiscent of the Tucker car.Since then, the Custer channelwing has virtually disappeared, and few have even heard of the aircraft, let alone its' questionable capabilities.

Famous last words in aviation

2009-06-04T14:06:00.000-07:00

By William Kershner

1.. If this tailwind holds up, we won't have to make an interim stop for fuel.
2.. I know we're pretty heavily loaded, but there's plenty of runway.
3.. An intersection takeoff will save us a couple of minutes.
4.. We can beat the squall line if we get out in the next five minutes.
5.. I don't need to check the fuel; I saw the fuel truck by the airplane, and I told line service to fill it up.
6.. This gas smells a little different, but I'm sure it's OK.
7.. Don't worry about those reports of heavy icing. I've flown flights like this and never even picked up a trace.
8.. Crosswind? Relax, I can land the box it came in with more crosswind than this.

Or my famous line to another pilot just before we flew across Memphis to pick up an airplane. We were preflighting an Aeronca Champion that had been sitting out for several weeks and had been drained of what seemed like several gallons of water:"There, that's got all the water."Twenty minutes later the Champ was sitting in a cabbage patch between four houses in a subdivision. The destination airport was about one-half mile away. One of the homeowners, hearing a strange noise in his backyard, walked around the house; the look on his face would have broken up both of us if we hadn't been still staggered by the transition from godlike birdmen to occupants of the muddiest garden in western Tennessee.There was a language problem since it appeared (but was not confirmed) that the gentleman had only recently arrived from some European country. We explained as best we could and thanked him for his wire fence that had slowed us to such an extent that our final touchdown was gentle indeed.In any event, the airplane was moved to the airport, repaired, and later ferried to the final destination.

And a personal case of famous last words that weren't really "last" words (fortunately):
The Combat Information Center indicated that Red Chinese snoopers were flying in the vicinity of the task force and needed interception.We manned our F4U Corsairs, started the engines back in the "pack," and prepared for a quick deck run and vector to intercept the Red airplanes.I was about the fourth or fifth in line and, after starting the engine, found that there was no indication of oil pressure - zilch, nada, nicht. Earlier we had had problems with the oil pressure transmitters; so, after the plane captain had checked the area behind, I elected to run up the engine at a high power setting to check for an unusual oil temperature rise during the (very) few minutes before launch.Then came the personal famous last (fortunately not really last) words "It's only the gauge," I said. (I didn't want to miss all the excitement).The deck run was normal; but during the first two or three minutes on climbout, that oil temperature gauge had my total attention. It turned out to be the gauge only. The snoopers turned back and were not intercepted. There were no hometown newspaper headlines such as "Local boy destroys an entire flight (squadron, group) of Red airplanes! Gets Navy Cross plus 20 or 30 other awards!"And, of course, there are the most famous last words of all:
"I don't think the ceiling is as low as they report. I'll drop down a little lower and see if we can break out."

looking after your eyes

2009-06-04T13:42:00.000-07:00

Looking after your eyes
You may not associate exercise and non-smoking with good eye health, but a healthy lifestyle can play a vital role in keeping your eyes healthy and maintaining good vision.
Here is a guide to how and why lifestyle choices affect your eyes, with advice from Dr Frank Eperjesi, the director of the optometry undergraduate programme at Aston University.
Nutrition, diet and exercise

Obesity is a major contributing factor to sight loss. It is estimated that the 10 million adults and two million children in the UK who are obese are twice as likely to lose their sight.
A report published by the RNIB (Royal National Institute of Blind People) identified a direct link between obesity and some of the common eye conditions that cause blindness. These are:
Age-related macular degeneration (AMD) AMD is the most common cause of adult blindness in the developed world. The macula is the central part of the retina at the back of the eye, and is responsible for picking up detailed visual information, such as reading words on a page, or sewing. It wears out naturally as we get older, resulting in poorer vision. Obesity speeds up the onset of AMD, and there is little treatment for the condition.

Diabetic retinopathy Obesity significantly increases the risk of developing type 2 diabetes. Someone with a body mass index (BMI) above 35 is up to 80 times more likely to develop the condition than someone with a BMI of less than 22. The most serious eye condition associated with diabetes involves the retina and, more specifically, the network of blood vessels within it. The vessels can allow fluid or blood to leak into the retina and damage it. This can result in serious loss of vision. (See video below)

Cataracts A cataract is a gradual thickening that develops in the lens of the eye. If you're obese, the risk of developing cataracts can be double that of people who are not overweight. Although cataracts are largely treatable, one in four cases of sight loss in people over the age of 75 is due to cataracts.

NutritionStudies show that antioxidants prevent the retina from damage done by smoking, alcohol and ultraviolet rays. As we age, the body is less efficient at getting rid of oxidants, and this can cause retinal damage.

An antioxidant called lutein is hugely beneficial. "Lutein is a protection factor," says Dr Eperjesi. "It absorbs harmful wavelengths of light and behaves as a powerful antioxidant. However, the body does not produce its own lutein, so for this protection system to work effectively we need 6-10mg a day."

It is estimated that the average western diet contains only 2-3mg per day, which means most of us lack lutein in our food. This is thought to be one of the reasons why macular degeneration has become more common.

Lutein is found in broad-leaf leaves such as spinach and kale, and in yellow vegetables such as sweetcorn and yellow peppers. But it is not just these vegetables that Dr Eperjesi recommends. "Evidence suggests that a diet rich in brightly coloured fruit and vegetables in general is good for antioxidants," he says. "And I'd say that five a day should be the bare minimum."
Finally, what about the widespread belief that carrots are good for your eyesight? "That's folklore, really," says Dr Eperjesi. "There is no protective element and they are low in lutein, but they do contain beta-carotene which, when converted to Vitamin A, is important for eye function."

AlcoholDrinking alcohol is not necessarily bad for your eyes. "Alcohol destroys antioxidants in the body," says Dr Eperjesi, "but the red pigment in red wine is a powerful antioxidant, so there are suggestions that drinking a glass of red wine in the evening won't do any harm in terms of macular degeneration. If you drink too much, however, the positive effects of the pigment will be outweighed by the negative effects of the alcohol."

ExerciseWhile it might seem odd that exercise can help the eyes, it can be important. "Good cardiovascular function is important, as poor circulation affects the blood vessels in the eyes," says Dr Eperjesi. Research shows that exercise may reduce the risk of sight loss that can occur from high blood pressure, diabetes and the narrowing or hardening of the arteries.
Smoking"After ageing, smoking is the biggest risk factor for developing macular degeneration," says Dr Eperjesi. Research shows that smokers are three to four times more likely to develop AMD compared with non-smokers.

As well as AMD, smokers are about three times more likely to develop cataracts, a major sight-threatening condition.
Scientists believe that smokers may be more susceptible because metals found in tobacco smoke can gradually build up in the eye. Whatever the reason may be, the risk of developing a cataract increases the longer and more heavily a person smokes.

Aside from these serious, sight-threatening conditions, smokers are also more likely to have problems if they wear contact lenses. Their corneas run a greater risk of getting irritated, which can seriously affect vision if they subsequently become infected.
The good news, however, is that all these risks start to drop as soon as you stop smoking, and they decline steadily the longer you don't smoke.

The sun
Protecting your eyes from the sun is very important and should not be underestimated. Under no circumstances should you ever look at the sun directly. Doing so could do irreversible damage to your eyesight and even lead to blindness. Sunlight can damage the retina and the lens of the eye, and studies show that people with outdoor jobs are more likely to suffer eye problems.
The College of Optometrists recommends buying good quality, dark sunglasses (these needn't be expensive). Look for glasses carrying the 'CE' mark and the British Standard BS EN 1836:1997, which ensures that the sunglasses offer a safe level of ultraviolet protection.

Regular eye examinations
It is recommended that you visit an optometrist every two years (or more frequently if advised). This is important because an eye examination can detect potentially blinding eye conditions such as glaucoma, or underlying health problems such as diabetes. The earlier the problem is detected, the faster it can be treated.
It is easy to neglect your eyes because they rarely hurt when there is a problem. But once your eyesight is lost, it may never be restored.

Videos: glaucoma & diabetic retinopathy
Watch a consultant ophthalmologist describe how diabetes can affect your vision and the possible treatments.
Also, watch a consultant ophthalmologist explaining what glaucoma is, how it can affect your vision and how it can be treated.

Facts emerge on Emirates tail strike...

2009-06-04T13:39:00.000-07:00

The much vaunted Emirates appears to be making its pilots cut corners on safety while its trusting passengers think otherwise...

The pilot of the Emirates Airline flight that nearly crashed at Melbourne Airport last month with 225 passengers on board had almost no sleep the previous day, according to Australia's Sunday Herald Sun newspaper. The newspaper has learned that the pilot of the plane was almost at the threshold of the number of hours he was legally able to fly - Emirates pilots are permitted to fly a maximum 100 hours each 28 days.
Not only that, but the pilot was following the airline’s orders to take off at reduced power to save money on fuel, the Sunday Herald Sun discovered. Several sources told the newspaper that Emirates – like many modern airlines – ordered its pilots to take off at reduced thrust when possible to cut fuel costs, emissions and wear on the aircraft. But an Emirates source told the newspaper that on take-off, flight EK407 to Dubai, was set at the "absolute minimum" thrust, leaving little room for error. In a statement to the Sunday Herald Sun, Emirates said safety was a top priority for the airline. "Safety is at the forefront of all operations within Emirates group," a spokeswoman said. A report due on Thursday was expected to show the accident happened after the incorrect weight was typed into the plane’s computers, causing it to set an adequate take-off speed.In addition, it is reported that air safety investigators are examining Emirates’ staff records, including the work rosters of some of its pilots, to see if there are systemic safety problems within the airline that could have contributed to the near disaster. The Australian Transport Safety Bureau is carrying out a full investigation of the incident, which is expected to take up to a year.
However, Emirates Airline yesterday told ITP publication Aviation Business that the true cause as to why its Airbus nearly crashed at Melbourne Airport will be released before the end of April. "There is a high probability that the speculation surrounding this incident will be contradicted," the airline’s spokesperson said.

Aircraft lightning

2009-06-04T13:18:00.000-07:00

August 14, 2006
What happens when lightning strikes an airplane?

Edward J. Rupke, senior engineer at Lightning Technologies, Inc., (LTI) in Pittsfield, Mass., provides the following explanation:
It is estimated that on average, each airplane in the U.S. commercial fleet is struck lightly by lightning more than once each year. In fact, aircraft often trigger lightning when flying through a heavily charged region of a cloud. In these instances, the lightning flash originates at the airplane and extends away in opposite directions. Although record keeping is poor, smaller business and private airplanes are thought to be struck less frequently because of their small size and because they often can avoid weather that is conducive to lightning strikes.
The last confirmed commercial plane crash in the U.S. directly attributed to lightning occurred in 1967, when lightning caused a catastrophic fuel tank explosion. Since then, much has been learned about how lightning can affect airplanes. As a result, protection techniques have improved. Today, airplanes receive a rigorous set of lightning certification tests to verify the safety of their designs.
Although passengers and crew may see a flash and hear a loud noise if lightning strikes their plane, nothing serious should happen because of the careful lightning protection engineered into the aircraft and its sensitive components. Initially, the lightning will attach to an extremity such as the nose or wing tip. The airplane then flies through the lightning flash, which reattaches itself to the fuselage at other locations while the airplane is in the electric "circuit" between the cloud regions of opposite polarity. The current will travel through the conductive exterior skin and structures of the aircraft and exit off some other extremity, such as the tail. Pilots occasionally report temporary flickering of lights or short-lived interference with instruments.
Most aircraft skins consist primarily of aluminum, which conducts electricity very well. By making sure that no gaps exist in this conductive path, the engineer can assure that most of the lightning current will remain on the exterior of the aircraft. Some modern aircraft are made of advanced composite materials, which by themselves are significantly less conductive than aluminum. In this case, the composites contain an embedded layer of conductive fibers or screens designed to carry lightning currents.
Modern passenger jets have miles of wires and dozens of computers and other instruments that control everything from the engines to the passengers' headsets. These computers, like all computers, are sometimes susceptible to upset from power surges. So, in addition to safeguarding the aircraft's exterior, the lightning protection engineer must make sure that no damaging surges or transients can reach the sensitive equipment inside the aircraft. Lightning traveling on the exterior skin of an aircraft has the potential to induce transients into wires or equipment beneath the skin. These transients are called lightning indirect effects. Careful shielding, grounding and the application of surge suppression devices avert problems caused by indirect effects in cables and equipment when necessary. Every circuit and piece of equipment that is critical or essential to the safe flight and landing of an aircraft must be verified by the manufacturers to be protected against lightning in accordance with regulations set by the Federal Aviation Administration (FAA) or a similar authority in the country of the aircraft's origin.
The other main area of concern is the fuel system, where even a tiny spark could be disastrous. Engineers thus take extreme precautions to ensure that lightning currents cannot cause sparks in any portion of an aircraft's fuel system. The aircraft skin around the fuel tanks must be thick enough to withstand a burn through. All of the structural joints and fasteners must be tightly designed to prevent sparks, because lightning current passes from one section to another. Access doors, fuel filler caps and any vents must be designed and tested to withstand lightning. All the pipes and fuel lines that carry fuel to the engines, and the engines themselves, must be protected against lightning. In addition, new fuels that produce less explosive vapors are now widely used.
The aircraft's radome¿the nose cone that contains radar and other flight instruments¿is another area to which lightning protection engineers pay special attention. In order to function, radar cannot be contained within a conductive enclosure. Instead, lightning diverter strips applied along the outer surface of the radome protect this area. These strips can consist of solid metal bars or a series of closely spaced buttons of conductive material affixed to a plastic strip that is bonded adhesively to the radome. In many ways, diverter strips function like a lightning rod on a building.
Private general aviation planes should avoid flying through or near thunderstorms. The severe turbulence found in storm cells alone should make the pilot of a small plane very wary. The FAA has a separate set of regulations governing the lightning protection of private aircraft that do not transport passengers. A basic level of protection is provided for the airframe, fuel system and engines. Traditionally, most small, commercially made aircraft have aluminum skins and do not contain computerized engine and flight controls, and they are thus inherently less susceptible to lightning; however, numerous reports of noncatastrophic damage to wing tips, propellers and navigation lights have been recorded.
The growing class of kit-built composite aircraft also raises some concerns. Because the FAA considers owner-assembled, kit-built aircraft "experimental," they are not subject to lightning protection regulations. Many kit-built planes are made of fiberglass or graphite-reinforced composites. At LTI we routinely test protected fiberglass and composite panels with simulated lightning currents. The results of these tests show that lightning can damage inadequately protected composites. Pilots of unprotected fiberglass or composite aircraft should not fly anywhere near a lightning storm or in other types of clouds, because nonthunderstorm clouds may contain sufficient electric charge to produce

alternate fuel

2009-06-03T11:25:00.000-07:00

With the advancement in aviation and a with the alarming concern over the global warming engine are being designed for better efficiency and less emission, different techniques are being explored for going green one effort is to burn bio diesel in the jet engines which produce less emission, less green house gases, and less dependencey on the earth decreasing reserve of the fossil fuel. Biodiesel can be obtained in many different ways like oil obtained from a plant named jatropa ( which is not ediable) can be used to make bio diesel, I hope in comming years need for alternative fuel would be focused more and we would be able to come up with differnt alternative fuel.