Propfan The Latest Buzzword In Aviation

Principal among these research programmes is a recently announced $59 million project linking Lockheed, NASA, Allison and a number of smaller specialised companies in test flying a propfan aboard a Gulfstream GIi jet to accurately measure the exact noise and vibration properties attained with a propfan. Preliminary work has already been undertaken by Lockheed using a C-140 Jetstar during 1982/83 with a fuselage-mounted profan. and this second stage will build on much of what was learnt ln the earlier programme. Either way, Lockheed and NASA hope to complete the entire project by 1988.

McDonnell Douglas is a firm believer in propfan and is keeping its options open on developing a 120/140-seat aircraft that it hopes to have available by the early ‘nineties. Little specific information has come out to date on this project and it is thought that ultimately it might eventuate that the scrapped MD-90 may re-emerge as a propfan.

Boeing are working closely with both Pratt & Whitney and General Electric and will mount units from both companies in place of the No 3 engine on Boeing’s own 727 aircraft for test flying during 1987. General Electric are pinning much faith on the propfan concept which they claim despite the problems will be unavoidable as a future powerplant owing to the fuel savings involved. GE launched their concept, dubbed UDF, or Unducted Fan, at the 1984 Farnborough air show. Many observers were, however, curiously startled by the fiercely scimitar-like counter-rotating UDF blades which looked more at home on the aft end of a nuclear submarine!

Enter the Russians. With the West about to embark on propfan and being at the edge of the learning curve in practical aspects, it was not surprising that several ‘soft’ overtures have come from the USSR to promote a collaborative effort in mastering the potential benefits of this ‘new’ technology. The Russians of course have been flying the nearest thing to a propfan for over three decades, and with startling success. Using engines rated at out to 14,000 shp the USSR has been flying the TU-114 Cleat and the Tu-20 Bear since 1955 with large contra-rotating propel/ors not that dissimilar to the Western concept of nineteen nineties propfan. Whether a collaborative effort comes to pass remains to be seen and if it does it may well originate from Europe where the USSR has better trading ties than with North America.

Airbus Industrie, while not discounting the fuel savings to be had with amature propfan aircraft, are staying with the proven medium by-pass ratio turbofan for their A320 150-seater. Airbus feel that in the medium term, or till at least the mid ‘nineties, propfans will not be any more attractive in Direct Operating Cost (DOC) terms than an A320 due to the high cost of developing the propfan and the level of additional maintenance required of the engine/ propel/or unit as it is developed to the state of a mature combination.

In an industry that literally abounds with buzzwords, propfan is one such word that you are certainly going to hear a lot more of in the years to come.