X-15 OPERATIONS FLIGHT REPORT



FLIGHT NO: 1-57-96 DATE OF REPORT: 9/16/65

PILOT: M. O. Thompson DATE OF FLIGHT: 8/25/65

CARRIER AIRCRAFT: B-52 #003 LAUNCH LAKE: Delamar

ENGINE SERIAL: 108 APU #1 16 APU #2 20

PURPOSE OF FLIGHT: 1. MIT Horizon Scanner (Tail Cone)

2. Aircraft Stability and Control


I. Discussion of Previous Operations

A. Operational procedures for cooling the Honeywell IFDS prior to cockpit closure have included the use of external air from an Airesearch expansion-turbine air-conditioner applied to the ram-air door opening. Although use of this air-conditioner introduces moist air into the elevator bay areas after purging with dry nitrogen, a setup of plus 40°F air at 3 psig had not caused malfunctions of the cockpit regulator for the previous seven flights. Flight l-A-94 was aborted because of a frozen open cabin regulator; it was also necessary to free the cabin regulator because of a frozen-close condition prior to taxi of flight l-A-95 (once the regulator was free, normal operation was restored). The average relative humidity values have been higher than normal during the current flight attempts. Until corrective procedures or changes can be made, the T/M antenna door will be opened to allow cabin regulator cycling prior to taxi. II. Aircraft Configuration Changes A. The IR Scanner and IRATRAN window were removed. The MIT Horizon-Scanner and special tailcone were installed as the prime experiment.

B. The Pace transducer was installed in the nose of the LH wing pod to measure high altitude density.

 III. Preflight Events A. APU load checks and BCS/RAS operational leak checks were accomplished on 8/9/65. The No. 2 APU catalyst bed exhibited some chugging; however, shock load response was good.

B. The RAS functional revealed a malfunction of the auto-cutoff (maximum "G" shutoff) portion of the RAS. When a "G" condition disengages the system, RAS cannot be reengaged consistently; however, this feature was not required and does not affect the operation of the motion damping.

C. The original flight attempt scheduled for 8/12/65 was delayed by rain until 8/17/65. Weather and wet lakes required reschedule for 8/20/65.

D. Flight l-A-94 was completed on 8/20/65 with M. Thompson as pilot and the X-15 was carried on B-52 #003. The cabin pressure regulator froze in the open position, ref: I-A. Post-flight inspection showed extensive accumulation of frost on the regulator and in the area of the regulator exhaust in the LN2 bay. The No. 2 APU tank showed a pressure rise with the system off. The cabin pressure regulator and the No. 2 APU helium shutoff valve were replaced.

E. Flight l-A-95 was accomplished on 8/24/65 with M. Thompson as pilot and the X-15 was carried on B-52 #003. The IFDS computer experienced a voltage transient with data switch ON at the one minute to launch point. Loss of the IFDS computer memory was apparent during the 10 minute turn called to evaluate the condition. Post-flight checks did not confirm component failure as a cause; however, because of doubt about the actual cause, the entire IFDS system was replaced. The cockpit pressure regulator was frozen closed when the canopy was closed prior to taxiing; cycling the regulator by closing off the sense line restored normal operation

 IV. Flight Events A. As a pre-cautionary measure, the cockpit-pressure regulator sense line was cycled closed to operate the regulator prior to taxi.

B. A peculiarity on the landing rotation and flare was experienced, requiring extraordinary pilot effort to recover a pitch-up motion. Later analysis showed inadequate forward trim capability with the particular aircraft center of gravity, flap operation effects, and rotation timing as experienced during the landing.
 
 

 Approved by: Prepared by:

Perry V. Row Ronald S. Waite

X-15 Senior Project Engineer X-15 Project Engineer