Dornier Do 31

Do 31
Dornier Do 31 in 1968
Role	VTOL transport
Manufacturer	Dornier Flugzeugwerke
First flight	10 February 1967
Status	Project cancelled April 1970
Primary user	German Air Force
Number built	3

The Dornier Do 31 was a West German experimental VTOL jet transport built by Dornier. The Do 31 was designed to meet a NATO specification (NBMR-4) for a tactical support aircraft for the EWR VJ 101 VTOL strike aircraft designed under the NATO contract of BMR-3. The project was cancelled in 1970 owing to high costs, technical problems and a change of requirement.

In the early 1960s, the German Air Force became increasingly concerned that its airfields were vulnerable to air attack from Eastern Bloc forces and actively researched the possibility of dispersed operations which included flying from Autobahnen but required aircraft with STOVL capabilities. Part of these trials involved the modification of German F-104 Starfighters to be rocket-launched from stationary ramps in what became known as the ZELL program. The Starfighters were to be recovered to short strips using aircraft carrier-type arresting gear. The Do 31 was intended to use the same strips as forward operating bases.

When the high cost, technical and logistical difficulties were realized, the German Air Force ceased trials involving VTOL aircraft such as the Do 31, VJ101, and the later VFW VAK 191B which resulted in the cancellation of these projects and further use of these aircraft was limited to research purposes only.

Initial designs incorporated a Bristol Pegasusvectored-thrust turbofan in each of the two inboard nacelles and four Rolls-Royce RB162 lift engines in each of the outer nacelles. It was planned to dispense with the outer nacelles and their engines when larger RB153 turbofans (of approximately 5,000 lbf (22 kN) thrust) became available. By mounting the engines in pods, the fuselage could provide a capacious hold with a rear loading ramp.

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