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Tests were conducted in the Arnold Engineering Development Center (AEDC) C Tunnel at a Mach number of 10 on a sharp slender cone and on the frustum, with three alternate spherical bluntness noses to determine the size of spherical roughness required to effectively trip to a turbulent boundary layer. The spherical roughnesses were placed on the surface of the sharp cone and at several flow-inclination angles on the spherical noses. Data are correlated in terms of k/d* and a trip-diameter Reynolds number that accounts for changes of local Reynolds number profile over the trip height. A definite effect of tripping effectiveness was noted as wall temperature changed. Laminar and turbulent heat-transfer results were in good agreement with the Eckert reference enthalpy method. Angle of attack affected transition by causing it to occur earlier on the leeward side for a smooth cone, but where transition was induced by roughness, it occurred earlier on the windward side. The results of the investigation may be utilized to determine allowable size of ablation roughness or spacing and position of roughness required for artificially inducing turbulence on cones and sphere cones for turbulent heating experiments in wind tunnels and flight. NomenclatureCp = specific heat at constant pressure, Btu/lb °R Cv = specific heat at constant volume, Btu/lb °R g = 32.2 ft/sec 2 = gravitational const h = enthalpy, Btu/lb H = q/T Q -T w = heat-transfer coeff, Btu/ft 2 sec°R J = 778 ft-lb/Btu = Joule's const k = trip diam, ft K = thermal conductivity, Btu/ft sec°R L = characteristic length, ft M = Mach number p = pressure, psf p r = (C P /K}n = Prandtl number q = heating rate, Btu/ft 2 sec RN = nose radius, in. RB = base radius, in. Rek = pkUkk/nk = trip Reynolds number Re x = peVeX/Ve = Reynolds number based on length Red* = peHeS*/v e = Reynolds number based on displacement thickness Rexk = In I P~^ V x = Reynolds number based on integrated J 0 \ fJLe / flow and length to the trip condition

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