Test Techniques for Jet Effects on Fighter Aircraft,
CALSPAN FIELD SERVICES INC ARNOLD AFS TN AEDC DIV
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A description of efforts to improve test techniques for jet effects on fighter-type aircraft at the Arnold Engineering Development Center AEDC is given. Work in defining levels of aerodynamic interference on aircraft afterbodies from three types of model support systems, a prediction technique for hot jet effects on afterbody drag, and a hot versus cold jet experiment on target-type thrust reverses is summarized. Support system interference from a strut, sting, and wingtip support on the afterbody axial force of the same jet-effects model are compared over the Mach number range from 0.6 to 1.5. A technique for predicting hot jet effects on afterbody drag from ambient temperature jet data is presented and evaluated at Mach numbers 0.6, 0.9, and 1.2. Experiments on a target-type thrust reverser revealed two distinctly different flow regimes characterized by flow attached to or detached from the surface of the afterbody. Significant differences were found in the conditions for flow attachment for the hot and cold jet flows.