No abstract

Unclassified 15«. DECLASSIFI CATION/DOWNGRADING SCHEDULE Approved for public release; distribution unlimited. 17. DISTRIBUTION STATEMENT (of the abatract entered In Block 20, It different from Report) 18. SUPPLEMENTARY NOTES 19. KEY WORDS (Continue on reverse alda If neceaaary and Identify by block numbed Projectile aerodynamics Supersonic flow Finite difference computations 20, ABSTRACT fCoirtfiiiw ao rmraram sfoto If nccMMty and Identify by block number) Three dimensional finite-difference flow field computation techniques have been employed to generate a parametric aerodynamic study at supersonic speeds. Computations for viscous turbulent and inviscid flow have been performed for cone-cylinder, secant-ogive-cylinder, and tangent-ogive-cylinder bodies for a Mach number range of 1.75 < M < 5. The aerodynamic coefficients computed are pitching moment, normal force, center of pressure, Magnus moment, Magnus force, Magnus center of pressure, form drag, viscous drag, roll damping and pitch damping. All aerodynamic coefficients are computed in a DD/^1473 EDFTION OF » MOV 65 IS OBSOLETE UNCLASSIFIED SECURITY CLASSIFICATION OF THIS PAGE (When Data Entered) UNCLASSIFIED SECURITY CLASSIFICATION OF THIS PAGEfHTian Data Bnland) 20. ABSTRACT (Continued) conceptually exact manner. The only empirical input is that required for turbulence modeling. Computed results are compared to experimental data fron free flight aerodynamic ranges and wind tunnels in order to validate the computational techniques. Parametric comparisons illustrate the effects of body configuration and Mach number for the ten aerodynamic coefficients. The results for Magnus and pitch damping are of particular interest.

Unclassified 15«. DECLASSIFI CATION/DOWNGRADING SCHEDULE Approved for public release; distribution unlimited. 17. DISTRIBUTION STATEMENT (of the abatract entered In Block 20, It different from Report) 18. SUPPLEMENTARY NOTES 19. KEY WORDS (Continue on reverse alda If neceaaary and Identify by block numbed Projectile aerodynamics Supersonic flow Finite difference computations 20, ABSTRACT fCoirtfiiiw ao rmraram sfoto If nccMMty and Identify by block number) Three dimensional finite-difference flow field computation techniques have been employed to generate a parametric aerodynamic study at supersonic speeds. Computations for viscous turbulent and inviscid flow have been performed for cone-cylinder, secant-ogive-cylinder, and tangent-ogive-cylinder bodies for a Mach number range of 1.75 < M < 5. The aerodynamic coefficients computed are pitching moment, normal force, center of pressure, Magnus moment, Magnus force, Magnus center of pressure, form drag, viscous drag, roll damping and pitch damping. All aerodynamic coefficients are computed in a DD/^1473 EDFTION OF » MOV 65 IS OBSOLETE UNCLASSIFIED SECURITY CLASSIFICATION OF THIS PAGE (When Data Entered) UNCLASSIFIED SECURITY CLASSIFICATION OF THIS PAGEfHTian Data Bnland) 20. ABSTRACT (Continued) conceptually exact manner. The only empirical input is that required for turbulence modeling. Computed results are compared to experimental data fron free flight aerodynamic ranges and wind tunnels in order to validate the computational techniques. Parametric comparisons illustrate the effects of body configuration and Mach number for the ten aerodynamic coefficients. The results for Magnus and pitch damping are of particular interest.

No abstract

20, ABSTRACT pCbntfliue mn reveram s£«te ft na)ce»amry and. ideniily by block number) Experiments were made on a loose ring model in a spin fixture to check the validity of the theory that predicts the effect of a loose internal component on the flight behavior of spinning and nutating projectiles. The inertial despin moment of the loose ring was obtained by recording the spin rate versus time. During the test, the complete model was allowed to decelerate freely in spin while it was held at discrete coning angles between DD \ J2H*73 1^73 EDITION OF r MOV 65 IS OBSOLETE UNCLASSIFIED SECURITY CLASSIFICATION OF THIS PAGE (Whan Data Entered) UNCLASSIFIED SECURITY CLASSIFICATION OF THIS PAOCCHTiwi Dmf Enfnd) 20. ABSTRACT (Continued). zero and 20 degrees and discrete nutation rates between zero and 600 RPM. The anticipated spin rate at the start of each spin-down was 6,500 RPM; however, sufficient spin power was not always available. Four loose rings, having 0.004, 0.012, 0.0225 and 0.040 radian cant angle clearance, were tested. The important polar angle relationship between the cant plane of the loose ring and the yaw plane of the projectile during spin-downs could not be measured. This experimental inadequacy resulted in an insufficient validation of the theory. Initially, in the absence of the cant-plane phase angle measurement, the correlation between theory and experiment was made by assuming a phase angle of 45 degrees. This correlation, made at a spin rate of 3,000 RPM, indicated a general support of the theory by the experiments. The test results, in conjunction with the spin theory, were also used for computation of the loose ring phase angles that existed during the spin-downs. These results indicate an average phase lag angle of approximately 30 degrees, although large variation: were observed with spin rate during the spin downs. Averaged phase angles from three flight tests were 34.0, 29.0, and 24.4 degrees.