Asymmetry in the parachute canopy filling process

Аuthors

Ivanov P. I.^*, Kurinnyi S. M.^**, Krivorotov M. M.^***

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

*e-mail: Ivanovpetr@rambler.ru
**e-mail: Kurinniys@yandex.ru
***e-mail: Krivorotovmm@mail.ru

Abstract

The main purpose of the work consists in studying dynamics and specificity of filling the large area parachutes of the main class employed for rescuing re­entry spacecraft as well as large weight cargoes airdrop of civil and military hardware. The problematic issues here are these associated with the occurrence of large aerodynamic load values while parachute dynamic filling, which may lead to premature loss of its strength. The issues of long delay in the filling process, which increases the path and height loss and is very dangerous while low-height airdrop, are of no less importance. The article tackles the issues associated with the filling process deviation from the rated value, such as asymmetry occurring while the parachute canopy filling.

The dependence between the filling time and aerodynamic load on the parachute, i.e. maximum drag force value, was established experimentally. The article demonstrates that with the parachute filling time increasing the aerodynamic loads on the parachute and overloads on the object decreased, while the filling path increased.

The relationship between the edge contour of the canopy inlet orifice shaping, filling time and aerodynamic loads on the parachute was established. One of the possible causes of both deceleration and intensive canopy filling dynamics, consisting in substantial asymmetry of the shaping process of the edge contour of the parachute canopy inlet orifice, was revealed.

The authors introduced the notion of the canopy contour shaping asymmetry coefficient at the intensive dynamics of the canopy filling process, as an effective tool for studying the processes of canopy edge shaping processes and their quantitative evaluation.

Setting the rated boundary value for the asymmetry coefficient it is possible to make judgments on the tendency of the canopy shaping by the degree of distance from this boundary. Thus, it will show the propensity of the specified parachute for the asymmetric filling and the ensuing negative consequences, associated with intensive dynamics of the filling process and load-carrying capacity loss. Practically, the asymmetry coefficient represents the square root of the ratio of impact pulses from the air- velocity pressure (which form local pressure drops along the carrying surface) for the canopy with asymmetry, and a canopy being filled symmetrically, under the same initial conditions on speed.

The larger the coefficient of asymmetry, the larger the dome is predisposed to asymmetric filling, the more shock impulses differ. In this association, the probability of the canopy and shrouds destruction increases in the local loading area from the pressure drop at the loads being measured by the strain sensor in the parachute thimble, which are substantially lower than its load-bearing capacity.

Keywords:

parachute system, parachute canopy asymmetric filling, contour edge forming process

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