Vought V-173
The Chance Vought V -173 was an experimental extremely short bootable ( ESTOL ) aircraft of the U.S. American manufacturer Chance Vought from the 1940s. The unofficial nickname Flying Pancake stems from the unusual structural design as a disc aircraft ago. The V -173 should serve as a test vehicle for the fighter project Chance Vought F5U.
History
Prehistory
Machine designer was Charles H. Zimmerman, a NACA engineer who developed a wind tunnel for free-flying test models in the early 1930s at Langley Field. Zimmerman developed for a design competition in 1933 advertised the NACA a slice plane that should achieve both high speeds, as should also possess the ability to float and won the competition. A practical use of the idea, however, rejected the NACA on the grounds that she was too "advanced". Zimmerman continued to develop his concept and built, among others, a man-carrying wooden model with two French 25 -horsepower Cleone engines. He gave the project, however, since it was not possible to synchronize the two engines.
In 1937 he then moved to Chance Vought, after he had convinced Eugene E. Wilson, President of the United Aircraft Corporation with his idea. Here he built a then, as V -162, designated, electrically driven tethered flight model. Due to the good results, the U.S. Navy was interested for this and presented research funds available. An unusual peculiarity of the model was that the rear quarter of the " hull ", together with the two vertical stabilizers, via pivot points should serve as a pivoted horizontal stabilizer.
Prototype
Two years after beginning his work at Vought design work and manufacturing drawings and aerodynamic studies have been completed so far with the help of the Navy funds that a prototype (V -173, BuNo 02978 ) could be built. To save weight and money the whole wing was covered with fabric. The drive of the 1360 -pound aircraft consisted of two Continental A-80 engine with 80 hp. The three-bladed propeller had a diameter of 5.03 m, which meant that the aircraft stood with his long-legged fixed landing gear at a steep angle of 22 degrees to the ground. For the wing without dihedral and twist, you put a symmetrical NACA 0015 profile. The high wing loading, together with the underpowered presented the biggest drawbacks of the design dar. For the projected fighter F5U, which must be based on the test vehicle V -173, were propeller blades with hub joints similar to those blow joints used in helicopters, provided both a hover, as well as with the respective powerful engines to a maximum speed of 800 km / h make (500 mph) possible.
The original concept was based on an interpretation without tailplane, should instead two ailevators in the middle take over this function at the end of the fuselage. Wind tunnel tests have shown, however, that in particular at low speeds and high angles of attack the effectiveness would be insufficient. Instead, first came to a flying tail- elevator is used, which was then used for the XF5U -1 and is still used today for most high- speed aircraft.
Testing
Boone T. Guyton led of the 13 -minute maiden flight on 23 November 1942 by factory airfield in Stratford (Connecticut) by, this is a very bad reaction behavior was to control commands. Even with the low engine power came the V -173 with no wind with a takeoff distance of 60 m, with 25 kt. Headwind a standing start was even possible. Wind tunnel tests with the machine at Langley Field showed that the high induced drag of an extremely low stretch having wing, largely is located ligands by interactions far ahead of the wing leading edge, counter-rotating large propellers with the edge vortices was lifted.
Guyton conducted 54 test flights, which turned out to be the biggest problem the noticeable vibrations in the cockpit. This was due to resonant oscillations between the propellers and the associated nacelle structure, which formed the body and supporting the drive shaft. Attached to the propellers vibration brought a certain improvement. The problem did not show up at the XF5U -1, since specially designed propeller blades were used, which prevented an unbalanced flow at high angles of attack. Up to an angle of 45 degrees Guyton could retain full control over the machine. A complete flow separation could not be achieved in practice, strikingly strong deceleration was in tight curves that made this interpretation appear to be particularly suitable for dogfights.
After the first of 13 flights to Guyton injured so badly that for a time the testing program had to be taken over by Richard Burroughs in an accident with an F4U Corsair. Charles Lindbergh led by the Flight No. 34 and also many Navy pilots flew the V- 173rd During testing, the aircraft was involved in some incidents, but all carried out without major damage to material and persons. This included, for example, a flight demonstration in 1947 at a demonstration event of the Chance Vought Corporation at which the airplane with Guyton at the wheel had teething problems and almost touched high-voltage cable.
Whereabouts
After the air show, 1947, the flight test was terminated and the V -173 first at the Naval Air Station Norfolk (Virginia) and then stored at the Air Museum of the Smithsonian Institution in Silver Hill (Maryland). After a restoration that took eight years, the aircraft was the Frontiers of Flight Museum in Dallas, Texas, passed.