Method for design parameters determination of the system “elastic aircraft - the launcher” at the underwater start

In this paper we developed a method for determining the design parameters of the system “aircraft - launcher”, taking into account the elasticity of the airframe. During the movement of the aircraft in the launcher, the aircraft interacts with water and elastic elements of the launcher’s amortization system. Accounting of the airframe’s elastic vibrations in water is a complex, interdisciplinary task, due to the physical diversity of the system “elastic aircraft - water” and the lack of the unified mathematical apparatus which describe the complexity of its behavior. Using the method of the simple layer potential and submitting the airframe in the form of a free beam, we have got the dependences for determining the coefficients of hydrodynamic forces acting on the elastic aircraft. To describe the dynamics of the aircraft motion in the launcher, we’ve got the system of differential equations. The results of the system of differential equations solutions are used to determine the distribution of internal force factors on aircraft axis and the dynamic forces influencing the launcher, and as well as determine the shortest distance between the aircraft and the launcher at startup. The paper presents the comparative results of the calculation of compression element launcher’s amortization with and without the elastic airframe. The presented method allows to more accurately determine the load, acting on the aircraft, and movement relative to the launcher, which is necessary for the development of new designs of aircraft and launchers with minimal weight and size.