Curtiss XP-46 Color Photographs

The XP-46 was an attempt by Curtiss’ chief engineer Donovan Berlin to improve the basic P-40 design based upon European design concepts. The XP-46 was to have a more powerful engine, heavier armament, and be slightly smaller than the Warhawk. The USAAC ordered two prototypes on 29SEP39 which were given the serial numbers 40-3053 and 40-3054.

Armament was to be two .50 caliber guns mounted in the lower nose and four .30 caliber guns in each wing, inspired by British designs. To speed the test program both prototypes were delivered without armament or radios, although the USSAC added requirements for self-sealing fuel tanks and 65 pounds of pilot armor. 40-3054 was the first to fly on 15FEB41.

Power was provided by an Allison V-1710-39 twelve-cylinder inline engine which developed 1150 hp. The airframe was smaller and lighter than the Warhawk, due to the higher wing loading Curtiss designed wing slats similar to those of the Messerschmitt Bf 109. The design missed its performance goals, and handling was more sluggish than the Warhawk. Note the starboard inner wheel well door has failed to retract.

Given the mediocre performance of the XP-46 prototypes the USAAC decided to direct Curtiss to emphasize improving performance of the Warhawk already in production. The P-40D was designed around the Allison V-1710-39 to take advantage of the higher horsepower.

Curtiss sold testing data from the P-40 and XP-46 designs to North American, who used the information to help design their NA-73X prototype which eventually evolved into the P-51 Mustang. North American had already begun design of the NA-73X at the time, so there is debate as to how much influence the Curtiss data actually had.

In the end there was not anything revolutionary in the design of the XP-46, and incremental improvements to the P-40 design did yield increased performance while not requiring tooling up for production of a new design. Opinions vary as to the aesthetics of the design, but it does not look out of place compared to its contemporaries.