The total pressure drag obtained by integration along the body axial coordinate x is CD = CM^^/K*, or CD/M^P* = C/K* = /(M.0)The axial force may be related to the drag coefficient by using the body axes as a reference : CA = CD cosa -CL sina (5) and for small a, CA = CD. Consideration must also be given to skin-friction drag; in general, the average skin friction in a laminar boundary layer maybe expressed as C F = CiRe L~1 12 . The total drag at a 0 is then given byAt hypersonic speeds, interaction effects between the external flow and the boundary layer can strongly influence the boundary-layer development. A measure of this effect on the inviscid pressure and drag is 1^ M m */Re L 1/2 (7) X = Mn'Wy/n where C* = (MTOO/MOOT 7 *) is based on Eckert's reference temperature 6 and is near unity. Since values of the wall temperature corresponding to the test results are uncertain, we assume that (C*) 1/2 = 1. Therefore,To obtain a simple form for correlation purposes, it is postulated that this relationship can be modified by combining the first, third, and fourth parameters, so that plots of C A Re L 112 / M m n /3 3 vs Moo/3 may provide useful correlations. For finite values of /3, the parameter ft is replaced by sin/3. Correlation of Experimental ResultsTo establish the influence of M m , several exponents n were tried; n = 3 worked best. The results of the axial force correlation for short and long blunted elliptical cones are presented in Fig. 2. Data from three wind tunnels are correlated in "weak" (x < 1) and "strong" (% » 1, K*» 1) interaction regimes. The correlation for the long model with strong ' « Jo-O 1 TEST DATA FROM D >• VARIOUS FACILITIES A J REF 4 \O 36 > Moo > 14 X>4 M s,n 10 20 (.0 Fig. 4 Correlations for L/D and C N /C^ for long body, viscous interaction isThe correlations for CN, CD, and CL in Fig. 3 show that the test data fall into two groups, one for weak interaction with x < 6.5 and the other for strong interaction with x > 7. Most of the data for strong interaction can be represented by the relations C N = 6.761 (M m sin/5) 1 -205 Re L~L ' 2 (10) CD = 5.209 (M m sin/3) 1 -155 He L -^ (11) CL = 8.962 (M m sin/3) 0 -96 Re L -112The ratios L/D and C N /C A were correlated by means of the same parameters and are shown in Fig. 4. Concluding RemarksSignificant parameters for aerodynamic force coefficients for hypersonic regime with viscous interactions have been inferred from simple analysis and serve well to correlate experimental data for blunted elliptical cones. Since 1) 7 = 1.4 was assumed for all cases (but lower y's are typical for hypervelocity facilities), 2) no attempt was made to account for wall temperature T w (meager information) in the expression for x, and 3) there is greater uncertainty in the test flow conditions at high M m , it is not surprising that the results for very high Moo show a larger scatter than those for lower Moo's. Nomenclature