Fiberglass Cloth, Rutan VariEze

Burt Rutan transformed the whole approach to the traditional design and construction of homebuilt aircraft when he began selling plans to build the VariEze ('very easy') during summer 1976. Propelled by a 100-horsepower engine, a VariEze, built to Rutan's specifications, could carry two adults for about 1,127 km (700 miles) at approximately 290 kph (180 mph). Loaded light without a passenger and only an hour of fuel on board, most VariEzes can climb at 608 m (2,000 ft) per minute and operate at altitudes near 7,600 m (25,000 ft). Rutan sold 4,500 plan sets by the end of 1979 and two hundred VariEzes were flying by 1980. James O. Eggleston generously donated this collection of VariEze components to the Museum in 1989. It consisted of foam blocks, fiberglass cloth, a preformed, one-piece canopy, miscellaneous hardware, landing gear struts, an assembly manual, and other parts.

Burt Rutan transformed the whole approach to the traditional design and construction of homebuilt aircraft when he began selling plans to build the VariEze ('very easy') during summer 1976. Propelled by a 100-horsepower engine, a VariEze, built to Rutan's specifications, could carry two adults for about 1,127 km (700 miles) at approximately 290 km/h (180 mph). Loaded light without a passenger and only an hour of fuel on board, most VariEzes can climb at 608 m (2,000 ft) per minute and operate at altitudes near 7,600 m (25,000 ft). The VariEze had other important attributes besides performance that appealed to many individuals who wanted to build their own airplanes. The aircraft looked exotic and unusual but-aisde from the airframe layout and the structural composition-the airplane was mechanically simple and orthodox. The builder with average mechanical skills could construct a VariEze quickly and inexpensively, compared to many homebuilt aircraft designs, and the airplane was economical to fly and maintain. Rutan sold 4,500 plan sets by the end of 1979.

Rutan's canard layout was visually striking but its purpose went beyond aesthetics. On canard airplanes, horizontal surfaces used for trim and control are mounted forward of the main lifting surface. According to Burt Rutan, the canard configuration had advantages over more conventional aircraft. It allowed him to design airplanes that a pilot could not stall so aggressively as to lose control of the aircraft. A canard configuration in the VariEze also allowed Rutan to use very short control linkages and made the airplane safer to fly.

Neither the two prototypes, nor the first VariEzes built from plans, used conventional ailerons mounted on the aft wing. Rutan opted to use only elevons attached to the canard. Elevons are both elevators that control pitch and ailerons that control roll, combined into one control surface. By using only elevons, the VariEze was simplified and easier to build.

Rutan had begun to study and experiment with canard aircraft designs in 1963. He built and flew a radio-controlled flying model canard a year later while finishing his junior year at California Polytechnic University, San Luis Obispo. He later earned his Masters degree in Aeronautical Engineering. Rutan's line of man-carrying canard aircraft began with the VariViggen. In 1968 he started to build this all-wood airplane and he first flew it during April 1972. Rutan's VariViggen bears more than an accidental resemblance to a Swedish military jet fighter, the SAAB J-37 Viggen, which first appeared during a press preview in 1965 and helped to inspire Rutan to create a canard airplane of his own design. "I wanted an aircraft for myself," Rutan recalled later, "as close to a modern fighter as possible - something like the F-104 or the F-4 [both in NASM's collection]. I wanted a big [control] stick, an array of buttons, high rate of roll-a real 'macho machine'-where I'd really feel like I was flying a century-series fighter."

Late in 1974, Rutan began to work on the VariEze. He had already aborted another offshoot of the VariViggen called the MiniViggen which was to have been an all-aluminum canard aircraft with a high wing and a horizontal stabilizer and elevator mounted low at the nose. Testing with models in a wind tunnel and atop an automobile fitted with instrumentation forced Rutan to scrap the MiniViggen as unstable and too costly, expensive, heavy, and difficult to rebuild into various experimental configurations. Rutan now focused on building a canard aircraft out of foam and fiberglass.

Before he began building the prototype VariEze (identified as N7EZ), he spent many hours studying the surface finish and construction details on high-performance European sailplanes. Craftsmen built these aircraft using foam cut to shape and then covered with fiberglass and glue. Ironically, Rutan selected a less complex and less expensive variation of this 'composite' construction method to build the first VariEze because it allowed him to change the airframe quickly. He could move a wing or control surface to different positions on the fuselage, testing various configurations more quickly. Radically altering a metal airframe for testing would have slowed the work tremendously. Rutan did not decide to market the VariEze as a composite airplane made of foam and fiberglass until some time after the prototype had flown.

To the canard configuration, Rutan added winglets to both wingtips. Richard Whitcomb, an aerodynamics specialist at the National Aeronautics and Space Administration (NASA), had developed this technology during the 1950s. Winglets decreased drag to boost climb rate and cruise speed. On the VariEze, Rutan made the winglets perform double duty as vertical stabilizers and rudders to control yaw. Rutan was eager to use N7EZ to explore further the performance of the canard layout. He reasoned that by breaking the world speed records for airplanes of the VariEze weight class (less than 500 kg/1,102 lb), he could fine-tune his canard design, and prove that a properly designed canard aircraft could outperform a conventional aircraft.

The first VariEze was ready after Rutan, his wife, Carolyn, and several friends worked for nearly four months. The aircraft flew in May 1975 and was powered by a Volkswagen engine modified for use in aircraft. Three months later, the VariEze appeared at the annual Experimental Aircraft Association Convention and Fly-In held at Oshkosh, Wisconsin, in August 1975. Don and Julia Downey call what followed the "Rutan Revolution."

The VariEze was so popular at Oshkosh that Burt immediately began to work on designing a VariEze specifically for homebuilders. He and his team built the second VariEze (N4EZ, see NASM collection) during winter 1975. At a glance, N4EZ is a duplicate of N7EZ but Rutan actually redesigned the second airplane to accept a heavier, more reliable Continental A-75 engine. Every dimension changed. For example, wing area increased from 5.3 sq m (59 sq ft) to 6 sq m (67 sq ft). Rutan redesigned the canard, as well, and employed a new airfoil for this wing that aerodynamics specialists had developed at the University of Glasgow.

Rutan began working on this airplane in December 1974 and first flew it in March 1976. During the construction, Rutan could not locate a suitable A-75 power plant, so he chose to use a Continental 0-200. This motor weighed about 13.5 kg (30 lb) more than the A-75, so Rutan added 4.5 kg (10 lb) of ballast to the nose.

Rutan began publishing plans in July 1976 and the first homebuilt VariEzes began to fly less than a year later in March. At that time, it was rare indeed for builders to go from a set of plans to a flying, high-performance airplane so quickly. The key to such rapid construction lay in Rutan's choice of composite construction. To build the composite, fiberglass/foam/fiberglass sandwich structure, the builder used a hot-wire cutter to slice the foam core to shape, then cover the core with epoxy resin and fiberglass cloth cut precisely to maintain strength at minimum weight.

When the homebuilders began to fly their VariEzes, two problems immediately surfaced that involved weight and control of the airplane. Rutan surveyed the builders in April 1978 and discovered that the average, finished airplane was 14-23 kg (30-50 lb) heavier than specified in the plans. Some builders had disregarded Rutan's fundamental design philosophy-the idea of a simple, lightweight aircraft equipped to operate in daylight and clear weather. These builders had added heavy instrument packages to fly at night and in bad weather. In turn, this equipment required more complex, and heavier, electrical systems. Some VariEzes weighed so much that they could not safely carry a passenger.

The control issue was a serious problem that demanded a lot of intense work to fix quickly. Considerable precision was required to build the correct incidence and twist into the aft wing. Several builders reported that the first flights in their airplanes had required full roll input to maintain a wings-level attitude. Error in wing incidence and twist were overpowering the elevons mounted on the canard. Rutan decided to redesign the rear wing to incorporate ailerons but to keep the elevator control in the canard. He and his team completed this herculean task in about two weeks and rushed the changes to anxious builders.

Despite these difficulties, the VariEze became extremely popular and Rutan eventually sold about 3,000 sets of plans. Two hundred VariEzes were flying by 1980. In 1985, Rutan decided to stop selling plans for all Rutan airplanes. He had recently started a new company, Scaled Composites, but the effort required to run firms had quickly become onerous and Rutan reluctantly chose to terminate sales of plans to homebuilders. The Rutan Aircraft Factory continued to assist builders laboring on projects under way at the time of this decision. James O. Eggleston generously donated this kit to the Museum in 1989. It consisted of foam blocks, fiberglass cloth, a preformed, one-piece canopy, miscellaneous hardware, landing gear struts, an assembly manual, and other parts.

References and Further Reading:

Cox, Jack. "VariEze Update," "Sport Aviation," April 1977.

Downie, Don and Julia. "The Complete Guide to Rutan Aircraft." Blue Ridge Summit, Penn.: TAB Books, 1987.

Gray, Bob. "The Canard Phenomenon," "Kitplanes," September 2000.

Rutan, Burt. "Reflections on Glass - VariEze - Designer's First Report," "Sport Aviation," January 1976.

____. "Tale of the Three EZ's: The Story of the VariEze and Long-EZ Aircraft," "Sport Aviation," February 1980.

Russ Lee, 9-3-04