FLIGHT NO. 1-24-40
Pilot -- Joseph Walker
RESUME OF FLIGHT REQUEST
2. Maintain 10° a until q =30°.t
3. Maintain q =30°, pushover to 0 g at 39 sec., maintain 0 g.
4. At t = 70, extend speed brakes.
5. At t = 80, shutdown engine. Set SAS 8-0-0.
6. At V = 5,600 fps, perform dv pulse.
7. Gradually increase. angle of attack to 10° and attempt to control airplane using b-dot technique if necessary.
8. Reset SAS at 8-6-8, perform pullup and rudder pulse at max. trim (approx. 15° a).
9. At V = 4,200 fps. establish level flight and set SAS at 8-0-0. Attempt to control airplane using b-dot technique.
10. Retract speed brakes. Initiate space-positioning turn to high key.
A. Please compare launch and recovery with previous flights.
B. Please describe any system failures or adverse conditions caused by engine start.
P.C. No failures.
C. Question pertaining to lateral trim.
P.C. When I went
back to SAS on to perform the rudder pulse, I discovered the airplane was
out of trim laterally because I took my hand off the side stick
intending to try to prevent pilot inputs, and wasn't able to do this. This
explains the former trouble in trying to keep wings level. As a matter
of fact, I think it probably made a more complicated problem out of the
P.C. Simulator: Constant a was maintained by use of a combination of force and trim.
Airplane: a during the rotation was up to about 13° and I then maintained 10° by reference to the horizontal cross bar on the 3-axis indicator. Also, I attempted to roll in longitudinal trim and as I stated at the debriefing, a combination of correcting the course and trimming longitudinally detracted my attention from the pitch angle and I suddenly discovered that I had passed the point of 30°, I immediately tried to correct the situation and get back: on the climb schedule.
1. Rotation in a was 10°. .
2. Climb attitude was 30°.
3. Wings level ±0°.
1. Rotation in a was ±3°, -0°.
2. Climb attitude was 35+.
3. Wings level ±5°.
4. A course correction of 5°.
C. Please describe any SAS residual motion feedback to the control stick. Is roll or pitch difference discernible? Compare with simulator. Did SAS residual feedback influence flight plan?
P.C. Simulator: SAS residual is noticeable on the simulator. The pitch mode is dominant. The SAS residual does bother the flight plan when constant q is being flown.
Airplane: There was no SAS residual this portion of the flight was very simple from the control standpoint.
D. Any other distracting factors present?
P.C. The later trim situation. Initially I thought it was caused by b, but I remember one flight with rudder held in so I deliberately moved the rudder and then took my feet off , moved them one way and then the other way and couldn't determine really that I was getting any effect out of them super sonically at all. I had to use aileron to take care of it super sonically. When I got down to low subsonic speeds I was able to move in enough rudder to. correct the lateral trim. The rudder required to do this was obviously a definite input.
E. Please rate overall launch rotation and climb task.
P.C. Simulator: Easy when. flying q trim change, and taking care to stay on course.
Airplane: Pitch 1, roll 1, yaw 1.
P.C. Simulator: Trim to 0g with center stick, with left hand on center stick. take over on side stick then use left hand to switch trim.
Airplane: The entire flight from launch to landing was made on the side stick.
B. Was effect of .speed brakes noticeable on performance? Stability?
P.C. Airplane: With the low opening rate used on the speed brakes you cannot detect that. you are decelerating and hence, it just seems to modify the acceleration. a little bit . I could not observe that there was any discernible input from opening the brakes. What I did notice was that I had to mentally tell myself to use a little more muscle to get my hand up to the speed brake handle. My hand was riding somewhere by my side and when the countdown started at 63 sec, I briefly thought I wasn't going to reach them. I was able to overcome this and actually had no problems at all in getting a hold of the speed brake handle. When I reached for the throttle for shutdown I was prepared and my hand was right up there.
C. Rate pilot task during acceleration.
P. C. Rating no . brakes closed: pitch 1, roll 1, yaw 1
Rating no . brakes open: pitch l , roll 1, yaw l .
D. Please describe instrument panel scanning sequence as engine shutdown approached.
1. What was primary cue for engine shutdown? Landing; Any distracting factors? Positive longitudinal of any bother?
P.C. Simulator: First cue pilot clock in conjunction with ground clock. Second cue V indicated.
Airplane: The primary cue was radio time call out. The stopwatch in the airplane didn't run. Secondary cue was velocity. No distracting factors. Longitudinal q see III.B.
2. Vmax was 5,600 fps..
3. Did you have to correct for any burnout or deceleration induced motions?
P.C.. Airplane: I particularly noticed this time whether there were any motions due to cutting the thrust off because I .had a pulse to do right after power off and the airplane was as quiet as sitting in your chair right now until I moved the rudder for the pulse. There was no pitching - no yawing - everything smooth and deceleration didn't seem to be much of a problem. I was aware of a small amount that seemed to be more like letting go of the pressure than getting tossed forward .
4. Please describe any system failures to date during flight.
P. C. There were no system failures.
P.C. Simulator: SAS off first a increased by using the trim button.
Airplane: The sequence was: I turned off roll and yaw SAS and performed the rudder pulse, at a = +3 after a couple oscillations I started the nose coming up by running the trim at the same time as I was moving the handle. I then. went to work holding the sideslip needle and I then checked as to what the actual a magnitude was and I found I had paused at something like 7° so I went on up and found that I actually did get up to an indicated 12° and cannot estimate the time period spent there. I essentially bounced back and forth between 8° and 12°a during that period and still doing well enough that I was under control and just relaxed the control .attempts while I reached down and turned the SAS back on for the high a pulse.
B. Did b oscillation become progressively worse as M decreased?
P.C. I wouldn't say exactly that the operation became progressively worse. I would say that the instability or control difficulty at the high angle of attack got a little worse as the Mach decreased. It was obviously that or I was getting very tired. By the time we were getting down to speed brake retraction, it was a lot harder job at the higher a than what I had on the earlier run.
C. What was bmax noted on crosspointers?
P.C. I believe that bmax was on the order of 3° to 4° at approximately a two second period. It seemed to me that we were running a rate of about one second to 1/2 cycle or even longer period and shortening up of course as we decelerated.
D. Please describe lateral accelerations on the pilot .
P. C. During the damper-off flying period I didn't experience any cockpit accelerations, although I did notice that there was enough at the larger sideslip excursions that I would catch myself leaning on the opposite rudder pedal. If you are ,going to lean to one or the other side, leaning on the one against the motion is the best; way to do it. It was sort of a bracing response more than an intentional control input. There was no effect on the arm movement at all. The lateral acceleration I did feel is still a square wave and it didn't feel as though there was fuel sloshing. I have felt fuel sloshing in the F-104s and you can tell the difference because you seem to get a movement out off the airplane and then a lurch as the rest if it catches up. We had none of this on the X-15.
E. Question pertaining to bank angle:
P.. C. At the maximum sideslip excursions you notice that the airplane is banking at that point and it goes back in the other direction. It seems as though you are far out in yaw before the bank starts taking place; and by the time you are yawing the opposite way, the wing moves in the other direction.
F. Describe and rate control task required to fly airplane using b technique.
P.C. Simulator: Pitch 5, roll 5, yaw 5 .
Airplane: I don't think I can give a fair rating. I believe that if we had a decent trim, I could rate the pitch at 1 or 2 with damper on, but this time I think it is apparent from all I have said, that I would rate it at 3. Lateral-directional rating would be about 5 at the higher a. The words and numbers of the rating scale do not fit this case, words call for a 5 rating, numbers a 3 1/2 rating. I was using the roll control to damp the directional oscillations.
G. From this flight experience, how useful is b-dot for extended emergency operation of airplane? (l) Nz<1.0, (2) Nz>1.0.
P.C. I believe that it will be apparent that the quieter angle of attack portions of these runs are the best from the overall control standpoint. When the pitch mode is bouncing up and down you get cross-products that give a difficult time. Actually, I don't think normal acceleration will bother you (within reason) if you are able to trim the airplane in pitch because it may even be a help in pinning your arm down a little more.
H. Kinesthetic motion cues complicated greatly, somewhat, or very little the airplane control task compared with .the fixed base simulator?
P.C. I believe the rotary stimulus was completely absent or low enough that it wasn't impressing at all.
I. Please compare X-15 and F-100 controllability using b-dot technique.
P. C. Simulator: The simulator and F-100 are comparable to 3,500 .fps except for discrepancy at high angles of attack. The F-100 was not flown for the 5,600 fps case.
Airplane: The F-100 does give the pilot a clue as to what the X-15 does in flight. In the F-100, it is a chore to keep working the b, particularly with the back and forth motion that we are getting. In the X-15, I just kept on working and didn't even have any confusion as to the control correction versus sideslip needle.
J. Please note any other distracting factors which complicated optimum airplane control during this portion of the flight.
P.C. No distracting factors.
K. Please recommend cockpit instrumentation and control system changes which would facilitate using b-dot technique.
P. C. Simulator: An error displacement type of unit may be helpful perhaps using yaw rate.
Airplane: Improving the trim system of the side stick may help. I do not know of any instrumentation improvement that we could make since I understand quickening does not help .
L. Please compare emotional stress level reached during this portion of flight with launch, speed run, and landing phases of flight.
P.C. I don't know what the physiological instrumentation indicated but as a matter of interest to me I was probably keyed up more in the last 40 seconds before launch than I was at. any other point during the flight. During the b-dot part of the flight I was just plain flat working.
P.C. We did not have the 25° trim on this airplane so it surprised me when I only achieved a = 13° at full trim, so I put in a little stick force to bring a up to 15° and this kicked the rudder. The angle of attack held steady.
B. Were any effects of speed brakes noted?
P.C. It didn't seem to make any difference that the speed brakes were open. When I closed them I didn't to notice any rapid decrease in vertical velocity and practically nothing from the acceleration standpoint .
C. Please describe airplane response to rudder pulse at 15°a.
P.C. Simulator: Light response with long period - well damped.
Airplane: The pulse did damp out.
P.C. Simulator: The period was shorter at the lower speed or a = 6°, about the same in difficulty and the lower speed is touchier if an error is made. Airplane: When I was up to 11° or 12° in angle of attack on two occasions I reduced the angle of attack; not because of the problem of flying the airplane, but because the control system in the back end of the airplane started vibrating. This time I was definitely impressed with the fact that it was the same kind of vibration that I had on the altitude flight. It was not the same amplitude out higher than any other vibration I have felt and it's characteristic was that of a vibration and distinct from the buffeting sensation that Rushworth was talking about. There was no question about it. This was vibration just as much as I am sure there wasn't any question in my mind that the other was buffeting. The frequency is about 13 cps. This vibration comes on when you pullup. The stabilizer deflections are large. I had this both at the higher and lower speeds, however, I didn't notice it at the highest combination of speed and angle of attack. It came on after I had slowed down some on the first b run that I ran into the vibration and then I also got it right away at the lower speed when I increased angle of attack. I did not notice the vibrations when performing the b technique. It was associated more with the up and down in angle of attack. I didn't seem to be able to get the same snap to the lateral control input as we were getting on the simulator, and maybe it is because I noticed the reduced control effectiveness a little more in flight. I just couldn't seem to make the sideslip needle come to a complete stop. I was, however, able to see it slow down.
P.C. I aimed one mile short of, the intended touchdown. point and initiated the flap deployment at 700 feet above the ground and again mostly attempt to retard the automatic flare feature of the flap deployment and establish a reduced closure rate as touchdown approaches.
One thing that impressed me about the side stick is that it is easy to lose your mental calibration of the stabilizer position. I got the impression that I just wasn't positive exactly where the stabilizer was, however, I knew whether I had nose down or nose up trim.
B. Where was flare initiation? V1? Hp?
P.C. It was at 300 knots and 700 feet or hp = 3000 ft.
C. Where was flare initiation relative to ventral jettison?
P.C. Flare initiation was later than ventral jettison but simultaneous with flap actuation.
D. What was touchdown speed?
P.C. I thought it was a little slower than the last flight.
E. Was the pattern tighter this time?
P.C. Yes. I was low due to avoiding the clouds and was running an analog computation in my head as to whether I would be better off to set up a right-hand base leg or go across the runway in a regular left-hand overhead. I finally decided to perform the left-hand pattern. The bank angle was a minimum of 45° and probably up to about 60° on the turn on to final approach as I was pulling 14° a at that point.
F. How far from planned point was touchdown?
P.C. 300 feet short.
G. Were aero controls used successfully for runout control?
P.C. No. They were not successful for runout control. Shortly after touchdown I brought up the flaps, back with the stick, and out with the speed brakes. The rudder and ailerons were applied without success.
H. Question pertaining to ground effect.
P.C. There is noticeable ground effect on this airplane as far as I am concerned. There seems to be a little bit more than for the F-104. Every time we get fairly close to and the ground and the best I can observe without making any control motion, I have to nose over a little in order to get closer to the ground to overcome the sensation of being too high. I attribute this to the fact that ground effect has made to presence felt. I have felt this in the last 3 flights and seen it while watching others land. It can be described as coming downhill at a reasonable rate and as far as a casual observation goes there is no pitching observable on the airplane and yet all you can do is that you stop going toward the earth and are under the impression you are about to land. In my own case, I nudge it over a little bit in order to make sure it gets down.
B. Would you recommend flight to higher velocity as the next step.
C. Other than kinesthetic cues, please note briefly airplane control characteristics which were not encountered on the simulator.
P.C. Possibly the pitch trim problem and the vibrations.
D. Any comment on ground control?
P.C. I thought we
had good ground control.