In order to improve the Merlin-powered Warhawk's performance in short-range combat, the P-40L version was created.
The P-40L (Model 87-B3) was basically a "stripped" version of the Merlin-powered P-40F-5-CU, in which 250 pounds of weight was saved by the partial removal of fuel, armament, and other equipment. The P-40L was otherwise virtually identical to the Merlin-powered P-40F-5-CU. Some of the P-40L production blocks featured planes with reduced armament and smaller capacity fuel tanks in order to obtain even more reduced weight and even better performance. The L-model was sometimes known as the "Gipsy Rose Lee", after the famous strip-tease dancer of the time.
The P-40L-1-CU had the same fuel and armament as the P-40F.
The P-40L-5-CU and subsequent P-40Ls had two of their wing guns removed to reduce the total armament to four 0.50-inch machine guns with 201 rounds per gun. Internal fuel was reduced by 31 Imp gal by the removal of front wing tanks.
The P-40L-10-CU had electrical aileron trim tabs and engine control changes.
The P-40L-15-CU had revised carburetor air filters and inter-aircraft signal lights.
The P-40L-20-CU had radio and electrical changes and provisions for an incendiary (destruct) grenade.
Despite the weight savings, the maximum speed of the P-40L was a mere 4 mph greater than that of the P-40F at rated altitude.
One hundred P-40Ls were sent to Britain as Kittyhawk IIs with no mark distinctions from the P-40Fs. The RAF serials for the P-40Ls were FS400/FS499. 160 other P-40Ls reached the RAF as Kittyhawk IIIs. Their serials were FL714/FL730, FR116/FR140, FR385/FR392, and FR413/FR521.
A certain number of P-40Ls were selected at random and were withdrawn from operational service and modified with the adoption of the 1360 hp Allison V-1710-81 engine in place of the original Merlin. These were used as advanced trainers. They were redesignated P-40R-2. At least 53 P-40L-->P-40R conversions took place which can be identified by serial number, but there were probably many more.
The P-40Ls were originally assigned the serial numbers 42-65202/65901.
These numbers were cancelled and were replaced as follows:
42-10430/10479 Curtiss P-40L-1-CU Warhawk 42-10480/10699 Curtiss P-40L-5-CU Warhawk 42-10700/10847 Curtiss P-40L-10-CU Warhawk 42-10848/10959 Curtiss P-40L-15-CU Warhawk 42-10960/11129 Curtiss P-40L-20-CU Warhawk 42-11130/11676 Curtiss P-40L-25-CU Warhawk - contract cancelled 42-14237/14296 Curtiss P-40L-30-CU Warhawk -- contract cancelled.