X-15 OPERATIONS FLIGHT REPORT



FLIGHT NO: 2-45-81 DATE OF REPORT: July 5, 1966

PILOT: L/Col Rushworth DATE OF FLIGHT: July 1, 1966

CARRIER AIRCRAFT: B-52 #008 LAUNCH LAKE: Mud Lake

ENGINE: S/N 106 APU #1 25 AN APU #2 22AN

PURPOSE OF FLIGHT: (1) External Tank Operation and Separation:

(2) Handling Characteristics with External Tanks

(3) Local Flow Data for Ramjet

(4) Martin Ablative Tests

I. Discussion of Previous Operations

A. The leaking NH3 jettison valve noted in the report of Flight 2-44-79 was replaced. No satisfactory explanation for this leakage has been obtained to date. II. Configuration Changes A. The external propellant tanks were modified as follows:
  1. Springs were added to He Q/D's to insure that full engagement would be maintained until tank ejection.

2. The drogue-chute release delay time was increased to maintain stability during main chute deployment.

3. Sleeves were added to the main chute nose-cone separator device to prevent loss of gas pressure from the separator. (Reason for failure of main chute to deploy from Lox tank on Flight 2-43-75).

4. The riser length for the drogue chute was increased to improve stability.

5. An FM TM system was installed in the Lox tank to transmit data on tank accelerations and rotational rates during separation.

6. Modified "thin" Teflon lip seals with Mylar back-up seal were added to the Lox drop tank feed line in place of the heavy gage lip seal originally provided.
 

 B. Incorporated relief by-pass line to protect Lox drop tank from excess boil-off pressure.

C. Cut RH engine firewall panel in two sections to facilitate installation.

D. Added third tank eject button-switch for "partial" full ejection of tanks.

 III. Preflight Events A. System preflight and engine ground run (June 17) with external tanks installed, progressed quite well except for an annoying Lox leak at the external tank feed line Q/D. Several redesigned seals were tried, and finally an acceptable seal was made, using a thin Teflon lip seal backed up with a thin Mylar ring.

B. Failure of S-29 switch in the engine control box during a hangar functional test forced replacement of the engine control box and the engine was rerun on June 22.

C. Captive Flight 2-C-80 was completed on Monday, June 27. Purpose of this captive was to rehearse for the drop flight and checkout the functioning of the external drop tank feed system. The feed system worked very well, although the He flow T/M indication for the NH3 tank failed. The SAS Pitch/Roll damper also failed. A new RH Pitch/Roll servo was installed and several Pitch/Roll module components of the SAS case were replaced. However, during subsequent alignment the new servo exhibited instability (severe "jitter") and was again replaced. Realignment of SAS was satisfactory, but an ASAS case failure required replacement of that item. Final SAS/ASAS preflight was completed on Thursday, June 30. In an effort to insure proper NH3 He flow indication, the transducer was replaced and a parallel T/M channel was provided.

 IV. Flight Events A. Flight 2-45-81 was made on Friday, July 1, 1966. Although NH3 external tank He flow was indicated during the pre-launch jettison check, no flow was indicated after launch and the pilot was directed to abort the mission. After approximately 23 seconds of full throttle, the pilot retarded to 50% throttle and shortly after that ejected the drop tanks using the full eject button. Tank separation was excellent and the landing at Mud Lake was accomplished without further incident. The loss of NH3 tank He flow after launch is being investigated. Both external tanks were recovered. Approved By: Prepared by:

Perry V. Row William P. Albrecht

X-15 Senior Project Engineer X-15 Project Engineer