Aerodynamics of Parachutes
Abstract:ESDU 09012 is intended to provide an introduction to the aerodynamics of parachutes for aeronautical engineers or students with little or no previous knowledge of parachute aerodynamics or design. The purpose of the Item is to provide such a reader with a basic grounding of the aerodynamic principles of parachutes, together with some information on the design solutions that have been produced to date. It is not the intension of this Item to serve as a design guide, because the design process is one which involves much multi-disciplinary knowledge, of which aerodynamics is just one facet; invariably structural, weight, packaging, operational concerns and cost usually have a significant, if not critical, influence on the final artefact. Moreover, it is clear that parachute systems tend to be rather individualistic in nature, usually evolving as a result of experimental test programmes (captive and free flight), together with computer modelling and, increasingly, CFD studies.
The design and development of most parachute systems is undertaken by a small number of specialist organisations and practitioners, whose publications, both corporate and personal, are the sources of information contained herein. The aim of this Item is to provide a basic introduction into this highly specialised field, with emphasis on applications relating to the airframe industry, not only as an introductory overview, but in two particular areas that have been identified as most likely to be of interest; the choice and sizing of aircraft braking and spin recovery parachutes. Although far from exhaustive, these subjects are covered in sufficient detail to offer some basic canopy size and selection guidance.
The Item provides a brief historical resume of parachute design and usage to the present day; it also and outlines the main parachute designs and provides basic aerodynamic, geometric and performance data for each parachute type. The effects of the main flow and geometric parameters are discussed, as well as the inflation process, drag area control methods, cluster parachute systems and pilot parachutes. The Item introduces the concepts of parachute stability and the added mass approximation in unsteady flow, and the specific applications of parachutes to vehicle braking, spin and deep stall recovery, ordnance stabilisation, emergency escape systems, supersonic deceleration and load extraction are all considered.
|Data Item ESDU 09012|