Date: 17 May 98 00:43:09 From: "P. Wezeman" <firstname.lastname@example.org> Organization: The University of Iowa References: 1 2 Followups: 1 2
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Of existing production aircraft, I would think that the logical choice would be the Lockheed C-130 Hercules. It is close to the size of the P-3 and is already used for some long range weather observation missions also performed by P-3's. An ASW version of the C-130 could save some weight by not having such a heavily reinforced cargo deck and possible by not having a rear loading ramp. Depending on how much interior volume the Navy wants, it might also have a shorter fuselage, perhaps the same length as on the earliest models. Given the conflicting requirements for an ASW aircraft to fly economically at both high and low altitudes, a four engine turboprop seems to be the best arrangement. At low altitude it can shut down and feather the outboard engines and fly on the inboard engines at near full RPM, where the engines operate most efficiently. At the speed used during search, propellers are much more efficient than turbofans. The Russians are testing an advanced counter-rotating propeller on a new airlifter with a cruise speed approaching 500 knots, and the Europeans are still talking about building a somewhat similar aircraft. Both of these are probably somewhat too big for an ASW plane, but I would expect that this type of engine would be used in preference to turbofans on a future purpose-built patrol aircraft. I believe that the British Nimrod ASW plane shuts down two of its four Rolls-Royce Spey engines while searching. Would it be possible or practical to do this with high-bypass turbofans, which would tend to windmill? I have seen the fans turning on an aircraft parked facing into a moderate wind. Peter Wezeman, anti-social Darwinist "Carpe Cyprinidae"