X-15 #670

12 August 1960

B-52 Takeoff: 0805 PDT

X-15 Launch: 0848 PDT

X-15 Landing: 0855 PDT

The prelaunch activities were considered normal and included a revised list that delays final LOX topoff and pressurizing tanks until less than three minutes to launch. Perhaps experience is a factor, but this revised procedure is considered an improvement and should be retained.

The inertial system appeared to be functioning properly just prior to launch. The altitude and directional indications were excellent, the inertial height indicated 45,300 feet, and vertical velocity wavered very slightly around zero while in level flight. The C-6 directional indication exactly matched the attitude gyro heading. The ADF needle fluctuated over a 20 range and indicated a heading change of 20 to the right while on launch heading.

After launch the engine operation and climb to 60,000 feet were normal. At 1.7 at 60,000 feet, SAS 0,4,8, a pitch pulse yielded about 5 cycles before the pitch damper was engaged at 1.8 M. It appeared at least 3 cycles were required to damp to one-half amplitude. At 1.0 M 1 1/2 g was applied and maintained in the rotation to 10 angle of attack. The average angle of attack on the indicator was 15 with the stick almost full back. A check of the attitude indicator showed around a 30 pitch angle in the climb. During the climb I noticed what appeared to be severs thumps in the control system (in attempting to recall I guess between 90 and 100,000 feet) which may have occurred while moving the stick on and off the aft stop. While attempting to make small changes to angle of attack.

Communications during the flight were excellent. As each 10,000 foot level was passed above 80,000 feet the ground control calls were uniformly 10,000 foot lower than that shown on the inertial height indicator. This situation prevailed during the climb and the entry.

Burnout occurred just prior to the 120,000 foot call. There were no transients in aircraft motion. A gradual reduction was made in angle of attack from 20 to 10. The effect of low dynamic pressure appeared evident in the slow response to longitudinal control motion. I tried to minimize control motion while angle of attack oscillated several degrees in a long period. There were no problems associated with roll or direction. By the time the 120,000 foot level was passed on the entry, damping and response improved enough to allow angle of attack to be accurately controlled. The entry pitch angle did not appear to exceed 30, there were no noticeable g forces on recovery, and entry angle of attack could be maintained with the stick less than full back.

After arriving level at about 60,000 feet, a rudder kick at SAS 4,0,0 was made just above 2.0 M. A large roll acceleration began with the yawing oscillation, one pilot input stopped the rapid band angle change and oscillations were allowed to continue. A second rudder kick near 1.8 M, SAS 4,0,0 yielded a predominantly directional oscillation. Positive damping was evident in both cases. At 1.5 M, dampers on, a pushover to 0g and a pullup to 10 angle of attack was completed. At the high key, 20,000 feet, a pushover was made to 2 angle of attack, then a pullup to 10 angle of attack.

During the entry, perhaps between 70 and 80,000 feet, a mild lateral directional oscillation was apparent, but disappeared during the pullout. Indicated Mach number at pullout was 2.52.

The pattern and landing were considered normal.

Robert M. White

Major, USAF