A WIND-TUNNEL INVESTIGATION OF THE AERODYNAMIC CHARACTERISTICS OF A FULL-SCALE SWEPTBACK PROPELLER AND TWO RELATED STRAIGHT PROPELLERS

摘要

An investigation of an NACA 10-(l.7)(062)-057-27 two-blade swept propeller has been conducted in the Langley l6-foot high-speed tunnel over a range of- blade-angle setting from 20° to 60 . The maximum value of helical tip Mach number was about 1.15.nTwo related straight propellers were also tested over the same operating range as the swept propeller. The straight propellers were tested for comparison purposes to evaluate the merits of the sweptback-blade design. At the design blade-angle setting the swept propeller maintained its low-speed level of maximum efficiency to a value of helical tip Mach number that was about 6 percent higher than that for the straight propellers. Results of the tests indicated, however, that the range of operation where the sweepback may be desirable for a propeller design is very narrow. When the propeller was operating at the design condition, the power absorbed by the swept propeller was only 50 percent of the design power coefficient, whereas the straight-blade propellers absorbed close to 100 percent of the power for which they were designed.