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When will a diesel be available for my aircraft? |
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News, facts, and comments on the coming revolution for piston-engine aircraft.News of September 30, 2007Read Plane and Pilot of this month to learn all about the Maule SMA turbo-diesel.Maule Air has presently 7 diesel planes in the shop. Brent Maule says that the backlog is growing, and they are confident that the plane will be certified for Sun n Fun. Bill Cox flew the plane, and writes: 'I dont know about you, but I cannot imagine a world without avgas. Within a few years, I may need to stretch my imagination. The reality is that avgas may not be with us for more than about another decade (if that long)… Maule Aircraft of Moultrie, Ga., has adopted a diesel, in this case, a French SMA, to power one of its line of bush planes. Societe de Motorisations Aeronautiques (SMA) of France is one of the oldest companies in the business of adapting diesels to aircraft, and it is now a wholly owned subsidiary of the French jet-engine conglomerate Snecma. SMA began developing an aviation diesel in 1998 and earned FAA certification for its first product in May 2004... From the firewall aft, there are few differences between the standard avgas Maule M-7 and the new Diesel M-9. Adapting the diesel does demand different instrumentation and controls and larger fuel filler openings atop the wings to accommodate the larger jet fuel nozzles. The panel includes change-outs of several gauges: manifold pressure, tachometer, oil pressure and temp, cylinder head temps, turbine inlet temp and fuel level (graduated in pounds rather than gallons). .. The sensations of takeoff are not that different from what you would experience in a standard Maule, provided you ignore the manifold pressure gauge. Takeoff power is about 90 inches of manifold pressure (yes, we said 90 inches, and no, dont expect to see any Maules running the pylons at Reno), purely a function of the diesel s turbocharger. Climb is similar to that of a standard Maule at sea level, but the diesel airplane gradually pulls away from the avgas model as the ground falls away, owing to the airplane s turbocharger. Above 5,000 feet, the diesel version will easily leave the avgas Maule behind… Using the Maule M-7 standard O-540 or IO-540 as the logical examples, avgas SFC works out to about 0.48 pounds/hp/hour at full power, 0.44 pounds at 65%. Converted to diesel power, the same airplane scores more like 0.35 pounds/hp/hour at all power settings. In more familiar terms, that means the SMA-powered Maule will cruise along at 75% power on about 8.5 gph, whereas the stock airplane will burn 11 to 12 gph… Cruise numbers between the two engine types are similar at lower altitudes, but the SMA-powered airplane s turbodiesel really begins to shine at higher altitudes where the turbo begins to provide some advantages. Critical altitude (the maximum height at which the turbo can supply sea level air) is 10,000 feet. Up at 12,500 feet, the diesel manages 138 knots compared to more like 130 knots in a standard Maule. The 12,500-foot altitude is currently the limit on the SMA Diesel Maule, but the company is hoping to receive approval for a step up to a max altitude of 20,000 feet in the near future… Maule hopes to certify the M-9-230 diesel at 2,800 pounds gross on wheels, and the airplane on display at this year Oshkosh AirVenture had a redesigned wing root section and tougher main landing gear to accommodate the higher weight. When the M-9-230 is certified some time next year, Maule hopes to offer a greater than 1,000-pound useful load for a 430-pound payload after full fuel. Like most previous Maules, the M-9-230 is a master of utility, with four doors to feed five seats or a quick-change option that allows pulling the aft seats to open up a large cargo area. The target price for the new Maule M-9-230 diesel is $250,000, and it is a safe bet there will be a number of takers. Many bush operators who fly a variety of aircraft ranging from Helios and Twin Otters to Maules will probably be delighted to stock their outlying strips with a single type of fuel. Similarly, there are also a number of places in the world where avgas may be simply unavailable. It is already happening in certain parts of the South Pacific.” posted at 5:36 AM |
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