X-17 R-26 PRELIMINARY FLIGHT REPORT. ANALYSIS OF TRANSITION AND AERODYNAMIC HEATING
LOCKHEED MISSILES AND SPACE CO INC PALO ALTO CA
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The X-17 R-26 vehicle re-entered the atmosphere at a nominal velocity of 5000 ftsec. Second- and third-stage thrust increased the velocity to a peak value of 13,300 ftsec. As the vehicle descended from 90,000 to 46,000 ft., the Reynolds number, based on free-stream conditions and body diameter, ranged from 1.0 to 16.5 million. Temperatures were measured at 23 locations on the nose, a 9-in. diameter, nickel-plated copper hemisphere. The surface of the nose was polished to a nominal 12-microin. rms surface finish, except for two narrow patches of 45-microin. rms roughness. These rough patches both covered a major thermocouple run. One patch started at the 20-degree body-angle location, while the other began at the 40-degree position. Data were also obtained on a smooth control run. The results of the data analysis indicate that transition first occurred on the 45-microinch rms roughness runs at the 45-degree position. The transition front then moved forward on both thermocouple runs onto the polished portion of the nose to the 15-degree location. Transition occurred on the smooth control run about 1.5 seconds after transition was detected on the rough runs. The most significant fact observed on this flight was that roughness caused early transition but did not control the rate or extent of the subsequent forward movement of the transition front.
- Unmanned Spacecraft