Curtiss P-6 Hawk - version overview:
XP-6
Conversion P-2, racing machine with Curtiss V-1570-1 engine Conqueror deployed in the National Air Races 1927.
P-6
The first fighter variant, variant P-1 Hawk with Conqueror engine in the new bow and rounded hull. A total of 25 machines used in the US and the Dutch East Indies.
XP-6A
The second racing machine for the National Air Race 1927, fuselage from P-1A, wings of XPW-8A a motor Conqueror.
P-6A
The second fighter variant, P-6 with ethylene glycol engine cooling. 9 machines built.
XP-6B
Conversion from P-1C, a record aircraft with a Conqueror engine and auxiliary tanks in sides of the fuselage, designed for a record flight to New York-Alaska and back.
P-6C
Temporary designation of the main fighter version, changed to P-6E before completion.
P-6D
Conversion of 12 P-6/P-6A to turbocharged engines.
P-6E
The main fighter variant, redesigned bow and self-supporting chassis. 46 machines built.
XP-6F
XP-6E equipped with V-1570-55 engine with turbocharger and covered cabin.
XP-6G
P-6E temporarily equipped with V-1570-55 engine without turbocharger.
XP-6H
P-6E temporarily equipped with four machine guns in the wings.
P-6S
Export variant for Cuba, three machines with Pratt & amp; Whitney R-1340.
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P-11
Version intended as a backup, if the Conqueror is not successful, with the Curtiss H-1640 Chieftain engine. None unbuilt, instead two completed as P-6 and one as YP-20.
YP-20
P-11 completed with Wright R-1870-9 Cyclone engine. Later rebuilt into a prototype XP-6E.
XP-22
P-6A, on which the new bow and self-supporting chassis were tested.
Y1P-22
Serial variant XP-22. Ordered 46 machines, renamed P-6C and then P-6E before completion.
XP-23
P-6E with half-shell fuselage and Curtiss G1V-1570-C engine with turbocharger.
YP-23
XP-23 after removing the turbocharger.
Source:
Bowers, P. M. Curtiss Aircraft 1907-1947, Putnam Aeronautical Books, London 1979. ISBN 0-370-10029-8.
Bowers, P. M. Curtiss Army Hawks, Aircraft in Profile No.45. Profile Publications, Leatherhead 1965.
United States Army and Air Force Fighters 1916-1961, Harleyford Publications, Letchworth 1961.
http://www.aerofiles.com/_curtx.html
XP-6
Conversion P-2, racing machine with Curtiss V-1570-1 engine Conqueror deployed in the National Air Races 1927.
P-6
The first fighter variant, variant P-1 Hawk with Conqueror engine in the new bow and rounded hull. A total of 25 machines used in the US and the Dutch East Indies.
XP-6A
The second racing machine for the National Air Race 1927, fuselage from P-1A, wings of XPW-8A a motor Conqueror.
P-6A
The second fighter variant, P-6 with ethylene glycol engine cooling. 9 machines built.
XP-6B
Conversion from P-1C, a record aircraft with a Conqueror engine and auxiliary tanks in sides of the fuselage, designed for a record flight to New York-Alaska and back.
P-6C
Temporary designation of the main fighter version, changed to P-6E before completion.
P-6D
Conversion of 12 P-6/P-6A to turbocharged engines.
P-6E
The main fighter variant, redesigned bow and self-supporting chassis. 46 machines built.
XP-6F
XP-6E equipped with V-1570-55 engine with turbocharger and covered cabin.
XP-6G
P-6E temporarily equipped with V-1570-55 engine without turbocharger.
XP-6H
P-6E temporarily equipped with four machine guns in the wings.
P-6S
Export variant for Cuba, three machines with Pratt & amp; Whitney R-1340.
--------------
P-11
Version intended as a backup, if the Conqueror is not successful, with the Curtiss H-1640 Chieftain engine. None unbuilt, instead two completed as P-6 and one as YP-20.
YP-20
P-11 completed with Wright R-1870-9 Cyclone engine. Later rebuilt into a prototype XP-6E.
XP-22
P-6A, on which the new bow and self-supporting chassis were tested.
Y1P-22
Serial variant XP-22. Ordered 46 machines, renamed P-6C and then P-6E before completion.
XP-23
P-6E with half-shell fuselage and Curtiss G1V-1570-C engine with turbocharger.
YP-23
XP-23 after removing the turbocharger.
Source:
Bowers, P. M. Curtiss Aircraft 1907-1947, Putnam Aeronautical Books, London 1979. ISBN 0-370-10029-8.
Bowers, P. M. Curtiss Army Hawks, Aircraft in Profile No.45. Profile Publications, Leatherhead 1965.
United States Army and Air Force Fighters 1916-1961, Harleyford Publications, Letchworth 1961.
http://www.aerofiles.com/_curtx.html