American 71 Heavy, contact departure 126.47
- 17 January 2006
- Reaction score
The Dornier Do 31 was a promising jet VTOL transport that flew in the late 1960s to mid-1970s before being cancelled due to a variety of factors, from technical concerns to political changes within NATO. First of all, some pictures of the actual aircraft demonstrator my illustration is based upon:
Good pictures of the demonstrator in flight
In the early 1961 NATO issued NBMR-3 (NATO Basic Military Requirement 3) which called for a Mach 2-capable VTOL fighter. Though the political and technical saga that stemmed from NBMR-3 is beyond what I wanted to cover here, suffice to say many promising concepts were sidelined via bad political decisions (most prominently the Hawker P.1154 VTOL fighter which would have been more impressive than the Harrier). In conjunction with NBMR-3 was also the release of NBMR-4 which called for designs for a jet VTOL transport to support the VTOL fighter force in the field. In February 1962 the German company Dornier began development of their candidate which would be the only design to reach flight testing. In 1967 the Do 31E began test flying and it featured two Pegasus engines under each wing for lift and cruise, plus eight Rolls-Royce RB.162 lift jets, four each in wingtip pods for jet lift.
Flown extensively, the primary insurmountable technical challenges that the Dornier team faced were the weight and complexity from having 10 engines, the drag from the wingtip pods, and safety issues in the event of one of the Pegasus engines shutting down while in hover. It would ultimately be cancelled in 1970.
But suppose there was a niche for a jet VTOL? It's not an ideal replacement for a helicopter (it's less efficient in hover) and it's not an ideal replacement for a conventional transport (it's less efficient in cruise), but there might be specialized roles where it might be worthwhile.
Technically the Do 31E was meant only as a demonstrator, but suppose the costs of the day dictated a minimum change version of the prototype to save time and money rather than pursue the more advanced versions Dornier had on the drawing board. Above is a Do 31 illustration in the colors of the Marineflieger's search and rescue fleet (which at the time and to this day are carried out by Westland/Sikorsky Sea King helicopters). I've added an underfuselage radome to house a weather/search radar. Given the relatively small size of the Baltic Sea and adjacent waters, the limited range of the Do 31 in the SAR role might have been offset by the promise of greater speed. MFG5 is the current operator of the Marineflieger's SAR helo fleet.
Suppose that the US special forces would also have a niche role for the Do 31- fast insertion and recovery of units behind enemy lines. The Do 31 according to the test pilots that flew the aircraft reported the plane was light on the controls and handled like a fighter jet- so this version (dubbed the HV-31A) is in Southeast Asia camouflage colors commonly used on USAF aircraft in the 1970s, even outside of Southeast Asia. I've kept the underfuselage radome, but added a refuelling probe, external tanks on stub wings as well as radar warning receivers (RWRs) on the nose and aft fuselage tailcone.