April 17, 1968

MEMORANDUM for Assistant Chief, Research Projects

Flight 1-75-133 was flown on April 4, 1968, by William A. Dana for the purpose of:

Operation of aircraft systems were satisfactory during the flight. Data were obtained from the WTR experiment, however, the system does not appear to have functioned similar to ground test results and is under investigation. Limited data were obtained from the Saturn insulation and fixed-sphere flow direction sensor experiments.

Flight Track and Profile

The radar track and profile for this flight are shown in figure 1.

The launch was at Delamar #2 on a magnetic heading of 201° from 45,100 feet, IAS of 225 knots, and at a Mach number of 0.83. The launch transients were normal. Engine light occurred 0.8 seconds after launch and 100 percent thrust occurred 1.7 seconds later.

The profile was flown essentially as planned. After launch the angle of attack was increased to the planned 11° and held until the planned pitch angle of 28° was reached at 22.7 seconds. The 28° pitch angle was maintained until shutdown at 79 seconds with a velocity of 5200 feet per second. The cockpit film indicated a shutdown velocity of 5270 feet per second. The pilot reported a "jumping" of the velocity indicator. About one degree of thrust misalinement was detected in angle of sideslip.

The pilot turned on Yaw RAS, RAS Auto cutoff, and Roll RAS after shutdown. At 112 seconds a good check of Hdot was obtained at 150,000 feet and the Western Test Range experiment was extended. The experiment was fully extended in 8.8 seconds. Data indicate that the aircraft attitudes were held within the ±2° allowed deviation and the dynamic pressure was below the experimentor's suggested maximum of 30 pounds per square foot during the experiment cycle. The overshoot to 185,000 ft from the planned 180,000 ft resulted from a higher average angle of attack of 2.5° from shutdown to peak altitude. Angle of attack reached 19° for reentry and averaged 15 to 16° during "g" buildup. Maximum "g" on reentry was 3.6.

Stability and Control

The time history of the significant stability and control parameters telemetered during the flight is shown in figure 2.

While ballistic, the pilot indicated that Roll RAS did not hold the aircraft as tight as he expected and felt that roll rates may not have been of large enough magnitude to fire Roll RAS. At 110,000 feet the pilot experienced a slight pitching oscillation. During the glide back to Edwards the pilot made requested checks of Pitch-Roll and Yaw ASAS and was satisfied that both were operating correctly. Higher than usual buffet was reported by the pilot at a Mach number of 0.9, angle of attack of 9° indicated, and at an altitude of 35,000 feet.

Weight and Balance

The time histories of the total airplane weight and longitudinal center-of-gravity position are shown in figures 3 and 4, respectively.

Air Force Western Test Range Launch Monitoring

Approximately 14 seconds past peak altitude, telemetry signals were received on the experiment's azimuth and elevation channels which differed from those observed during ground testing. The pilot was requested to retract the experiment. There was no telemetry indication that the experiment came down when the pilot activated the retract switch. Approximately 18 seconds later, the pilot activated the emergency retract switch and the experiment retracted in 4.7 seconds. The pilot then saw both indicator lights go out and heard the doors shut. This discrepancy is under investigation and will be resolved before the next flight of this experiment.

Saturn Insulation

Postflight investigation of the camera mounted in the right rear wing tip pod showed that the film had broken and very little data were obtained from the camera. The heater blanket will be improved to prevent breakage of the film on the next flight.

Operational Discrepancies

No discrepancies were noted.

Data Systems Discrepancies

Discrepancies noted on the flight were:

James R. Welsh, Head

X-15 Research Project Office