September 2, 1966

MEMORANDUM for Chief, Research Projects Office

Flight 1-67-112 was flown on August 25, 1966, by John B. McKay for the purpose of obtaining data for: a) micrometeorite collection (#l3), b) horizon scanner (#l7), c) rarefied gas flow (#16), e) electrical loads, f) wing tip pod acceleration, and g) reaction augmentation system (RAS).

The maximum velocity was 5150 fps (3511 mph and a Mach number of 4.73) at an altitude of 146,000 feet. The maximum altitude reached during flight was 256,000 feet.

Acceptable data were obtained on all experiments.

The major malfunctions which occurred during the flight were the loss of telemetry one second after launch and an inertial system computer failure during the reentry portion of the flight. To correct these problems, the following courses of action are being taken: a) replace the power amplifier which caused the telemetry problem, b) perform laboratory tests to duplicate the inertial computer failure and c) replace the inertial system computer in the airplane.

The sky brightness experiment was not available for this flight because the investigation of the cause for the fuse failure encountered on flight 1-66-111 was still in progress.

Flight Track and Profile

The radar track and profile for this flight are shown in figure 1. The launch was at Delamar Lake from 45,000 feet altitude. Launch was normal with approximately 16.5° of right roll being experienced. During the process of reaching for the throttle to start the engine the pilot inadvertently bumped the jettison handle. Immediately the pilot realized what had happened, corrected the situation, and accomplished engine light in a normal sequence. Engine light occurred 5.0 seconds after launch with 100% power being attained in 1.5 seconds. Rotation after launch initially peaked at 20° angle of attack then lowered to 10° and dropped as low as 4°, but was immediately increased to 9° which was maintained until the planned pitch attitude was reached in approximately 30 seconds.

Pitch attitude was maintained at 38° as planned for the powered portion with a slight increase just prior to shutdown.

Engine shutdown was accomplished at 5150 fps as planned after 83.4 seconds of powered time. These conditions together with the slight increase in pitch attitude just prior to shutdown resulted in a peak altitude of 256,000 feet, 6,000 feet higher than was planned.

The entry angle of attack during dynamic pressure buildup varied from 18 to 22 degrees and averaged the planned 20° angle of attack. The maximum normal acceleration during the entry was 5.5 "g" with a "g" level greater than the planned 5 "g" being maintained for approximately 5 seconds. These conditions resulted in an entry dynamic pressure slightly lower than the planned 1140 psf.

After entry the pilot had to hold a high "g" left turn into the base high key because of a high energy condition which existed. A normal acceleration of more than 3 "g" was held for approximately 1 minute.

Micrometeorite Collection

This experiment was activated during the flight by the pilot, at an altitude of approximately 200,000 feet. The experiment extended from the left-hand wing pod nose cone and proceeded through its automatic timing cycle as planned. The experiment functioned normally, exposing five collector surfaces 19 seconds each and the sixth face 38 seconds. The experiment remained extended for a period of 133.2 seconds, until it was retracted by the pilot as the airplane descended through 180,000 feet.

The collector package flown on this flight was different from previously flown packages in that the thermocouple wiring had been removed by the experimenter.

The collector package and flight data have been returned to the experimenter for a detailed analysis.

Horizon Scanner

Preliminary analysis of data indicate that the horizon scanner functioned only partially as expected. The photometer functioned normally but the tracker mechanism did not acquire the star it was programmed to acquire. It is not known at this time whether the problem is in the information supplied to the experiment by the inertial system computer or whether it is a tracker system malfunction.

After flight, the experiment was removed from the airplane and taken by the experimenter back to his lab for a calibration of the photometer and a complete operational checkout of the equipment. The preliminary results of this checkout showed the roll attitude of the system was off 4 to 5 degrees and the tracker system was not functioning properly. These discrepancies are being corrected in preparation for the next flight.

Rarefied Gas Flow

The preliminary analysis of data showed no apparent problems on the rarefied gas flow (pace transducers) experiment for this flight. Data are presently being analyzed in detail.

Electrical Loads

Data for the survey of the electrical loads on the APU's were recorded on this flight. A preliminary review indicates only a portion of data recording channels operated during the flight. The data also show that no power transients were experienced during this flight as were experienced during flights 1-65-108 and 1-66-111.

Wing Tip Pod Accelerometer

Data obtained during this flight were for wing tip pods having approximately equal weight and cg position. On the previous flights the tip pods were unequal in weight (» 25 lbs difference).

These data are being analyzed to determine if the present weight limitations imposed on the pods can be increased to accommodate future wing pod experiments.

Reaction Augmentation System

A reaction augmentation system was installed in the airplane for this flight. The system operated during the ballistic portion of the flight with no apparent problems. The pilot commented that it made the pilot's task of controlling the airplane easier.

Sky Brightness

This experiment was unavailable for this flight. Tests were in progress to investigate the cause for the fuse failure encountered on flight 1-66-111.

The investigation consisted of centrifuge and environmental chamber tests performed at FRC facilities.

The centrifuge test consisted of mounting the experiment in the centrifuge and running the centrifuge at a level where 3.5 "g" longitudinal acceleration was measured at the mid section and 6.5 "g" was measured at the aft end of the experiment. Current and voltage required to run the experiment during the test were monitored. No failure occurred.

Several test runs were made in the environmental chamber with the voltages and current required to run the experiment being continually monitored. One run was made using altitude environment only and two runs were made using altitude and temperature environment. A failure of the 2 amp slow blow fuse occurred on each of the runs with the altitude and temperature environment. On both runs the failure occurred at approximately the same altitude (140,000 feet) and temperature (-40° C to -70° C) as existed when the failure occurred during flight 1-66-111.

The experimenter instrumented five areas where the problem could exist and the environmental test runs were repeated. No failure occurred on any of the runs. Results of these runs convinced the experimenter the problem area was the connector through which power is supplied to the experiment when it is in flight configuration, since the connector was bypassed on the repeat of the environmental test runs.

The experimenter replaced the connector. With the new connector installed the experiment was again tested in the environmental chamber in a flight configuration. No failure was encountered.

At present the experimenter has taken the experiment back to the lab for a recalibration and checkout.
 
 

Operational Discrepancies

During the prelaunch portion of the flight the B-52 launch panel operator could not get the climb tank to pressurize. Therefore, the X-15 liquid oxygen tank was topped off from the B-52 cruise liquid oxygen tank.

During the entry maneuver at approximately 80,000 feet altitude and 4800 fps velocity the inertial system computer failed. The computer was removed from the airplane after flight and the failure investigated. It was found that the values for all the quantities on the R channel of the computer program went to zero for a reason yet to be determined.

A new computer will be installed in the airplane for the next flight to correct this discrepancy.

Instrumentation Discrepancies

The following parameters did not function during flight:

APU power A phase #l

APU power B phase #l

APU power C phase #l

DC Auxiliary

Milt. Vn/VTE

The following parameters did not calibrate properly:

Upper Vertical Stabilizer position

Roll Horizontal Stabilizer position

Pitch Horizontal Stabilizer position

Upper Speed Brake position

The traces on the three component accelerometer (A-8-3M) and the chamber pressure (P-61-2) recorders became blurred and fuzzy during flight. The traces recording the DC Bus and right-hand bellcrank loads were also erratic.

One second after launch the telemetry stopped functioning but began working approximately five minutes after launch. The problem was found to be the failure of a power amplifier and has been corrected by replacing the amplifier.
 
 
 
 

E. J. Adkins, Chief

X-15 Research Projects Office