Computation of aerodynamic load on gliding parachute while its deploying and overloading, acting on the airdrop object

DOI: 10.34759/vst-2021-2-115-126

Аuthors

Ivanov P. I.

Research Institute of Aeroelastic Systems, 85, Garnaeva str, Feodosia, Crimea Republic, 298112, Russia

e-mail: Ivanovpetr@rambler.ru

Abstract

The article presents a design procedure for aerodynamic load acting on the gliding parachute while its deployment and reloading to the airdrop object. The computational dependencies, which can be employed for quantitative estimation of these parameters, are presented. The average operational (aerodynamic) load and the upper confidence limit of the aerodynamic load acting on the gliding parachute while its deployment are the basic initial parameters when calculating the strength of gliding parachutes.

This information is utterly important while the parachute strength calculating and its appearance forming. The problem statement is as follows. To form, as a first approximation, methodological recommendations for calculating the aerodynamic load on the gliding parachute and the reloading on the airdrop object in the process of the parachute deployment, which can serve as a basis for further scientific research on the proposed method refining and adjusting. The article presents the main definitions and assumptions, as well as the method itself in the engineering statement. Maximum value computing of the axial overload acting on the landing object is based on a semi-empirical dependence that adequately reflects the integral average of the maximum overload value during the gliding parachute deployment.

While developing the engineering mathematical model of the dome (wing) filling of the gliding parachute, the theoretical part supposed that aerodynamic load on the dome (wing) is an additive function of three, practically simultaneously occurring processes. They are:

— impact loading of the lower wing shell, due to the jet of the incoming flow impact, its spreading and the lower wing generatrix straightening forming a local stretch of the lower shell;

— the air intakes filling in the of the stretched part zone of the lower shell; the local zone forming of the executed part of the upper shell and the wing profile;

— loading the completed part of the upper shell (the formed part of the wing) by the pressure drop while its flow around by the external flow.

The article presents computing dependences of the overload acting on the airdrop object on various parameters (the parachute area; the object mass; the height; and the speed of bringing the system into action) for both cargo and human parachute systems. While computing a number of empirical coefficients, the computations used the results of data processing of a vast number of flight experiments with both human and cargo parachutes.

A brief algorithm for the parachute strength computing a when forming the shape of a gliding parachute is given.

The results of the presented work may be useful for designers, testers, calculators, and scientists working in the field of parachute building and engaged in the gliding parachute systems design and testing.

Keywords:

gliding parachute, aerodynamic load on the parachute, reloading to the airdrop object, parachute strength

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