Download or read book On the Dynamics of the Opening Shock of a Parachute written by Friedrich S. Weinig and published by . This book was released on 1951 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt: Existing theories of the parachute have not been found fully satisfactory, particularly as regards the influence of attitude on the opening shock forces. The previous theories took into account the axial acceleration components of the air masses. The present theory takes into account the radial as well as the axial components and results in a more satisfactory theory. The application of the theory depends on twelve aerodynamic coefficients which must be established by test.
Download or read book A New Look at Parachute Opening Dynamics written by Peter R. Payne and published by . This book was released on 1972 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: There is some evidence to indicate that injuries associated with parachute opening shock are much less frequent than injuries associated with the acceleration loads imposed by ejection seats, even though the stresses presumed to be induced in the human body may often be of the same order. Since all such data is based on operational experience, the details are necessarily vague, and it is hard to draw firm conclusions. The Aeromedical Research Laboratory, USAF, as part of its studies of aircrew injury, decided to see whether there was any difference between the dynamics of parachute opening when used with a rigid anthropometric dummy of the type normally used to obtain opening shock data, and a human parachutist whose body is naturally more resistant.
Download or read book Dynamics of the Opening Parachute written by J. R. Foote and published by . This book was released on 1952 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A model of the opening parachute is proposed and the equations of continuity and of motion are written. The two main parameters are: a coefficient to account for cloth porosity, and a coefficient to provide some choking of the mouth due to looseness of the cloth. The equations are solved under certain assumptions and the results are used to predict both how the force on the suspended load and how the opening rate vary with time. Experimental data is used to select values of the porosity coefficient for various altitudes. In each case the predicted shock force maximum is of the proper order of magnitude, as shown by experiment. A drag term is used which is the sum of the usual type of viscous drag term and a set of inertial drag terms calculated by F.S. Weinig for an expanding sphere. The viscous drag term is of leading importance. The drag coefficient is varied with the porosity coefficient by means of a type of formula indicated by experiment. This gives a greater drag coefficient at higher altitudes and helps to cause a greater shock force at higher altitudes and helps to cause a greater shock force by giving a greater opening rate and less parachute filling time.
Download or read book Notes on a Theoretical Parachute Opening Force Analysis Applied to a General Trajectory written by William P. Ludtke and published by . This book was released on 1988 with total page 74 pages. Available in PDF, EPUB and Kindle. Book excerpt: The report presents a method for calculating the inflation reference time and opening shock forces of the solid-cloth family of parachutes when deployed at an arbitrary trajectory angle to the horizontal. The method is extended to other types of parachutes, but it is limited in that the inflation reference times are not calculated as part of the deployment process. Particular inflation times must be provided as input data to the furnished computer program. The variation of opening shock force versus inflation reference time may be surveyed by providing several values or using actual field test data. Examples are used to demonstrate the effects of canopy cloth rate of airflow, altitude, and trajectory deployment angle for constant velocity and constant dynamic pressure altitude profiles. Keywords: Variable deployment angle, Inflation time, Parachute technology, Opening shock, Calculation methods, Altitude effects.
Download or read book A Linearised Theory of Parachute Opening Dynamics written by Helmut G. Heinrich and published by . This book was released on 1972 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: The inflation of a parachute encompasses problems of aerodynamics, dynamics, and elasticity. The most noticeable effects of the interaction of the events are the opening force and the filling time. Attempts to analyse the opening process and to predict the opening force date back to 1927. Since then a considerable number of methods have been published. Some of them are primarily analytical, others more empirical, and several deal with isolated problems. The earliest and most analytically oriented studies are by Scheubel and O'Hara.
Download or read book Numerical Solutions to the Opening Dynamics of a Parachute written by Bruce R. White and published by . This book was released on 1974 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: In view of existing closed solutions of the parachute opening problem, a numerical solutions technique is presented for generating solutions of the maximum opening force vs deployment velocity of a 28-ft solid flat parachute with a suspended weight of 200 lbs. Also calculated are the filling times of the inflation process. Time-dependent functions of the aerodynamic drag, included air mass of the canopy, apparent mass, inflow velocity function, and a non-linear area-time curve, are used with the momentum and continuity equations at altitudes of 6000, 13,000, and 21,000 ft in the numerical solutions. An idealized canopy shape-time development assumption is made in the calculations. The calculated maximum forces agreed well with experimental test data for some of the empirically selected velocity functions for the 13,000- and 21,000-ft altitude test cases. The maximum calculated forces of the 6000-ft altitude was found to be low in comparison with the experimental field tests. The calculated filling times by use of the continuity equation are generally found to be in excess of the measured filling times from the field tests.
Download or read book An Analysis of Parachute Opening Dynamics written by Jarmo Ilmari Uotila and published by . This book was released on 1973 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Method for the Calculation of Parachute Opening Forces for High Altitude Balloon Payloads written by Peter L. Miller and published by . This book was released on 1975 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the questions most frequently asked by scientists/experimenters who design balloon payloads concerns the magnitude of the opening forces of the parachute recovery system. Existing theory and an analytical method recently developed for horizontal deployment are adapted to balloon systems requirements. Engineering methods are used to develop expressions which allow the assessment of the parachute opening forces.
Download or read book Dynamics of the Opening of Reefed Parachutes written by Ishwar Chandra Bhateley and published by . This book was released on 1961 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Study of Parachute Opening written by J. R. Foote and published by . This book was released on 1958 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt: A model of the opening parachute is considered which permits extensive mathematical analysis. Included are the effects of nine physical parameters, governing drag, initial speed and diameter, parachute dimensions and load, altitude, cloth permeability, and a choking factor representing a difference between the model geometry and observed parachute geometry. The governing equations are developed to a point permitting calculations of system speed, opening rate, and shock force as functions of time. Numerous calculations were made in which the choking factor was varied to yield experimentally-known forces, the variation of this factor having been guided by means of analysis of motion pictures of parachute openings. Other theory was developed for calculation of the individual effects of all the parameters upon the shock force. The nature of current measured data and an insufficient number of calculations have not permitted a verification of this theory for calculation of the individual effects of all the parameters.
Download or read book Calculation of Parachute Opening Shock Forces written by Thornton Blanchard and published by . This book was released on 1958 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book WADC Technical Report written by United States. Wright Air Development Division and published by . This book was released on 1953 with total page 1278 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Study of Parachute Opening written by J. R. Foote and published by . This book was released on 1958 with total page 58 pages. Available in PDF, EPUB and Kindle. Book excerpt: An outgrowth of Study of the Parachute Opening, Phase I was the realization that more information was neeeded about the actual mouth area as compared to the model mouth area used in that study. The experimental determination of this in terms of a k-factor, the correlation of this with the opening shock forces, and the processing of this data was the purpose of this study. For various reasons the study was incomplete. This report indicates what was to be done, what was done, the difficulties that arose, and make some suggestions about overcoming these difficulties. The point of view taken is that a successful conclusion of the study would have been of some importance and the record of this incomplete study might help to eliminate difficulties in a future study of this type.
Download or read book Analysis of Parachute Opening Dynamics with Supporting Wind Tunnel Experiements written by Helmut G. Heinrich and published by . This book was released on 1968* with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: The study is concerned with identification of significant terms in the process of parachute inflation. For finite mass cases, the equations of motion for parachutes inflating in free air and in wind tunnel experiments are established and organized in view of the nonsteady terms of canopy size, systems velocity, included and apparent masses, and the time derivatives of these terms. Wind tunnel experiments are described, the results of which yield graphical and numerical time functions for the significant terms of the equation of motion and the force-time histories. The wind tunnel results are compared with full size test information and certain identities are shown. The significant terms are combined to functions unique for the test conditions and substituted in the equation of motion. Force-time functions so derived compare satisfactorily with measured force histories and the contributions of the individual terms to the instantaneous parachute force can be seen.
Download or read book Drag and Dynamics of Single and Clustered Parachutes in Freestream and with Wake and Ground Effects written by Helmut G. Heinrich and published by . This book was released on 1966 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt: Results of wind tunnel studies concerned with transient and steady state performance of single and clustered parachutes in cargo extraction systems are presented. In Part 1, circular flat and ringslot canopies singly suspended and in clusters of 2, 3, and 4, were deployed in freestream, in the wake of an aircraft, and near a simulated ground. As a further means of analysis, wake pressure surveys were performed on the DHC-4 Caribou and the C-130 Hercules aircraft and are presented in Part 2.
Download or read book Parachute Opening Shock Calculations with Experimentally Established Input Functions written by Helmut G. Heinrich and published by . This book was released on 1976 with total page 105 pages. Available in PDF, EPUB and Kindle. Book excerpt: Parachute opening shock calculations with experimentally established area- and velocity-time functions are shown which, in combination with the momentum and continuity equations, yield force-time histories that satisfactorily agree in shape and force level with measured force-time diagrams. Two conjugate functions were found which approach and provide satisfactory force-time histories of solid flat circular parachutes of 3-100 ft diameter, with loads of 0.5-5400 lb at snatch velocities between 50 and 360 fps.
Download or read book Numerical Solution Methods to the Opening Dynamics of a Parachute written by Bruce Richard White and published by . This book was released on 1973 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt:
