FOK REFERENCE

Results are presented from recent investigations of the aeroaynamic heating rates of blunt nose shapes at bkch numbers up t o 14. Data obtained i n flight and wind-tunnel tests have shown that the flat-faced cylinder has about 50 percent the stagnation-point heating rates of the hemisphere over nearly the en t i r e Mach number range. Tests made a t a mch number of 2 on a series of ' bodies.made up of hemispherical segments of varying radius of curvature showed that slight amounts of curvature can decrease the local ra tes a t the edge of the flat-faced cylinders with only a slight increase i n the stagnation rate. The t o t a l heat t ransfer t o such slightly curved bodies is a l so somewhat smaller than the t o t a l heat transfer t o flat-faced cylinders. Comparison of several tests with theoretical heating-rate distri-butions showed that both laminar and turbulent loca l r a t e s can be pre-dicted by available theories (given the pressure distribution about the body) reasonably w e l l, although the sca t te r of the available data st i l l leaves open the choice between the theories a t the.edge of the bodies, where they u s u a l l y di f fe r. Tests on a flat-faced cylinder a t a Mach nutiber of 2.49 and a t angles of a t tack up t o l5O showed the movement of the apparent stagna-t ion point from the center of the body t o the 50 percent windward sta-t i o n at 15 ' angle of attack. The heat transfer near the windward edge increased about 30 percent while that near the leeward edge decreased about 20 percent at 1-5 ' angle of attack. Preliminary results on a concave nose have indicated the possibil-i t y that this type of design may be developed t o give heating rates significantly lower than even the flat-faced cylinder rates. The test resu l t s have a l s o shown, however, the existence of an urmteady flow phenomenon which can increase the heating rates t o extremely high values. * T i t l e, Unclassified