Design Innovation and Purpose
Steve Wittman conceived the W-5 Buttercup in 1937 as more than just another light aircraft—he intended it as a technological demonstrator that would surpass contemporary designs like the Piper Cub, Aeronca Chief, Taylorcraft, and Luscombe. The aircraft's most revolutionary feature was its variable camber wing system, incorporating full-span leading edge slats and slotted trailing edge flaps that allowed pilots to modify the wing's shape for optimized performance at different flight phases. This technology, considered futuristic in 1938, would later become standard on high-performance military and commercial aircraft.
Wittman completed construction of his prototype in 1938, creating an aircraft that weighed just 690 pounds empty but could carry a maximum takeoff weight of 1,390 pounds. The tapered rod landing gear design contributed to the aircraft's clean aerodynamic profile, helping achieve its impressive 145 mph maximum speed—substantially faster than most light aircraft of the period.
Commercial Interest and Production Prospects
The Buttercup's performance capabilities caught the attention of Fairchild Aircraft when Wittman made an unplanned landing at their Hagerstown, Maryland facility. Impressed by the aircraft's advanced design and performance, Fairchild executives negotiated with Wittman to license the design for development into a four-place certified production model. Wittman sold the production rights to Fairchild, anticipating that his experimental design would evolve into a commercially successful light aircraft.
However, World War II intervened before Fairchild could pursue production. The company's wartime obligations to manufacture military aircraft prevented development of the civilian Buttercup variant, and the design never entered commercial production. This represented a significant missed opportunity, as the Buttercup's advanced features might have established new standards for general aviation aircraft in the post-war boom.
Steve Wittman: Designer and Builder
Steve Wittman was not a traditional aircraft manufacturer but rather an individual designer-builder whose innovative approach to aircraft design spanned decades. Beyond the Buttercup, Wittman created multiple aircraft designs including the Big X in 1945, the Tailwind series, the Bonzo, and the V-Witt. His work demonstrated that individual innovators could develop aircraft designs rivaling those produced by major manufacturers.
Wittman remained active in aviation throughout his life, using the original Buttercup to provide Young Eagles flights in his later years. He continued performing aerobatic demonstrations well into his nineties, showcasing the enduring capabilities of his 1938 design. The National Aviation Hall of Fame recognized his contributions by inducting him posthumously in 2014.
Technical Specifications and Performance
The Continental C-85-12F engine that powered the Buttercup was a four-cylinder horizontally opposed piston engine producing 85 horsepower from 188 cubic inches of displacement. This powerplant, reliable and lightweight, was commonly used in light aircraft of the era and provided the Buttercup with a cruise speed of 123 mph and excellent fuel economy from its 29-gallon fuel capacity.
The aircraft's 20-foot, 3-inch length and 5-foot, 9-inch height created a compact profile, while the 30-foot wingspan provided adequate lift area for the variable camber wing system to function effectively. The slats and flaps allowed pilots to reconfigure the wing for maximum lift during takeoff and landing, then retract them for higher cruise speeds—a level of sophistication unusual in light aircraft of the period.
Legacy and Influence
The Buttercup's design philosophy directly influenced Wittman's later creation of the Tailwind series, which became one of the most successful homebuilt aircraft designs. The Tailwind incorporated lessons learned from the Buttercup's five decades of service as Wittman's personal test bed, and kit versions remained in production through at least 2020.
Earl Luce Jr., an Experimental Aircraft Association member, developed replica Buttercup plans that first flew in 2002, making the design available to homebuilders for the first time. Tragically, Luce and a passenger died in a crash while flying his Buttercup replica over Orleans County, New York in May 2023, at age 70.
Museum Preservation
The original 1938 Wittman W-5 Buttercup, serial number 5 with registration N18268, is permanently housed at the EAA AirVenture Museum in Oshkosh, Wisconsin, specifically at Pioneer Airport. The aircraft was donated by the estate of Steve and Paula Wittman, ensuring that this unique example of 1930s aviation innovation remains preserved for future generations to study and appreciate. The museum display allows visitors to examine the advanced wing design features that made the Buttercup a significant step forward in light aircraft development.