The first production P-40 was flown April 4, 1940, with an Allison C-15 (V-1710-33) originally rated at 1,090 hp at 15,000 feet. Although 366-mph was achieved in early tests, bearing problems caused the Army to restrict this engine to 1,040 hp and limited top speed to 357-mph.
Armament included two .50-caliber guns with 200 rpg on the cowl and provision for a .30-caliber gun with 500 rpg in each wing, but no armor or bomb racks were carried. The first three aircraft were delivered in natural metal, but the remainder introduced the olive drab paint with gray under bottom of wartime Army planes, while these P-40s were the last model delivered with the traditional tail stripes.
Two hundred of the P-40 model reached the Army by October 15, 1940. Three went to Wright Field for tests, and technical schools at Chanute and Lowry Fields each got one. Eighty reached the 8th Pursuit Group, which moved from Langley to Mitchel Field in November; 80 went to California’s 20th Pursuit Group, which went from Moffet to Hamilton Field in September; and 35 to Selfridge Field for the new 31st Pursuit Group. Now the Army squadrons had a type comparable with the Bf 109E, although weaker in speed and firepower to the Spitfire.
On October 12, 1940, near Norfolk, the USS Wasp flew off 24 P-40s from the 8th Pursuit Group and nine O-47As of the 2nd Observation Squadron. This was the first time U.S. Army fighters flew off a Navy carrier, and would become a common wartime delivery method. HMS Argus had flown off 12 Hurricanes for Malta the previous August 2.
The remaining 324 P-40s had been deferred in April 1940 to enable earlier delivery on the Curtiss H81A-1s ordered by France and taken over by Britain. The deferred Army aircraft were to be replaced later by ships incorporating armor, fuel tank protection, and more firepower. Some may have been expected to get the P-40A designation not used on actual production aircraft.
France had ordered 100 Curtiss H81A-1 fighters, along with H75As on October 5, 1939, with a guaranteed top speed of 360-mph. The first example was flown June 6, 1940, with French equipment, provisions for four 7.5-mm wing guns and two 13-mm nose guns, and wavy camouflage paint. After the RAF took over Curtiss fighter contracts on June 17, 1940, when France surrendered, H81A contracts were increased to 1,180 aircraft.
Delivery of 100 H81A-ls, named the Tomahawk I by the RAF, began September 18, 1940. They differed from the P-40 in having 83 pounds of pilot seat armor, Superflexite fuel tank covers, four .30-cal. wing guns with 1,960 rounds and two .50-cal. nose guns with 380 rounds each. They were followed in October by 40 Tomahawk IA models with .303-cal. British wing guns. The Tomahawk Mk. IIA, or H81A-2, whose deliveries began October 30, had standard British equipment with 89 pounds of armor. Top speed had been reduced to 345 mph by the increased weight. By the end of 1940, 558 Tomahawks had been accepted at the factory by the RAF.
The Army’s equivalent of the H81A-2 was the P-40B ordered September 12, 1940, which was the first Air Corps fighter with Superflexite self-sealing tanks. There were 93 pounds of armor, two .50-caliber nose guns with 760 rounds, and four .30-caliber wing guns with 1,960 rounds. Delivery of 131 began January 3, 1941, followed, beginning March 31, by 193 P-40C fighters. That model had a new radio, 24-volt electrical system, a new fuel system with Hewitt internal self-sealing, and a drop tank.