Junkers Ju 87 near Sagan, 13 Ju 87s and 26 crew members were lost when they crashed into the ground almost simultaneously. The planes dived through cloud, expecting to release their practice bombs and pull out of the dive once below the cloud ceiling, unaware that the ceiling was too low and unexpected ground mist formed, leaving them no time to pull out of the dive. On 1 September 1939, the Wehrmacht invaded Poland, triggering World War II. "Generalquartiermeister der Luftwaffe" records indicate a total force of 366 Ju 87 A and Bs were available for operations on 31 August 1939. The first
Junkers J 2 fuselage directly below the stabilizer's leading edge root. The wings had at least three different airfoil changes between root and tip, and had sections of them electrically roll-welded for stronger, more continuous bonding for greater strength. The resulting aircraft was intended to be smaller than the J 1 demonstrator, but with its steel structure, it almost equalled the J 1's completed weight. One feature pioneered in the J 2 that would also be used in later all-metal monoplanes designed and built by Junkers in World War I, was a "unitized" forward fuselage structure, combining the engine mount, wing roots and