The development of the production Me 262 was terribly slow. The Germans were in such a desperate hurry that far too few prototypes were built and typically only one test model was flightworthy at any time. At several points, problems with the Junkers engine seemed insurmountable. The turbine fans frequently failed, as did the Zweibel, the onion-shaped exhaust cone. This cone presented a dangerous problem: it would detach and seal the exhaust opening, flaming out the jet and sending the plane out of control. Yet by June of 1944, the Junkers engines were in full-scale production.
