Akademik Veri Yönetim Sistemi
47th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition, Orlando, FL, Amerika Birleşik Devletleri, 5 - 08 Ocak 2009, (Tam Metin Bildiri)
In this paper we present preliminary results of a study on an aerodynamic-assisted transition technique for a ducted-propeller Vertical Takeoff and Landing Unmanned Aerial Vehicle from hover to forward flight and vice versa. The technique utilizes a variable-incidence wing, whose pitch orientation with respect to the ducted propeller is a control variable. A fourth-order point-mass model is used for the modeling of the aircraft dynamics in the study. For the dynamic analysis, the aerodynamic forces and moments database is developed both in pre-stall and post-stall regime using a three-dimensional vortex lattice code. Then a parametric optimization of the thrust, pitch angle, and wing incidence during the transition maneuver is studied. The objective is to achieve a transition scheme with minimal variation in altitude, reduced transition time and reasonable thrust-to-weight ratio. The results indicate that with proper scheduling of the pitch angle and wing incidence, the objective can be achieved. Based on the parametric analysis results, nonlinear constrained optimization based on energy approach and Sequential Quadratic Programming (SQP) algorithm is performed to generate the transition trajectories. A trade-off within the defined objectives of the transition is also discussed. The results obtained can be used as a benchmark for future closed-loop transition controller development. Copyright © 2009 by Adnan Maqsood & Tiauw Hiong Go.