The new Brewster fighter had a modern look with a stubby fuselage, mid-set monoplane wings and a host of advanced features. It was all-metal, with flush-riveted, stressed aluminum construction, although control surfaces were still fabric-covered. The XF2A-1 also featured split flaps, a hydraulically operated retractable main undercarriage (and partially retractable tailwheel), and a streamlined framed canopy. However (as was still common at this time), the aircraft lacked self-sealing fuel tanks and pilot armor. Fuel was only 160 U.S. gal (606 l), stored in the fuselage. Powered by a 950 hp (708 kW) single-row Wright R-1820-22 Cyclone radial engine, it had an impressive initial climb rate of 2,750 ft/min and a top speed of 277.5 mph (447 km/h). The aircraft was then tested in 1938 in the Langley Research Center full-scale wind tunnel, where it was determined that certain factors were contributing to parasitic drag. Based on the tests, improvements were made to the cowling streamlining and carburetor/oil cooler intakes, and the Buffalo's speed rose to 304 mph (489 km/h) at 16,000 ft (4,879 m) without any increase in power. Other manufacturers took notice of this 10% increase in speed and efficiency, and wind tunnel tests grew to be standard procedure in the US. With only a single-stage supercharger, high-altitude performance fell off rapidly. Fuselage armament was one fixed .50 in (12.7 mm) M2 Browning machine gun with 200 rounds and one fixed .30 in (7.62 mm) AN Browning machine gun with 600 rounds, both in the nose. The Navy awarded Brewster Aeronautical Corporation a production contract for 54 aircraft as the F2A-1.