X-15 Flight: 3-9-18
August 14, 1962
Pilot: Joseph Walker
2. Climbout at q = 32° and pushover to zero g at 70 seconds.
3. Burnout at about 83 seconds and perform 30° right roll.
4. At peak, engage q Hold, open speed brakes and maintain q » 10° for entry.
5. At 1 g turn y damper to fixed gain, reaction control off, and perform y pulse.
6. Use CSS during high key turn.
I didn't put in any left stick input in prior to launch this time and it flopped out of there and drifted over to the right a little. I was unable to achieve satisfactory rotation to the desired angle of attack using side stick trim command, either because of improper amount of deflection or having decided that I needed more pitch rate than what it could drive out to.
On the climbout at q = 32° and pushover at zero g, I maintained q manually and also maintained manually the a for achieving 32°. I also had some joggles in q due to trying to locate zero trim command. I didn't get it the first try at it. I used that to pushover to zero g, over ran, under ran, over ran, under ran, etc. Finally I could have had about 1° down there, and forcibly moved the stick around so that it held on to about 2°. I never did get it down exactly zero. Other than that I can do a reasonably smooth job of flying this thing manually. It takes more attention and fussing with that trim knob than it's worth. It's no problem getting enough pitch rate to get up to angle of attack. It is easier to shove the handle and push down the last few degrees to zero. Incidentally, that was about the same a as we were coming out with yesterday on the simulator when I pushed over to zero.
It seemed like it might be a little easier flying q than it is angle of attack, but still the same troubles are there. It tends to drift around low or high if you're spending any length of time making changes to either hold it up to q or bring it down. You over run it slightly. Almost the identical control problems I experienced with SAS once I'm trimmed on vernier.
Now I have mentioned already that after getting squared up with power on and instituting the pullup I had to turn right to get back to 205°. I had to continually correct right to hang onto it and when I got by burnout, which as I have said before didn't seem to give any pulse particularly at cutoff, it must not have been too much associated with asymmetry after all, it was just the problem of holding heading.
It was real convenient to go into right roll because this helped hold the heading after burnout too. A11 the way over the top I had no particular difficulty in heading.
Walker: Yeh, it was like surprise, surprise. It jiggled and jittered a couple of times, but never an insistent tendency to turn and I had less trouble holding it. Maybe I didn't hold this close tolerance on the bank angle, as I have been doing on the simulator, but it seemed like it wasn't any trouble at all.
Then, on top, after engaging hold, I decided to go ahead and level off. It just seemed to come back to level, all but the last few degrees just by itself by just relaxing on the stick. I looked down there to see whether I had turned the wrong switch on.
Walker: I wasn't aware of it until I went to let it back out.
There weren't any conscious intentional lateral inputs except those required to stop the roll and as I mentioned I didn't seem to ever get a rhythmic enough cycle going on that I really had an awareness of practicing b-dot. It was probably hitting the right way a couple of times because everything just stopped going about like that until the control movement I made and then it would take off again, so I think that I had a kind of irregular motion. With the sideslip pegged over to the side it is not coming through the middle too often either, it's pretty hard to fly b-dot with b over there. I did try to hit it a couple of times and I kind of lucked out on it. It wasn't anything real coherent as a planned assault by b-dot technique except when I would come back up and I would try to do something about it, but you can't fly b-dot and hunt around to find out what the sam hill it is that you haven't fixed. This doesn't work too good either.
Well, I would say that the q hold was doing very well. I did roll the pitch trimmer in order to make up for a sag that occurred when I hit the switch and I probably locked on, as it was steady below zero q and you use this thing back up until I got back up to zero.
Walker: I engaged it when we hit zero q and I think we had started drifting back down from the peak. I'm pretty sure we had as a matter of fact, because then I looked at the altitude again and saw that it was coming downhill already.
P.C.: Yes.
2. Was there any FCS malfunction?
P.C.: Yes.
3. Compare flight with simulator for FCS operation.
P.C.: I guess it's reasonably close. This departure has to do with the sidestick trim command.
P.C.: I didn't deviate from the pre-launch checklist except what was forced on me.
2. Was analyzer operation distracting?
P.C.: There was some distraction there and it was temporary on test 8 on the analyzer check. The only distraction was recognizing that we had a temporary on test 8 and then charged on. The only other distraction was waiting for the thing to get done. Seemed like it never would get done. Of course, I was waiting for it to get done so I could catch up a little bit on the check list.
3. Did you observe the horizontal surface indicators during analyzer operation?
P.C.: You observe them.
4. What was surface positions at end of test? Did you retrim? What setting?
P.C.: 2° nose down at the end of the test and I retrimmed to zero.
5. Did surfaces drift after FCS engagement?
P.C.: I believe our surfaces did the same thing that they had before, they increased, drifted about 1/2 a degree while we were in the turn then it came back again after we got out, although it was a little difficult telling there. That was the most damped meter I have ever seen.
P.C.: I guess I have already beat the rap by saying that I didn't hold in control for launch, so we rolled off a little to the right slightly.
2. Did FCS remain engaged through launch and engine light off?
P.C.: FCS remained engaged and I can certify to this due to the fact that I took two looks at it after launch, one right after the clatter of the shackle and the throttle was going forward and the other one after I got steady on the pullup in good shape.
3. Did you use trim for rotation?
P.C.: Yes.
4. Was the pitch rate onset satisfactory?
P.C.: The basis for saying that I didn't like the pitch rate was because it wouldn't get up above 10° so I went to manual and pulled on up there.
5. Describe the behavior of angle of attack during rotation.
P.C.: Inadequate.
6. What was the maximum angle of attack?
P.C.: Maximum angle of attack was about 13°.
7. What was the maximum normal acceleration?
P.C.: I didn't get the maximum acceleration. However, I do know that the q was 500.
8. Did you change the pitch trim setting? How much?
P.C.: I changed the pitch trim setting by about an equal amount of deflection, with the second input on top of the first one.
9. Did you have to trim f after drop?
P.C.: No, I didn't have to trim roll. Maybe I should have?
10. Were there any objectionable limit cycles in the FCS during rotation?
P.C.: We didn't have objectionable limit cycles in the FCS during rotation, but later on in the flight we did.
11. Was auto trim operation noted?
P.C.: Yes, auto trim functioned nicely.
12. Rate piloting task for drop and rotation.
q 2 , f 1 , y 2 .
13. Within what tolerances was q held?
P.C.: Once we got the q I held it to ±1. Actually that was the worst, it was ±1/2 most of the time.
14. Did you note reaction control operation?
P.C.: I didn't notice any reaction control operation until long beyond this point. Over the top I didn't notice any reaction control activity, although there might have been some. I can't hear it on roll. We were near the peak when I commented that you could hear this thing chugging away.
15. Was pushover and zero "g" difficult to hold?
P.C.: They weren't difficult to hold except for once again locating the right place for the pitch rate. I finally got around to remembering to zero that thing when I was through with it up on top. It was about 3/4 of a degree nose down and I knew that because I looked at it several times trying to adjust for angle of attack as I was approaching level up there.
Funniest thing happened. When I went to go to q Hold it was coming by there at a fairly good clip so rather than lose time I snapped my head over there to see the switch and it was just like a gyroscopic effect. I just left everything behind when I was moving my head and when I came back out, it was back over there and I had to catch up with it. I thought that must be the old dizzy business that they talked about at zero g and so I moved my head over there again and sure enough it was just like I had got ahead of everything and then it swung in here and I came back this way and swung back and never got confused.
16. Did you use trim for pushover or zero "g?"
P.C.: I did try to use trim during pushover, but I overshot the zero "g" a little.
17. Was the trim operation satisfactory?
P.C.: In spite of the fact that we hiked the friction up to about twice as tight -- at least a 1/3 more than it was before - still it feels loose.
P.C.: Well now, burnout conditions were 138,000 altitude and 5,700 ft/sec velocity.
2. Were there any transients at burnout?
P.C.: I didn't have any transients at burnout.
3. Within what limits were you able to hold a, b, y and f?
P.C.: Well, I think I already would settle on about 2°a finally after wandering up and down there trying to establish the right pitch rate trying to hold a steady zero. The b stayed right in there. It didn't get a degree off, I believe, even in the course of 30° bank angle holding. That might have been a maximum excursion on b. Afterwards, when I got leveled out on the q Hold it seemed to wander by itself about 2° and there is the thing that they said wouldn't happen this flight but this quieted itself down and it damped out. I made sure to hang on to the 205° over the top.
4. Was control satisfactory for the 30° right bank?
P.C.: The control was satisfactory for the right bank and so I held easily what would have been a degree f on heading and bank angle must have been within 2° when I was intentionally holding 30°. There wasn't any trouble holding when you paid attention to the presentation.
5. What heading change did you observe during the roll maneuver?
P.C.: I thought possibly that this one b wandering was some ambiguity but it didn't seem to twitch in response to BCS. It just seemed to drift over there where the airplane was drifting and then came back and wandered a little bit left and then died down, so I didn't observe any heading changes during the roll maneuver.
6. Give pilot ratings for control task during manual control at zero angle of attack.
P C.: I'd give this control task during the roll q 1.5 , f 1.5 , y 1 .
7. Did a/b become unreliable?
P.C.: No.
8. Could you detect reaction control operation?
P.C.: Yes.
9. Did heading drift?
P.C.: No.
10. What were the indicated peak altitude and velocity?
P.C.: Velocity was 5400 and altitude 195,000.
11. At what conditions did you engage q hold? Within what limits did it hold? Were there any transients?
P.C.: q » 0° with f = 30°, it drifted
12. Was the a buildup oscillatory?
P.C.: Yes.
13. What was the maximum a?
P.C. a maximum » 23°.
14. Discuss the fixed gain y pulse and resulting lateral-directional oscillation.
P.C.: Before the roll damper went off q 1 , f 1 , y 1.5 .
After the f went off at
a < 10 q 1 , f 3 , y 2 .
a » 20 q , f 9 , y 9 .
a » 15 q , f 7 , y 7 .
15. Were the speed brakes open?
P.C.: Speed brakes were open.
16. Did you control bank angle?
P.C.: Bank angle, I guess you might say, that I controlled bank angle within ±90°. It really whopped over there too.
17. What was the maximum "g" for entry?
P.C.: Maximum "g" for the entry -- that must have been 3. I think I may have been up to three when I got that gain back on then and hauled it on around in the turn.
18. Did you get an H202 low light?
P.C.: Since I did in fact, forcibly put the reaction control back to work, I naturally had a peroxide low light and no problem. I think I was in the right turn. Either then or just before pulling out after having gotten the roll axis back on. I believe it was before really getting into the right-hand turn. I think it popped on right about the time I was sure it pretty well pulled out. After the operation of the other I wasn't the least bit surprised.
P.C.: I did use the CSS button.
2. Were there any transients? Could you detect any changes in stick forces?
P.C.: As I indicated before, no transients -- didn't notice any change in the stick force. I wasn't on CSS very long either.
3. Did you detect any limit cycle oscillations?
P.C.: Yes, limit cycle oscillations occurred in the roll channel immediately upon reset of roll damper. That was less than 1,000 q and came on again later on too as I dove off the altitude out there but I didn't notice any in the traffic pattern this time.
4. Could you detect gain cycling?
P.C.: In this question about gain cycling, I think I had some kind of that action while this was trying to pull the nose up to hold zero q at very low q there was some vibration in there. Two or three times, now unless it might have been just jarring as the chain of command back there changed the stabilizer hauling on up or something like that, but this was the only time I ever ran across it.
Walker: No, but this is the only time that I can remember noticing anything similar to limit cycle gain drop down.
P.C.: We did get a pitch channel kickoff at touchdown. (Fixed gain) I thought it was off, because when I turned the other two off by individual switches it seemed like the switch positions were more or less aligned. There you got me, but if you hadn't asked that question I would have positively said the switch was down and the light was on. Now, I don't know. Well, I do remember though that after turning the other switches they were all the same direction.
7. Give pilot rating for task during approach and landing.
P C.: Just too much attention to attitude to just indicated velocity. There wasn't any problem lateral or directional, and I still say -- give me an airplane with speed stability for landing -- it caused me to miss the mark. Actually the mark doesn't enter into it except for the fact that I could see that I had it made and I was settling and I tried to just mildly nudge the nose up in order to insure that I didn't start sinking faster and I just got too much pitch change, so I went to work and pushed the nose back down and pulled on back and got it on. So the landing task went up to about l-l/2.
P.C.: The FCS in operation and performance was pretty good up till the time that it had a mind of its own. Apparently, due to the fact that we got an unexplained trip out, roll was briefly unsatisfactory, but when the things were working according to Hoyle through the manual control part of it I would say that it was excellent.
2. What changes would you like to see made to the FCS?
P.C.: I realize if you want to be on fixed gain you couldn't stand a blinking light with the light on, but for the enunciator of failure to "off" I think a blinking light would be highly desirable and I'd like to see it right up there upon the panel where it's in plain view. I made the same remark to them about the generator failure lights too and it seems like this coming on and staying there is just not attention getting at all unless you happen to be looking with your eye aimed in that direction. I think it would make a major improvement in the pilot's well-being rather than having to continuously worry that he has overlooked something down there.
My confidence level has gone up after what happened to me up there and I feel better about it than I would otherwise. I really do. One, because it happened completely unannounced and I sat there for awhile battling with it without really knowing what the trouble was. It's not too bad a thing actually, if you were stuck with this thing off after quieting down and hauling up to it till it began to feel like it was getting away and then dropping off rather than staying down at a conveniently low a. You get less q pullout that way. After finding out what was the major cause of this thing I could have held onto 10° I'm sure, even if I had to go below it and get quiet and ease on up. If we get some warning up there so that a guy can tell right away what's going on it would help. I don't particularly like the idea of going all the way in one shot to zero on a channel, even though it did come back on. Maybe the next time it wouldn't stay on. If it was like he thinks, possibly in bottoming out of the stabilizer then why did it kick off?
Walker: I don't
think I knocked it off myself either. It was exactly the same thing you
know on the simulator when you were kicking the yaw clear off on me when
it started building up.
9-18-62