External airbags application onboard a helicopter

Aeronautical and Space-Rocket Engineering

Strength and thermal conditions of flying vehicles


Аuthors

Nikolaev E. I.1*, Nedelko D. V.1**, Shuvalov V. A.2***, Yugai P. V.1****

1. Kazan National Research Technical University named after A.N. Tupolev, 10, Karl Marks str., Kazan, 420111, Russia
2. Kazan Helicopters, 14, Ulitsa Tetsevskaya, Kazan, 420085, Russia

*e-mail: nikolaev_ei@kazanhelicopters.com
**e-mail: airat9415@mail.ru
***e-mail: vshuvalov@kazanheliopters.com
****e-mail: pavelyugai@yandex.ru

Abstract

The subject of the presented article is an energy absorption system in the form of external airbags, fixed under a helicopter fuselage. The external airbags are meant for reducing the risk of injury of the passengers and helicopter damage in case of a crash landing.

The study of the external airbags impact while crash landing was performed by the finite elements method. The airbags mathematical model, accepted in the computations, assumes gas simulation by the thermodynamic parameters (pressure, temperature) averaged by the airbags volume. The article presents the airbags initial characteristics for the case of the gaseous nitrogen application. Gas leakage from the airbags is determined by the area of the vent hole and the value of relative pressure for initiation of the gas outflow from the vent hole. The initial pressures values and the holes areas were selected by the condition of overloads minimizing and the strength of airbags material ensuring.

The purpose of this work consists in analyzing the helicopter fuselage loading with the external airbag, and identifying the time dependencies of main thermodynamic parameters of the gas work. The study of a helicopter collision encompasses the moment of time of the airbags contact with the ground to the moment of the fuselage gaining a stable position on the ground. The process visualization of the helicopter fuselage spatial position changing so far as the airbag crimping is demonstrated. Velocities and overloads in the helicopter fuselage center of mass are presented according to the results of computations. The obtained dependencies of pressure, temperature and mass flow rate may be employed for technical requirements forming to the external airbags and gas generating elements structures. Computational results considered in the article allows drawing inference on the possibility of the external airbags application for the helicopter energy shock absorbing and increasing the rate of passengers and a crew survivability. The presented values of loads acting on the fuselage from the airbags side may be employed for the detailed designing of the airbags fixing to the fuselage. The conclusion presents the issues which may become a further development of the research topic.

Keywords:

energy absorption, helicopter emergency landing, external airbags, airbag gas dynamic characteristics, helicopter shock simulation

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