Heinkel He 118

The Heinkel He 118 was a German dive bomber design that competed with the Junkers Ju 87 for production, but was never ordered for the Luftwaffe. Only a small number were built, serving as the inspiration for the Japanese Yokosuka D4Y.

Design
Designed by the Günter brothers, the He 118 followed many of the design notes of the Günter's designs of the era, notably the elliptical wing planform and rounded tail surfaces. The He was, in many ways, an aluminum version of the mixed-construction Heinkel He 70 Blitz, suitably strengthened for the dive bomber role.

It was a conventional cantilever monoplane with an inverted gull wing of elliptical planform mounted mid-way up the fuselage. It was considerably more streamlined than the Junkers competitor, with retractable landing gear and an internal bay for its bombs.

The design was intended to fill a role similar to an attack bomber like the Henschel Hs 123 rather than the pure dive bomber like the Stuka. It was intended to bomb from a shallow angle, more properly known as "glide bombing", with the second crew member acting as the bomb aimer using a bombsight.

Production and testing
In trials, however, it was discovered that the maximum dive angle was only 50°.

On 27 June 1936, Ernst Udet arrived at the Heinkel manufacturing company to try out the He 118. Soon after he commenced his first dive from about 13,000 feet the propeller suddenly feathered, shearing off the reduction gears, and the He 118 disintegrated around the pilot. Udet parachuted to safety. The Ju 87 repeatedly demonstrated dives at 90 degrees with no trouble, and so was officially declared winner of this contest.

Heinkel complained in his biography that Udet ignored instructions and flew the aircraft outside of its limits. He suggests that this failure doomed his design, in spite of the historically recorded facts of the superior dive angle of the Stuka.

Only 15 He 118s were built and two of these were given to Japan, where they were given the designation DXHe and provided the inspiration for the Yokosuka D4Y naval dive bomber.

One of the other examples was used by the Heinkel company as a flying testbed for the Heinkel HeS 3 turbojet, with the jet engine slung under its fuselage. Although its pilot took off and landed using the He 118's piston engine, he started the turbojet engine in flight and flew under its power in July 1939, the first time any aircraft made any part of a flight under jet power. The following month the Heinkel He 178 would use the engine to make history's first flight powered entirely by a turbojet engine.

Variants

 * He 118 : Dive bomber prototypes.
 * He 118A-1 : Eight production aircraft, powered by a 634 kW (850 hp) DB 600C engine.
 * DXHe1: Two He118s supplied to the Imperial Japanese Navy Air Service for evaluation in 1938.

Operators

 * Japanese Imperial Navy
 * Japanese Imperial Navy