The Drag of Airplane Wheels, Wheel Fairings, and Landing Gears: I

Tests were made in the 7- by 10-foot wind tunnel and in the 20-foot tunnel of the National Advisory Committee for Aeronautics to determine the drag of a number of airplane wheels, what fairings, and landing gears designed or selected for an airplane of 3,000 pounds gross weight. all tests were made on full-sized models; those in the 7- by 10-foot tunnel were made at air speeds up to 80 miles per hour and those in the 20-foot tunnel were made at air speeds up to 100 miles per hour. Although most of the landing-gear tests were made in conjunction with a fuselage and at 0° pitch angle, some of the tests were made in conjunction with the fuselage plus wings and a radical air-cooled engine and at pitch angles from -5° to 6° to obtain an indication of the general effect of these various items on landing-gear drag. All tests were made in the absence of propeller slipstream.

The results of the investigation show that the lowest drag recorded for any landing gear tested was 13 pounds, at 100 miles per hour and 0° pitch, and that it might be possible to reduce this drag approximately C pounds by totally encasing the wheels of this gear in fairings. The highest landing-gear drag recorded was 98 pounds. Other points of interest brought and were: Fitting-plus-interference drag of ordinary types of landing gears averages about 44 percent of the drag due to these gears; low-pressure wheels and tires may be used with little or no increase in landing-gear drag; the proper wheel fairing may reduce the drag due to a landing gear more than any other refinement; fairing of all struts is of great importance; and landing gears having a single supporting strut have less drag than any other types of nonretracting gears. Also, the substitution of low-drag or retractable landing gears for conventional types on high-drag airplanes results in a negligible increase in high speed. Low-drag or retractable gears used in place of conventional gears on low-drag airplanes result in a substantial increase in high speed or saving in power at the same speed, the low-drag gear accomplishing a large percentage of the gain obtainable from the use of the retractable gear.