MEMORANDUM for Chief, Research Division
FROM: X-15 Research Project Office
SUBJECT: Flight Research Report on flight 3-41-64, flown 4/23/65, pilot Capt. J. Engle
I. Purpose of flight
A. Ablative tests - the flight requirements were to extend speed brakes prior to burnout, attain a Mach number greater than 5 and a greater than O° but less than 4°.
Heat transfer tests - the additional requirement for this test was to keep altitude below 90,000 ft.
B. Handling qualities evaluation - the flight requirements were to obtain pilot handling qualities evaluations at angles of attack of O° and 6° at approximately M = 3.5 and 0°, 6°, and 12° in the subsonic region.
C. Boundary layer noise - flight requirements for this study were to maintain approximately 625 psf in the altitude range of 65 K to 75 K feet in a velocity range of 2,625 to 3,350 fps.
D. Although the nose gear modification checkout program was not listed on the Flight Request, gear instrumentation was installed but no flight requirements were necessary.
The flight plan was based on the ablative test flight requirements up to burnout and then on those for the handling qualities evaluation.
A slightly higher thrust was experienced during the flight but this did not adversely affect the flight plan. The altitude was exceeded by only l,000 feet.
The final data workup was not available at the time of
this writing. However, the Mach program was available from which the following
have been gathered:
| Film Time | q | M | a |
| 206 sec | 1215 | 5.3 | 2.8 |
| 216 sec | 1212 | 5.34 | 2.16 |
Although the above is not final data, it does serve to indicate how closely the profile was flown. The Mach program also indicates that the desired ranges of parameters was reached for BLN data and that the pilot obtained the handling qualities data at the requested angles of attack.
III. Instrumentation by Experiments
Ablative and heat transfer tests: 12 channels on thermocouple oscillograph 0-25.
Handling qualities: no special instrumentation was required.
Boundary layer noise: 4 tracks on tape recorder #38.
Nose gear modification checkout: 7 channels on oscillograph 0-7.
Local flow: 11 channels on oscillograph 0-7.
B. Results
The ablative material was sprayed on the fixed upper vertical fin. The flight was planned so that when the ablative material started ablating the speed brakes would be near full extension. Deposition of the ablative material onto the speed brakes was looked for and none was found. These results, however, are encouraging but not conclusive.
The data obtained from the roughness panel for heat transfer test concluded this experiment.
Handling qualities: Although no specific instrumentation was required, the standard attitude and acceleration recorders functioned properly.
Boundary layer noise: The lower forward microphone was installed along with its associated pressure rake and accelerometer. The only malfunction recorded was of the pressure transducer which sensed the pressure from the outermost probe on the rake.
Malfunctions for the tape recording system are now being recorded on the "squawk" sheet.
The new transducers on the BLN rake are supposed to reduce and simplify the computer program for data reduction. The final data from the BLN installation on this flight has been promised by Tom Lewis by the 6th working day after the flight.
Nose gear modification checkout: Since flight 3-40, plans were made for an altitude flight. Efforts were then made to retain the strain gaged nose gear door brackets even though the brackets with the Belleville washers were ready for installation. It was agreed that the bracket loads on the 180,000 foot flight would not be excessive and data could be obtained.
Subsequent to this, Hidden Hills Lake dried out and the plane could be flown on a heating flight from Hidden Hills instead of the altitude flight from Delamar. The strain gaged brackets were then replaced by the ones with Belleville washers. These washers are designed to absorb bracket loads which were expected to be greater on the heat flight. Therefore, bracket loads data were not obtained, but data were obtained on the uplock hook and the attachments (levers) which are connected between the brackets and the strut.
Local flow: The forward rake has been removed and impact pressures are still being recorded on the aft rake (sta. 96) to determine what effect the forward rake had on its readings.
Main gear: NAA is reviewing loads obtained on the drag braces on the bungees which are to be installed for the next flight.
The conditions of the lakes and the weather caused a considerable delay.
Considerable difficulties were encountered in the engine runs for this flight. So much so, in fact, that a meeting was held to determine if any changes had been made in quality control checks. However, nothing out of the ordinary was uncovered.
No major instrumentation malfunctions occurred on this flight, and the flight was flown as planned.
Final data workup and reports from 0perations Engineering,
Stability and Control Section, and Control Systems Section were not available
for this report. Final profile work up was completed on May 4, 1965.
Joseph A. LaPierre
Aerospace Engineer