Optimal maneuvers including thrust angle-of-attack of supersonic aircraft.

In this dissertation, novel methods in analyzing the optimal maneuvers of a supersonic aircraft on cruise, turning, and climb are presented. Besides much improvement in computational efficiency, some interesting results are displayed explicitly. First, the problem of fixed fuel-maximum range steady state cruise is studied with a more realistic specific fuel consumption factor as a function of the Mach number and the altitude. Therefore, the solution is applicable to the turbojet, turboprop and the turbofan engines commonly used in modern aircraft. After this preliminary analysis, the singular perturbation-singular control theory is successfully used to relax the steady-state constraints in fixed fuel-maximum range cruise. In addition, the effect of the thrust angle-of-attack on fuel efficiency is studied and it is found to be negligible. Second, the optimal maneuvers for the fastest turning, and turning subject to prescribed end-point Mach numbers are analyzed. As expected, with very high thrust, the maximum turning rate is conducted at high angle-of-attack. But with specified end-point Mach numbers, and moderate thrust, the angle-of-attack is usually near the stall angle-of-attack and the optimum thrust control alternates between no thrust and maximum thrust. The switching is always made at the same turning rate and the number of switches depends on the flight altitude, the end-point Mach numbers and the heading change. The formulation allows the consideration of a variety of thrust producing propulsion systems which include the rocket, the turbojet, and the turbofan. Finally, a non-sensitive, robust and accurate procedure is presented which does not require prior knowledge of a reference trajectory for computing the optimum trajectory for minimum-time-to-climb to an altitude. This computing procedure is also valid for a variety of propulsion systems. It is shown that for rocket-powered aircraft the optimum climb starts immediately, while for air breathing propulsion systems, it may be necessary to use a dive to accelerate the aircraft to a sufficiently high Mach number before the actual climb. Again, the effect of the thrust angle-of-attack is considered and it is found to be negligible for high speed maneuvers.PhDAerospace EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/103867/1/9409829.pdfDescription of 9409829.pdf : Restricted to UM users only