MEMORANDUM for Acting Chief, Research Division
FROM: X-15 Research Project Office
SUBJECT: Flight Research Report on flight 3-40-63
I. Purpose of flight
A. Ablative tests - the flight requirements were full speed brakes for 20 seconds prior to burnout, attain a Mach number greater than 5.5, and a greater than O but less than 3 during this time period.
B. Skin friction - the flight requirements were to maintain constant q between 700 and 900 psf, at M » 5.5 with a greater than 0 but less than 3.
C. Flow field
D. Boundary-layer noise
E. Nose gear modification checkout
II. Flight Plan
The flight plan was based on the ablative test flight requirements up to burnout and on those for the skin friction experiment after burnout. After the constant q condition, the pilot was to perform the pitch and roll pulses at his discretion. The flight plan was also based on a 59,500# thrust engine with 82.5 seconds of burn time.
During the flight, the burn time was actually 81.4 seconds at a thrust of approximately 60,000#. The higher thrust accelerated the airplane to a higher altitude and even though the pilot made corrections, the planned altitude was exceeded by approximately 4,000 feet. This caused q to drop below the planned minimum but the pilot made a correction to pick up the desired value. This value (700 psf) was held to within +8 and -16 psf over a 50 second period. For a 10 second period included in the above, q was held to within 2 psf of 696 psf. An angle of attack from 7° to 5° was needed to hold this value of q.
The flight was flown by Captain Joe Engle.
III. Instrumentation by experiments
Ablative tests; 12 channels on thermocouple oscillograph 0-25.
Skin friction: 23 channels on oscillograph 0-23 and manometers P-11 and P-27.
Flow field: 35 channels on oscillograph 0-7, 0 23; manometers P-2, P-8.
Boundary layer noise: 4 tracks on tape recorder 38.
Nose gear checkout; 5 channels on oscillograph 0-7.
B. Results
The Martin, 25 S, ablative material checkout was flown on this flight. All instrumentation worked and the test was successful.
Skin friction: A lamp burned out on manometer P-11 but this did not adversely affect the experiment. No major malfunctions occurred. All recorded data appears to be acceptable.
Flow field: No malfunctions occurred. All recorded data appears to be acceptable.
Boundary-layer noise: Malfunctions still are not being recorded on "squawk" sheets. As reported in the last report a static pressure on the BLN rake malfunctioned, and also a thermocouple installed at the dummy .microphone position malfunctioned. Two weeks prior to the scheduled date of this flight, a work order was initiated to install more accurate transducers on the BLN rake. This work order could not be completed because it would cause a two day delay of the flight date. Therefore, these above factors make it necessary that wind tunnel data be used along with the flight data. This is a much longer process than is necessary to obtain useful data from this flight.
Nose gear checkout: No malfunctions occurred on this flight. "Door bracket loads were meaningless because of misplacement of the gages during installation. As a result, the gages were not placed symmetrically about the elastic axis of the bracket and, hence, were extremely sensitive to side loads caused by thermal deformations of the door. The maximum stress gage data was invalidated because of the placement of the compensating gages in an area remote from the sensing gages. This made the bridge overly sensitive to temperature changes and the flight data were questionable. Only uplock hook loads were attained, (peak at 3389#)." Quote from February 8, 1965, memorandum to X-15 Research Planning Office.
An APU run was attempted on January 20, 1965, but not completed due to gear case oil leakage.
A satisfactory APU run was made on January 21, 1965.
The aircraft was mated on January 28, 1965.
Flight was canceled on January 29, 1965, due to weather.
Flight was flown on February 2, l965.
B. MH-96 fixed-gain evaluation
Pitch, as well as roll pulses, were made on adaptive and fixed gain settings. Higher ratings were obtained for adaptive than for fixed gain as expected. The two pitch pulses on adaptive were made at 84 percent maximum and 79 percent maximum gains. The second pulse produced rate limited servos, due to a pitch rate of 6.1°/sec.
At 79 percent of maximum adaptive pitch gain, six-degrees-per-second amplitude of the rate oscillation would be expected to produce servo rate limit for frequencies between 0.7 and 0.8 cps. No roll commands were made during servo rate limiting and lateral directional difficulty was not experienced.
Summary
No major instrumentation malfunctions occurred on this flight and all data appears useful, with the exception of BLN.
An exceptionally constant q was obtained on this flight and should prove valuable.
All recorders went through instrument service after the
flight.
Aerospace Engineer