An Experimental Determination of Dynamics Coefficients for the Basic Finner Missile By Means of the Translational Dynamic Balance

Report number E -73.3, published by this Laboratory in June 1957, (Ref. 1) presents certain dynamic coefficients for a model of the Basic Finner Missile (Fig. 1) which had been measured on the angular dynamic balance in the High Speed Water Tunnel at this Laboratory. Several of the desired coefficients, specifically Y_r' coefficient of rotary force derivative Y_v' virtual inertia coefficient (lateral acceleration) N_r' coefficient of rotary moment derivative N_v' virtual moment of inertia coefficient (lateral acceleration) remained undetermined at that time. By employing the translational dynamic balance and its associated internal moment balance, it had been hoped that the missing values for these coefficients would be supplied. Only partial success has been achieved, insofar as numerical results are concerned, at contract expiration time. The coefficient of static force derivative, Y_v', and the virtual inertia coefficient, Y_v', have been measured as part of this investigation. These coefficients have been designated Z_w' and Z_ẇ' in this report to comply with the new direction of model motion with respect to the tunnel coordinate system. Since the first of these, Z_w', had already been determined in the angular dynamic measurements, only the presentation of a value for Z_ẇ' is new. This coefficient had appeared in linear combination with the coefficient of rotary force derivative; hence the latter important quantity also is now uniquely determined. In addition to the force reactions, the moments arising from transverse velocity and acceleration components were also measured, but under conditions of undetermined deflection of the model-spindle assembly. For this reason the moment coefficients have not been presented here, nor have the experimental procedures used to obtain them been included. Instead, a detailed discussion of both the apparatus and the experimental procedures has been planned for reference 3