The P-66 Vanguard, like the P-64, was initially built after purchase by another government. The Swedish government signed a contract on Feb. 6, 1940, for 144 Model 48Cs. By the time the first of the Vanguards was ready for delivery in September 1941, the United States had an embargo in place and impounded the aircraft.
The British initially took over the order, but the United States diverted 129 aircraft to China instead. The remaining 15 aircraft were redesignated P-66s and used by the AAF as trainers. All 144 P-66s were assigned AAF serial numbers (42-6832 to 42-6975).
The production P-66 differed from the Model 48 mainly in the forward fuselage. The Model 48 had a streamlined cowling around the radial engine similar to the XP-42. Because of cooling problems, the cowling was changed to a more standard type before production started.
Impounded Swedish aircraft; renamed P-66
TECHNICAL NOTES: Armament: Four .30-cal. machine guns and two .50-cal. machine guns Engine:Pratt & Whitney R-1830-33 of 1,200 hp Maximum speed: 340 mph Range: 850 miles Span: 36 ft. 0 in. Length: 28 ft. 5 in. Height: 13 ft. 1 in. Crew: One