Notes on the Application of Apparent Mass Effects on Parachute Deployment
NAVAL SURFACE WARFARE CENTER SILVER SPRING MD
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This report sets forth, without experimental proof, the reasons as to why the author feels that apparent mass effects in parachute deployment are not as important to the analysis derived in Reference 1 as usually perceived. This commentary applies to the parachute opening shock phase of deployment. Canopy- wake recontact which occurs after the canopy has been fully inflated for a definite period of time is a different problem. In the final phase of finite mass deployments the unrestrained air mass that inflated the canopy has a higher trajectory velocity than the parachute system. This higher trajectory velocity together with changes in the canopy shape catapults the air mass from the parachute resulting in a temporary loss of system mass which tends to compensate for other air masses that may have been added. Infinite mass deployments also have added air masses in addition to the air mass contained within the canopy. Dynamic drag areas obtained from infinite mass deployments implicitly include these effects. In infinite mass deployments where the velocity differential between the internal air mass and the system are minimal the deflation effects will not occur. The validity of these ideas can be verified by the comparison between calculated and experimental results. Parachute technology, Finite mass operation, Apparent mass, Intermediate mass operation, Catapult effect, Infinite mass operation.
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