Experimental Aircraft page 1
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The subject of experimental aircraft encompasses two broad yet distinct categories. The first category is centered around the Experimental Aircraft Association--a group of flying enthusiasts whose main interest is designing and building their own flying machines. The second category is centered around professional research and involves scientific observation aimed at improving the many modern aircraft being flown throughout the world. Much of this category stems from NASA (National Aeronautics and Space Association) and their work at the Dryden Flight Research Center. Both categories have achieved the goal of improving the field of aviation and advancing the science of aeronautics. In this article we will look at the EAA and the work done by NASA in an attempt to better reveal the subject of experimental aircraft.

The Experimental Aircraft Association was established in 1953. It is a group of aviation enthusiasts whose primary bond is homebuilding airplanes. The association also represents owners of warbirds, antiques and classics, ultralights and amateur aerobatic pilots. The main figure, founder and president of the EAA is Paul Poberenzy. With the aid of his wife, son and full time staff, the EAA has seen great success. Currently there are nearly 700 EAA chapters around the world. Local chapters put out newsletters and hold meetings at which home based airplane builders exchange ideas and information. The are also hosts of the popular fly ins.

On a national level the EAA provides a voice in Washington, D.C. for sport aviators to speak about proposed legislation. They also promote a nationwide designee program under which some 900 aviation experts work with members and their projects to help meet high standards of airplane construction. The EAA Aviation Center and Air Museum was opened in the 1980's in Oshkosh, Wisconsin.. It contains nearly 100 aircraft and is open to the public.

To the thousands of EAA members, the most passionate and engulfing subject is that of the home built aircraft. To fly an aircraft that you built yourself, and maybe even designed yourself is to take the thrill of flight one step further. For years homebuilts had the reputation of crude, simple aircraft. Most were originally made of a combination of wood, fabric and steel tube. More recently the use of composite materials has gained popularity. Some of the more complex high-performance homebuilts are highly labor intensive with perfectionist builders spending as much as 5,000 hours on their construction over a 10 year period. Some homebuilts are made from plans while others come in kits. As long as the builder is responsible for at least 51% of the work required to make the airplane, it can be certified in the experimental category as an amateur built aircraft intended for recreational purposes. Homebuilts cannot be flown for hire, used commercially, rented or leased.

If the homebuilt is the EAA's most passionate subject, then their most passionate event is the annual air show held each summer in Oshkosh, Wisconsin. For one week during the month of August over 500,000 people from around the world attend the Oshkosh air show. The event showcases all of the elements of experimental aviation and provides opportunities for the many enthusiasts to get together and see what is new. Days are spent browsing through the rows of airplanes on display throughout the grassy fields. Fellow builders and pilots exchange ideas and tips. The is a "Fly Market" where all kinds of aviation related memorabilia may be purchased. There are also exhibit halls where homebuilding suppliers sell everything from landing-gear legs to upholstery and plans.

Dubbed as the world's biggest aviation event, the fun at Oshkosh wouldn't be complete without an air show. Every afternoon some of the best known pilots in the business put their aircraft through dazzling routines. There are also pyrotechnic displays, mass fly-pasts, aerobatics routines and various stunts that change from year to year. During the event Oshkosh is also the world's busiest airport, handling four times more take-off and landings than Chicago O'Hare International Airport. The regular and extra flight controllers who work the Oshkosh tower are the busiest in the world during the event. Keep in mind that many of the visitors fly to the event in airplanes built by themselves. Bustling with activity, the Oshkosh air show is a tribute to the love of flying by the thousands of EAA members.

In contrast to the Oshkosh air show and homebuilt hobbyists of the EAA, but no less important in the world of experimental aircraft, is the world of research airplanes. Research airplanes are built to explore new areas in the science of flight and to solve problems that are forecasted to occur up to 25 years from the present. Some research planes are used to learn how to design airplanes that will fly faster than any previous airplane. Some are designed for learning how to develop airplanes that can take off from a space as small as a parking lot instead of a long runway. The aircrafts are not meant to carry passengers or freight or to be put into mass production; they are simply an effective way to advance the field of aviation. To learn how airplanes might be able to accomplish new feats scientists and aeronautical engineers research current airplane designs. They then proceed to experiment with modifying an existing design or creating an entirely new airplane. Computers are used as electronic drafting tables in the design process. The use of computers allows engineers to find out how a new or modified airplane will fly even before it is built. Once a good design is developed, a large scale radio-controlled model of the real airplane may be built. Several models of varying designs are often built in order to find out which one works best. If all goes well a research airplane is built.

Flying a research plane is a task not be taken lightly. Only the best, highly trained pilots are candidates for the job. Years of hard work and millions of dollars are at stake. In-flight recorders and telemetering equipment radio data to technicians on the ground. The test pilot must be able to feel every movement of the plane and sense potential problems immediately. If the first flight goes as planned it will be a simple take-off, a gradual climb, some easy maneuvers and a modest landing. Only once the plane has passed the initial first flights and been carefully checked by mechanics and engineers will it be able to test the realm of it's performance levels.

Past research planes have centered around high-speed research airplanes. The "sound barrier", an imaginary wall airplanes were thought to encounter when they flew at the speed of sound (750 mph at sea level and 650 mph at high altitudes) is in fact what forced designers and engineers to build pure research airplanes. On October 14, 1947 Army Air Force Captain Charles E. (Chuck) Yeager flew the Bell XS-1 (later called the X-1) at 700 mph, becoming the first person to fly faster than the speed of sound. Six years later on November 20, 1953 test pilot Scott Crossfield flew a Douglas D-558-II skyrocket at 1,291 mph becoming the first person to fly faster than Mach 2.

X-1 D-558-II
X-1 D-558-II

Another area of research airplanes is that of the V/STOL (Vertical/Short Take Off and Landing) plane. With the intent of overcomin g the need for the long runways demanded by many modern planes V/STOLS have evolved. In V/STOLS engineers have crafted a machine to work much like both an airplane and helicopter. Such machines can take off straight up in the air or after only a very short stroll down a runway. V/STOLS may be powered by propellers or jet engines. They are particularly useful for supporting ground troops in battle and thus have had heavy emphasis in the military arena.

XV-15: Tilt-Rotor

When discussing the topic of research airplanes one cannot help but to mention the NASA Ames Research Center, Dryden Flight Research Facility. Located on the western edge of the Mojave desert, the facility is the nation's premier site for high-performance aeronautical flight research. It is located at the southern end of a 500 mile high-speed flight corridor and benefits from almost ideal weather for flight testing. Dryden also benefits from Rogers Dry Lake, a 44 square mile natural playa used for aviation research, test operations and emergency landings. Nearby Rosamond Dry lake provides an additional 22 square miles of similar smooth clay surface. All of these factors have combined to make the Dryden Research Center a huge success in pioneering aeronautical research.

Dryden Flight Research Facility

September 1996 marks the 50th anniversary of the Dryden Flight Research Center; half a century of exploration, discovery and contributions to the nation's aerospace industry. The center started out as a small desert outpost and has evolved into one of the most sophisticated centers of its kind in the world. Major programs in recent years have included Mission Adaptive Wing, Advanced Propellers, Oblique Wing and the F-15 HiDec (Highly Integrated Digital Electronic Control) program. Current major programs include the F-18 High Angle of Attack Research Vehicle, the F-18 Systems Research Aircraft and research involving the SR-71, X-34, B-52 and CV-990 airplanes. Last but certainly not least is Dryden's involvement with the U.S. Space Shuttle program. The center was the site of the space shuttle approach and landing tests in 1977. Since the first orbital flight in April 1984 the majority of landings have been at Dryden. After the landings, the space shuttles are serviced at Dryden for the ferry flights back to the Kennedy Space Center in Florida piggyback atop the NASA 747 Shuttle Carrier Aircraft.

AD-1_oblique F-15_HiDEC SR-71
AD-1: Oblique Wing F-15_HiDEC SR-71

B-52 CV-990 Shuttle
B-52 CV-990 Space Shuttle

Over the years one project of particular interest and importance (and the one from which the space shuttle was derived) has been the X-plane projects. The X-planes began with the idea of designing an aircraft that could fly faster that the speed of sound. With this feat accomplished soon other planes were in the works. For example, the X-1A, 1B and 1D planes were designed to investigate aerodynamic phenomena at speeds over Mach 2 and altitudes above 90,000 feet. The X-1E experimented with an extremely thin wing design and a more efficient engine turbo pump. The X-3 provided important information on high speed flight and related control problems. The X-3 also provided insight into aircraft tire technology. The X-5 was built to research variable-sweep wings. The X-9 missile assessed the feasibility of an air-to-surface nuclear missile. Subsequent X-planes would be built to explore such areas as jet-powered vertical takeoff and landing capabilities, high altitude long range reconnaissance, forward swept wings and advanced composites used to decrease drag on an airplane's wings.

B-52 CV-990 Shuttle
X-3 X-5: variable sweep X-29: forward-swept wings

The most successful of the X-planes, however, may be the X-15. First flown on September 17, 1959, the X-15 explored high-speed, high altitude manned flight. The X-15 proved that manned flight near the Mach5+ speed at altitudes over 250,000 feet were feasible. Ultimately it would set an altitude record for aircraft at 317,750 feet and reach a top speed of Mach 6.7 (4,520 mph). The information gathered from the X-15 flights proved useful to the U.S. space effort as well. The Mercury, Gemini and Apollo spacecraft all implemented various X-15 technologies. The X-15 pioneered the feat of engineer designing a craft to go into space and then return to a horizontal landing on Earth. After more than twenty years of work this concept evolved into the space shuttle.


Today the engineers at Dryden are still hard at work pushing the boundaries of the unknown. Additional notable projects are the F-16XL supersonic laminar flow project aimed at developing technology to help make a high speed civil transport aircraft more aerodynamically efficent and therefore more cost efficient. There is also the F-15 Advanced Control Technology for Integrated Vehicles--an attempt to improve the performance and maneuverability of aircraft and help private industry with thrust-vectoring engine technology. The Reusable Launch Vehicle research effort is exploring technologies designed to make access to space more efficient and economical. A final program of note is the Environmental Research Aircraft and Sensor Technology Program. This is a program attempting to develop remotely controlled aircraft capable of sustained, slow flight at high altitudes to gather currently unavailable information about our atmosphere.

F-16XL F-15ACTIVE CV-990
F-16XL F-15ACTIVE Tier_3: Darkstar

With each of these projects many new and complex problems arise. Such is the nature of the field of experimental aircraft. A good example of this is the role computers have played in this field. The emergence of computers has revolutionized aircraft design and made more capable ground test and simulation possible. For many modern aircraft, computer software is a necessity. This fact alone has created countless questions and possibilities regarding experimental aircraft. In August, 1996, NASA and the U.S. Air Force introduced a jet-powered aircraft equipped with state-of-the-art flight control technologies that demonstrated a computerized flight control system that learns as it flies. It is called the Low-Observable Flight Test Experiment (LoFLYTE). The experimental LoFLYTE aircraft will be used to explore new flight control techniques involving neural networks, which allows the aircraft control system to learn by mimicking the pilot. The aircraft is remotely piloted and has been designed to demonstrate that neural network flight controls are superior to conventional controls. Neural networks are computer systems that actually learn by doing. If all goes as planned, technologies being implemented in the LoFLYTE program could eventually find their way in to commercial, general aviation and military aircraft.

Experimental aircraft is a broad field. It captures the hearts and minds of aviation enthusiasts of many different levels. Whether it be the amateur homebuilder or the professional engineer conducting pioneering research on state-of-the-art equipment, it is a means by which the field of aviation evolves and advances. Today's research and discoveries will be continually improved upon as humans learn more about the concept of flight. Experimental aircraft are the essence of science and technology. Their presence and contributions to the field of aviation will be forever linked.

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