Vought XF5U "Flying Pancake
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johnbr
2nd Lieutenant
wuzak
Captain
Just had a though about the engine/gearbox/propeller arrangement.
The XF5U prototype used R-2000 engines. That schematic looks like it has turbines.
The interesting thing about turbines is that the power turbine could be separate from the gas generator section. You could have the power turbine in line with the propellers, while the main part of the engine remains where it is. Weight would be saved by not having the gearboxes and drive shafts.
The XF5U prototype used R-2000 engines. That schematic looks like it has turbines.
The interesting thing about turbines is that the power turbine could be separate from the gas generator section. You could have the power turbine in line with the propellers, while the main part of the engine remains where it is. Weight would be saved by not having the gearboxes and drive shafts.
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johnbr
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johnbr
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johnbr
2nd Lieutenant
Spin tests of a 1/16-scale model of the Chance Vought XF5U-1 airplane have been performed in the Langley 20-foot free-spinning tunnel. The effect of control position and movement upon the erect and inverted spin and recovery characteristics ae well as the effects of propellers, of stability flaps, and of various revisions to the design configuration have been determined for the normal fighter loading. The investigation also included spin recovery parachute, tumbling, and pilot-escape tests. For the original design configuration, with or without windmilling propellers, the recovery characteristics of the model were considered unsatisfactory. Increasing the maximum upward deflection of the ailavators from 45 deg to 65 deg resulted in greatly improved recovery characteristics. Dimensional revisions to the original airplane configuration, which satisfactorily improved the general spin and recovery characteristics of the model, consisted of: (1) a supplementary vertical tail 34 inches by 59 inches (full-scale) attached to a boom 80 inches aft of the trailing edge of the airplane in the plane of symmetry, (2) a large semispan undersurface spoiler placed along the airplane quarter-chord line and opened on the outboard side in a spin, or (3) two additional vertical tails 64 inches by 52 inches (full-scale) located at the tips of the ailavators. A satisfactory parachute arrangement for emergency spin recovery from demonstration spins was found to be an arrangement consisting of a 13.3-foot parachute attached by a 30-foot towline to the arresting gear mast on the airplane and opened simultaneously with an 8-foot parachute on the outboard end of the wing attached by a 3-foot towline. Tests indicated that pilot escape from a spin would be extremely hazardous unless the pilot is mechanically ejected from the cockpit. Model tumbling tests indicated that the airplane would not tumble.
swampyankee
Chief Master Sergeant
- 3,954
- Jun 25, 2013
Part of the reason for gearboxes and driveshafts was to provide cross-shafting, so the failure of one engine wouldn't be quite so unpleasant.
CORSNING
Tech Sergeant
Great stuff John. Thank you for posting all those great pictures and
information.
Calculated performance and specification of the Vought fighter and
and prototype:
Standard Aircraft Characteristics Arcive
and scroll down to F5U Flapjack.
information.
Calculated performance and specification of the Vought fighter and
and prototype:
Standard Aircraft Characteristics Arcive
and scroll down to F5U Flapjack.
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johnbr
2nd Lieutenant
Good stuff!
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johnbr
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johnbr
2nd Lieutenant
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johnbr
2nd Lieutenant
The XF5U-1 during testing
Role Fighter
Manufacturer Vought
Designer Charles H. Zimmerman
Status Cancelled 17 March 1947
Primary user United States Navy
Number built 2
Developed from Vought V-173
The Vought XF5U "Flying Flapjack" was an experimental U.S. Navy fighter aircraft designed by Charles H. Zimmerman during World War II. This unorthodox design consisted of a flat, somewhat disc-shaped body (hence its name) serving as the lifting surface.[1] Two piston engines buried in the body drove propellers located on the leading edge at the wingtips.
Design and development:
A developed version of the original V-173 prototype, the XF5U-1 was a larger aircraft. Of all-metal construction, it was almost five times heavier, with two 1,600 hp (1,193 kW) Pratt & Whitney R-2000 radial engines. The configuration was designed to create a low aspect ratio aircraft with low takeoff and landing speeds but high top speed.
Normally, a wing with such a low aspect ratio will suffer from very poor performance due to the degree of induced drag created at the wingtips, as the higher pressure air below spills around the wingtip to the lower-pressure region above. In a conventional aircraft, these wingtip vortices carry a lot of energy with them and hence create drag. The usual approach to reducing these vortices is to build a wing with a high aspect ratio, i.e. one that is long and narrow. However, such wings compromise the maneuverability and roll rate of the aircraft, or present a structural challenge in building them stiff enough. The XF5U attempted to overcome the tip vortex problem using the propellers to actively cancel the drag-causing tip vortices. The propellers are arranged to rotate in the opposite direction to the tip vortices, with the aim of retaining the higher-pressure air below the wing. With this source of drag eliminated, the aircraft would fly with a much smaller wing area, and the small wing would yield high maneuverability with greater structural strength.
The propellers envisioned for the completed fighter were to have a built-in cyclic movement like a helicopter's main rotor, with a very limited ability to tilt up and down to aid the aircraft in maneuvering. An ejection seat was fitted to allow the pilot to clear the massive propellers in the event of an in-flight emergency. Although the prototype was unarmed, a combination of machine gun
eneral characteristics:
Crew: One, pilot
Length: 28 ft 7 in (8.73 m)
Wingspan: 32 ft 6 in (9.91 m)
Height: 14 ft 9 in (4.50 m)
Wing area: 475 ft² (44.2 m²)
Empty weight: 13,107 lb (5,958 kg)
Loaded weight: 16,722 lb (7,600 kg)
Max. takeoff weight: 18,772 lb (8,533 kg)
Powerplant: 2 × Pratt & Whitney R-2000-7 radial engine, 1,350 hp (1,007 kW) each
Performance:
Maximum speed: 413 knots / 475 mph at 28,000 ft (estimated)[8] (765 km/h at 8,534 meters)
Range: 1,064 miles (1,703 km)
Service ceiling: 34,492 ft (10,516 m)
Rate of climb: 3,000 ft/min (914 m/min)
Wing loading: 35 lb/ft² (172 kg/m²)
Power/mass: 0.16 hp/lb (0.27 kW/kg)
Armament:
6 × .50 machine guns or 4 × 20 mm cannon
2 × 1000 lb. bombs
s and cannons would have been installed under the nose.
Role Fighter
Manufacturer Vought
Designer Charles H. Zimmerman
Status Cancelled 17 March 1947
Primary user United States Navy
Number built 2
Developed from Vought V-173
The Vought XF5U "Flying Flapjack" was an experimental U.S. Navy fighter aircraft designed by Charles H. Zimmerman during World War II. This unorthodox design consisted of a flat, somewhat disc-shaped body (hence its name) serving as the lifting surface.[1] Two piston engines buried in the body drove propellers located on the leading edge at the wingtips.
Design and development:
A developed version of the original V-173 prototype, the XF5U-1 was a larger aircraft. Of all-metal construction, it was almost five times heavier, with two 1,600 hp (1,193 kW) Pratt & Whitney R-2000 radial engines. The configuration was designed to create a low aspect ratio aircraft with low takeoff and landing speeds but high top speed.
Normally, a wing with such a low aspect ratio will suffer from very poor performance due to the degree of induced drag created at the wingtips, as the higher pressure air below spills around the wingtip to the lower-pressure region above. In a conventional aircraft, these wingtip vortices carry a lot of energy with them and hence create drag. The usual approach to reducing these vortices is to build a wing with a high aspect ratio, i.e. one that is long and narrow. However, such wings compromise the maneuverability and roll rate of the aircraft, or present a structural challenge in building them stiff enough. The XF5U attempted to overcome the tip vortex problem using the propellers to actively cancel the drag-causing tip vortices. The propellers are arranged to rotate in the opposite direction to the tip vortices, with the aim of retaining the higher-pressure air below the wing. With this source of drag eliminated, the aircraft would fly with a much smaller wing area, and the small wing would yield high maneuverability with greater structural strength.
The propellers envisioned for the completed fighter were to have a built-in cyclic movement like a helicopter's main rotor, with a very limited ability to tilt up and down to aid the aircraft in maneuvering. An ejection seat was fitted to allow the pilot to clear the massive propellers in the event of an in-flight emergency. Although the prototype was unarmed, a combination of machine gun
eneral characteristics:
Crew: One, pilot
Length: 28 ft 7 in (8.73 m)
Wingspan: 32 ft 6 in (9.91 m)
Height: 14 ft 9 in (4.50 m)
Wing area: 475 ft² (44.2 m²)
Empty weight: 13,107 lb (5,958 kg)
Loaded weight: 16,722 lb (7,600 kg)
Max. takeoff weight: 18,772 lb (8,533 kg)
Powerplant: 2 × Pratt & Whitney R-2000-7 radial engine, 1,350 hp (1,007 kW) each
Performance:
Maximum speed: 413 knots / 475 mph at 28,000 ft (estimated)[8] (765 km/h at 8,534 meters)
Range: 1,064 miles (1,703 km)
Service ceiling: 34,492 ft (10,516 m)
Rate of climb: 3,000 ft/min (914 m/min)
Wing loading: 35 lb/ft² (172 kg/m²)
Power/mass: 0.16 hp/lb (0.27 kW/kg)
Armament:
6 × .50 machine guns or 4 × 20 mm cannon
2 × 1000 lb. bombs
s and cannons would have been installed under the nose.
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johnbr
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johnbr
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