Warhawk, Kittyhawk II
In 1941, P-40D Ser No 40-360
was fitted with a 1300 hp British-built Rolls-Royce Merlin 28
engine with a single-stage two-speed supercharger. It flew for
the first time on June 30, 1941. This experimental P-40D could
be distinguished from the stock P-40E by the absence of the
top-mounted carburetor air scoop. The Merlin engine did much
to overcome the limitations imposed by the Allison, and a total
of 1311 examples powered by the American-made version of the
Merlin built by the Packard Motor Car Company were ordered under
the designation P-40F.
The P-40F and later versions
were known by the name *Warhawk* in US service.
The first 699 planes of the
P-40F series had no dash numbers, since the production block
designation system was not yet in effect. The dash numbers were
first used with the P-40F-5-CU model, which introduced a fuselage
elongated from 31 feet 2 inches to 33 feet 4 inches in order
to improve directional stability. This longer fuselage was retained
in all later P-40 versions. The P-40F-10-CUs had manual instead
of electrically-operated cowl flap controls. The P-40F-15-CUs
had winterizing equipment, and the P-40F-20-CUs had a revised
oxygen flow system for the pilot. A radio mast was fitted to
late production P-40Fs.
The P-40F was powered by a Packard-built
Merlin V-1650-1 twelve-cylinder Vee liquid-cooled engine rated
at 1300 hp for takeoff and 1120 hp at 18,500 feet. Maximum speed
was 320 mph at 5000 feet, 340 mph at 10,000 feet, 352 mph at
15,000 feet, and 364 mph at 10,000 feet. An altitude of 10,000
feet could be attained in 4.5 minutes, and an altitude of 20,000
feet could be reached in 11.6 minutes. Maximum range was 700
miles at 20,000 feet (clean), 875 miles (one 43 Imp gal drop
tank), and 1500 miles (141.5 Imp gal drop tank). Service ceiling
was 34,400 feet. Weights were 6590 pounds empty, 8500 pounds
normal loaded, and 9350 pounds maximum. Dimensions were 37 feet
4 inches wingspan, 33 feet 4 inches length (P-40F-5-CU and later),
10 feet 7 inches high, 236 square feet wing area. Armament consisted
of six 0.50-inch machine guns in the wings.
One hundred and fifty P-40Fs
were supplied to the RAF under Lend-Lease. The RAF assigned
them the name Kittyhawk II. The Kittyhawk IIs were offset from
USAAF allocations 41-13697/14599. RAF serials were FL219/448.
Unfortunately, P-40Ls were also mixed in with this lot with
no mark distinctions, so it is impossible to tell which planes
were Fs and which were Ls by merely looking at the RAF serial
number. In the event, very few of these aircraft actually served
with the RAF. FL273 and FL369-448 were returned to the USAAF
for use in North Africa in 1942/43. FL230/232, 235, 236, 239/240
were lost at sea before reaching the RAF. FL263, 270, 276, 280,
383, 305, and 307 were handed over to the Free French, who operated
them in North Africa. 100 were transferred to the USSR.
The designation YP-40F was unofficially
assigned to P-40F Ser No 41-13602 used for experimental tests
of the cooling system and the tail rudder. The coolant system
was moved aft in several different configurations, including
a mounting fitted inside a thickened wing-root section.
USAAF serials of the P-40F were
41-13600/13695 Curtiss P-40F
41-13696 Curtiss P-40F Warhawk (order cancelled)
41-13697/14299 Curtiss P-40F Warhawk
41-14300/14422 Curtiss P-40F-5-CU Warhawk
41-14423/14599 Curtiss P-40F-10-CU Warhawk
41-19733/19932 Curtiss P-40F-15-CU Warhawk
41-19933/20044 Curtiss P-40F-20-CU Warhawk
A number of P-40Fs were selected
at random, withdrawn from operational service, and fitted with
Allison V-1610-81 in place of their original Merlins. These
planes were intended for training duties. These were redesignated
P-40R-1. Similar conversions from the P-40L were designated
P-40R-2. Army records report that over 600 such conversions
were made, but only 70 such conversions can be confirmed by
War Planes of the Second World
War, Fighters, Volume Four, William Green, Doubleday, 1964.
The American Fighter, Enzo Angelucci
and Peter Bowers, Orion Books, 1987.
United States Military Aircraft
since 1909, Gordon Swanborough and Peter M. Bowers, Smithsonian
Institution Press, 1989.
Curtiss Aircraft, 1907-1947,
Peter M. Bowers, Naval Institute Press, 1979.
The Curtiss P-40 Tomahawk, Ray
Wagner, Aircraft in Profile, Volume 2, Doubleday, 1965.
British Military Aircraft Serials
1912-1969, Bruce Robertson, Ian Allen, 1969