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Propulsion Selection for 85kft Remotely Piloted Atmospheric Science AircraftThis paper describes how a 3 stage turbocharged gasoline engine was selected to power NASA's atmospheric science unmanned aircraft now under development. The airplane, whose purpose is to fly sampling instruments through targeted regions of the upper atmosphere at the exact location and time (season, time of day) where the most interesting chemistry is taking place, must have a round trip range exceeding 1000 km, carry a payload of about 500 lb to altitudes exceeding 80 kft over the site, and be able to remain above that altitude for at least 30 minutes before returning to base. This is a subsonic aircraft (the aerodynamic heating and shock associated with supersonic flight could easily destroy the chemical species that are being sampled) and it must be constructed so it will operate out of small airfields at primitive remote sites worldwide, under varying climate and weather conditions. Finally it must be low cost, since less than $50 M is available for its development. These requirements put severe constraints on the aircraft design (for example, wing loading in the vicinity of 10 psf) and have in turn limited the propulsion choices to already-existing hardware, or limited adaptations of existing hardware. The only candidate that could emerge under these circumstances was a propeller driven aircraft powered by spark ignited (SI) gasoline engines, whose intake pressurization is accomplished by multiple stages of turbo-charging and intercooling. Fortunately the turbocharged SI powerplant, owing to its rich automotive heritage and earlier intensive aero powerplant development during WWII, enjoys in addition to its potentially low development costs some subtle physical advantages (arising from its near-stochiometric combustion) that may make it smaller and lighter than either a turbine engine or a diesel for these altitudes. Just as fortunately, the NASA/industry team developing this aircraft includes the same people who built multi-stage turbocharged SI powerplants for unmanned military spyplanes in the early 1980's. Now adapting hardware developed for reconaissance at 65-70 kft to the interests of atmospheric science at 80-90 kft, their efforts should yield an aero powerplant that pushes the altitude limits of subsonic air breathing propulsion.
Document ID
19970004802
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Bents, David J. (NASA Lewis Research Center Cleveland, OH United States)
Mockler, Ted (NASA Lewis Research Center Cleveland, OH United States)
Maldonado, Jaime (NASA Lewis Research Center Cleveland, OH United States)
Hahn, Andrew (NASA Ames Research Center Moffett Field, CA United States)
Cyrus, John (Naval Air Warfare Center Warminster, PA United States)
Schmitz, Paul (Power Computing Solutions, Inc. Cleveland, OH United States)
Harp, Jim (Thermo Mechanical Systems Co. Canoga Park, CA United States)
King, Joseph (Thermo Mechanical Systems Co. Canoga Park, CA United States)
Date Acquired
September 6, 2013
Publication Date
October 1, 1996
Subject Category
Aircraft Propulsion And Power
Report/Patent Number
NASA-TM-107302
E-10390
NAS 1.15:107302
Meeting Information
Meeting: AUVSI 1996
Location: Orlando, FL
Country: United States
Start Date: July 16, 1996
End Date: July 19, 1996
Sponsors: Association for Unmanned Vehicle Systems
Accession Number
97N12828
Funding Number(s)
PROJECT: RTOP 537-10-20
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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