X-15 PILOT QUESTIONNAIRE - FLIGHT NO. 2-15-29

(Major R. M. White)

I. LAUNCH A. Rate pilot task required to stabilize launch lateral-directional motions, and establish a = 10° pitch angle.
  1. Rating No. in pitch 2 roll 2 yaw 1

2. Did longitudinal acceleration hinder assist not affect X initial trim at a = 10°?
 

 B. Side X center stick preferred to establish initial trim? Please comment on choice .

(Pilot's comment) Where high longitudinal accelerations are present during thrust, it is desirable to use side stick from launch to eliminate control changeover at critical flight conditions.

C. Adjustment of trim or stick force preferred for longitudinal control?

(Pilot's comment) Combination. First deflect surface holding necessary force; then trim to reduce force to zero.

D. Rate airplane damping about pitch 1 , roll 1 , yaw 1 axis.

 II. CLIMB A. Rate pilot success in performing q = 30° climbout maneuver.
  1. Rating, No. in pitch 2 , roll 1 , yaw 1 .

2. 30° pitch attitude held ± 2° .

3. Was vernier presentation adequate? Yes.
 

 B. Please comment on effect of longitudinal acceleration in accomplishing climbout .

(Pilot's comment) No adverse effect at approximately 3g (Ax). Appears to depend primarily on good head position, which on this flight was excellent.

C. Adjustment of trim , or stick , preferred for longitudinal control?

(Pilot's comment) Combination with preference to hold a small force in anticipation of damping a when going to zero g pushover.

D. Wings were held level ± < 5° during climb?

E. Rate airplane damping about pitch 2 , roll 2 , yaw 1 axis.

F. Rate control effectiveness about pitch 2 , roll 2 , yaw l axis.

 III. ACCELERATION AT ZERO G A. Rate pilot task during acceleration run to Vmax.

1. Rating No. in pitch 2 , roll 2 , yaw 1 .

B. Please comment on airplane stability and trim to Vmax.

(Pilot's comment) There were no lateral or directional trim changes noted. Only small corrections were necessary in pitch while holding zero g. Stability at 0° a appeared good in all axes both in its level (which I couldn't determine anyway) and in the short-period modes. No residual oscillations were apparent.

C. Adjustment of trim X , or stick , preferred for longitudinal control during acceleration run?

(Pilot's comment) It is more desirable to trim out stick force and continue to use trim to maintain O° a.

D. Cues for determination of engine shut-down point were:

1. Ground control X .

2. Inertial Altitude meter X .

3. Inertial velocity meter X .

4. Clock X .

5. Other X . Please explain.

(Pilot's comment) Due to the first engine shutdown and a reset of the clock, my clock timing was out of sequence with ground timing by approximately 7 seconds. (Don't ask how this occurred.) I used my own time first, then shifted to ground time when their pushover (to zero g) point matched more closely the predicted altitude (as per my inertial height indicator). While listening to their time callouts I checked inertial velocity and the shutdown time (from the ground) matched perfectly the intended shut-down velocity.
 

 E. Was sufficient time available to prepare for engine shutdown without exceeding planned Vmax?

(Pilot comment) Yes.

F. Vmax was 4,600 ± 100 FPS?

G. Out of trim motions developed at shutdown of about ± 2° , in pitch, ± ?° in roll, ± ?° in yaw?

(Pilot's comment) No serious motions were apparent in any axes. I'm really only guessing a small but high rate motion in pitch since the pitch SAS channel malfunctioned.

H. Please describe airplane response to rudder pulse?

(Pilot's comment) At zero g, very stiff. Deadbeat in about 1 1/2 cycles.

I. Please describe airplane response to pitch pulse?

(Pilot's comment) Good here also. Damped in about 2 cycles.

 IV. PULLUP T0 a = 15° A. Rate pilot task required to stabilize at a= 15°.
  1. Rating No. in pitch 3 , roll 3 , yaw 4 .

2. Airplane trimmed at a = 15° ± 1° .

(Pilot's comment) Force used to hold a = 15°. Trim not adequate.
 

 B. Beyond the stabilizer trim control limit was:
  1. Longitudinal control response linear X or nonlinear ___ with a.

2. Longitudinal force linear X or non-linear with a.

3. Was any longitudinal force reversal required during the pullup? No
 

 C. Please describe airplane response to aileron pulse.

(Pilot's comment) A pulse was not required. At 15°, there were small rolling oscillations which gave a continual directional oscillation. The directional oscillation appeared undamped although I was feeding the oscillation by attempting to damp it manually -- all the time holding zero longitudinal control force to maintain 15° a. The pilot definitely had a good task flying the beast in this condition (SAS remained 4-4-6) and although it wasn't definitely required, if I had had more time at 15° a before the space-positioning turn, I would have used the b technique to damp the directional oscillation.

 V. SPEED BRAKE DECELERATION A. Rate pilot task during deceleration to V = 2,000 FPS with speed brakes open. 1. Rating No. in pitch 3 , roll 3 , yaw 4 . B. Apparent trim change due to speed brake deployment was approximately 3 - 4°, nose down, about lateral axis?

C. Longitudinal trim between pulse maneuvers was held at a = 15° ± 1°?

D. Lateral trim between pulse maneuvers could be maintained ± 10°?

E. Please comment on airplane response to control pulses.

(Pilot's comment) Same as previous item. Use of speed brakes did not seem to change a thing (except greater longitudinal force necessary to hold 15° a).

F. Please comment on aileron versus rudder input for directional control.

(Pilot's comment) As per simulator experience and this flight, it seems lateral control is predominant control for directional control.

G. Please comment on aileron versus rudder input for lateral control.

(Pilot's comment) Lateral control first. I stay off rudders unless I really need them .

H. Apparent trim change due to speed brake closing was °, nose , about axis?

(Pilot's comment) Not noticeable.

 VI. GENERAL QUESTIONS A. The outstanding deficiency noted during the flight occurred about the longitudinal and vertical axis, and resulted from inadequate stability X , damping , control effectiveness , control force , SAS X (Gains should go up in roll and yaw), cockpit presentation , g effect or other sources .

B. Other than acceleration effects, did NASA X , NAA X , simulator adequately predict the airplane motions encountered on this flight?

(Pilot's comment) NAA simulator was a little better than aircraft and NASA simulator was worse. I'd say the NAA simulator was a little closer to the airplane.

C. Please comment on general handling characteristics of X-15 as compared with century-series fighters. (F-104, for example).

(Pilot's comment) Except for longitudinal acceleration and the experience at high a's are comparable in many respects. Good response in all axes, effective speed brakes, in fact better at (low a' s ) because of the absence of inlet ducts (and its associated noises) and the absence of a rotating engine with its gyro effects. In general, the pilot is pleased with the same things as ever, good control effectiveness, good response to his inputs, etc. The X-15 has satisfied these in many areas, including the landing phase, and in some cases the qualities are superior to many of those in century-series fighters.