Chance Vought V-173

Chance Vought V-173
Type:	Experimental airplane
Design country:	United States
Manufacturer:	Chance Vought
First flight:	November 23, 1942
Number of pieces:	1

V-173 in a state of construction without landing gear fairing

The Chance Vought V-173 was an experimental extremely short takeoff (ESTOL) aircraft made by the US manufacturer Chance Vought in the 1940s. The unofficial nickname Flying Pancake comes from the unusual structural design as a circular wing aircraft . The V-173 was to serve as a test vehicle for the Chance Vought F5U fighter aircraft project .

history

prehistory

The machine was designed by Charles Horton Zimmerman, a NACA engineer who developed a wind tunnel for free-flying test models in Langley Field in the early 1930s . For a design competition announced by the NACA in 1933, Zimmerman developed a disk plane that was supposed to reach both high speeds and have the ability to hover, and thus won the competition. However, the NACA rejected any practical use of the idea on the grounds that it was too "advanced". Zimmerman developed his concept further and built u. a. a man-carrying wooden model with two French 25 hp Cleone engines. However, he gave up the project because it failed to synchronize the two motors.

In 1937 he switched to Chance Vought after convincing Eugene E. Wilson, President of the United Aircraft Corporation, of his idea. Here he built an electrically powered tethered flight model called the V-162. Due to the good results, the US Navy was also interested in this and made research funds available. An unusual peculiarity of the model was that the rear quarter of the "fuselage" together with the two vertical stabilizers, pivoted via pivot points, was supposed to serve as a horizontal stabilizer.

Prototype construction

Two years after he started working at Vought, construction work, production drawings and aerodynamic studies were completed with the help of Navy funds to the point that a prototype (V-173, BuNo 02978) could be built. To save weight and money, the entire wing was covered with fabric. The drive of the 1360 kg aircraft consisted of two Continental A-80 engines with 80 HP each. The three-bladed propellers had a diameter of 5.03 m, which meant that the aircraft with its long-legged fixed landing gear was at a steep angle of 22 degrees to the ground. A symmetrical NACA 0015 profile was used for the wing without V-position and offset . The high wing loading with the underpowered represented the biggest drawbacks of the design. For the projected fighter F5U , which should be based on the test vehicle V-173, were propeller blades with hub joints, similar to those used in helicopters strike joints , provided both a hover as to make a top speed of 800 km / h (500 mph) possible even with the corresponding more powerful engines.

The original concept envisaged a design without a horizontal stabilizer, instead two ailevators in the middle at the end of the fuselage should take over this function. However, wind tunnel tests showed that their effectiveness would be insufficient, particularly at low speeds and high angles of attack . Instead, a flying tail elevator was used for the first time , which was then also used on the XF5U-1 and is still used on most high-speed aircraft today.

testing

Boone T. Guyton carried out the first flight , which lasted 13 minutes, on November 23, 1942 from the works airfield in Stratford (Connecticut) . It showed a very poor response to control commands. Even with the low engine power, the V-173 managed in calm conditions with a take-off distance of 60 m, with 25 kt. Headwind was even possible to start from a standing start. Wind tunnel investigations with the machine in Langley Field showed that the high induced drag of the wing, which has an extremely low aspect ratio, was largely canceled out by the interaction of the large, counter-rotating propellers with the tip vortices, which are far in front of the leading edge of the wing.

Guyton carried out 54 test flights, the biggest problem being the vibrations that were felt in the cockpit. This was due to resonance vibrations between the propellers and the associated nacelle structure, which formed the casing and bearing of the drive shaft. Vibration dampers attached to the propellers brought some improvement. The problem did not arise with the XF5U-1, as specially shaped propeller blades were used here, which prevented an asymmetrical flow at high angles of attack. Guyton was able to maintain full control of the machine up to an angle of attack of 45 degrees. A complete stall could practically not be achieved, the sharp decrease in speed in tight curves was striking, which made this design appear particularly suitable for aerial battles.

After the first 13 flights, Guyton was so seriously injured in an accident with an F4U Corsair that Richard Burroughs had to take over the test program for a while. Charles Lindbergh conducted Flight 34 and many Navy pilots flew the V-173 as well. During the test, the machine was involved in a few incidents, but all of them took place without major damage to material and people. This included, for example, a flight demonstration in 1947 at a demonstration event by the Chance Vought Corporation, in which the aircraft with Guyton at the controls had starting difficulties and almost touched high-voltage cables.

Whereabouts

The V-173 in the Frontiers of Flight Museum (2015)

After the air show in 1947, flight tests were ended and the V-173 was first stored at Naval Air Station Norfolk (Virginia) and then in the Air Museum of the Smithsonian Institution in Silver Hill (Maryland). After an eight-year restoration , the aircraft was given to the Frontiers of Flight Museum in Dallas , Texas .

Technical specifications

Parameter	Data
crew	1
length	8.13 m
span	7.12 m
height	3.79 m
Wing area	39.67 m 2
Max. Takeoff mass	calculated: 1025 kg, actually: 1360 kg
Top speed	221 km / h
Rate of climb	7 min at 5000 ft
Engines	two Continental A-80s with 80 PS (59 kW) each
Propeller diameter	5.03 m

See also

• List of aircraft types

literature

• Art Schoeni: The flying pancakes, Part 1 . In: Airplane Monthly November 1975, pp. 566-571
• Art Schoeni: The flying pancakes, Part 2 . In: Airplane Monthly December 1975, pp. 624-627
• Bill Norton: US Experimental & Prototype Aircraft Projects , Specialty Press, 2008, ISBN 978-1-58007-109-3 , pp. 165-168

Web links

Commons : Vought V-173  - Collection of Images, Videos and Audio Files

• Historical footage of flights of the V-173 and the previous tethered flight models (accessed on December 2, 2013)

Individual evidence

1. ↑ Flieger Revue X, No. 44, p. 8.