The effects of Reynolds Number, Section Shape, and Turbulence Stimulation on the Lift of a Series of Model Control Surfaces

Abstract

A series of model control surfaces with equal areas but varying aspect ratio, was lasted in a towing tank on a ground board. The size of the fins, approximately 3 inches span and two inches chord, is typical of control surfaces used on models which are about five feel long. Lift and drag on the fins were measured over a range of angles of attack of 0 to 35 degrees. The tests covered a range of chord-based Reynolds numbers between 42,000 and 150,000. Two sets of fins were tested, one having flat-plate sections and the other having NACA 0015 sections. The fins were each tested with and without turbulence stimulation In the form of tape with a serrated leading edge placed at 5% of the local chord aft of the leading edge of the foil. The study has shown that the lift of the NACA 0015 fins was insensitive to Reynolds number in the range of the tests, and that the lift rates compare well with the results of previous tests carried out at high Reynolds numbers. Differences were noted in the characteristics of flat-plate and NACA 0015 fins which would indicate that the use of flat plates in the place of foil-shaped fins to save model construction cost is not good practice. Turbulence trips increase the measured drag, as expected, but also reduce the lift rate, most noticeable on the flat-plate fins.