X-15 OPERATIONS FLIGHT REPORT



FLIGHT NO: 2-43-75 DATE OF REPORT: November 17, 1965

PILOT: L/Col Rushworth DATE OF FLIGHT: November 3, 1965

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

ENGINE: S/N 104 APU #1 25 AN APU #2 22AN

PURPOSE OF FLIGHT: Empty External Tank Evaluation:

Handling Qualities

Tank Separation & Trajectory

I. Discussion of Previous Operations

None II. Configuration Changes A. Incorporated the following EO's in preparation for installation of external tanks:

Electrical Circuit Modifications

899492 899495 887946 900111

899493 899496 887947 900112
 
 

Structural Beef-up of Side Fairings & Bulkhead #340.312

898963 898977 898905

898973 898978 898981

Hadley Valve Heater Circuit

900102 900104

Plumbing Modifications

849675 849676

B. That portion of propellant system involving transfer from external tanks was disabled per W.O. 671-0-2923.

C. Relocated TM antenna to forward fuselage (approximately Sta. 95) to eliminate transmission pattern interference with external drop tanks installed.

D. Installed ventral camera for photo coverage of external tank separation (200 F.P.S., 16mm). A second camera installed in the C.G bay was later abandoned because of freeze-up of the camera in the excessive cold adjacent to the Lox tank.

E. Removed emergency jettison helium source isolation valve and replaced with straight thru union.

F. Installed updated high pressure helium relief valves in helium #1 and #2 system.

 III. Preflight Events A. Two dummy tank ejection tests were made with the X-15 astride a 10 foot deep pit prepared next to the NASA ramp. Preloaded cables were used to apply simulated aerodynamic drag and side loads to the dummy tanks. The first test used a half charge ejection force (simulating malfunction of one of the two pyrotechnic systems in each tank). The first test also simulated low "Q", approximately 300 psf. The second test used a full charge ejection force and simulated high "Q", approximately 600 psf. Both tests were successful, the first being conducted on September 29, 1965, and the second on October 2, 1965. High speed motion pictures showed good separation. During both tests hydraulic and electrical power were supplied to the X-15 and the SAS engaged. SAS remained engaged throughout both ejection tests. Subsequent inspection showed no damage to the X-15.

B. Following the successful ejection tests, the X-15 was prepared for flight with empty drop tanks. Final installation of the tanks was accomplished on Saturday, October 23, 1965, and a successful engine ground run was made Monday, October 25, 1965. A SAS resonance check with the empty tanks installed revealed no system instability or resonance on October 26, 1965.

C. A first attempt at flight 2-43-75 was canceled prior to B-52 engine start with the following squawks:
 

1. Internal Fox helium source leak thru Marotta valve and helium #l relief valve.

2. Drop tank-to-X-15 lip seal failure.
 

 D. A second flight attempt on Monday, November 1, 1965, was canceled prior to B-52 engine start when it was observed that NH3 was leaking back into the supposedly "empty" NH3 drop tank. The NH3 transfer valve was replaced with a solid plate and the lip seals in the tank-to-X-15 transfer lines were covered with solid pressure plates. This action precluded the possibility of lip seal external leakage, and isolated the NH3 drop tank from the NH3 in the internal tank. IV. Flight Events A. Flight 2-43-75 was completed on Wednesday, November 3, 1965. Tank ejection and separation appeared quite good. Further study of the tank trajectories is in progress. Stability of the tanks with the drogue chute deployed was not good and the tanks tumbled about excessively. The NH3 tank main chute deployed successfully and that tank was recovered in excellent condition. The main chute of the Lox tank did not deploy although subsequent inspection showed all pyrotechnic releases to have fired. However, one of the two explosive bolts which secure the main chute in the nose cone did not fully shear its locking pin and thus the cone was not released. The Lox tank was recovered but is not repairable. As a result of this flight, the following modifications will be made to the tank recovery system:
  1. Larger drogue-chute

2. Modified explosive bolts in the nose cone (bolts will be fitted with a sleeve to retain the ends of the shear pins and thus prevent gas pressure loss when the pin is sheared).
 

 All other systems in the X-15 operated normally.

It is not planned to fly with external tanks again until the above two squawks against the recovery system are fixed.
 
 
 
 
 
 

 Approved By: Prepared by:

Perry V. Row William P. Albrecht

X-15 Senior Project Engineer X-15 Project Engineer