ESDU 89014 D
ESDU 89014 D 2004-SEP-01 Normal force ptchng moment and sde force of forebody-cylnder combnatons for angles of attack up to 90 degrees and Mach numbers up to 5
ESDU 89014 D 2004-SEP-01 Normal force ptchng moment and sde force of forebody-cylnder combnatons for angles of attack up to 90 degrees and Mach numbers up to 5
Item No. 89014 provides a simple empirical means of estimating the normal force and pitching moment of axisymmetric forebody-cylinder combinations for angles of attack up to 90 degrees and Mach numbers up to 5. Although derived using wind-tunnel test data for cylinders with tangent-ogive and cone forebodies (with and without blunting) and secant-ogive and ellipsoid forebodies, the method is expected to give reasonable estimates for any axisymmetric forebody-cylinder combination with a smooth forebody shape. The method requires as inputs the normal-force-curve and pitching moment-curve slopes at zero angle of attack, which may be taken either from test data or calculated using Item No. 89008, and simple geometrical parameters which may be obtained from Item No. 77028. The use of the method is illustrated by a worked example. The effects of boat-tailed may be estimating using Item No. 87033. The calculation procedure is programmed in ESDUpac A9034, see Item No. 90034. At high angles of attack at subsonic and transonic Mach numbers, asymmetric vortex flow may occur on the leeward side of the body. This phenomenon, which is known to depend on such minor factors as small imperfections at the nose, has the effect of producing an out-of-plane force distribution that can result in large side forces and yawing moments. The Item considers this subject by providing a description of asymmetric vortex flow and the resulting forces, including effects of Reynolds number and forebody blunting. A discussion of Mach number effects is also given, together with an envelope of maximum side force.