Two rocket-propelled research models have been flight-tested to determine the effect of the intersection of thin aerodynamic surfaces and the effect of moderate sweepback of thick aerodynamic surfaces on low-lift buffeting. Data from the test of a configuration having 6-percent-thick unswept surfaces mounted in a conventional intersecting-tail arrangement on a clean body show that low-lift buffeting and a change in trim normal-force coefficient were encountered simultaneously at transonic speeds. Low-lift buffeting may be induced by the inter¬ference effects of thin intersecting surfaces and local interference effects on an intersecting-tail arrangement may be partially responsible for persistent transonic trim changes. Data from this test indicate an increase in drag coefficient over that of a comparable symmetrical con-figuration. Data from the test of a configuration having 12-percent-thick surfaces swept back 35° also show that low-lift buffeting and a change-in trim normal-force coefficient occurred simultaneously at tran¬sonic speeds. Sweeping back a thick surface reduces the buffet inten¬sity, normal-force trim change, and total drag coefficient. Buffet intensity data from the two tests are presented.
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