Type: experimental all-composite canard homebuilt
Powerplant: 1 x 62 hp VW 1834-cc engine conversion or 49 hp Franklin 2A4 series
First flight: 21 May 1975
Burt Rutan was already well-known among experimental aircraft enthusiasts for his VariViggen—a two-place homebuilt design based loosely on the Saab 37 Viggen jet fighter— when the Model 31 Varieze (“very easy”) prototype made its public debut in 1975. The VariEze was a fairly high-performance homebuilt all-composite canard aircraft which used a Volkswagen engine conversion. Rutan's stated goals for the design included reduced susceptibility to departure/spin and efficient long range cruise; these goals were achieved. The use of a canard configuration allowed a stall resistant design, at the price of somewhat increased takeoff and landing speeds and distances relative to a similar conventional design with effective flaps. Burt Rutan also refered to the aircraft as the "Glass Backwards" since it was a fiberglass plane where the front canards could move backwards sort of like the streamlined shape of a diving hawk wing (a feature which was later implemented in the Beechcraft Starship design).
Rutan selected an innovative "composite" construction method to build the prototype. In the design and development phase, this allowed Rutan to make quick changes to airframe configurations. For homebuilders, it later proved to be a wonderfully simple and safe construction technique. The "tail first" canard layout was visually striking, but its purpose went beyond aesthetics. It allowed Rutan to design airplanes that a pilot could not stall so aggressively as to lose control of the aircraft.
To the canard configuration, Rutan added winglets to both wingtips, which decrease drag to boost climb rate and cruise speed. Richard Whitcomb (an aerodynamics specialist at NASA) had developed the theory of this technology during the 1950s, but it had never been put into practice. On the VariEze, Rutan made the winglets perform double duty as vertical stabilizers and rudders to control yaw.
The Model 31 first flew on May 21, 1975. Rutan originally intended to use the prototype (registered N7EZ) only as an aerodynamics research aircraft for testing canard designs and configurations, but later that year, the prototype was shown at the 1975 EAA Oshkosh Fly-In, where Dick Rutan piloted it to an under 500 kg class world closed-course distance record of 1,638 miles, flying for 13 hours, 8 minutes, and 45 seconds, on 40 gallons of fuel.
Innovative construction and design, plus spectacular performance, made the VariEze a sensation. The new airplane attracted so much positive interest there that Rutan designed and built a slightly larger, more powerful version and offered plans for sale. This was the very popular Model 33 VariEze homebuilt, hundreds of which have been constructed.
Both the Models 31 and 33 prototypes flew originally with elevons on the canard for both pitch and roll control, but the design was changed to pitch control with the canard elevators and roll control with mid span wing ailerons after a few aircraft were built. The design later evolved into the Model 61 Long-EZ and other, larger cabin canard aircraft. Within four years of the appearance of N7EZ, about 4,500 plan sets had been sold.
The Model 31 is believed
in history to fly with winglets.
that a properly designed canard aircraft could outperform a conventional
aircraft. After being owned by Dick Rutan for a number of years and
refitted with a less-powerful Franklin engine, it was eventually donated
to the EAA Museum.
Population: 1 (c/n 001) [N7EZ]