Base-Drag-Reduction Experiments on the X-33 Linear Aerospike SR-71 Flight Program
Whitmore, Stephen A. and Moes, Timothy R. (2000) Base-Drag-Reduction Experiments on the X-33 Linear Aerospike SR-71 Flight Program. Journal of Spacecraft and Rockets 37(3):297-303.
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Abstract
Drag-reduction tests were conducted on the Linear Aerospike SR-71 experiment. The Linear Aerospike SR-71 experiment flight tested a 20% scale model of an
X-33 forebody with a linear-aerospike engine mounted at the rear of the body. The entire apparatus was mounted on top of an SR-71 aircraft. This paper suggests a method for reducing base drag by adding surface roughness along the forebody. Calculations show a potential for base-drag reductions of 8-14%. Flight results corroborate the base drag reduction, with actual reductions of 15% in the high-subsonic flight regime. An unexpected result is that drag benefits persist well into the supersonic flight regime. Flight results show no overall net drag reduction. The applied roughness caused forebody pressures to rise and offset base-drag reductions. Apparently, the grit displaced streamlines outward, causing forebody flow compression. Clearly the drag optimization must be modified to include not only the base pressure drag and viscous forebody drag coefficients but must also include the forebody pressure distribution. Because of the mixed experimental results-there was no overall net drag reduction, the existence of an optimal forebody surface roughness must still be proven. Clearly, however, the forebody grit method has been proven as a viable drag-reduction tool.
| EPrint Type: | Journal Article (Technical) |
|---|---|
| Keywords: | Aerospike engine, base drag, LASRE, SR-71 aircraft, single-stage-to-orbit, X-33 vehicle |
| Subjects: | (01 - 09) Aeronautics: (05) Aircraft Design, Testing And Performance Aircraft/Project: LASRE Aircraft/Project: SR-71 Blackbird Aircraft/Project: X-33 |
| ID Code: | 1832 |
| Deposited On: | 08 Febuary 2008 |
| Additional Information: | 7 pages. Whitmore, Moes, NASA Dryden Flight Research Center. |
