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A computational fluid dynamic technique is demonstrated for a time-accurate store separation event at transonic speeds. An overlapping grid approach is used coupled with an implicit Euler flow solver with a fluxdifference split scheme based on Roe's approximate Riemann solver and a six-degreeof-freedom trajectory code. All major trends of the trajectory are captured and surface pressure distributions are predicted. Three sources of error are identified and discussed.

The ability of an Euler code to predict mutual aerodynamic interference in the transonic regime was investigated. One-, two-, and three-body combinations of a cruciform-finned configuration were examined at Mach numbers from 0.80-1.20. Predicted surface pressure distributions were compared with wind-tunnel data on three finned bodies. The Euler code was found to predict body pressure well in many interference regions, although shock location often was less accurate due to viscous effects in the strongest interference flowfield near Mach 1. Rigid-body physics of the three-body combination was investigated from integrated pressure distributions. Force and moment behavior was found to be strongly dependent on Mach number.= upper body X/C = axial location per local chord length X/L = axial location per body length = angular positior

A jump angle prediction theory is developed for supersonic free-flight missiles. Six-degree-of-freedom trajectory computations indicate that the theory accurately predicts the jump angle of finned bodies for a wide range of conditions. Initial conditions and jump angle values of actual missiles are established by range test firings of flechettes. The raw data are fitted to a fourth-order polynomial and an epicyclic motion and results put into initial condition form. The initial conditions are applied both to the theory and six-degree-of-freedom trajectory computations and results compared to target data. The agreement between the theory and test results indicate the data reduction method and theory provide an accurate means of predicting dispersion of flechettes. Initial conditions are shown to be valid at the start of free flight, generally downrange of the sabot separation. Analysis of the firing data indicates that the initial conditions result from an impulse imparted to the flechette through sabot separation and asymmetrical muzzle blast. Initial transverse linear velocity is shown to be the single most influential term in the jump equation. Maximum yaw location is shown to locate the initial conditions of free flight. Initial momentum imbalance is presented as the reason dispersion exists. Cz d i Nomenclature = static moment stability coefficient =total aerodynamic asymmetry moment coefficient =Magnus moment stability coefficient = static force stability coefficient =total aerodynamic asymmetry force coefficient -.p0 = Magnus force stability coefficient = missile diameter = denotes z-axis component in complex system I x " = axial moment of inertia I y = transverse moment of inertia j% = complex jump angle K = amplitude coefficient in angular motion solution m = missile mass M a = static moment stability derivative M d = lag moment stability derivative MK = asymmetry moment derivative = Magnus moment stability derivative = pitching velocity moment stability derivative p = missile roll rate q = complex angular velocity = q + ir q = pitching velocity r_ = yawing velocity S = complex lateral translation = y+iz t =time u = velocity along x-axis v = velocity along .y-axis w = velocity along z-axis x = downrange position component y = swerve position component z = heave position component Z a = static force stability derivative Z d = iag force stability derivative z d f = asymmetry force derivative Z p/3 = Magnus force stability derivative Z q = pitching velocity force stability derivative a = complex angle of attack = 0 + iot a = pitch angle of attack P = yaw angle of attack Presented as Paper 81-0222 at the AIAA 19th Aerospace Sciences Meeting, St. Louis, Mo., 6* e = aerodynamic asymmetry vector = 6 r + /6 6 6 = angular motion phase angle 7 = axis system rotation angle X = angular motion damping rate o) = angular motion frequency =X+/o> p = air density Superscripts (') = derivative with respect to time ( )' = parameter in rotated axis system Subscripts 0 = initial condition parameter N = nutation arm parame...