X-15 #6670

13 April 1960

B-52 Takeoff: 0826 PST

X-15 Launch: 0914 PST

X-15 Landing: 0923 PST

Takeoff was on lakebed runway 17 and appeared smooth with no vibration noted in the X-15 cockpit. The ventral fin was armed shortly after lift-off. During climb low face plate heat was selected then turned off in approximately four minutes. Heat was felt on my face and although it had not become uncomfortable, it was decided to turn it off for the first flight. As the climb progressed, the LOX tank pressure rose to 9 psi and WALC tank pressure to 3 psi. These values remained nearly constant until the tanks were pressurized.

The tank pressures were redundantly and incorrectly referred to as WALC and ALC on several of my readouts. It is hoped in the future that the ground control will be punctual in questioning calls that are misleading, erroneous or questionable. This pilot requests and expects this assistance to help insure a successful mission.

At 38,000 feet the B-52 SAS maneuver was completed and SAS reset satisfactorily. The stable platform procedures appeared to follow according to plan with a successful gyro cage and uncage and with heading following with approximately 15° difference from other directional indicators in the X-15 and B-52. At 45,000 feet the inertial height indicator read exactly 45,000 feet.

All pre-launch activities occurred normally and results were as expected until the 5 minute warning to launch. I did not hear this call and fell one minute behind in procedure. In the rush to catch up I unfortunately missed turning the data switch on. When B-52 power was turned off at approximately 3 minutes to launch all SAS channels sent off and were satisfactorily reset.

The MC-2 suit pressurized in the climb to 45,000 feet but was never uncomfortable. When the cockpit was pressurized cabin altitude went to 35,000 feet, the suit pressure decreased, and remained satisfactory throughout the flight. The vent air valve was maintained between one-quarter and one-half turn open. This was comfortable, although slightly cold prior to launch. Suit heat was always left off. Breathing qualities were good on the ground and improved considerably above 20,000 feet. When the sun was on the faceplate heavy faceplate reflection was apparent.

The launch and entire flight was made using the center stick. The drop was as expected , not violent, but a positive departure from the pylon. SAS 4, 4, 8, Roll-off to the right was slight, perhaps 10° bank angle, and caused no concern. Chambers 2 and 4 on both engines were lighted immediately and the airplane rotated to 10° angle of attack. Light buffet was noted and I felt I would start uphill by 40,000 feet. Deliberate pause was made between lighting the remaining chambers, waiting for a chamber pressure indication of 200 psi before proceeding in like manner to each successive chamber. The lack of acceleration until all eight chambers were operating was a slight surprise. Lowest altitude during drop was between 37,000 and 38,000 feet.

During climb I fell behind the pitch angle change required to maintain 8° alpha (also a little surprising) and held 6° alpha. Pushover was initially to less than 0.5g at 46,000 feet. During climb and for the powered portion of the flight a low magnitude roll oscillation of about 1 cycle per 2 seconds persisted and was considered annoying. After level off pitch pulses were made in the following sequence: 4, 4, 8; 2, 4, 8; 6, 4, 8. Damping to low amplitude was rapid in all cases. During the pitch pulses the transonic trim change started the aircraft downhill. I recognized afterwards a moderate control deflection is required to maintain altitude but compromised in order to get the pulses before the first turn.

The first positioning turn was made at 1.7 Mach number, 44,000 feet and SAS 4, 4, 8. During the turn g was increased to 2.8 then decreased to 2.0. The roll oscillation persisted in the turn and for part of the turn the aircraft kicked back and forth several times in a yawing oscillation. This appeared as a yaw damper action rather than a result of the roll.

Upon completion of the turn a rudder kick was made at SAS 4, 4, 8. Damping was very rapid with no bank angle change. Another rudder kick was made at SAS 4, 0, 0. The airplane damped quickly (I honestly made no attempt to count cycles) with a slight roll to the right then a bank angle change to the left of perhaps 10°. Right rudder was used in the kick. At SAS 0, 4, 8 and about 1.8 Mach number a pitch pulse was made and the noticeable oscillations appeared to subside in about five or six cycles. With SAS at 4, 4, 8 and 1.9 Mach number lower chamber 3 was shut down, then upper 3 shut down at which time upper 1, 2, and 4 chamber pressures sagged about 10 psi, then recovered. Upper 1 was shut down, SAS placed at 4, 0, 0, Mach number about 1.97, altitude 44,000 feet, and a right rudder kick. While the oscillations were damping along with a right then a left roll, burnout occurred. I immediately initiated a left turn of about 2g toward the base re-engaging roll and yaw dampers in the turn. Transients were never noted during damper engaging operations.

On the glide toward the base the flaps were extended at 290 KIAS, then immediately retracted at 250 KIAS. I tailwind put me directly over the main base with excessive altitude. I put my head in the cockpit, saw the data switch off, and placed it on perhaps 2-1/2 to 3 minutes prior to landing. Airspeed was increased to 340 KIAS to get rid of excess altitude and on final approach the speed was reduced to 300 KIAS prior to flare. Speed brakes were opened slightly and closed twice to prevent excessive speed, once on downwind and again on base leg. The ventral fin was jettisoned on final approach with a noticeable thump, the landing instrumentation turned on, and the flare initiated at 300 KIAS. Flaps were started down as the flare neared completion, and although not unexpected the flap trim change gave me a noticeable increase in altitude followed be a sizable push force and stick deflection to compensate. The landing gear lanyard was pulled as speed decreased through 240 KIAS. After arresting sink rate and hearing the chase pilot's call of five feet I held what I had, felt what seemed a smooth touchdown on the main skids followed shortly be the jarring impact of the nose gear. Immediately after touchdown, estimated at 185 KIAS, the speed brakes were opened, the stick pulled aft and moved to the left to prevent what felt like a slight tendency to turn right.

Handling qualities during the glide to landing were considered very good. The roll oscillation was not apparent and lateral response was fine. The longitudinal control was effective, responded exactly as I desired, and the force levels seemed satisfactory. Except for the longitudinal trim change with flap deflection, which is considered easily controllable, the F-104 landing simulation proved an excellent primer for the X-15 landing operation. Visibility from the cockpit is somewhat restricted during turns but is considered adequate.

Based on the experience of this flight the following recommendations are offered for consideration:

1. At the five minute to launch warning call have the X-15 pilot acknowledge the time, the B-52 pilot repeating the call if necessary for X-15 pilot confirmation.

2. Move the DATA ON-CALIB item to the two minute warning with ground control requesting confirmation if the X-15 pilot does not call out this item.

3. Ground control take immediate action to question or advise on erroneous or questionable callouts from the airborne vehicles, or errors of omission or commission in the pre-launch countdown.

4. Investigate the roll oscillations with a view toward correcting a possible damper deficiency.


Robert M. White

Major, USAF