The Curtiss P-40 series was in no way a very special fighter but was a more than average fighter-bomber, just two other US fighters were build in larger numbers the Republic P-47 Thunderbolt and the North American P-51 Mustang.

The base for the P-40 series was model 751, a model 75/XP-37A airframe was adjusted for the Allison V-1710-11 Line-engine (858 kW) and it became the first American fighter witch flew at a constant height at a speed of more than 483 Kph. (300 miles).

The type was bought by the US Army Air Corps under the name P-40 with a less powerful V-1710-33 engine.

Export versions where the Hawk 81-A1 for France, and the Tomahawk Mk I for the United Kingdom.

Improved models were:

P-40B (Tomahawk  Mk IIA):    with self closing fuel tanks, armor and better weaponry.

P-40C (Tomahawk Mk IIB):    with improved self closing fuel tanks, and two extra machineguns in the wings.

P-40D (Kittyhawk Mk I):    powered by the V-1710-39 engine (858 kW) with improved turbo to keep up performance at higher altitudes.

P-40E:    With 4 wing machineguns

Kittyhawk Mk IA:    Identical to the P-40E only 6x wing machineguns

P-40F / P-40L (Kittyhawk Mk II):    New Packard V-1650-1 engine (969) an American build Rolls-Royce Merlin

The greatest power of the P-40 was the performance as fighter-bomber at low altitude and further developments were:

P-40K (Kittyhawk Mk III):    P-40E with V-1710-33 engine

P-40M:    with the V-1710-71 engine

and the final P-40N (Kittyhawk Mk IV):    with V-1710-81/99/115 engine and alterations to decrease weight for improvement of performance.