Direct Lift Control for a Variable Sweep-Wing Aircraft.
AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING
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A DLC Direct Lift Control system was designed for the F-111A to investigate the handling qualities such a system would produce on a variable sweep-wing aircraft. Flaps, symmetrically operating spoilers, and the differential elevator were adapted to respond to the pilots normal longitudinal column movements with the intent of applying lift forces in the desired direction of flight without pitching the aircraft. The closed-loop controller consists of fixed-gain normal acceleration, pitch angle, and pitch rate feedbacks to the servos. The fixed gains were selected by use of a digital optimization program based on Kalmans Linear State Regulator Theory. The controller was then tested with a piloted analog computer simulation based on the short period approximation to the longitudinal equations of motion. Approach and landing, in-flight refueling, and transsonic flight were investigated the latter two at more than one wingsweep. It was found that with DLC more precise changes in altitude or rate of climb can be made without significant increase in normal acceleration. In addition, rates of climb or descent up to 2000 feet per minute from level trim condition can be made with less than plus or minus one-half degree change in pitch angle. Crossover was eliminated. Author
- Attack and Fighter Aircraft
- Fluid Mechanics