The Diesel engine has demonstrated the lowest specific fuel consumption of any prime mover (as low as .26 Ib/hp hr for large 2-stroke marine Diesels). It uses fuel which is much cheaper and still contains more energy per gallon than gasoline or avgas. There were Diesel aircraft engines decades ago (Guiberson, Packard, Rolls-Royce, Clerget, Fiat...). In the 1930's the Junkers JUMO. With today's materials and engineering it is possible to achieve greater goals in power plant design. The Aurora will employ this new technology to advance the range and payload above the existing available light twins.
Diesels offer these advantages over conventional spark ignition engines:
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This engine has only one-third the moving parts of a 4cyl Lycoming or Continental. The cylinder heads are cast as part of the block. There are no head gaskets to blow, no head bolts. internal parts are installed through the bottom of the engine. The lower crankcase is secured to the upper crankcase with 14 high-strength studs. This, along with the inherent stoutness of the block and compactness of the V-4 design, makes the engine extremely rigid, strong and light.
The Diesel engine has demonstrated the lowest specific fuel consumption of any prime mover (as low as .26 Ib/hp hr for large 2-stroke marine Diesels). It uses fuel which is much cheaper and still contains more energy per gallon than gasoline or avgas. There were Diesel aircraft engines decades ago (Guiberson, Packard, Rolls-Royce, Clerget, Fiat...). In the 1930's the Junkers JUMO.
Following these almost forgotten examples we develop a new piston engine for the general aviation: the ZOCHE aero diesel. It is a radial engine with 4 cylinders per row. It is a direct drive. highly charged, direct fuel injected, air cooled two-stroke cycle diesel. The opposed-cylinder, spark ignited aircraft engine taken as baseline, aero diesels offer many advantages:
The very compact ZOCHE aero diesel incorporates the latest cylinder technology as well as refinements like tungsten counterweights and full aerobatic pressure lubrication. The ZOCHE aero diesel's high efficiency reduces the amount of rejected heat, thereby minimizing cooling air requirement. Cooling problems are further reduced by the fact that there are no areas in this diesel engine which demand such exact cooling as the cylinder head of a spark ignited engine. Charge air pressure is generated by a combination of a highly efficient mechanical blower and a turbocharger. This reduces the power loss at altitude. Recent improvements include a proprietary pneumatic starter system which uses the gear driven supercharger as a starter turbine. The fuel injection pump together with its feed pump, the fuel filter and all connecting plumbing are integrated into the crankcase assembly. The intake manifold is a part of the crankcase casting, further reducing the parts count and improving reliability. In 1992 the project was awarded the prestigious Philip Morris Research Prize.
Propeller Shaft Rotation is clockwise (viewed from anti-propeller end), there are 3 Accessory Drive Pads running at Crankshaft Speed. Weight includes: Pneumatic Starter, Alternator (1 kW, 12 or 24 V), hydraulic Prop-Governor, Turbo- and Supercharger, Oil- and Fuel-Filter. Minimum Starter Air Reservoir is 8 liter at 30 bar (2.1 gallon at 435 psi). Motor Mounts are at the Rear of the Cylinder Heads. CG is located in the Plane of the Cylinders. Engines will be certified to JAR-E and FAR 33, a TBO of 2,000 hours is anticipated. Patents DE 3525665,·DE 4020826, EP 0231223, US 4,781,028, US 5,197,416, Japan 63-500818, Patents pending. LBA-Nr. I-EC 45.
Last fall under a competitive procurement program among jet engine companies, NASA selected Williams International to join NASA in a $100 million cooperative effort to revitalize the once-flourishing light aircraft industry in the United States through small turbofan engine technology. Under the program, Williams and its industry team members, which include Williams suppliers and future aircraft company customers, provide 60 percent of the resources and NASA provides 40 percent for the initial engine demonstration phase.
Williams, currently in the component design phase of the engine technology program, is emphasizing low cost manufacturing processes suitable for high quantity production, and is active with key suppliers to minimize materials and purchase parts costs. The new Williams engine has been named the "FJX-2."
Dr. Sam Williams, Chairman of Williams International, said, "Our objective is to replace aging, piston-powered light aircraft with all new, four-place single and six-place twin, turbofan-powered modern aircraft. This means we must develop a turbofan in the 700 pound thrust category that is very low in cost at a high production rate, is extremely quiet, is light in weight, and is very reliable."
Not intended for production, the "V-JET II" was designed by Dr. Sam Williams to demonstrate the new Williams FJX-2 high bypass ration engine characteristics in flight over the anticipated speed and altitude range for future "turbofan-powered, light aircraft era."
The aircraft at Oshkosh this year will be powered by two existing low bypass ratio, 550 lb thrust, FJX-1 turbofan engines developed by Williams. These interim engines are being used to check out the aircraft's performance and systems prior to installation of the new high bypass ratio, FJX-2 engines being developed in cooperation with NASA. The new engines are to be installed during the fourth year of the NASA/Williams program and demonstrated at Oshkosh during the year 2000.
According to Williams, the "V-JET II" will be used primarily to demonstrate the new turbofan engines over a range of flight speeds and altitudes that are expected to be required in future turbofan-powered light aircraft. Installation characteristics, engine performance data, noise levels, exhaust emissions, and flight parameters will be reviewed with the aircraft companies that are participating in the program as members of the NASA/Williams General Aviation Propulsion (GAP) team.
Another purpose of the "V-JET II" flight demonstrations will be to stimulate interest on the part of aircraft companies in designing and developing production aircraft utilizing this new propulsion technology. Williams said, "When the public views the 3800 lb "V-JET II" powered with the existing small turbofan engines, the interest will begin to build. However, later in the program when they view this sleek aircraft powered with extremely quiet, very low cost, light weight, high bypass ratio turbofans, the potential for a revival of the light aircraft industry through turbofan power should certainly be underway. I believe every light aircraft pilot dreams of being a jet pilot. This low cost turbofan technology can make this a reality."
Last Update: 23 July 1997
NASA Contact:
Leo Burkardt Leo.A.Burkardt@lerc.nasa.gov
NASA/LeRC GAP Program Manager
Tel: (216)977-7021
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