Weird Wings: From the BV 141 to the Grumman X-29
There’s an old aviation saying: “If an airplane doesn’t look right, it won’t fly right.” That doesn’t stop aircraft designers, often with government support, from developing aircraft that don’t look right. Most don’t get past the drawing board stage, but there are a few that are built and fly. Often times it causes many to ask, why? In many cases, it’s changing requirements rather than the odd design that puts an end to these strange aircraft.
Blohm und Voss BV 141
In 1937, the Reichsluftfahrtministerium (RLM) issued a specification for a short-range reconnaissance aircraft capable of fulfilling the light bomber, low-level attack and smokescreen-laying roles. While Dr. -Ing. Richard Vogt decided to develop an aircraft as a private venture. Dr. Vogt’s design was to get around the problem single engine aircraft had with obstructing visibility.[i]
There wasn’t much interest in Dr. Vogt’s design. Ernst Udet, the chief of the Technischen Amt, Development Section did give Dr. Vogt some encouragement.[ii] The resulting asymmetric design was the Ha 141-0. It made the first flight on February 25, 1938. The aircraft’s flying characteristics were good. Ernt Udet was one of those who test flew the aircraft. A contract was put in for three prototypes. Ha 141-0 was re-designated the Blohm und Voss BV 141 V2.[iii]
The aircraft’s fuselage housed the engine. The crew compartment was a nacelle on the starboard wing. The initial crew nacelle was deemed unacceptable so it was redesigned. The BV 141 V1 began flight trials in September 1938. V1 had a mishap on October 5. The BV 141 V3 was also available so V3 continued the flight tests.[iv]
The RLM had to admit the aircraft met specifications and had good handling characteristics. The RLM ordered five pre-production aircraft, the BV 141 A. flight tests of the A series began on January 1940. On February 14, 1940 the RLM approved the BV 141 B design. Among the changes the B series had an asymmetric tailplane. Most of the horizontal stabilizer was on the aircraft’s port side. The Luftwaffe convinced the RLM to cancel plans for the BV 141 production on April 4, 1940. [v] The BV 141 B-0 made its first flight on January 9, 1941. The B series had many technical difficulties. The Blohm und Voss delivered the last BV 141B on May 15, 1943.[vi]
[i] [ii] [iii] [iv] [v] [vi] The Warplanes of the Third Reich, by William Green © 1970.
Vought V-173 "Flying Pancake"
A popular concept in World War II was an all wing aircraft. The Vought V-173 got its nickname, Flying Pancake, because its wing was flat and circular. The V-173 was a proof-of-concept design. Designer Charles Zimmerman believed an aircraft with propellers at the wing tip and a uniform airflow an aircraft could have excellent performance and the ability to land at very low speeds. These are good characteristics for a carrier aircraft.
Vought made a proof-of-concept aircraft, the V-173. The Vought V-173 made its first flight on November 23, 1942. This aircraft underwent 131-hours of flight testing in 199 flights. Vought’s experimental pilot Boone T. Guyton made 54 flights in this aircraft. Charles Lindbergh also made a flight in the V-173.[i] It had unusual but controllable flight characteristics. The aircraft had several forced landings with little damage to the aircraft or pilot.[ii] During flight testing some people reported the V-173 as an Unidentified Flying Object (UFO). With the dawn of the jet age the V-173 had little purpose and the U.S. Navy canceled the contract in 1947.
[i] Vought.org, http://www.vought.org/products/html/v-173.html, last accessed 4/23/20.
[ii] The National Air & Space Museum, Vought V-173 “Flying Pancake”, https://airandspace.si.edu/collection-objects/vought-v-173-flying-pancake/nasm_A19610120000, last accessed 4/23/20.
Junkers Ju 287
In June 1943 the Germans needed a jet bomber that was faster than the Ar 234 Blitz. A Junkers design had four turbojets and swept-back wings. Swept back wings had low-speed stability problems. The designers attempted to get around the problem by sweeping the wings 25 degrees forward. The RLM ordered the first prototype of this aircraft, the Junkers Ju 287, in March 1944. Since the initial trials were to test the low-speed stability the Ju 287 had fixed landing gear.
The first flight took place on August 16, 1944. The Ju 287 flew well at low speed but there were indications of wing twisting. There was an upward twisting of the wingtips and leading edges in a fast climb. This would cause the aircraft to nose up more than desired.[i] In March 1945 Junkers received a production order for 100 Ju 287s by September 1945. Soviet forces captured the existing prototypes and conducted tests on the aircraft until 1948. The second prototype was fitted with swept-back wings and reportedly attained a speed of 1,000km/hr. (621 mph). [ii]
[i] [ii] German Jet Genesis by David Masters, © 1982, P. 101.
The swept-forward wing had many theoretical advantages but a high performance swept-forward wing aircraft would be unflyable. In the 1980s composite materials, fly-by-wire, and other on-board computer capabilities made a supersonic swept-forward wing aircraft feasible.[i]
This resulted in “the most aerodynamically unstable aircraft ever built” [ii], the Grumman X-29. The X-29 made its first flight on December 1984. Two X-29s were built. The National Aeronautics and Space Administration (NASA) and the U.S. Air Force (USAF) jointly developed these aircraft. The USAF acquired these aircraft and from March 1985 to April 1990 made 279 test flights. The USAF decided stealth was more important than maneuverability so a swept-forward wings fighter never came into being. Other advanced technologies of the X-29 were incorporated into modern military aircraft. [iii]
[i] [ii] [iii] DARPMA, X-29, https://www.darpa.mil/about-us/timeline/x29, last accessed 4/28/20.
This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.
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