Thrust vectoring

Abstract: The authors' proposal to convert military thrust vectoring flight control (TVFC) technologies into civil transport applications, translates combat-agility capabilities into unprecedented flight-safety standards. Dealing with the latter, this article compares future vectored-aircraft safety potentials and classes with current unsafe flight standards dictated by conventional flight control (CFC). A few simplified analytical results are presented to illustrate new classes and fundamentals of catastrophic failure prevention when TVFC replaces partial or complete loss of CFC in future civil and fighter aircraft.

Abstract: We describe results of a study carried out at the University of Leicester in collaboration with Volvo Aero Corporation, on the design of integrated flight and propulsion control systems for a large civil transport aircraft. The use of the aircraft engines (via differential thrust and/or thrust vectoring) for the purposes of emergency flight control is examined in detail. An industry standard modelling and simulation tool (IFPClab), containing a detailed model of the Boeing 747-100 transport aircraft, was developed for the study using the MATLAB/SIMULINK software environment. IFPClab has a flexible, modular structure, which can easily be adapted to different aircraft and engine configurations. Propulsion based flight control systems, for use in the event of a partial or total failure of the traditional aerodynamic control surfaces, are designed using modem robust multivariable control methods. Evaluation of these control systems in non-linear simulations indicates that large civil transport aircraft may be effectively controlled using only collective and differential thrust. The addition of thrust vectoring, however, is seen to significantly improve the flying qualities that may be achieved.

Abstract: : The objective of this thesis is to determine the optimal controls and trajectories which minimize the time to turn for a high performance aircraft with thrust vectoring capability. All determinations are subject to practical physical constraints. The determined controls and trajectories are then compared against other methods of turning in minimum time to conclude the effects and advantages of thrust vectoring. The results indicate that the use of vectored thrust can substantially reduce turning times and increase in-flight maneuverability. The greater the velocity at which the turn is initiated, the more the range of thrust vectoring capability is used and the greater the reduction in turning time. Originator-supplied keywords include: Optimization; Thrust vectoring; Vectored thrust; Minimum time turns; Steepest-ascent method; and Optimal controls.

Abstract: Counterflow thrust vectoring is an innovative technique that uses no movable components to redirect a thrust producing jet. This system relies on fixed curved surfaces and a secondary stream flowing in opposition to the main jet. This paper reports on experimental results of the application of 2-D counterflow thrust vectoring to the exhaust of a gas turbine engine. Characterization of the jet response to counterflow is presented for different secondary flow gaps. Continuous and proportional control of the jet was demonstrated for vectoring angles up to 25o. The jet attaches to the collar wall for high counterflow levels. The secondary mass flux needed to vector the main jet is less than 6% before attachment, with thrust losses below 8%. The temperature in the vacuum line rises to the point where special caution must be taken when operating electronically controlled valves, which also proved to be affected by pressure losses in the vacuum line. Regarding the system dynamic response, a slew rate of 160o/s was observed. However, the counterflow thrust vectoring system operates in a very inhospitable environment regarding noise and interference, which degrades the measurement for high sampling rates. Based on these results an optimal gap size of 0.625 times the nozzle height was chosen for further studies concerning shear layer mixing enhancement, dynamics and controls.