Construction began late in the same year and the engine ran for the first time in August 1940, but produced only thrust, just half what was desired. The first flight test took place in mid-1941, mounted underneath a Messerschmitt Bf 110 testbed airframe. Problems continued, however, so delaying the program that while the Me 262 V1 prototype airframe (the first aircraft intended to use the engine) was ready for flight-testing, there were no power plants available for it and it actually began flight tests with a supplementary, conventional Junkers Jumo 210 piston engine in the nose. It was not until November 1941 that the Me 262 V1 was flown with BMW engines, which both failed during the test. The prototype aircraft had to return to the airfield on the power of the piston engine, which was still fitted.