domingo, 5 de novembro de 2017

GM / FISHER XP-75 EAGLE: The eagle that did not fly!

Fisher XP-75 Eagle (Photo militaryfactory.com).

        Many people do not know, but some automobile manufacturers have risked themselves in the world of aviation, whether at it's manufacturing airplanes like FIAT and FORD, or just engines like BMW. Rolls Royce still manufactures aeronautical engines and the Japanese Mitsubishi and Honda manufacture aircraft in addition to cars. A carmaker who was very influential in the IIWW, but that is little quoted is General Motors, that's right, GM helped the Grumman in the manufacture of some aircraft to meet the demand for war. But what few know is that GM even designed its own airplane, and it's him that we'll talk about in this matter!

        In October 1942, the contract for two prototypes, designated "XP-75", was signed with the Fisher Body, a division of GM. The design concept was to use the exterior wing panels of the North American P-51 Mustang, the Douglas A-24 (SBD) tail set, Vought F4U landing gear and a general layout equal to the Bell P-39 Airacobra, with the engine located in the middle of the fuselage (behind the cockpit), with the propeller driven through cardans (extension bars). At an early stage of the project, however, Curtiss P-40 Warhawk's outer wing panels were replaced with P-51 panels.


Fisher XP-75 Eagle (Photo militaryfactory.com).

       The aircraft was developed in response to the requirement of the United States Army Air Force for a fighter aircraft that possessed an extremely high rate of climb with the most powerful liquid-cooled engine available then the Allison V-3420. By mid-1943, the need for long range escort fighters became more urgent than interceptors with high ascent rates, so the order was 6 XP-75 modified for long-range role. At this time, an order of 2,500 production aircraft was also abandoned, but with the proviso that if the first P-75A were unsatisfactory, the complete order would be canceled.

       At the time, General Motors was engaged in several war effort projects, including the mass production of several different types of aircraft, including TBF Avenger. Some sources claim that the P-75 was the result of a scheme for General Motors to be forced to build the Boeing B-29 Superfortress. The P-75's design was "high-priority" to help GM relieve the additional pressure of Superfortress production. With the name, "P-75 Eagle", designation chosen in reference to the French 75, weapon in the First World War considered a symbol of defeating the Germans. The "Eagle" was given extensive media coverage prior to its first flight, being announced as a "wonder plan".

Fisher XP-75 Eagle (Photo 1000aircraftphotos.com).

       Equipped with a 24-cylinder W-engine (two V-3420-19 engines) with approximately 2,600 hp, driven by counter-rotating propellers, the XP-75 first fly on November 17, 1943. The second XP-75 flew shortly afterwards, and all long-range XP-75s entered the test program in mid-1944. The test program brought numerous problems of adaptation, including calculation error of the center of mass of the aircraft, engine failure to produce its expected power, inadequate engine cooling, high-speed ailerons performance problems, and poor "bearings" characteristics. The long-range XP-75s were redesigned including a modified tail mount, new canopy "bubble", and a V-3420-23 engine that corrected most of the deficiencies by the time the first P-75A Eagles entered the flight test in September 1944.

       By this time, the Army Air Force decided to limit the number of types of combat aircraft in production and then new models that were not available before the end of the war would not go into large-scale production. Because the Lockheed P-38 Lightning twin engine and the North American P-51 Mustang demonstrated excellent long-range capabilities, the P-75A Eagle's production cycle was substantially completed on October 6, 1944. It was decided to use the six production aircraft to complete the experimental work and development of the V-3420 engine. As a result of these events, the P-75A did not complete the formal performance tests due to termination of the production contract. Ultimately, only eight XP-75s and six P-75A's were built.
XP-75 Eagle Expansion Bar and Motor (Photo aviation-history.com).

General features:

Crew: One
Length: 40 ft 5 in (12.32 m)
Wingspan: 49 ft 4 in (15.04 m)
Height: 15 feet in 6 (4.72 m)
Engine: 1 Allison V-3420-23 24-cylinder dual-V with liquid cooling, 2,885 hp (2,150 kW)
performance.
Maximum speed: 433 mph (697 km / h) to 20,000 (6,100 m)
Range: 2,050 miles (3,300 km)
Service ceiling: 36,400 feet (11,100 m)
Ascent rate: 4,200 ft / min (21.3 m / s)

Weaponry:

6x caliber .50 (12.7 mm) machine guns mounted on the wings
4x caliber .50 (12.7 mm) machine guns mounted on the fuselage
2x 500 lb (227 kg) pumps










Rene Maciel / Rock Aircraft.
Editor and Private Pilot.




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