MIAMI – Airways explores ten of the rarest birds that have taken to the skies, a unique look at aircraft that highlight the remarkable evolution of flight.
There are the usual suspects: Bleriot XI. Boeing B-29. Mitsubishi Zero. Howard 500. Cirrus VK30. Lockheed PV-20 Harpoon. Antonov An-225 Mriya. For this list, we will take a look at other rare aircraft designs, including military and experimental, from around the world.
McDonnell XF-85 Goblin
The McDonnell XF-85 Goblin is an American prototype fighter plane designed by McDonnell Aircraft during World War II. It was designed to operate as a parasite fighter from the bomb bay of the massive Convair B-36 bomber.
The XF-85 was designed to protect bombers against enemy interceptor aircraft, a requirement that was shown during World War II. The Air Force (USAAF) halted the program after McDonnell completed two prototypes.
The XF-85 was a small jet plane with an unique egg-shaped fuselage and a forked tail stabilizer design. In 1948, prototypes were created and put through rigorous testing and assessment.
The design was promising in-flight testing, but the aircraft’s performance was inferior to that of the jet fighters it would have faced in battle, and docking proved problematic. The XF-85 was quickly shelved, and the prototypes were confined to museum collections.
During World War II, the Vought V-173 “Flying Pancake” was an experimental test plane created as part of the Vought XF5U “Flying Flapjack” program.
Both the V-173 and the XF5U had an unusual “all-wing” design with flat, disk-shaped hulls (thus the name) that served as the lifting surface. The propellers on the leading edge at the wingtips were driven by two-piston engines hidden in the fuselage.
The V-173 made its first flight on November 23, 1942, with Vought Chief Test Pilot Boone Guyton at the controls. The last flight of the V-173 was on March 31, 1947. Zimmerman’s notion of a fighter capable of near-vertical takeoff and landing has been validated in 131.8 hours of flight time over 190 flights.
Blohm & Voss BV 141
The Blohm & Voss BV 141 was a German tactical reconnaissance aircraft that was renowned for its unusual structural asymmetry during World War II.
Despite its good performance, the Blohm & Voss BV 141 was never ordered into full-scale production due to a lack of the selected engine and competition from another tactical reconnaissance aircraft, the Focke-Wulf Fw 189.
The pilot, observer, and rear gunner were placed in a Plexiglas-glazed crew gondola on the starboard side, similar to that seen on the Fw 189, while the fuselage on the port side ran smoothly from the BMW 132N radial engine to a tail unit. The weight placement appeared to cause a propensity to roll at first inspection; however, the weight was equally supported by lift from the wings.
The countering of generated yaw was a more involved affair in terms of thrust vs drag asymmetry. It was determined that it was primarily relieved at low airspeed due to a phenomenon known as P-factor, and at standard velocity, it was readily controlled by trimming.
The Stipa-Caproni, also known as the Caproni Stipa, was an Italian experimental vehicle developed in 1932 for the Italian Air Ministry by Luigi Stipa was one of the strangest-looking aircraft ever. To improve the efficiency of the aircraft’s engine, it had a hollow barrel-shaped fusselage with the engine and propeller within, acting as a large Venturi tube and increasing lift by 37 percent.
The Stipa-Caproni was found to be significantly quieter than other planes of the period. Unfortunately, the “intubed propeller” design created so much aerodynamic drag that the engine efficiency gains were negated, and the aircraft’s max speed was just 131 km/h.
The prototype flew several times from Taliedo and Guidonia airports, was simple to operate, but not suitable for serial manufacture, and was forgotten. This kind, on the other hand, was a significant step forward in the development of jet propulsion. The abilities learned with it were eventually used to the design of the Caproni Campini N-1, for example.
Douglas X-3 Stiletto
The Douglas X-3 Stiletto was a 1950s experimental jet aircraft built by the Douglas Aircraft Company with a narrow fuselage and a long tapered nose. Its main goal was to look into the design characteristics of an airplane capable of sustained supersonic speeds, which included the first usage of titanium in critical airframe components.
The Douglas X-3 Stiletto was the sleekest of the early experimental planes, but its scientific achievements were not as expected. The X-3 was meant to reach a top speed of over 2,000 m.p.h., but it was woefully underpowered for the job and could not even achieve Mach 1 in level flight.
Despite the failure of the research aircraft, Lockheed designers used data from the X-3 experiments to develop the Lockheed F-104 Starfighter, a successful Mach 2 fighter with a trapezoidal wing shape.
Bartini Beriev VVA-14
The Bartini Beriev VVA-14 Vertikano-Vzletayushchaya Amfibiya (vertical take-off amphibious aircraft) was a Soviet wing-in-ground-effect aircraft designed in the early 1970s.
It was designed to be able to take off from the water and fly at great speeds over long distances, as well as do actual high-altitude flights while still being able to glide effectively just above the sea surface using the aerodynamic ground effect.
The VVA-14 was created by Robert Bartini, an Italian-born designer, in response to a perceived need to destroy US Navy Polaris missile submarines. The last plane was decommissioned in 1987.
Avro Canada VZ-9 Avrocar
The Avro Canada VZ-9 Avrocar was a VTOL aircraft created by Avro Canada as part of a top-secret US military project during the Cold War’s early years. The Avrocar planned to use the Coandă effect to generate lift and thrust from a single “turborotor” that blew exhaust out of the disk’s rim. It would have looked like a flying saucer in the air.
Originally intended to be a fighter-like aircraft capable of extremely high speeds and altitudes, the project was continually cut back and finally abandoned by the US Air Force. The US Army then took up development for a tactical combat aircraft need, essentially a high-performance helicopter. T
he Avrocar was found to have unsolved propulsion and stability difficulties during flight testing, limiting it to a degraded, low-performance flying envelope; as a result, the project was shelved in September 1961.
The SNECMA C.450 Coléoptère (French for “beetle,” descended from Greek for “sheathed wing”) was a vertical take-off and landing (VTOL) aircraft developed by SNECMA and constructed by Nord Aviation. While construction on the plane went to the test flight phase, the project was never taken farther than that.
Several attempts to develop a feasible VTOL aircraft were made across the world in the 1950s, including the Coléoptère. The design was informed by SNECMA’s prior experiments with wingless test rigs known as the Atar Volant. The Coléoptère was a single-person aircraft with an innovative circular wing that allowed it to take off and land vertically, requiring no runway and very little space.
The single prototype, which took to the air for the first time in December 1958, was destroyed on its ninth flight on July 25, 1959. While there were plans to create a second prototype at one point, funding was never secured.
The NASA AD-1 was an aircraft and accompanying flight test program that successfully showed an aircraft wing that could rotate obliquely from zero to 60 degrees during flight between 1979 and 1982 at NASA Dryden Flight Research Center in Edwards, California.
The AD-1, a compact subsonic jet-powered research aircraft, was used to showcase the unusual oblique wing (Ames-Dryden-1). During the study phase, the aircraft was flown 79 times to assess the fundamental pivot-wing idea and collect data on handling qualities and aerodynamics at various speeds and degrees of pivot.
The AD-1 took to the air for the first time in late 1979. Over the next 18 months, the wing was gradually rotated until it achieved a full 60-degree angle in mid-1981. The aircraft was flown for another year, collecting data at various speeds and wing-pivot angles until August 1982, when it was finally retired.
The AD-1’s final flight took place during the Experimental Aircraft Association (EAA) annual exposition in Oshkosh, Wisconsin, where it was flown eight times to display its unusual design.
The Ling-Temco-Vought (LTV) XC-142 was a tri-service tiltwing experimental aircraft meant to test the operational feasibility of V/STOL transports.
On September 29, 1964, an XC-142A made its first conventional flight, and on January 11, 1965, it made its first transitional flight by lifting off vertically, converting to forward flight, and landing vertically. Its service sponsors dropped out one by one, and the initiative was finally canceled owing to a lack of interest after effectively showing its capabilities.
The aircraft “modified” for V/STOL operations by tilting its wing to the vertical. During hover, differential clutching of the propellers provided roll control, while the ailerons in the airflow supplied yaw control. The aircraft had a separate tail rotor that was positioned horizontally to lift the tail, rather than the more common anti-torque rotors on helicopters that are positioned vertically, for pitch control.
To avoid being damaged during loading, the tail rotor was folded against the tail when on the ground. In order to hover in a tailwind, the wing could be rotated to 100 degrees, past vertical.
Featured image: NASA AD-1 overhead view. Photo: NASA, Public Domain. Article sources: Allen, Francis (Winter 1993). “The Ultimate Escort?: McDonnel XF-85 Goblin”. Air Enthusiast. No. 52; Naval Fighters Number Twenty One Chance Vought V-173 and Xf5U-1 Flying Pancakes. Steve Ginter. 1992.; Green, William. Warplanes of the Third Reich. London: Macdonald and Jane’s, 1979; Guttman, Robert (March 2010). “Caproni Flying Barrel: Luigi Stipa Claimed His ‘Intubed Propeller’ Was the Ancestor of the Jet Engine”. Aviation History; Hartman, Edwin Phelps (1 January 1970). Adventures in Research a History of Ames Research Center 1940-1965. University of California Libraries; Russia’s Amphibious Aircraft: The Bartini Beriev VVA-14; “Avrocar: Saucer Secrets from the Past”. Winnipeg: MidCanada Entertainment. 2002. Archived from the original on 4 August 2006; Buttler, Tony & Delezenne, Jean-Louis (2012). X-Planes of Europe: Secret Research Aircraft from the Golden Age 1946-1974. Manchester, UK: Hikoki Publications; AD-1 Construction Completed, Dryden X-Press, February 23, 1979; Norton, Willam (2006). VOUGHT / HILLER / RYAN XC-142A TILTWING VSTOL TRANSPORT. Air Force Legends. Nº213 (First ed.). California, United States: Ginter Books.