Topological Optimization of the Strength Element of the Aircraft Compartment Made of Metal-Matrix Composite Material

At present, in order to increase the weight efficiency of parts and structures of promising aircraft and rocket-space vehicles, various types of additive technologies and topological optimization methods are being actively introduced. Their purpose is a significant reduction in time and financial costs in the manufacture and creation of fundamentally new geometric solutions. The article considers approaches to selecting the geometric parameters of the strength elements of the flight vehicle body made of a metal-matrix composite material based on VT6 titanium alloy, reinforced with a finely dispersed silicon carbide powder, which is produced by direct laser growth technology. On the basis of numerical simulation, the dependences of the metal-matrix composite material physicomechanical and thermophysical characteristics on the volume fraction of silicon carbide have been determined. It was found that the use of a metal-matrix composite material and the optimization of geometric parameters with adaptation to the direct laser growth technology allows reducing the weight of the strength element of the flight vehicle body by more than 30% (depending on the overall dimensions).

CMAC Trained Optimum Mid course Guidance for Tactical Flight Vehicle

This paper discusses design and validation of neural network based mid-course guidance law of a surface to air flight vehicle. In present study, initially different optimal trajectories have been generated off-line of different pursuer-evader engagements by ensuring minimum flight time, maximum terminal velocity and favorable handing over conditions for seeker based terminal guidance. These optimal trajectories have been evolved by nonlinear programming based direct method of optimisation. The kinematic information of both pursuer and evader, generated based on these trajectories have been used to train cerebellar model articulate controller (CMAC) neural network. Later for a given engagement scenario an on-line near optimal mid-course guidance law has been evolved based on output of trained network. Training has been carried out by CMAC type supervisory neural network. The tested engagement condition is within input/output training space of neural network. Seeker based homing guidance has been used for terminal phase. Complete methodology has been validated along pitch plane of pursuer-evader engagement. During mid-course phase, the guidance demand has been tracked by attitude hold autopilot and during terminal phase, the guidance demanded lateral acceleration has been tracked by acceleration autopilot. System robustness has been studied in presence of plant parameter variations and sensor noise under Monte Carlo Platform.

Configuration of a Monopulse Antenna Assembly for Small Diameter Flight Vehicle Applications

In this letter, configuration of a monopulse direction-finding (DF) antenna assembly is presented which can be applied for small diameter flight vehicle applications. The assembly consists of five antennas which consist of four radome mounted antennas and a slot fed cavity antenna. All antennas are located inside of a tangent ogive radome of 1.52 λc inner radius where λc corresponds to the wavelength of the center frequency. To verify the DF performance of the antenna assembly, sum (Σ) and delta (Δ)-patterns are measured and its Δ/Σ monopulse curves are presented.

Heat transfer analysis of supercritical methane on cooling channel of electromechanical actuator under various flight acceleration overloads

The crucial distinction of heat transfer between the earth environment and the high-acceleration overloads of flight vehicle is the secondary flow resulting from the gravitational buoyancy force and centrifugal one, which influences the heat transfer of supercritical fluid significantly. Hence, in this work, the effect of various flight acceleration overloads on turbulent convection heat transfer in the cooling channel of flight vehicle electromechanical actuator is investigated numerically. The cooling channel is constructed from a helically coiled tube with an inner diameter of 8 mm, coil diameter of 74 mm, and screw pitch of 10 mm, the operation pressure covers the range of 5-9 MPa, and the gravity ranges from 1 g to 50 g. Based on this model, the heat transfer characteristics of supercritical methane in the cooling channel of flight vehicle electromechanical actuator under various acceleration overloads are studied, aiming to obtain a deep understanding of flow and heat transfer mechanism and thermal performance of supercritical methane in the cooling channel under the conditions of actual flight. The simulation result indicates that with the high-g overload, the heat transfer enhancement becomes obvious and the effect of secondary flow caused by the flight acceleration exhibits the non-negligible influence. The secondary flow caused by flight acceleration overloads disturbs the flow acceleration of the main stream that weakens the suppression of heat transfer. However, the effect of gravitational buoyancy does not dominate on forced convection heat transfer even under the high acceleration overload.

Bifurcation analysis for a novel flight vehicle with pitch-control single moving mass

Moving mass flight vehicle is a strongly nonlinear system under high speed flying conditions. The system attitude dynamics becomes even more complex due to the coupling between the internal moving mass with large mass ratio and the vehicle body. This article investigates the open-loop nonlinear dynamics of a novel flight vehicle with pitch-control single moving mass from the prospective of bifurcation theory and continuation methods. Of particular interest is the influence of moving mass parameters on the number of system equilibrium points, stability of equilibrium curves, bifurcation characteristics, and the longitudinal static stability. Numerical results reveal the bifurcation phenomena existing in the proposed flight vehicle; the generated bifurcation diagrams illustrate that the multiple sets of limit points and Hopf points divide the moving mass parameter space into different regions with different values and types of stability, thus indicating the significant role of the moving mass parameters in the system nonlinear dynamics. Finally, a design strategy for the moving mass parameters is concluded based on the bifurcation analysis results.