Pilot --- Major Robert M. White
B. Please describe any system failures, and resultant airplane control task at launch or after engine start.
P.C. There were no system failures.
C. Please describe longitudinal trim technique used to establish a = 10° climb. Do you feel this is optimum technique?
P.C. I've done just as in the past, and used the control force predominantly to get up to 10° a and then after establishing there start trimming in. On this particular flight, I averaged probably 8° rather than 10° in the climb. I was a little bit behind just .about all the way. The technique I've used in the past was still used and I suspect I will continue to go ahead and rotate to this stabilizer deflection and holding the force, and once established on the planned a, go ahead and trim out the force.
P.C. The longitudinal control task was the primary concern here as far as roll and yaw were concerned. The direction seemed to be good and the primary attention was devoted strictly to maintaining angle of attack and rotating and maintaining a certain climb angle.
B. Climb attitude was held at 30° ± 3° , with wings level ±3°? Were any heading corrections made during climb?
P.C. I think I made one heading correction during the climb. I talk about holding it within +3° but I was behind the 10°a we desired. I just about reached a 30° pitch angle at time to pushover so we got the 30°, bobbled around a little bit of an oscillation and then pushed over so the pitch attitude wasn't a stabilized condition for very long.
C. Did longitudinal acceleration effect airplane controllability during climb ?
P.C. No. Again, as we have experienced in the past, we start to feel this longitudinal g coming on. Your position in the cockpit is good. I think this is of prime importance, and it doesn't have any adverse effect, as far as I am concerned, as far as your ability to control the airplane.
D. Please comment on the following items pertinent to the side stick control characteristics:
P.C. I thought it was quite good in pitch and roll. There just seemed to be no problems at all. I was getting the return of the rate that I desired and it reacted beautifully. The damping was excellent. It was not sensitive anywhere.
2. Stick centering in roll.
P.C. I didn't have any adverse feeling about the centering being less than I would desire. As a matter of fact, it changed fairly well and some of this might be modified by the fact that the glove is inflated, as the pressure, it was coming on at that time. Still it didn't have any bad effect on me. I would rather see it about where it is than increasing it a great deal. Particularly if we lost damping, and had to run back to seek this breakout force, it might add to the problem.
3. Inadvertent stick motion when changing trim.
P.C. You do get a little bit of this because you're trimming out force and backing off holding this force and trying to be compatible with the leading force. As you come in with trim, a little inadvertent motion on the stick does result, but this is small, and, as a matter of fact, is quite similar to the simulator. Of course, we don't have any just sitting in the 1.0 g state except, for instance, when you change your angle of attack to hold a certain q. You will have a little bit of bobbling, but you damp it out very quickly, so it is about the same and it is not particularly disturbing.
4. Compare lateral control holding pitch force, with lateral control, force trimmed out.
P.C. During the climb, this isn't too bad. You are a lot better off in developing some excellence with lateral control when you do have the longitudinal force trimmed out. Particularly so later on (high a) when we have to use a large longitudinal control deflection. There, if you are holding a large force because you have a large deflection the lateral control is complicated a little bit I think. Concerning the climb, the lateral control isn't too difficult where the force you are holding isn't too large and you tend to start trimming some of this force out. But it is preferable I think, and you can exercise more excellence in lateral control when you do have this longitudinal force trimmed out.
5. Was side stick comfortable in this trim range (4° < a < 10°)?
P.C. As a result
of this particular flight I have decided to have the stick from my cockpit
configuration moved forward just a bit. I think the contributing factor
here is the 28-foot pack (parachute) I used. This gets me a little bit
further forward in the cockpit. I personally don't find this objectionable.
At least not to the point that I don't want to use it. I still prefer to
use the 28-foot pack, but for an optimum configuration for myself I would
want the side stick just a little bit forward.
P.C. On this item, the rating in pitch, roll, and yaw I will give it all a number 2 . I consider it quite good. I think the amount of attention or effort that you are putting into this is complete, but compared to other tasks you might come up with in the flight, it wasn't difficult at all, so I would rate the task that I had during this portion of the flight as rather easy.
P.C. Considering the pushover phase, I'd give it a 2 all the way, in pitch, roll, and yaw. During the speed run after we were established at zero g, I'd give it a number 1 for pitch, roll, and yaw also, because at zero g the airplane is just wonderful. There is no particular problem. You get it pushed over to zero g and trimmed out near zero g and you can just sit there with your hands in your lap, and it will continue on.
B. Pilot's attention was directed principally toward ·V control mode during speed run? Please comment on airplane controllability to Vmax?
P.C. I'd say the change of velocity or time rather than this control task because while we were at zero g control tasks weren't required, and the airplane controllability, of course, was just excellent. It didn't do a thing that disturbed me.
C. Was sufficient time available to anticipate engine shut down point:
P.C. Very definitely
yes, particularly on this flight. We had gone up to 75 seconds in time,
and I was able to divert a lot more attention on this flight than I had
in the past, to my change in inertial velocity, height, and rate-of-climb
indications. So compared with the changing time as I observed on the clock,
I was going ahead and making checks of the inertial velocity to give myself
checks as to what the inertial velocity should be at various times
P.C. Here there was a combination of the time as it registered on the clock in the cockpit and in addition to that I used the inertial velocity indication, and I think in this case, this one flight, I regarded the ground callouts as purely a backup.
2. Were any distracting factors present?
P.C. Yes, loss of
cockpit pressure and then inflation of the suit.
E. Did engine shutdown introduce any airplane motion transients?
P.C. I would say no to that. On this particular shutdown, didn't do as I had done in the past where I'd snap the throttle back and shut it off. I just did a nice gradual retard from 100% to 50%, banged it outboard and then shutdown. You might say that my shutdown was at 50% thrust rather than from 100% to zero. I suppose the decay in thrust is quite different than it might have been in previous cases and nothing happened in airplane motion that disturbed me at all. In fact, I can't even recall any little bobble in pitch, yaw, or roll.
E. Did deceleration introduce any inadvertent control motion?
P.C. They may have. I don't recall anything unusual. There may have just a little bit because the deceleration was very evident. I was up against the restraining harness in the shoulders as I started slowing down right after shutdown. This might have effected it a little bit, but again, the thing that modifies a lot of this is that the damping is so good at these gain settings that even if there were some small motion introduced it would be damped out so rapidly that it wouldn't bother me at all.
F. Please describe any system failures, and resultant airplane control task at engine shut down.
P.C. Of course, the main one was cabin pressure failure but the control task at engine shutdown was not seriously affected by this. I am talking about the control task right at shutdown and I don't think the inflated suit really added anything. No failures occurred because of shutting off the engine.
G. Other than the instruments, are any new cues developing to indicate the airplane is traveling at great speed?
P.C. I haven't been impressed that there are any.
H. Rate pilot task to steady airplane before performing rudder pulses at a = O°.
P.C. The rating
here I'd say is a 1 right across the board in pitch, roll, and yaw.
The airplane is trimmed out and we are at zero g, and once we shut the
engine down the only control input I make essentially is to go ahead and
boot the rudder. The airplane is trimmed and flying beautifully and there
are no control tasks required to set it up. It actually had been set up
when we got trimmed at zero g and then with no motions, because of engine
shutdown, all that is required is to go ahead and do the rudder pulse.
I consider it excellent.
P.C. I was impressed
it was completely damped in not more than a cycle. In fact, you almost
don't believe it and you go ahead and give it another kick. I think the
second kick might have been a little healthier and stronger than the first
one to make sure you do displace the airplane and get some response out
of it. It is very good there.
P.C. Considering that for this portion of the flight the pilot task was not very much different, I consider it fairly similar to the last flight. This has been comparatively the easiest portion of the flight, assuming you do have some damper operation helping you out, so just for this portion of the flight I wasn't impressed. It really wasn't any different.
In the pullup to elevated angle of attack, the airplane was trimmed at about 13° and was maintained within 1° using maximum trim. Force would be required to maintain the 15° a trim angle that we are looking for, and I think the big modification here was the fact the pressure suit was inflated. I was willing to accept the maximum trim angle of attack rather than trying to hold force, but there is one thing that modifies this. Ordinarily you would go ahead and increase force, even with the suit inflated. However, when you have your arm in close to your side, and you are using the side stick and the suit is inflated, what happens in the underarm is that pressure is exerted against the arm and against one of the arteries in the arm, and it is cutting off blood circulation. I feel this is the source of the tingling sensation in the arm that I talked about and it is further aggravated if you are holding force.
2. Was pullup steady X , or oscillatory (slight)
P.C. I would say
it was fairly steady. May have just a little bit of oscillation on it,
but I think that it was fairly steady. You don't seem to get this overshoot
that you tend to get when you run into the nonlinear stabilizer effectiveness
area until you get to about 15° or 16°.
C. Describe and rate control task required to steady airplane before performing first rudder kick and sideslip?
P.C. I think a series of rudder kicks here is no problem. We got the airplane trimmed to about 12° or 13° or whatever it gave us when we finally got trimmed back on the stabilizer. You could practically fly the airplane hands off and boot the rudder and let it go, and then your only action would be to right the roll that developed. I think in the most severe cases, I let the bank angle change as much as 30° to 35° and then righted the airplane. The sideslip, I consider that kind of a weak one (in magnitude), but again there was no particular problem in steadying the sideslip and then just letting go of the controls.
The damping was
very rapid. Prior to performing the rudder kick and the sideslip the airplane
was steady as a rock. I had no tendency to want to hang onto the controls
after the control pulse. I was readily willing to let it go.
2. Rating No. in
pitch 1 , roll 1 , yaw 1 (sideslip).
2. Yaw steady , or oscillatory X ?
3. Please comment on aileron-rudder control response.
P.C. Very slight
oscillation in yaw and the aileron-rudder control response was pretty good.
As I mentioned in the debriefing, the roll sensitivity was a little problem.
I think it is probably partly the negative dihedral effect too, or the
fact you have to concentrate on holding correct bank angle in the direction
opposite the direction you normally do when using a certain rudder deflection
2. Stick centering in roll. Refer back to corresponding question in Section II.D.
3. Inadvertent stick motion when changing trim. Refer back to corresponding question in Section II.D.
4. Compare lateral control holding pitch force, with lateral control, force trimmed out. Refer back to corresponding question in Section II.D.
5. Was side stick comfortable in this trim range? Please suggest any modifications which would increase utility of side stick.
P.C. With the suit inflated during the latter portion of the flight I went ahead and changed over to the center stick. I did reach down and switch the trim so I would have trim authority on the center stick. I found it a lot less desirable with the suit inflated flying the airplane on the center stick. I just didn't seem to like it. I went back to the side stick and this required a concerted effort to do, to get this inflated arm back down in position, but I just preferred to do it, until we got down to a lower level where I would transition to the center stick for landing. This surprised me and I thought it was rather significant that I would go in this direction when I think some of the tendencies have been in the opposite direction, but I felt I could maintain more precise control. In fact, in the first positioning turn, when I turned to the west to get rid of some of the energy so I could get back into the landing circuit, I felt I could control the airplane more precisely staying over there on the side stick than wiping out the cockpit with this center stick. It just didn't seem that I wanted to do this.
The comfort starts
being compromised at the higher trim settings because the stick pivots
back and you start to run out of, well if you had a fully articulating
wrist, I suppose it would help. This becomes a comfort item after a while
when you have your hand cocked back in this position. You reach a limit
to the point where you can rotate around a wrist pivot point, and finally
get to a place where you have to raise your arm up in order to pull back
on the stick.
P.C. I think the primary reliance during most of the flight at high angle of attack is on the instruments. There is only one stimulus I feel you do pick up externally and that is roll. I think, on flying the instruments, I will accept some small bank angle error and probably correct this last, but if the bank angle becomes large, I think the cue from outside the airplane is just as good or stimulating to you as the attitude indication on the three-axis ball.
G. Recalling last flight, please compare pilot task with SAS 4-4-6, to pilot task experienced on this portion of the flight with SAS 8-6-8.
P.C. I feel a very marked difference in the lateral-directional handling qualities of the airplane. As I said before, the damping here was so high I just wasn't particularly concerned about the airplane flying along in this angle of attack region. You could pulse the controls and let go of the thing, where with 4-4-6 my concern was keeping the airplane steady. It was a continual pilot task to keep the airplane straight, and as a matter of fact, with 4-4-6 I never was really able to set the thing up, make it steady, and then pulse the airplane and see what kind of motions we would get.
H. Based on this flight and simulator experience, please comment on adequacy of SAS 8-6-8 for performance of reentry from an altitude mission.
P.C. I thought that 8-6-8 indicated to me that it would be a superior SAS setting particularly for the reentry portion of the mission, and I liked it quite well. I feel a 200,000 foot entry with this SAS setting would be a real easy thing to do.
P.C. No, even if you are tired or hot, you become stimulated again when you finally get down to the landing phase.
B. How far from planned touchdown point was touchdown?
P.C. I consider that I was just about right on the spot. As I have done in the last couple of flights, and particularly here again, my primary concern was to try to get as close to the spot as possible. I am interested in how the records look because as we approached the point, I specifically looked for the landing spot, and hoped to arrive and touchdown on the point. I was holding the airplane off as we were slowing down, and I got down to what I considered an acceptable distance from the ground, and just as the point was coming up I relaxed on the stick. I would guess that this might show up as a change in angle of attack. I would suspect maybe a reduction in angle of attack. The sink rate, I was impressed that it was a little bit higher than it had been before.
C. Were aero controls used for runout control?
P.C. Yes they were. I started going off to the left of the runway and went ahead and used aft longitudinal control and right lateral control at about halfway through the runout and it seemed that it helped to straighten the airplane out and I got back paralleling my original path.
P.C. Cabin pressure.
B. Other than motion stimulus, please note briefly airplane control characteristics which were not encountered on simulator.
P.C. I wasn't impressed with anything that was radically different than what we had experienced on the simulator as far as control itself was concerned. The comparison with the simulator for the mission I think was rather good. I feel on this flight, just as I have in practically all I've done that the simulator is perhaps the most valuable tool the pilot can use in preparing for the flight .
One feature -- the
inflated suit during the flight -- the helmet is wedged up in the canopy
so this restricts your ability to move your head from side to side. It
doesn't have any serious effects, or it doesn't give you any concern during
the normal portion of the flight where you are traveling straight ahead,
but in the positioning to get into the landing circuit, it does seem to
make quite a bit of difference because you couldn't see some of the points
we were passing when we tried to look off to the side. It wasn't till you
get below 35,000 feet (suit deflates) that you began to have any mobility
again as far as turning your head around is concerned .
P.C. The X-15 compares favorably with the F-104 and in some ways is a lot better, particularly on the last flight with the high damper gains that we had.
D. In your opinion, would an airplane with the X-15, SAS on, flight characteristics be usable in AF operational service?
E. How effective was ground control in accomplishment of flight mission?
P.C. Ground control
was adequate on this flight mission.