ESDU 09012-2009
Aerodynamics of parachutes

Standard No.
ESDU 09012-2009
Release Date
2009
Published By
ESDU - Engineering Sciences Data Unit
Latest
ESDU 09012-2009
Scope
"INTRODUCTION Parachutes are usually soft fabric devices whose shapes have been designed to produce@ upon deployment@ a retarding force for the purpose of slowing and/or stabilising a given payload during its movement through the air. The word parachute itself comes from the combination of the French words parare@ to protect or shield@ and chute@ the fall; the combination of words in ??parachute' actually means ""fall protection"". The main design criteria are that when stowed it should have minimal mass and occupy minimal space@ and upon deployment it should reliably open within an acceptable time frame with acceptable transitional loads@ and provide the desired rate of descent with an acceptable level of stability. In the development of this Item it has been borne in mind that the end user would most likely be an aeronautical engineer or student with little or no previous knowledge of parachute aerodynamics or design. The aim is to provide such a reader with a basic grounding of the aerodynamic principles of parachutes and some familiarisation with the design solutions that have been executed to date. The Item does not aim to be a design guide; the design process is one which involves much multi-disciplinary knowledge@ of which aerodynamics is just one component; structural considerations@ weight@ packaging@ operational requirements and cost may all have a strong@ if not decisive@ bearing on the final outcome. Furthermore@ it is clear that parachute systems tend to be rather individualistic in nature and evolve largely from extensive experimental programmes@ both captive and free flight@ together with large computer models and@ in some instances@ CFD simulation. The design and development of most parachute systems is in fact 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. Section 3 provides a brief historical r??sum?? of parachute design and usage to the present day. Section 4 outlines the main parachute designs and provides basic aerodynamic@ geometric and performance data for each type; it also provides definitions of the main geometric and aerodynamic parameters. Section 5 covers the effects of the main flow and geometric parameters and Section 6 describes the inflation process and drag area control methods@ cluster parachute systems and pilot parachutes. Section 7 provides an introduction to stability@ the added mass approximation and trajectory analysis@ and Section 8 covers the specific applications of parachutes to vehicle braking@ spin and deep stall recovery@ ordnance stabilisation@ emergency escape systems@ supersonic deceleration and load extraction."

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