Plane: X-15 No. 1 6670 Date: Sept. 23, 1960
Flight: 1-13-25 B-52 TO: 0910
Pilot: LCDR F. S. Petersen USN Launch: 0952
Chase: Capt. Robert Looney F-100F Total: :07
Capt. Robt. Rushworth F-104D
Mr. Joseph Walker F-104A
Purpose of Flight: Pilot Checkout and Familiarization
(a) Cabin helium source pressure dropped during the pre-engine start interval from 3400 psi to about 3100 psi with the helium shut-off switch off. During taxi and initial B-52 climb the helium shut-off switch was turned on and cabin source topped off to 3400 psi with no detectable drop in engine helium source. Following this top-off of cabin source, its pressure gradually increased to 3550 psi at cabin pressurization (9 min. to drop) with the helium shut-off switch off.
(b) The pilot at 3 minutes to drop turned internal data on, calibrated, and for some unknown reason turned the data switch off. Internal data was turned on during X-15 climb at about 45,000 ft. following a reminder from NASA control.
(c) Although the
stable table appeared to cage and uncage normally, there was still a small
(estimated I 7 ) very long period pitch oscillation extant at launch. The
period of this oscillation was so long that the motion itself was not evident
and its existence was deduced by seeing the three axes indicator in various
pitch positions during instrument scans. In contrast the roll axis appeared
to be properly aligned with no oscillations as long as 8 minutes before
launch. Inertial altitude was as accurate as its readability during the
B-52 climb from 40,000 to 45,000 ft. and at launch.
2. The pilot held about 1-1/2 to 2 inches of left lateral control on the center stick at launch. This appeared to be the proper amount of correction to compensate for the right wing drop at launch. However following drop the X-15 was on a heading about 5° to the left of that which existed before launch. The X-15 came off the pylon with a definite nose down motion (horizontal stabilizer set at zero). It appeared to require less aft stick motion to establish 8° angle of attack after the drop than was anticipated from simulator practice. However, no difficulty was experienced in establishing 8° angle of attack.
3. The rocket chambers were started slower than optimum but all eight chambers started normally. The round out altitude was 36,500 feet. The slow start undoubtedly contributed to this low value. During the 8° angle of attack climb the transonic nose down trim change was evident but easily controlled. The airplane was pushed over at 42,500 ft. to 1/2 g to level at 50,000 ft. No control peculiarities were noted during the pushover and the acceleration from 1.2 to 1.6 was made at 50,400 feet. The nose down trim change during this acceleration appeared to be of lesser magnitude and was easier controlled than anticipated from simulator practice.
4. At 1.6 a 12° angle of attack left turn was initiated, This turn (about 2-1/2 g) had just about been trimmed when the pilot felt some variations in longitudinal acceleration and thereafter noticed the chamber pressures and manifold pressures on the upper engine dropping to zero. At this time an overspeed light was noticed on the upper engine. While keeping the airplane in a left turn two attempts were made to start the upper engine. During these attempted simultaneous starts on No. 2 and No. 4 chambers, fluctuations in manifold pressures and chamber pressures were observed but starts were not obtained. The pilot believed erroneously that the lower engine was still running but inability to hold altitude and airspeed variations from values expected for single engine operation forced the pilot to the inevitable conclusion that both engines were shut down. Joe Walker in prime chase and Milt Thompson in NASA 1 both informed the pilot at about this time that the lower engine was indeed dead. No attempts were made to start the lower engine. Pilot preoccupation on the upper engine starts triggered by only an upper engine overspeed light and preoccupation in continuing the accelerating turn perhaps contributed to this lapse. During the accelerating turn back towards Rogers Dry Lake two pushovers from relatively high angles of attack were made. The first followed the nose up condition resulting from trim change while decelerating from l.6 to 1.2. The second followed the nose up condition resulting from trim change while decelerating through the transonic regime. Positive control response was available for handling both cases. Light to moderate airframe buffet was present during higher angles of attack attained as the airplane became subsonic. This persisted at all airspeeds less than about 220 kts. The minimum speed observed was slightly less than 200 kts.
5. The glide back to Rogers Dry Lake, and the approach were made at about 300 kts. While turning final speed was increased to a maximum of 330 kts. The end of runway 18 was reached with 25,000 ft. and about 380° of turn required for a left hand overhead approach. This was near minimum altitude and the initial 220° to 240° of the turn were made quite tight.
With about 120° of turn to go it became clear that altitudes and positions were adequate and the turn was eased. The turn was apparently not eased enough as altitudes were about 1500 ft. high when turning on final. Speed was increased and flaps and gear extended earlier than normal at chases suggestion to help alleviate this condition. The ventral ejected normally. Trim change with flap extension was hardly noticeable and no difficulties were experienced with flare and landing. Touch down speed was about 200 kts. The jolt resulting from nose wheel contact was less than anticipated. During run-out a slight tendency to turn right was controlled with left lateral control.
6. Nothing during
the flight surprised the pilot with the exception of early engine shutdown.
The trim changes and aircraft responses were as anticipated. The approach,
flare, and landing felt comfortable. It is felt that this validates the
training procedures which are SOP.
Forrest S. Petersen