A flexible reflector antenna is designed, fabricated, and experimentally validated for application to small satellites. A doubly curved reflector surface is constructed using a triaxially woven fabric-reinforced silicone (TWFS) composite. The mechanical properties of the TWFS are analyzed through finite element analysis based on a representative unit cell model. In addition, both the mechanical and electromagnetic properties are experimentally characterized and utilized as fundamental parameters for the structural and electromagnetic design of the reflector antenna. To demonstrate the feasibility of the proposed concept, a prototype reflector with a diameter of 0.6 m is manufactured, and a series of performance tests are conducted. Based on the experimental results, the potential applicability of TWFS based flexible reflectors to small satellite communication antennas is presented.
This study proposes an optimal flight path planning method to minimize the radar detectability of unmanned aerial vehicles. To this end, a virtual mission environment was constructed by applying the Lambert conformal conic projection to digital terrain elevation data. Radars were placed at arbitrary locations within the mission area, and terrain-induced visibility was analyzed and reflected in the detectability assessment. The detectability metric was defined as the signal-to-interference ratio, which incorporates the effects of ground clutter into the conventional signal-to-noise ratio. The ground clutter was modeled using the Constant Gamma Model. For optimal path generation, a particle swarm optimization algorithm was employed. The proposed method was evaluated on both simplified and real-world terrain datasets, and the resulting waypoint sequences successfully guided the UAV along routes characterized by low detectability, short flight distance, and frequent traversal through radar shadow regions.
The fixed-wing UAV, which is launched from a canister for rapid mission deployment, has a tandem-wing configuration that ensures a large wing area even under constrained design conditions, considering storage requirements. Therefore, it is essential to develop a nonlinear simulation model that accurately reflects dynamic characteristics. In this study, the aerodynamic characteristics are analyzed using Computational Fluid Dynamics (CFD) and Vortex Lattice Method (VLM) methods, and the propulsion system was modeled by converting the thrust and torque coefficients for commercial propellers into advance ratio based equations. The proposed guidance and control approach for the nonlinear dynamic model was demonstrated using a hardware-in-the-loop simulation (HILS) environment.
This study presents the development of a computational landing guidance and control algorithm for a reusable launch vehicle technology demonstrator (RLV-TD), designed to validate key technologies for reusable launch systems. To generate fuel-optimal trajectories that satisfy vehicle performance and stability constraints, an onboard trajectory optimization method is implemented using a customized SOCP (Second-Order Cone Programming) solver tailored for embedded system environment. A trajectory tracking guidance algorithm is developed to ensure accurate execution of the optimal trajectory under model uncertainties and disturbances. Furthermore, a precision attitude control algorithm is designed to maintain stability in the presence of flexible body dynamics, including structural bending and sloshing. The proposed algorithms are validated through high-fidelity 6-degree-of-freedom simulations and verified via flight experiments using the RLV-TD platform. The results confirm the feasibility and effectiveness of the proposed approach in real-world scenarios.
A store is any device intended for internal or external carriage, mounted on air vehicle suspension and release equipment, which may or may not be intended to be for in-flight separation from the air vehicle. Stores include missiles, rockets, bombs, nuclear weapons, mines, fuel and spray tanks, torpedoes, sonobuoys, dispensers, pods, targets, decoys, chaff and flares, and suspension equipment. In this study, the effect on the backflow of the aircraft is examined through flow analysis according to the installation of the 2.75-inch rocket launcher fairing mounted on the Rotary-Wing Aircraft (500MD). The structural safety of pairing following high-temperature/high-pressure firing was compared and examined by analysis. The componet hammer test was conducted on the ground to confirm the vibration impact of the additional installation of external mounts. When the main excitation frequency was avoided, the effectiveness of the installation of rocket launcher fairing was confirmed through a flight shooting test. In addition, it is possible to determine the airworthiness of the tail of the aircraft due to the launch of a 2.75-inch rocket mounted on a Rotary-Wing Aircraft.
