Model 75 The Prototypes
November 1934: Construction on the prototype began after the USAAC issued specifications
for an all metal low-wing fighter capable of 300 mph. This became the Model 75.
May 1935: Flight testing began at Buffalo, New York with a civil registration number
27 May 1935: The Model 75 was submitted at Wright Field, Dayton, Ohio for competition
flight trials. None of the other contenders were ready to compete at this time.
Engine: Wright SR-1670-5: 900hp. (the engine was troublesome).
Proposed armament: 1 x 0.5 in./200 rds. + 1 x 0.3 in./500 rds. in upper cowl.
15 August 1935: Seversky's SEV-1XP finally is submitted for competition. The USAAC
favored Seversky's entry but Curtiss protested that Seversky had been given an
unfair advantage of time. The Material Division deferred competition until April 1936.
15 April 1936: The Model 75B is submitted to Wright Field and the AAC flight competition
trials were resumed.
Model 75B: Fuselage behind the canopy was scalloped to improve rear vision.
Engine: Wright XR-1820-39 (G5) Cyclone: 950 hp./2,200 rpm./Take-off.
850 hp./S.L.to 6,000 ft.(1,830 m.). The engine was troublesome and required
four engine changes during the trials.
The canopy was strengthened. Test weight: 5,075 lbs. Speed: 285 mph. ( 294 mph.
had been guaranteed by Curtiss).
16 June 1936: Seversky won the fighter trials & the P-35 gets a production contract for
seventy-seven aircraft. Three weeks later Curtiss got an order for three Model 75Bs
7 August 1936: The USAAC stipulated that the three Y1P-36s are powered by Pratt &
Whitney R-1830 Twin Wasp engines.
March 1937-22 June 1937: The Y1P-36 successfully passed official AAC trials.
Maneuverability was excellent except for some jerkiness at the start of spins
or rolls. Effectiveness of controls were excellent at all speeds. Stability and ground
handling were commendable. Engine: Pratt & Whitney R-1830-13: 950 hp./T.O.
900 hp./2,550 rpm./12,000 ft. Speed 294.5 mph./10,000 ft. (3,048 m.). Range:
752 mls./256 mph./126 imp. gal. Climb: 3,145 fpm./S.L., 10,000 ft./3.44 minutes.
Edited by CORSNING, 24 December 2016 - 02:35 PM.