Drag Reduction and Improved Fuel Economy of Aircraft Employing Outboard Horizontal Stabilizers. A Revue.

Abstract

S projected (or planform) area of aerodynamic surface The potential of using outboard horizontal stabilizers (OHS) to reduce aircraft drag and hence improve fuel economy was investigated both experimentally and theoretically. The feasibility of OHS configurations on the basis of the structural stress levels expected was also studied. The findings of the work showed that from simple, low Reynolds number, wind-tunnel tests at a wing-chord based Reynolds number of approximately 6 x 10 4 , and also from theoretical analyses for a higher Reynolds number of 9x10 6 , lift/drag (L/D) value increases in the region of 30 to 50% for wing and tail surfaces can be expected relative to corresponding values for conventional aircraft. The analytical stress-level work showed that contrary to what, on a first thought basis, might be expected there were no major stress problems. Flight tests employing radio-controlled, powered, model aircraft (i.e. UAVs) showed that aircraft of the OHS type were easily controlled in flight and were stable. An examination was made of additional areas that may contribute yet further to the development of the OHS concept. U flight velocity w downwash velocity (+downwards) W weight x distance aft from wing leading edge y displacement from center of wing Y y/b