ORIGINAL: a65l
The XP-72 meets most of your requirements, but the engine is a little light.... and down on horsepower
There you go, a651. You got it, and you're up! The reason the horsepower seems low is the prototypes used the first, unsupercharged, engine. And, I should have said "over" a ton, rather than "nearly" two tons. My error, sorry. There were two more versions of the engine waiting in the wings, Check out planned clue (10). Take it away, Sir. Thanks; Ernie P.
Question: What WWII aircraft do I describe?
Clues:
(1) Really, really, fast for a propeller driven aircraft.
(2) Only two prototypes were completed. Testing results were so impressive, with such exceptional performance, an order was placed for 100 production aircraft.
(3) The order was cancelled, because it was felt other types of aircraft were needed more.
(4) This aircraft was to be an interceptor; and it was decided priority must be given to longer range fighters.
(5) Power, a lot of it, was delivered by an experimental liquid cooled radial engine.
(6) The first prototype flew for the first time in early 1944. The second prototype flew in mid 1944.
(7) The second prototype used a contra-rotating propeller.
(8) A new generation of turbojet powered interceptors was on the horizon by the end of WWII, so this promising new interceptor was relegated to the scrapheap.
(9) The engine produced over 3,000 HP, and weighed nearly two tons.
(10) The prototype reached 480 MPH, even though the planned remote supercharger had not yet been installed. The supercharged 3,650 HP engine was expected to exceed 500 MPH easily; and a planned 4,000+ HP engine was expected to yield over 540 MPH.
(11) This was a derivative, or development of, a very well known and successful WWII fighter.
Answer: The Republic XP-72
The Republic XP-72 was an American prototype interceptor fighter developed as a progression of the P-47 Thunderbolt design. The XP-72 was designed around the Pratt & Whitney R-4360 twenty-eight cylinder radial air-cooled engine with a supercharger mounted behind the pilot and driven by an extension shaft from the engine. The armament consisted of six 0.5 in wing-mounted machine guns and underwing racks for two 1,000 lb bombs.
Design and development
The XP-72 development paralleled that of another Republic design, the XP-69 that was to be powered by an experimental forty-two cylinder Wright R-2160 radial engine mounted behind the pilot and driving contra-rotating propellers through an extension shaft. The XP-69 was intended for high altitude operations and featured a pressurized cockpit and armament of two 37 mm cannon and four 0.5 in machine guns. As the XP-72 displayed greater promise than the XP-69, the XP-69 was canceled on 11 May 1943 and an order for two XP-72 prototypes was placed on 18 June 1943.
Operational history
The XP-72 flew for the first time on 2 February 1944, equipped with a four-bladed propeller. The second prototype was completed on 26 June 1944 and was equipped with an Aero-Products contra-rotating propeller. As the XP-72 displayed exceptional performance during flight tests an order for 100 production aircraft was awarded. The order included an alternate armament configuration of four 37 mm cannon. By this time the war had progressed to where the need was for long-range escort fighters and not high-speed interceptors. Also, the advent of the new turbojet-powered interceptors showed greater promise for the interceptor role. Thus, the production order for the P-72 was cancelled.
General characteristics
Crew: One
Length: 36 ft 7 in (11.15 m)
Wingspan: 40 ft 11 in (12.47 m)
Height: 16 ft (4.88 m)
Wing area: 300 ft² (27.9 m²)
Empty weight: 11,476 lb (5,216 kg)
Loaded weight: 14,433 lb (6,560 kg)
Max takeoff weight: 17,490 lb (7,950 kg)
Powerplant: 1× Pratt & Whitney R-4360-13 radial engine, 3,000 hp @ sea level (dash 13 engine) (2,574 kW)
Performance
Maximum speed: 480 mph[1][N 1] (789 km/h at sea level)
Range: 1,200 miles (1,932 km)
Service ceiling: 42,000 ft (12,805 m)
Rate of climb: 5,280 ft/min (26.8 m/s)
Wing loading: 48.1 lb/ft² (235 kg/m²)
Power/mass: 0.24 hp/lb (0.39 kW/kg)
Armament
6× 0.50 in Browning machine guns
Notes
1. ^ Note: Test pilot Tom Bellinger stated flatly that the no flights ever exceeded 500 mph. The dash 13 engine was not supercharged. With the planned but never installed dash 19 engine (with a remote supercharger) rated at 3,650 HP at 25,000 ft. (3,000 HP at sea level) a top speed of 504 mph at approximately 25,000 feet was expected. Planned further development of the dash 19 engine was expected to yield approx 4,000 hp and a speed of 540 mph at 25,000 ft.
The Wright R-2160 Tornado was an experimental 42-cylinder, 6-row liquid-cooled aircraft engine. It was proposed in 1940 of 2,350 hp (1,752 kW) for experimental aircraft such as the Republic XP-69.
General characteristics
Type: 42 cylinder radial engine. 6 rows, 7 cylinders per row
Bore: 4.25 in (107.9 mm)
Stroke: 3.625 in (92 mm)
Displacement: 2,160 in³ (35.39 l)
Length: 96 in (2438 mm)
Diameter: 35.5 in (901.6 mm)
Dry weight: 2,400 lb (1088.6 kg)
Components
Valvetrain: Pushrod, two valves per cylinder
Supercharger: 2 x Turbosuperchargers
Fuel system: Direct injection
Fuel type: 100/130
Oil system: Dry sump
Cooling system: Liquid cooled
Performance
Power output: 2,350 hp (1,752 kW)
Specific power: 1.08 hp/in³
Power-to-weight ratio: 0.97 hp/lb