High-speed monorail rocket sleds for aerodynamic testing at high Reynolds numbers.

Abstract

The use of a monorail rocket-sled system is detailed and recommended as a method of obtaining aerodynamic data in a regime of high Mach and Reynolds numbers. Sled designs and the data collection system are discussed in detail. The system has been used successfully to acquire pressure data on cone-cylinders. These data are compared with data from free-flight rockets, wind-tunnel tests, and computer calculations. The sled-testing technique appears to be the most promising method of simulating flight conditions at low altitudes at Mach numbers up to M = 8. A principal advantage is the high degree of accuracy possible in determining actual test conditions, which include Mach number, static pressure, and static temperature. Exploratory tests indicate that sleds may be used to collect other types of experimental data such as heat-transfer and boundary-layer transition. To date, excellent data have been obtained at 7430 fps (M = 6.53), which to our knowledge is the highest velocity ever attained by a rocket sled. At this speed, and the Holloman Air Force Base track altitude, the Reynolds number was 42 X 106/ft, and the dynamic pressure was 55,000 psf. Nomenclature CD, CL = drag and lift coefficients, respectively, based on sled cross-sectional area M = Mach number Pm = measured model surface pressure POO = freestream ambient pressure Re = freestream Reynolds number To, Tw, Tm = total, wall, and freestream temperatures, respectively U = freestream velocity, fps