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.^[1] The project was cancelled in 1970 owing to high costs, technical problems and a change of requirement.

Design and development

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.^[2]

When the high cost, technical and logistical difficulties were realised 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 Pegasus^{[note 1]} vectored-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.

In all, three test prototypes were built, these being E1, E2 and E3 - the "E" indicating Experimentell (Experimental). E1 was powered only by the Pegasus engines, and was designed to test horizontal flight. E2 was a static test airframe, and did not fly. E3 had both Pegasus and RB162 lift engines installed, and was designed to test the vertical flight mode. The first prototype (E1) first flew on 10 February 1967 with just the two Pegasus engines. The third prototype (E3) flew in July 1967 with all ten engines fitted. The first hovering flight took place on 22 November 1967. Full forward and backward transitions were made in December 1967.

The Do 31 established several Fédération Aéronautique Internationale (FAI) world records during its ferry flight to the 1969 Paris Air Show.^[3]^[4]^[5]^[6]^[7]

It was the first, and so far only, vertical take-off jet transport ever built. The project was cancelled in April 1970, although it made its final public flight on 4 May 1970 during the ILA in Hanover. One of the factors that led to the cancellation was the large drag and weight of the lift engine pods which reduced the useful payload and range compared to conventional transport aircraft.

To cope with the complex and fast computations necessary for vertical take-off, the Do 31 was equipped with a Dornier DO-960 hybrid computer.

Survivors

Do 31 E3 on display at the Deutsches Museum Flugwerft Schleissheim

Both flying prototypes have been preserved in Germany, the fate and current location of the non-flying test bed (E2) is not known.

Dornier Do 31 E1, D-9530, is preserved and displayed at the Dornier Museum Friedrichshafen.^[8]
Dornier Do 31 E3, D-9531, was initially put into storage at Oberpfaffenhofen, then for several years on display in the open in the courtyard of the Deutsches Museum and after restoration is now on display at the Deutsches Museum Flugwerft Schleissheim at Oberschleissheim near Munich^[9]

Operators

Artist drawing

Germany

German Air Force (Luftwaffe)

Specifications (Do 31E)

Flight deck of the Do 31

Data from "The Observers Book of Aircraft"^[10]

General characteristics

Crew: 2
Capacity: 36 troops or 24 casualty stretchers
Length: 20.53 m (67 ft 4 in)
Wingspan: 18 m (59 ft 3 in)
Height: 8.53 m (28 ft)
Wing area: 57 m² (613.56 ft²)
Loaded weight: 22,453 kg (49,500 lb)
Useful load: 3,500 kg (7,715 lb)
Max. takeoff weight: 27,422 kg (60,500 lb)
Powerplant:
- 2 × Rolls-Royce Pegasus BE.53/2 turbofan, 68.95 kN (15,500 lbf) each
- 8 × Rolls-Royce RB162-4D Vertically mounted turbojet lift engines, 19.57 kN (4,400 lbf) each

Performance

Maximum speed: 730 km/h (452 mph)
Cruise speed: 650 km/h (404 mph)
Range: 1,800 km (1,120 mi) with maximum payload
Service ceiling: 10,700 m (35,100 ft)
Rate of climb: 19.2 m/s (3,780 ft/min) -using Pegasus engines only

Notes

↑ By the time of the first flight, Rolls-Royce had taken over Bristol Engines.

References

↑ Jackson, 1976. p. 143.
↑ Jackson, 1976. p.29.
↑ "FAI Record ID #5536 - Speed over a recognized course, München - Paris. Class H (VTOL aircraft)" Fédération Aéronautique Internationale Record date 27 May 1969. Accessed: 4 October 2015.
↑ "FAI Record ID #15153 - Speed, München - Paris. Class H (VTOL aircraft)" Fédération Aéronautique Internationale Record date 27 May 1969. Accessed: 4 October 2015.
↑ "FAI Record ID #15151 - Altitude, München - Paris. Class H (VTOL aircraft)" Fédération Aéronautique Internationale Record date 27 May 1969. Accessed: 4 October 2015.
↑ "FAI Record ID #15152 - Duration, München - Paris. Class H (VTOL aircraft)" Fédération Aéronautique Internationale Record date 27 May 1969. Accessed: 4 October 2015.
↑ "FAI Record ID #6370 - Distance, München - Paris. Class H (VTOL aircraft)" Fédération Aéronautique Internationale Record date 27 May 1969. Accessed: 4 October 2015.
↑ Dornier Museum press release (German language) Retrieved: 9 August 2009
↑ Deutsches Museum, Do 31 www.deutsches-museum.de Retrieved: 5 April 2010
↑ Green, 1968. p. 88.

Bibliography

Green, William. The Observer's Book of Aircraft. London. Frederick Warne & Co. Ltd., 1968.
Jackson, Paul A. German Military Aviation 1956–1976. Hinckley, Leicestershire, UK: Midland Counties Publications, 1976. ISBN 0-904597-03-2.

External links

Wikimedia Commons has media related to Dornier Do 31.

Engine placement (#6)

Dornier and Zeppelin-Lindau aircraft

Zeppelin-Lindau 1914-1919	Rs.I Rs.II Rs.III Rs.IV C.I C.II CS.I CL.II D.I V1

Dornier designations 1919-1933	Do A Do B Do C Do D Do E Do F Do G Do H Do J Do K Do L Do N Do O Do P Do Q Do R Do S Do T Do U Do V Do X Do Y Delphin Komet Libelle Merkur Spatz Wal

RLM designations 1933-1945	Do 10 Do 11 Do 12 Do 13 Do 14 Do 15 Do 16 Do 17 Do 18 Do 19 Do 20 Do 22 Do 23 Do 24 Do 25 Do 26 Do 29 Do 212 Do 214 Do 215 Do 216 Do 217 Do 317 Do 318 Do 335 Do 417 Do 435 Do 635 P.59 P.85 P.174 P.184 P.192 P.231 P.232 P.238 P.247 P.252 P.254 P.256 P.273 P.1075

Dornier designations post-1945	Do 24 Do 25 Do 27 Do 28 Do 29 Do 31 Do 32 Do 34 Do 128 Do 132 Do 228 Do 231 328 328JET 428 528 728JET 928JET Aerodyne Alpha Jet Projekt 621 Seastar S-Ray 007

See also Claudius Dornier and Dornier Museum Friedrichshafen

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