Subject: Number Thirty-One in the Series--the Curtiss XP-31 Swift

From: [email-masked] (Joseph F Baugher)
Date: 21 Oct 92 17:07:15 GMT

>From Joseph F Baugher <[email-masked]>

The Curtiss Model 66 Swift was an unsuccessful competitor against the 
Boeing XP-936/P-26 for the US Army's interim monoplane pursuit of 
1932.  Encouraged by the Army, Curtiss undertook the development of 
a new pursuit as a private venture for which the Army agreed to 
provide the powerplant and the military equipment under a bailment 
contract.  The experimental project number XP-934 was assigned.  

The all-metal Swift drew heavily on the Curtiss A-8 Shrike attack 
plane.  Like the P-26, the Curtiss Swift was an intriguing mixture of 
the old and the new.  It was fitted with a low-mounted monoplane wing 
with external bracing struts.  The fixed, nonretractable undercarriage 
was enclosed by a set of spats.  The pilot's cockpit was fully 
enclosed by a sliding canopy.  The wing was fitted with trailing-edge 
flaps and carried a set of full-span leading-edge slats that opened 
automatically at 15 mph above stalling speed.  Armament was four 
0.30-cal machine guns, two in troughs in the nose and two in external 
packages on each side of the cockpit.  

The Swift had originally been planned for the 600 hp Curtiss Conqueror 
liquid-cooled V-12 engine, but the Army believed that this engine was 
nearing the end of its development cycle and insisted that the 
powerplant be changed to the 700 hp Wright R-1820 Cyclone air cooled 
radial.  The aircraft was also fitted briefly with a Pratt & Whitney 
Wasp radial.  

The Swift left the factory in July 1932.  During the early flight 
testing, the performance was found to be rather disappointing.  Within 
a month, the Cyclone radial was replaced by a Curtiss G1V-1570F 
Conqueror of 600 hp, which was the engine that Curtiss had wanted all 
along.  Although the speed increased, other performance 
characteristics suffered from serious overweight.  Maximum speed was 
215 mph at sea level, initial climb rate was 2130 ft/min, service 
ceiling was 22,700 feet, and range was 396 miles.  Weights were 3334 
lbs. empty, 4143 lbs. gross.  

The Army bought the XP-934 in February 1933 and assigned it the 
designation XP-31 and the serial number 33-178.  The civil-type engine 
was replaced by an equivalent military-type V-1570-53 engine.  The 
XP-31 was redesignated ZXP-31 (Z for obsolete) and was retired to an 
Air Corps mechanics' school in July 1936.  

Sources: 

  United States Military Aircraft Since 1909, Gordon Swanborough and 
  Peter Bowers, Smithsonian Institution Press, 1989.  

  The American Fighter, Enzo Angellucci and Peter Bowers, Orion Books, 
  1987.  

  Curtiss Aircraft: 1907-1947, Peter M. Bowers, Naval Institute Press, 
  1987.  

Joe Baugher       AT&T Bell Laboratories    2000 North Naperville Road 
		  Naperville, Illinois 60566-7033.   (708) 713-4548