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Hello everybody. I’d like to suggest the Fisher P-75A Eagle for the US aviation tech tree in War Thunder. It was a prototype fighter designed and developed by the Fisher Body Division of General Motors for the US Army Air Forces’ fast-climbing interceptor requirement in 1942. It was Fisher’s first aircraft to enter the Army Air Force service; the design consisted of parts from the P-51 Mustang, SBD Dauntless, F4U Corsair, and P-39 Airacobra, allowing it to assemble quickly and mass produce. Because of politics and performance issues, Fisher had built only 14 aircraft before the cancellation since the requirement changed to long-range escort, which the P-38, P-47, and P-51 had already excelled in their wartime service.
Key Characteristics
- Long-range escort fighter
- Powerful Allison V-3420 liquid-cooled piston engine, powered by two P-39’s V-1710 engines geared together to drive a propeller shaft
- 6-bladed Contra-rotating propellers
- A conglomerate of P-51’s wing panels, SBD’s tail assembly, F4U’s landing gears, and P-39’s powerplant
- Armament of ten 0.50-cal. M2 Browning machine guns and two 500-lb bombs
History
Design and DevelopmentThe development of the P-75 fighter by the Fisher Body Division of General Motors Corporation began in September 1942 in response to the US Army Air Forces’ requirement for a fighter with exceptional climb performance. GM had been providing manufacturing services for Grumman aircraft, and the Fisher Body expressed an interest in contributing to the American war effort by designing and producing an aircraft of its design and powering it with the V-3420.
However, with only experience in automotive designing and being a major manufacturer of Sherman tanks, Fisher Body was a relatively inexperienced aeronautical design organization compared to Curtiss, Grumman, and North American, so, in January 1942, it hired chief designer Donovan R. Berlin of Curtiss, known for designing the P-36 and P-40 aircraft. Berlin and design team had submitted a proposal in September 1942 for a large single-seat fighter that made use of outer wing panels in an inverted gull configuration from the North American P-51 Mustang, the tail assembly from the Douglas SBD Dauntless, and the undercarriage from the Vought F4U Corsair in a layout of the Bell P-39 Airacobra with the engine located in middle of the aircraft with the contra-rotating propellers driven through extension shafts. The armament was planned to consist of four .50-cal. machine guns with 300 rpg in the nose and six more with 235 rpg in the wings, with wing hardpoints for two 500-pound bombs. The reason for reusing other aircraft parts was to simplify and shorten the time of development and production so that their initial prototype could be completed within six months and mass production could initiate soon after.
In October 1942, after reviewing the design proposal, the Army awarded Fisher Body Division of GM a contract for two initial XP-75 prototypes, with the first aircraft expected to be completed within six months (May 1943). In reality, it would last more than a year before a definitive P-75 contract was signed.
The XP-75 would be the first aircraft powered by the experimental V-3420 power plant in its central section, behind the cockpit, rated at 2,600 horsepower. The aircraft’s performance was estimated at 440 mph at 20,000 feet, 5,600 feet per minute initial climb rate, and a service ceiling of 38,000 feet. In the early design stage, the Curtiss P-40E Warhawk outer wings panels were temporarily substituted for the P-51 panels.
In spring 1943, the mockup inspection began, with the P-40 wings retained. However, the design would be required to change substantially. By the summer of 1943, the need for long-range escort fighters became more urgent than the fast-climbing interceptors. Therefore, a decision was made to order six more XP-75A aircraft modified with expanded wing tank fuel capacity and production variant 2,885-hp V-3420-23 liquid-cooled engines for long-range operations. The definitive contract was signed on October 1, 1943. Only the first two original XP-75s were ready for flight by September 30, 1943, and the first modified XP-75 for the escort role was delivered by December 1943. A letter of intent to order 2,500 P-75A Eagles was issued by the Army in July 1943, but the complete order would be canceled if the XP-75 failed to meet the expectations.
Flight TrialsThe first two prototypes were assembled in Detroit, Michigan, and all other aircraft were to be assembled at the Fisher Body Division plant in Cleveland, Ohio. While it had difficulties in the design and construction stages, the XP-75 flew for the first time on November 17, 1943, and the second XP-75 flew shortly after that. Engineering difficulties arose in the test flights. The most severe flaw was longitudinal instability resulting from an incorrect estimate of the aircraft’s center of gravity location. The aircraft had excessive aileron forces at high speeds, resulting in a low roll rate, and spins were very tricky to manage. Also, the Allison engines had trouble with power loss and inadequate cooling. Fisher’s engineering team must rectify these issues as soon as possible since they were expected to deliver the first production aircraft in six months.
Subsequently, the engineers introduced redesigns into the XP-75s for long-range operations. For instance, the ailerons were altered to increase their span and include a hydraulic boost, improving the roll rate. The tail assembly was modified by adding a dorsal extension and a small ventral fin that improved the spins. The canopy was replaced with a bubble canopy for better visibility. The aircraft had corrected its center of gravity location by extending the nose forward several inches. Many other minor changes were applied in the redesign. Fortunately, they managed to identify and correct the deficiencies immediately before delivering their first production P-75A aircraft.
The first modified XP-75A began flying in February 1944, and the third XP-75A (44-32163) crashed on April 8, 1944, which may have been performing unauthorized low-level aerobatics that fatally claimed the pilot’s life. At this time, the program would have to be extended to running for further tests, but it was probably too late since the P-38s, P-47s, and P-51s were filling escort roles in 1944 and demonstrated their solid long-range capabilities. Also, the cost overruns were becoming a setback for Fisher with its P-75 program due to the engineering changes to fix the deficiencies. The contract was changed to order 25 P-75As in production.
The program continued, and the official performance trials were attempted and made in June 1944. It had questionable results due to improper operation, but the improved XP-75A (44-32161) achieved 418 mph at 21,600 feet and 2,990 feet per minute climb rate. However, its engine probably only produced 2,210 horsepower at maximum, and the aircraft’s weight had gained more than 1,300 pounds, degrading the performance.
On September 15, 1944, the first production P-75A was finally rolled out and entered its initial test flight. The P-75A, in its production configuration, had a new and angular tailplane and new ailerons to rectify the former issues, new blunt wing tips, a small ventral fin to cure the spinning problems, and a bubble canopy. All other minor changes previously used to rectify the problems were applied in the production aircraft.
Two more production P-75As were delivered to Eglin Field for tactical suitability trials. Tragically, one P-75A (44-44549) was lost in a fatal crash on October 10, 1944. After the trials, the speed runs revealed that the aircraft fell short of the guarantee by 30 mph. An experimental intercooler for the first stage of the supercharger was installed on P-75A (44-44551) to produce more power, but it was too late to prove to the Army officials. The P-38s, P-47s, and P-51s proved exceptional in their wartime service, persuading the Army that they do not need the P-75s in the future.
The Army had decided not to undertake large-scale production of any new P-75As since they fell short of their expectations. Consequently, the production contract was canceled on October 6, 1944, at 20 aircraft. This resulted in five P-75As being completed (44-44549/53) and a sixth (44-44554) delivered incomplete to serve as a spare kit. These six production aircraft were sent to experimental work to reduce drag and perform propeller tests. The experimental program was terminated on November 8, 1944.
After the victory over Japan, most aircraft were soon scrapped. One aircraft (44-44551) was given away to Allison for flight trials with the new intercooler, but it did not fly. The last completed P-75A (44-44553) has survived in an unairworthy condition and is preserved in the Air Force Museum at Dayton, Ohio. The aircraft went through an extensive restoration in 2008. After the end of the P-75 program, only two XP-75s, six XP-75As, and six P-75As were built.
EpilogueDespite having little or no experience in designing their aircraft and having a dismal failure with the P-75 program, the Fisher engineering and production staff did their best with their effort in designing and engineering the P-75, considering many other clean designs from reputable aeronautical firms had taken longer and had more trouble than the P-75. Ultimately, the P-75A was Fisher’s first and last aircraft designed and assembled. Had the initial requirement for an interceptor not changed to a long-range escort, the P-75 program would probably have achieved partial mass production for the Army during World War II.
Specifications
Fisher P-75A EagleGeneral Characteristics
- Crew: 1 (Pilot)
- Length: 41 ft 5 in (12.62 m)
- Height: 16 ft 6 in (5.02 m)
- Span: 49 ft 4 in (15.04 m)
- Wing area: 347 sq ft (32.24 sq m)
- Propeller Type: 6-bladed contra-rotating propellers
- Propeller Diameter: 12 ft 7 in (3.84 m)
- Powerplant: Allison V-3420-23 liquid-cooled piston engine
→ 2,600 hp (1,912 kW) @ 3,000 rpm @ sea level @ takeoff
→ 2,885 hp (2,122 KW) @ 3,000 rpm @ sea level @ war emergency
→ 2,100 hp (1,545 kW) @ 2,600 rpm @ 17,000 ft (5,182 m)
→ 2,300 hp (1,692 kW) @ 3,000 rpm @ 20,000 ft (6,100 m)- Internal Fuel: 638 US gal. (2,415 L)
- Oil Tankage: 28.5 US gal. (108 L)
- Empty Weight: 11,255 lb (5,219 kg)
- Gross Weight: 17,815 lb (8,081 kg)
- Max. Takeoff Weight: 19,420 lb (8,809 kg)
Performance (Estimates)
- Power-to-Weight Ratio: 0.16 hp/lb (0.26 kW/kg)
- Sea Level Speed: 400 mph (644 km/h)
- Critical Altitude Speed: 404 mph @ 22,000 ft (650 km/h @ 6,706 m)
- Wing Loading: 51.51 lb/sq ft (251.5 kg/sq m)
- Rate of Climb: 3,450 fpm (17.5 m/s)
- Service Ceiling: 36,400 ft (11,595 m)
- Combat Range: 2,150 miles (3,460 km)
- Max. Range: 3,850 miles (6,196 km)
Armament
- Guns (Total: 2,610 rounds):
- 6 x .50-cal. M2 Browning machine guns (wing-mounted, 235 rpg, 1,410 rounds)
- 4 x .50-cal. M2 Browning machine guns (fuselage-mounted, 300 rpg, 1,200 rounds)
- Bombs:
- 2 x 500-lb bombs
- Drop Tanks:
- 2 x 110-gal. drop tanks
Diagrams
Conclusion | Why it should be in the game
The Fisher P-75A Eagle was an initial interceptor that later changed to the ill-fated long-range escort fighter for the US Army Air Forces. Only 14 aircraft were produced, and the P-75 program was terminated since the P-38, P-47, and P-51 aircraft made the P-75’s role redundant. I feel the Fisher P-75A Eagle should be added as the researchable aircraft in War Thunder between P-38J/L Lightnings and F-82E Twin Mustang since the P-75A was already a production unit only built in limited quantities. With its design, it would be a unique aircraft that differed from its conventional peers and came with ten heavy machine guns, reckoning itself as a fearsome and overweight fighter.
- World War Two Fact Files - United States Army Air Force Fighters Part 2 (1978)
- Fighters of the United States Air Force: From World War I Pursuits to the F-117 (1990)
- U.S. Experimental & Prototype Aircraft Projects: Fighters 1939-1945 (2008)
- Fisher P-75 Eagle
- Fisher P-75-Aircraft of the Month-March 2000
- General Motors - Fisher P-75 Eagle
- Fisher (General Motors) P-75 Eagle Fighter | Old Machine Press
- P-75 Eagle – The Unstable Interceptor - PlaneHistoria
- The Fisher P-75 Eagle: Two Engines, Too Many Problems - Jets ’n’ Props
- Fisher XP-75 / P-75 Eagle Single-Seat, Single-Engine Interceptor Prototype
- Fisher P-75 Eagle - Wikipedia
Thank you for taking the time to read my suggestion! 😃