Stout Batwing

The Stout Batwing was a low aspect ratio flying wing aircraft designed by William Bushnell Stout. The aircraft was the first example of wood veneer construction on American aircraft and an early practical example of "thick wing" or blended wing fuselage design. The internally braced wing was also one of the first American aircraft designed without drag-producing struts. The "thick wing" design would later be applied to a series of Stout aircraft leading to the Ford Trimotor.

Development

During World War I, William Bushnell Stout was employed by Packard in 1917 when he was appointed as a technical advisor to the War production board. The board gave Stout a contract to develop a blended-wing body aircraft. Funded by the Motor Products Corporation, Stout developed the "Batwing" aircraft with the intent to market the aircraft to the United States Army Air Service.^[1] Stout first experimented with an all-wood flying wing design with a glider design, the "Batwing Glider", tested at Ford Airport in 1926.^[2] Stout's design was nicknamed "Bushnell's Turtle" (a reference to the unrelated David Bushnell's American Turtle shape).^[3]

Design

The blended-wing Batwing was designed to have all surfaces of an aircraft used to provide lift, eliminating the added drag of a conventional fuselage. This concept is applied to all flying wing aircraft. The Batwing differed slightly with the addition of a set of horizontal stabilizers at the rear of the aircraft for stability.

The aircraft was an early example of wood-veneer aircraft construction. The wings were covered with a 3 ply wood veneer only 1/20th of an inch thick. The internal bracing consisted of hundreds of spruce struts. Nine spars tested to 1 ton of load each.^[4] Bill Stout developed the all-metal Ford Trimotor shortly after Anthony Fokker brought his all wood Fokker Trimotor, "Josephine Ford" to Ford field. Stout went on to promote all-metal over wood construction, despite the Batwing being a pioneer in veneer aircraft construction.^[5]

To reduce drag, the aircraft employed a cantilever wing without support wires or struts. This required a "thick" wing to build a spar strong enough to support the aircraft. To maintain the shape of the wing, the chord also had to be longer as the wing became thicker. In the case of the Batwing, the chord was the entire length of the aircraft. Since the spar did not need to be as thick toward the tips to support the load, the chord decreased further out along the wing, forming an oval shaped wing. As ideal as this was, it caused significant engineering challenges maintaining the center of pressure on the aircraft.^[6] Further aerodynamic drag reductions came from having the water-cooled engine embedded into the wing with retractable radiators.^[7]

The pilot sat in an open cockpit placed at the top of the aircraft. Visibility was restricted downward by the placement. The Batwing was the first example of a cantilevered wing and veneer skin in the United States.^[8]

Operational history

The mockup of his first thick winged aircraft design was built at the Widman woodworking plant in Detroit, Michigan. The 150 hp engine was acquired from Charles Warren Nash who had a budding interest in the project.^[9] The first flight was in Dayton, Ohio in 1918. The pump shaft on the engine was broken, but the plane was flown anyway. Although the flight was successful, the test pilot Jimmie Johnson commented that the aircraft was too dangerous to fly because of the limited visibility. Stout later called the visibility "abominable". The test aircraft was put into storage. Soon afterward, Stout submitted British patent #149,708, with a Batwing aircraft with the corners squared off rather than the oval design of the prototype. The updated aircraft was never produced. Stout went on to focus on more conventional aircraft featuring the advancement of all-metal construction, but continued to maintain the plane of the future will look like the batwing.^[10]

Variants

Stout drew up plans for a scaled-up version of the Batwing, with a 100-foot wingspan. The larger aircraft would have solved the visibility issues, but did not get past the planning stage. The all-metal "Batwing 11" was publicized as being capable of 200 mph with a forty-foot wingspan and magnesium construction.^[11]

Stout also used the term "batwing" in the name of future aircraft that used cantilever wings.

Specifications of the Stout Batwing

Data from SAE Dec 1922

General characteristics

• Wingspan: 20 ft (6.1 m)
• Wing area: 480 sq ft (45 m²)
• Empty weight: 1,542 lb (699 kg)
• Powerplant: 1 × Hispano-Suiza 8 V-8 water-cooled piston engine, 150 hp (110 kW)

Performance

See also

Related development

• Stout Batwing Limousine

Aircraft of comparable role, configuration and era

• ARUP S-4

References

Wikimedia Commons has media related to Stout aircraft.