Maximum speed was increased to 448 mph and climb rate to over 4,500 ft/min (1,180 m/min) as opposed to the 2,900 ft/min (884 m/min) of the F4U-1A. US Navy performance trials The "4-Hog" retained the original armament and had all the external load (i.e., drop tanks, bombs) capabilities of the F4U-1D. The windscreen was now flat bullet-resistant glass to avoid optical distortion, a change from the curved Plexiglas windscreens with the internal plate glass of the earlier Corsairs.