The Brewster Model B-339E, as modified and supplied to Great Britain was distinctly inferior in performance to the F2A-2 (Model B-339) from the original order. It had a less powerful () engine compared to the F2A-2's 1,200 hp (895 kW) Cyclone, yet was substantially heavier due to all of the additional modifications (some 900 lb/400 kg). The semi-retractable tail wheel had been exchanged for a larger fixed model, which was also less aerodynamic. Top speed was reduced from 323 mph (520 km/h) to 313 mph (504 km/h) at combat altitudes.