Flight 3-23-39 was flown by Major R. Rushworth on 7 November 1963 for an evaluation of heat transfer with a sharp leading edge on the upper vertical stabilizer and to evaluate lateral-directional controllability with dampers off. The flight was accomplished without incident and the flight objectives were achieved. There were no failures or malfunctions during the flight, however, the left wing tip Mach probe was irreparably damaged, probably during post-flight ground operations.

The maximum velocity during this flight was about 4200 fps; maximum dynamic pressure was about 1550 psf; and maximum altitude was about 82,000 feet.

Heat transfer data was obtained during a level flight steady speed run at a low angle of attack for about 45 seconds. During the run, velocity varied between 4050 fps and 4215 fps; altitude varied between 67,000 feet and 65,500 feet; dynamic pressure varied between 1450 psf and 1560 psf; angle of attack was 2.5° ± 1°; and sideslip was a steady 1/2° right. The sharp leading edge of the vertical stabilizer showed some visible evidence of heating but was not damaged or deformed.

Controllability was investigated with roll and yaw dampers off and speed brakes open and closed while decelerating from M » 3 to M » 2 at altitudes above 68,000 feet. Angle of attack varied from 2° to 12°. The pilot reported that the stability was good and that it was necessary to disturb the airplane with lateral pulses. Pilot ratings of controllability were:

Angle of Attack Speed Brakes q f y

5°-12° Open 1.5 4 3

2°-5° Closed 1.5 3 3

The pilot reported light buffet during the approach at about M » 0.9, a » 12° and h » 35,000 feet. The landing was slightly long at 190-185 KIAS in a moderate cross wind. The airplane turned about 80° left before stopping.
 
 
 
 

Elmor J. Adkins

Aerospace Engineer