Aircraft: X-15 No. 670 Date: 12/9/60
Config: Ball Nose Installed

Cockpit Presentation From Alternate Airspeed System.

Takeoff: 11:21
Flight: 1-19-32 Launch: 11:53
Pilot: N. A. Armstrong Land: 12:04
Chases: F-100F Maj. Daniel Total: :11
  F-104A Maj. White    
  F-104D LCDR Petersen    

Launch Aircraft: B-52 No. 008

Capt. Allavie

Maj. Cole

J. Russell

Subject: Ball Nose Evaluation, Alternate Airspeed Evaluation

1. The launch occurred over the Palmdale VOR station at 45,000 feet, 0.82 Mach number, on a heading of 030 magnetic. The separation was smooth with a small right roll and no pitching. Standard control positions and trim were used. 8 chambers were ignited without difficulty and an indicated 8° angle of attack round out initiated. 13° a was reached without buffet, but the aircraft may have been slightly supersonic at this time. The pitch vernier was set for 25.0 degrees and nulled correctly at an indicated 25° pitch angle on the 3-axis ball. A 1/2 g pushover was initiated at an indicated pressure altitude of 41,500 ft. (44,000 inertial). Altimeter correlations while level at 50,000 feet showed the pressure altitude from the alternate airspeed system to agree quite well with the predicted value.

2. A directional pulse with roll and yaw SAS modes de-energized was obtained at approximately 1.4 Mach number. A 2.5 g turn was initiated at approximately 1.65 M. Angle of attack readout was only 7° as opposed to the 11° expected. The aircraft was trimmed in the turn and the following pulses recorded:

Pitch pulse - pitch SAS mode out

Roll pulse - roll SAS mode out

Yaw pulse - roll and yaw SAS modes out

No specific variations from the simulator dynamics were noted. Additional altitude correlation after rolling out of the turn at 1.7 M indicated that the pressure altitude continued to follow the predictions.

3. A left sideslip with abrupt release (roll-yaw SAS off) was performed at 1.6 Ml (1.8 M), 45,500. Burnout immediately followed full speed brake extension. A pitch pulse with SAS pitch mode disengaged was recorded at Ml = 1.40 prior to initiation of space positioning turn. During the decelerating 2 g turn, angles of attack as high as 14° were observed on the indicator as opposed to the 10° expected.

4. During the glide back to the lake, 250 KIAS (260 KCAS) was maintained to improve subsonic ranging information. The early part of the glide down at 10° bank angle followed by an extended wings level period. An airspeed calibration pushdown.- pullup was recorded at 250 KIAS at approximately 20,000 feet. The angle of attack range was 0 - 11° (indicated). Numerous airspeed comparisons between the X-15 and the F-104 chase during the return glide and approach indicated that the corrections were generally as predicted and the planned approach airspeeds would be satisfactory.

5 A left crosswind component of about 5 knots was in existence at the time of landing. Shortly after touchdown, a right (downwind) turn was initiated using full right roll control and near full right rudder. The tendency toward an uncontrolled skid was sufficiently strong at times to require a reduction in the amount of pro-turn control input.

6. During the Number 2 APU starting sequence, the hydraulic pressure indication hung up at 200 psi for approximately 15 seconds. The pressure then rose rapidly with very little overshoot indicating possible difficulties in the transmitter or gauge.

7. Inertial attitudes were satisfactory at all times. Inertial altitude appeared proper during the first 3 minutes of flight and seemed to stick at a value of 55,000 feet. After touchdown, inertial altitude was incorrectly reported as approximately 54,000 feet and should have been reported as 54,000 feet. The time of the inertial altitude rise during the flight was not noted.

8. The angle of attack and sideslip crosspointer presentation was considerably erratic with continual jitter. The angle of attack indicator was relatively steady.

Neil A. Armstrong

Aeronautical Research Pilot