The Americans also tested a Me 262A-1a/U3 unarmed photo reconnaissance version, which was fitted with a fighter nose and a smooth finish. Between May and August 1946, the aircraft completed eight flights, lasting four hours and forty minutes. Testing was discontinued after four engine changes were required during the course of the tests, culminating in two single-engine landings. These aircraft were extensively studied, aiding development of early US, British and Soviet jet fighters. The F-86, designed by engineer Edgar Schmued, used a slat design based on the Me 262's.