Model 75A was the company designation for a Curtiss-owned demonstrator
which carried a civilian registration of NX22028. This demonstrator
aircraft was used to carry out several company-originated experiments.
First, it was fitted with an external mechanical supercharger mounted
underneath its Pratt & Whitney R-1830 engine and briefly designated
Model 75J. Then, it was experimentally fitted with a
turbosupercharged R-1830-SC2-G engine. The supercharger was fitted
underneath the nose just aft of the engine cowling, and the
intercooler was mounted underneath the trailing edge of the wing. The
company designation for this modification was Model 75R. Empty and
normal loaded weights went up to 5074 lbs and 6163 lbs. During trials
in January 1939, it attained a maximum speed of 330 mph at 15,000
feet. However, the poor reliability and complexity of the
turbosupercharger led the USAAC to decide not to proceed with a
supercharged variant of the P-36, choosing instead to purchase the
turbo-supercharged Seversky (Republic) XP-41, which had been converted
from the last P-35. After trials at Wright Field, the aircraft was
returned to the Curtiss plant in Buffalo, where it was fitted with a
Wright R-1820 engine and resumed its role as a demonstrator.
Sources:
-
Curtiss Aircraft, 1907-1947, Peter M Bowers, Naval Institute Press,
1979
-
The Curtiss Hawk 75, Aircraft in Profile No. 80, Profile
Publications, Ltd. 1966
-
War Planes of the Second World War, Fighters, Volume Four, William
Green, Doubleday, 1961.
- Air Enthusiast, Volume 1, William Green et al, Doubleday, 1971.
