Type: all-composite canard homebuild
Powerplant: 1 x 100 hp Continental C85 or O-200 (typical)
Significant date: 15 March 1976
After the Model 31 VariEze prototype was successfully built and test-flown, setting a distance record in its first months of existence, it aroused considerable interest with homebuilders. Consequently, Burt Rutan introduced the improved Model 33 VariEze prototype, registered as N4EZ. This new aircraft used a Continental O-200 aircraft engine, giving it more horsepower, faster speed and longer range. It also featured a larger wing, and many other detail changes. Two separate Model 33 prototypes were built by the Model and Composites Section of NASA's Langley Research Center and then tested in the 30 x 60 Full Scale Tunnel. This led to improvements that were implemented in Rutan's kitplane version. The Model 33 was shown at Oshkosh in 1976, and plans were offered in July 1976 to amateur/home aircraft builders.
While resistant to pitch departures, a few builders discovered a potential for a novel lateral departure mode resulting from one winglet stalling at large sideslip angles. An outer wing leading edge droop (or vortilons on some examples) was added to alleviate this problem, and rudder travel was reduced. The design's stall resistance did not appear to translate to a lower accident rate than other homebuilts; a review of the NTSB database from 1976 to 2005 shows 130 total accidents and 46 fatal accidents out of a fleet of about 800 (691 registered in 2005).
The prototype N4EZ had approximately 700 flying hours before being donated to the museum Mid-America Air Museum in Liberal, Kansas, where it is currently exhibited. The Varieze is notable for popularizing the canard configuration and moldless composite construction for homebuilt aircraft. Approximately 2000 aircraft were under construction by 1980, with about 300 flying by late 1980.
Some time circa 1978, Rutan gave a series of canard design seminars to the Air Force Flight Dynamics Lab at Wright Patterson Air Force Base, Ohio. They had a VariEze built to use as a flight test platform for some RPV avionics, with a pilot in the back seat and a lot of test gear in front. The whereabouts of that aircraft are unknown, but its specifications remind one of the VZ-10 used by the Air Force's OPFOR.
Several other versions were customized by the homebuilders, leading to variants designated Airsport EZ (a.k.a. VariEze O-235) [N49LK, etc.], VariEze Turbo II, DAV-EZ [N7CE], or VariEze 1 [N69EZ] and others. However, it is rarely unsafe to tinker with a Rutan design without precautions, which resulted in many accidents in the past, and might explain quite a few crashes in these alternate versions. Of course Burt Rutan has never encouraged, least of all endorsed, any of these modifications, and every builder does it at his own risk without RAF being in any way liable for mistakes. As an aside, and though there never was a flying jet-powered variant of the VariEze, a static one is currently on exhibit at the Cradle of Aviation Museum in Long Island, hanging in the Red Planet Café area, only for decoration purposes.
Burt Rutan then took the "Eze" design one step further by designing a long-range version of the VariEze, with more room, more fuel, and more payload, designated the Model 61 Long-EZ. Like the VariEze, the Long-EZ was a hit with homebuilders. Several thousand VariEzes and Long-EZs are flying or under construction around the world, and more VariEze's and LongEze's were constructed than any other homebuilt type of that ear. Plans sales ceased in 1985 when RAF ceased all homebuilt-related activity. As for the prototype N4EZ, it is currently on exhibit at the Smithsonian institution.
Besides their innovative canard designs, the VariEze and Long-EZ introduced many homebuilders to composite construction—a sandwich of rigid polyfoam skinned with fiberglass. While Rutan did not invent composite construction, he refined the techniques for homebuilding and commercial manufacturing of composite aircraft structures. His designs and construction techniques helped make it possible for amateur builders to produce safe, fast, good-looking, and economical sport aircraft.
Population: 1 prototype (c/n 002) [N4EZ]