Calculation of Parameters for Manufacturing the Bearing Surfaces by Pressurization

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CTURAL MECHANICS AND STRENGTH OF FLIGHT VEHICLES

Calculation of Parameters for Manufacturing the Bearing Surfaces by Pressurization R. Sh. Gimadieva, V. I. Khaliulinb, *, and N. V. Levshonkovb a

b

Kazan State Power Engineering University, ul. Krasnosel’skaya 51, Kazan, 420066 Tatarstan, Russia Tupolev Kazan National Research Technical University, ul. Karla Marksa 10, Kazan, 420111 Tatarstan, Russia *e-mail: [email protected] Received December 17, 2019; revised February 19, 2020; accepted February 19, 2020

Abstract—The statement and the technique of solving a new class of problems for calculating the process parameters of the manufacture of inflatable bearing surfaces of aircraft are proposed. The technique development is based on dependencies of interaction dynamics of the stretchable fabric with internal pressure in the wing cavity. The model takes into account the imbalance of the pressure and tension forces in the shell surface that initiate its high-frequency oscillation. The algorithms obtained allow predicting and then correcting the shape of the wing profile in accordance with the aerodynamics guidelines. DOI: 10.3103/S1068799820020014 Keywords: inflatable wing, manufacturing technology, soft shell, wing shape calculation.

INTRODUCTION Large dimensions of load-bearing lift surfaces cause certain inconveniences during an aircraft transportation, basing, and storage. Various transformable structures are used to improve portability, including folding wings [1] or helicopter blades [2], disk wings with retracting [3] or folding blades [4], etc. Soft inflatable load-bearing aerodynamic surfaces ensure compactness of an aircraft during storage and transportation. Aircraft with inflatable units are a separate class. The first experiments with inflatable wing were carried out in the 1930s. These experiments were continued in 1956–1973 within the scope of the US military program aimed at the development of an inflatable aircraft with a weight of more than 300 kg. The literature provides the examples of development and operation of manned aircraft of totally inflatable units [5], unmanned aerial vehicles [6], inflatable helicopter hulls, and paragliders [7]. There are also hybrid wings with a rigid front and inflatable rear part [8]. The subject of research is also the aerodynamics of the flow around the profile [9, 10], oscillations in the inflatable wing [11], and the assessment of the temperature effect on the inflatable wing properties [12, 13]. A number of aeroelastic and mechanical issues of the soft wing are considered in [14–25]. The most common technical solution is a multi-spar (multi-walled) wing [12], [6]. Sometimes, spars are tubular [6]. In a multi-walled structure, the straightness of generatrix lines of the surface along the wing span is easily implemented and the bending moment is well perceived. At the same time, another layer of fabric, which is mounted on top the inflatable system to ensure the smoothness of the surface, makes the design heavier. Besides, it is difficult to create the specific aer