The design of the Curtiss P-40 ("P" stands for "Pursuit" - the USAAC/USAAF designation for fighters) began in 1937 (maiden flight of first prototype XP-40 on October 14, 1938) and was based on the radial-engined P-36 (manufacturer designation Hawk 75A) of 1935 origin.
The P-40 is undoubtedly remaining one of the most controversial Allied fighters of the Second World War. Its performance was invariably inferior to the performances of the fighters by which it was opposed, but it was tractable and capable of absorbing much battle damage. Praised or abused, the P-40 was the only relatively modern fighter available to the USAAF, when it went to war, but perhaps the most surprising aspect of its history was the fact that it was retained in production in one form or another until December 1944, long after more advanced types were available in quantity.
The P-40's principal shortcoming was its poor performance at altitude, a direct result of the requirements to which it was produced. These requirements ("ascendancy of bombardment over pursuit" military doctrine) had been formulated at a time when coastal defense and ground attack were expected to be its primary tasks, no possibility of high-altitude enemy attack against the USA being envisaged. Thus, low-altitude flying qualities and rugged construction were given precedence. Due to these characteristics, the P-40 was generally found wanting in the types of combat fought over Western Europe and - to a lesser extent - North Africa and the Pacific theater. On the other hand the air war on the Russian front came very close to the nature of sorties the P-40 had been originally constructed for. Nevertheless the Russians considered the P-40's ability to absorb battle damage to be inferior to that of the Bell P-39 Airacobra.
The designations used for the members of the P-40 type family are very numerous and - at the first glance at least - confusing. This partially results from the fact that three different designating systems were in parallel use:
Within those designating systems there were additional pre- and suffixes to denote sub-variants. The British used "Mark" numbers - sometimes with an additional letter to denote minor differences - (e.g. "Tomahawk Mk.IIB"). The American system was developed to its final form during the production run of the P-40 and finally (from P-40F on) consisted of a version letter, followed by a production batch number and two letters denoting the production facility. Under this system "P-40N-5-CU" designated a P-40N variant of the second production batch (normally the batch numbers had the sequence -1, -5, -10, -15 and so on, but sometimes there were exceptions of interspersed batch numbers, too), produced by Curtiss at Buffalo or Columbus. One source quotes that "CS" instead of "CU" denoted P-40s built at St. Louis. The following table lists the different versions of the P-40 and their respective designations.
|Variants of the P-40 family and their designations|
|US Army||Production batches||Manufacturer||Royal Air Force||Numbers built||Comments|
|XP-40||-||Hawk 75P||-||1||First prototype|
|P-40||-||Hawk 81||-||199||First production model|
|P-40A||-||?||-||1||P-40 converted for photo reconnaissance|
|-||-||Hawk 81A-1||Tomahawk Mk.I, IA and IB||140||Export version of P-40, originally ordered by France, taken over by the RAF|
|-||-||Hawk 81A-2||Tomahawk Mk.IIA||110||Export version of P-40B|
|-||-||Hawk 81A-3||Tomahawk Mk.IIB||930||Export version of P-40C|
|P-40D||-||Hawk 87A-1||-||22||First variant of "second generation" P-40|
|-||-||Hawk 87A-1||Kittyhawk Mk.I||20||Export version of P-40D|
|P-40E||-||Hawk 87A-2||Kittyhawk Mk.I||820||-|
|P-40E-1||-||Hawk 87A-3||Kittyhawk Mk.IA||1,500||Purchased with Lend-Lease funds for Great Britain|
|XP-40F||-||Hawk 87D||-||1||Prototype with Packard-built V-1650-1 Merlin engine|
|YP-40F||-||?||-||1||Modified P-40F-1-CU with deep, aft moved ventral radiator|
|P-40F Warhawk||F-1-CU, F-5-CU, F-10-CU, F-15-CU, F-20-CU||Hawk 87D||Kittyhawk Mk.II||1,311||First production model with Merlin engine|
|XP-40G||-||Hawk 81A-G||-||1||66th P-40 fitted with Tomahawk Mk.IIA wings|
|P-40G Warhawk||-||Hawk 81A-G||-||43||P-40s fitted with Tomahawk Mk.IIA wings|
|P-40J||-||?||-||0||1942 project of P-40E with turbo-supercharger|
|XP-40K||-||?||-||1||P-40K-10-CU with radiators in swollen wing centre section|
|P-40K Warhawk||K-1-CU, K-5-CU, K-10-CU, K-15-CU||Hawk 87D||Kittyhawk Mk.III||1,300||-|
|P-40L Warhawk||L-1-CU, L-5-CU, L-10-CU, L-15-CU, L-20-CU||Hawk 87D||Kittyhawk Mk.II||700||Lightweight version of P-40F|
|P-40M Warhawk||M-1-CU, M-5-CU, M-10-CU||Hawk 87D||Kittyhawk Mk.III||600||Built exclusively for Lend-Lease supply to Great Britain|
|P-40N Warhawk||N-1-CU, N-5-CU, N-6-CU, N-10-CU, N-15-CU, N-20-CU, N-25-CU, N-26-CU, N-30-CU, N-31-CU, N-35-CU, N-40-CU||Hawk 87W||Kittyhawk Mk.IV||5,219||Last production model, modified cockpit canopy from N-5-CU on|
|XP-40N||-||?||-||1||Redesigned P-40N, similar to XP-40Q|
|XP-40Q||-||?||-||1||Radically redesigned P-40K with cut-down rear fuselage and "bubble" canopy|
|P-40R Warhawk||R-1 (ex-P-40Fs), R-2 (ex-P-40Ls)||Hawk 87D||-||300(?)||Re-engined P-40Fs and P-40Ls with Allison V-1710-81 due to shortage of Merlins|
There also existed two-seat training versions of different models under the designation TP-40. The designations RP-40 and ZRP-40 were assigned to (old) airframes with restrictions in use.
According to the (thoroughly checked) table above P-40 production totalled 13,198 machines. In some sources more than 14,000 machines are claimed, but this figure possibly contains cancelled batches and modifications may be counted twice. These planes served with more than a dozen air forces. Besides the USA, the British Commonwealth and the Soviet Union a prominent user was China, where the P-40s of the American Volunteer Group with their sharkmouth-painted noses became famous.
Western sources quote the figure of 2,097 P-40s of all variants delivered to the Soviet Union. 366 of them were Tomahawks or the similar P-40G Warhawk, the remaining being Kittyhawk variants. With few exceptions which were delivered directly from the USA they came from Great Britain. According to a Russian source 2,134 P-40s were put in service with the Soviet air forces (from 2,574 examples sent to Russia).
The Russians were only moderately satisfied with this type. Especially the engines caused much problems, they were lacking air filters and consequently tended to wear down rapidly. Additionally, the difficult supply situation during 1942 often prevented a necessary replacement - sometimes with fatal results. Maybe in an attempt to find a solution for those engine problems a number of Kittyhawks at the Leningrad front were fitted with Russian M-105 engines.
|P-40 variants in Soviet service
(Detailed data of other versions may be found in the references and links quoted below)