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S8 Engenharia Aeroespacial |
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Title:
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OSCILLATION ANALYSIS OF BALLISTICS ROCKETS
BY USING FREE OSCILLATION
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Summary :
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ABSTRACT. A ROCKET IN BALLISTIC FLIGHT, WHEN IT SUFFERS SOME TYPE OF LATERAL DISTURBANCE, INCLINES IN RELATION TO ITS INITIAL TRAJECTORY. THIS INCLINATION CREATES LIFT ON ITS STABILISER SURFACES (FINS), RESULTING IN A FORCE CONTRARY TO ITS INCLINATION. THIS OSCILLATORY MOVEMENT REPEATS IT SELF UNTIL THE OSCILLATIONS DISSIPATE AND THE ROCKET CONTINUES IN ITS INITIAL TRAJECTORY. THE OSCILLATORY MOVEMENT CAN LAST FRACTIONS OF SECONDS; EVEN SO IT CONSUMES ENERGY OF THE PROPELLENT IN DETRIMENT OF THE ROCKET RANGE. TO ANALYSE THE DERIVATIVE OF THE MOMENT OF YAW WITH RESPECT TO THE ANGULAR SPEED OF YAWING (NR) AND ITS DERIVATIVE OF MOMENT OF YAW WITH RESPECT TO LATERAL SPEED (NV), TWELVE MODELS OF ROCKETS IN SCALE 1:1 WHERE USED, COMBINING TRAPEZOIDAL, SHORT, TRIANGULAR TRAPEZOIDAL AND DELTA FINS WITH CONICAL, PARABOLIC AND HELMET NOSES, IN THE LAE1 WIND TUNNEL. THE ASSEMBLY OF THE TEST APPARATUS USED A MODEL IN THE WIND TUNNEL MOUNTED HORIZONTALLY ON A VERTICAL AXLE, ADAPTED FROM THE EXPERIMENT PERFORMED BY SIMMONS(1920). THE MODEL BEING DEFLECTED FROM ITS BALANCE POSITION EXECUTES A DAMPED OSCILLATION. THE ANALYSIS FOR THIS OSCILLATION REVEALS VALUES OF THE CALCULATION OF THE MOMENT OF YAW DERIVATIVE. THIS PROCEDURE IS KNOWN AS THE METHOD OF FREE OSCILLATION. THE RESULTS DEMONSTRATED THE EFFICIENCY OF THE DELTA TYPE FINS IN THE ROCKET EQUIPPED WITH A CONICAL NOSE. ALL THE MODELS PRESENTED CONES OF CONVERGENT STABILITY.
KEYWORDS: ROCKETS, LATERAL STABILITY, FREE OSCILLATION METHOD.
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Author :
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Catalano, Fernando Martini
Izola, Dawson Tadeu
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Paper View :
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