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Utility of the Lunar Landing Training Vehicle

Commentary Copyright © 1995 by Eric M. Jones.
All rights reserved.
Last revised 28 June 2011

 

Apollo 11 Commentary

Following 102:27:14:
Neil spent 285 hours - 30 percent of his training for Apollo 11 - in various LM simulators other than the LLTV Buzz spent 332 hours in various LM simulators. They also spent 56 hours in briefings about LM systems.

Armstrong - "I would add, along that same line, that the time requirements necessitated that we accept the conclusions and recommendations of the crews that went before us. So, we did not spend an extraordinary amount of time on things that had already been done and had worked as expected. We focused a great deal of our attention on those things which had not been done before and which we would be expected to pass on to the crews behind us."

Following 102:46:23:
Armstrong - "I would say that the Lunar Module flew better than the LLTV - fortunately. However, it was a reasonable simulation of the Lunar Module, and it was the best we had. The full-mission (but stationary) Lunar Module simulator worked very well, but the real in-flight situation provided by the LLTVs provided a reality that was hard to duplicate in a fixed-base simulator."

Link to 1988 discussion of the LLRF, 'Wingless on Luna', that Armstrong gave at the Wings Club in 1988.

Armstrong - "What the LLTV gave you was not so much the seat-of-the-pants dynamics as the real-world visual. (Chuckling) That and the fact that, if you make a mistake, you can't hit the reset button."

From the Apollo 11 Technical Crew Debriefing, Section 24.22 Lunar Landing - LLTV, LLRF, LLTV's, and LMS
Armstrong - "For the type of trajectory that was required for us to fly (with a long manual flight at the end), the LLTV was a most valuable training experience. Like all simulations, it's primarily a confidence builder to derive the required information from the information that's at hand. In the flight situation, the information that I used in the landing was primarily visual. It was augmented by information inside the cockpit that Buzz relayed to me. I did very little gauge monitoring during the final descent, that is, below 300 feet. It is primarily an out-the-window job, picking a suitable landing spot and getting into it. The full-scale simulations are the only ones that do this – the LLTV and the LLRF. I would have to recommend continuing them both, at least until we have a few more landings under our belt. I would suggest that more attention be given in the LLTV to changing your landing spot while you're in the trajectory."

Aldrin - "And how to deviate from an automatic trajectory and smoothly pick up what you want to do in the way of deviations."

Armstrong - "I believe the LLTV can do that job and do it safely. That means that you probably have to do a few more total trajectories than we did in preparation for this flight. I suggest that a dozen is a desirable number – a dozen lunar trajectories in the LLTV. It takes about half a dozen before you're comfortably flying on a lunar trajectory, and after that, a couple of different deviations to different touchdown areas. The LLRF lighting simulation was quite interesting, but in retrospect, it's not a very good simulation of the lunar lighting situation. In the flight, you see much more daylight, at least at our Sun angle (10-degree Sun angle). It was much more of a daylight landing situation than the (LLRF) simulation that was portrayed by the night lighting simulation at Langley Research Center."

Aldrin - "They essentially set up a situation where there was no available horizon. That certainly was available in the actual case."

Armstrong - "The LMS new model is really a fine addition to the simulator. If you could afford building a model for Apollo 12, so that their last 2 months of simulation would be going into the Surveyor site, then I think you would get a substantial improvement in your confidence level to get to the desired touchdown site."

Aldrin - "I think this is particularly true if they stick to the objective of going to that specific area. We have enough available information from the Surveyor itself to build that model. Armstrong - "I know that's an expensive item to provide, but our experience with looking at the L&A of Site 3 indicates that you really can get a good understanding of that local area in your many landing simulations in the LMS."

Aldrin- "In looking back on the choices that I made with regard to my participation in landing simulations, I think they were generally correct. I don't think that I suffered by not being exposed any more to the LLTV. I think one session at Langley was worth the effort. I concentrated on manual use of the throttle and I think that's probably what future LMP's should concentrate on, also. I think Neil agrees that if we did have to execute a complete manual landing, it would probably best be done by the Commander concentrating on attitude control and voicing to the LMP what rate of descent and what changes he wanted. It appeared to be a very difficult task for one person to accomplish all of these. Whereas, when the tasks were split, and use was made of the instruments to manually control the throttle, and a fair amount of practice was made, use of that good performance could be anticipated by a manual throttle landing. For the most part, this can be done in the LMS."

Apollo 12 Commentary

Following 110:33:56:
Conrad - "I think everybody agreed that the LLTV was very essential to a successful landing. One of the problems which we were talking about earlier at lunch is that you have to realize that the visual on the simulator was very bad. We had a plaster-of-paris lunar surface (called the L&A) and a B&W television camera that ('flew' to it). So you're looking at a flat, no-depth boob tube - a television - in the window. So, the last five hundred feet, if you were watching that out the window in the simulator, it wasn't any good. It just didn't really resemble the real world."

Bean - "It was a virtual image something or other. Which was a flat TV with some optics that..."

Conrad - "Tried to give it depth..."

Bean - "But it didn't."

Conrad - "It was the best they had at the time. We didn't have a moving-base simulator, either. (In more recent times, Shuttle crews have been able to train in simulators that move in response to crew inputs and, thereby, give much more realistic simulations.) So, the LLTV was critical, to get a real feel. And the reason Al made the comment about maneuvering is that the LMP's didn't fly the LLTV."

NASA built two LLRVs and three LLTVs. Three of these five vehicles were lost in accidents. Because of the jet engine, the LLTV was actually a less stable vehicle than the LM and, therefore, was harder to fly. For this and other reasons, it was decided that only people who absolutely needed the experience - mission commanders and their backups - would fly the LLTV. None of the LMPs ever flew one.

Conrad - "By the time I flew, Neil had jumped out of one LLTV (May 6, 1968) and at least one of our Ops pilots bailed out. (Actually two non-astronaut test pilots, Joe S. Algranti and Stuart M. Present, bailed out, on December 8, 1968 and January 29, 1971, respectively). (NASA Administrator) Dr. Gilruth, bless his soul, just worried to death that somebody was going to get bagged in an LLTV. And so, he asked everybody when they came back (from the Moon) 'Do you think it's necessary to fly the LLTV?' And, the feeling that I think Neil had and myself - and I'm quite sure the rest of the guys - was 'Yes, you really should go ahead and fly the LLTV.' But, having had the three accidents and having that one vehicle left, Dr. Gilruth asked the guys to figure out how many flights we got on a vehicle before we crumped one. And it turned out to be like 260 flights or something like that. To finish the training after the third accident, they had to fly 240 more flights; and, so, when Gene (Cernan, the Apollo 17 Commander) flew the last flight in his training, the thing went to the Smithsonian or whatever because nobody was ever going to fly that thing again as far as Gilruth was concerned. And he almost didn't authorize the training, see. And so, at least the early guys pushed very hard for everybody to continue flying it."

Bean - "I remember you talking about it when they asked you. And really pushing hard for it."

Conrad - "Al hadn't flown one, and that's why he made the remark when I started really maneuvering the thing around. Because you had big attitude changes up there, because you're in a low gravity field. He had seen that kind of a maneuver, probably, inside the simulator. But that virtual image display and the fixed base didn't really give you any feel for it. So, the first time Al really experienced that was at the Moon. And I just passed it off 'Yeah, I'm busy doing what I was doing.'!"

Bean - "We were all flying helicopters and you didn't maneuver a helicopter any where near like that. Up there, you really had to move the LM to maneuver it. So Pete got used to it and I was thinking helicopter kind of stuff. So, when you (Pete) suddenly maneuvered much more than a helicopter, it caught me by surprise. But to you, well, that's the way you do it. I think it's because, on Earth, you're supporting the weight with a certain amount of thrust. So, let's say you've got to knock off ten foot per second forward. You pitch up to a certain angle to do that and you get used to that kind of maneuver. You go on to the Moon; you've got one sixth the thrust to hold this same mass up and ten feet per second forward with that mass is the same as it was on Earth. But, in order to stop it (from moving forward) with one-sixth the thrust, you're going to have to pitch up a lot harder. So I think it's just strictly the fact that you're operating with less thrust than a helicopter for the same weight and the same momentum. So, in order to use it, you've got to get that thrust vector up higher faster or you're just never going to slow down the translations, or get one going and then stop it. When you think about it, it makes sense. But, at the time, it just seemed like 'God, what's he doing?' It felt to me like you were pitched too far (back), you know. And you probably were doing quite a bit because you've got to get it (pitched) up there to get the little ol' thrust vector to work."

Conrad - "That's right, you have to move it more to get the maneuver. So it looks really bad to you, although nothing serious is happening."

Bean - "It looked normal to you!"

[Conrad, from the 1969 Technical Debrief - "I think the manual control of the LM was excellent. The LLTV is an excellent training vehicle for the final phases. I think it's almost essential. I feel it really gave me the confidence that I needed. I think the (immobile) simulator did an excellent job in manual control and LPD training all the way down to the last couple of hundred feet. I think both devices worked very well together."

Apollo 14 Commentary

Following 108:15:18:
Shepard, from the 1971 Technical Debrief - "The control of the vehicle, I thought, was good. Here again, of course, I did practice with the LLTV (Lunar Landing Training Vehicle), as well as the LLRV (Lunar Landing Research Vehicle), and in the LMS (Lunar Module Simulator). I felt completely comfortable and completely in control of the vehicle all the time."

Apollo 15 Commentary

Following 104:42:48
Jones - "When Jim said 'You've got P66', is it fair to assume that you were looking out the window?"

Scott - "As I recall, I went out the window as soon as we got down there (that is, at pitchover). Everything inside is for Jim. For me to come in and go back out, really takes too much time. You know, I might comment on this part of it. Another objective we had, based on the previous flights, was to stay on a constant flight path - a constant rate of descent - and get it down. The previous flights, as I recall, had all leveled out high and then had come back down. And we looked at their trajectories, and it seemed to be a trend, that the guys would start stopping too soon and use up a lot of propellant, doing a stairstep thing. So one of the things that we trained on and thought about, was to keep it going and keep it coming down a constant flight path so that we could save gas for the hover, if we needed it. The stairstep appeared to be a trend that people got into because there's no definition on the ground. There's no runway. With the LLTV (Lunar Landing Training Vehicle), you have the runway and it's very easy to determine how high you are when you know how wide the runway is and how long it is. When you get to the Moon, there's no runway. There's nothing there to tell you how high you are; and I think the trend had been for people to start slowing up their rate of descent too soon - because, of course, you don't want to get too close, too fast, 'cause then you can't stop."

Jones - "When Jim said 'You've got P66', is it fair to assume that you were looking out the window?"

Scott - "As I recall, I went out the window as soon as we got down there (that is, at pitchover). Everything inside is for Jim. For me to come in and go back out, really takes too much time. You know, I might comment on this part of it. Another objective we had, based on the previous flights, was to stay on a constant flight path - a constant rate of descent - and get it down. The previous flights, as I recall, had all leveled out high and then had come back down. And we looked at their trajectories, and it seemed to be a trend, that the guys would start stopping too soon and use up a lot of propellant, doing a stairstep thing. So one of the things that we trained on and thought about, was to keep it going and keep it coming down a constant flight path so that we could save gas for the hover, if we needed it. The stairstep appeared to be a trend that people got into because there's no definition on the ground. There's no runway. With the LLTV (Lunar Landing Training Vehicle), you have the runway and it's very easy to determine how high you are when you know how wide the runway is and how long it is. When you get to the Moon, there's no runway. There's nothing there to tell you how high you are; and I think the trend had been for people to start slowing up their rate of descent too soon - because, of course, you don't want to get too close, too fast, 'cause then you can't stop."

Scott, from the 1971 Technical Debrief - "The LPD (Landing Point Designator) was real good. I felt we were heading toward the point for which the numbers were being read. Manual control on the vehicle was excellent. I think it was more positive than the LLTV. I'll make one general comment. I felt very comfortable flying the vehicle manually, because of the LLTV training, and there was no question in my mind that I could put it down where I wanted to. We landed exactly where I was headed. In spite of the fact that the rear pad was in a crater, that's just where I wanted to land. I think our horizontal velocities were zero lateral and I had about 1 foot per second forward to keep from backing into anything. That's exactly what I wanted. There was no tendency to overshoot in attitude or overshoot in the selection of the landing site. I think all of this was because of the time that I had to work with the LLTV."

In a 1995 letter, Dave commented that he may not have been aware of the crater in which he put the rear pad because "it was shallow and probably had no shadow".

Scott, from the 1971 Technical Debrief - "I guess I can't say enough about that (LLTV) training. That puts you in a situation in which you appreciate propellant margins and controllability (because the vehicle could fail and crash). I think the LLTV is an excellent simulation of the vehicle. I think if you had to move from one point to another, you could do it quite well. I would recommend an altitude of at least 150 feet so you don't get into the dust problem. I think dust is going to be variable with landing sites."

Jones - "It seems to me that Jim's giving you a lot more LPD angles than I remember other LMP's giving the Commanders. And he doesn't give you a first H-dot (descent rate) until 500 feet, which is just before you go into P66. You two had obviously worked this final part many, many times."

Scott - "Oh, yes. And I wanted as much from Jim as I could get. I mean, I was outside the window. Everything from inside the cockpit was from Jim. So I had a lot of sources of information. We did that on the launch, too. We had everybody with a role talking to me. And sometimes simultaneously with the ground. And I remember having learned this from Jim McDivitt. Because he did this back on Apollo 9. To sort out the voices and take the one you wanted, and to get as much data as you could possibly have without an overload. You can block out what you don't want to hear. So when Jim and I worked on this, I remember we worked on him giving as much as he could, because I wasn't going to do any talking. I was going to do the flying. I was going to do outside the window, and he was going to tell me what was going on inside. We were comfortable doing it that way."

Jones - "You had rate meters and the like around the window, but you were entirely out the window."

Scott - "Entirely out the window. Because, from the LLTV training, keep it steady and you'll land it. I knew I could land the machine if it would stay upright and the engine kept burning. And all the other things I had was icing on the cake. So if Jim could feed me all this information, that was even better."

Jones - "So, basically, down to 400 or 500 feet, the computer's controlling the descent rate and you're basically just telling it where you want to put it down. And, below 500 feet, you take over and control the descent rate."

Scott - "Which probably gets you into the discussion of why people didn't use an automatic landing, like Jim Lovell would have. Lovell would have, he said, let the automatic system go. I don't know if you've had any other discussions on this point, but there were a lot. Because the automatic system would probably have done very well."

Scott - "I worked the rationale out with Jim (Irwin). The guy on the right's got to have some input 'cause, if the guy on the left screws up, it's bad news for the guy on the right. You know, if you're riding in the back of an airplane or in the right seat of an airplane, it's a lot more uncomfortable than if you have hold of the stick. And there are a lot of stories about that that are kind of interesting. But we sort of worked it as a team, because I could get all that data. My feeling was, if I'm in the loop mentally I can respond more quickly than if I have to watch an automatic system and take over and then get my mind in the loop. So I was more comfortable in flying a manual descent than an automatic descent. Not that I thought that the automatic descent wouldn't work. It would probably work. But, if something goes wrong, I'm in the loop already. And my mental computer is already running at full speed so, if there's a hiccup somewhere, I'm already on top of it. Whereas, if you have an automatic hiccup, you got to decide what it is you do to get into the system. That's why, in my opinion, I would always make the lunar landing manually. Mainly, because it's a challenge; but also because you (the pilot) are already on top of it and you're reaction to a failure or a problem is going to be much quicker. We were asked, 'Why don't you land automatically? Don't you think the system will work?' Of course, I think the system would work. But on the other hand, I think we - as a group flying the machine, the PGNS, AGS, Irwin, and me, we're all flying that thing - I think we as a collective entity are safer and more efficient if there's a focal point. And I was the focal point. Jim fed things into my ears. The Moon fed things into my eyes, and I could feel the machine operating. I had never heard a comparison with other flights, because we all left when we got through, right? I was very comfortable with Jim giving me as much as he could give me."

Journal Contributor Mike Poliszuk notes "Scott talks extensively about the time he spent looking inside vs. outside the cockpit. Had the technology been available at the time, a heads-up display (HUD) - window projected or projected onto a helmet-mounted display - would have been useful. At the minimum the LPD could have been displayed directly for the Commander, so the LMP would not have had to read the numbers aloud. Other data, such as h, h-dot, lateral rates could also have been projected; and with proper software, this data could have been portrayed in some graphical format that integrated all needed data into a form easily interpreted by the Commander."

Jones - "One of the things that Jack and Gene talked to me about was working hard on the AGS, not only as an abort system, but as...I don't want to misquote them, but to have confidence that they could have landed with it if they had to. They say that mission rules were, if the PGNS went out, you abort back to orbit. But they said they slogged the AGS pretty hard - with the updates and the like - that they felt fairly confident that they would have had good enough information out of it to land."

Scott - "I'll give you two comments. I was around when McDivitt and Schweickart spent a good portion of their lives on the AGS on Apollo 9. And it was not as capable as the PGNS. It was exactly what it was supposed to be - an abort guidance system. It was not as capable as the primary guidance system. But, from a technical, physical point of view, it would probably give you, in retrospect, enough information to make a manual landing from on the order of 400 or 500 feet. Just like an LLTV landing. If you can land the LLTV, then you could probably land on the AGS, because it would keep the system running. But, on the other hand, on a lunar mission, A, management would not let you do that. If I were a manager, I would not let you do that, because it's just not built to do that. And, B, when Jim and I were in our mission, we didn't ever consider that; we didn't spend any time on it. We were involved in other things and...Not that it wasn't a good idea because, when Gene and Jack got to their turn, things were much more mature, and they could spend time looking at that. And it's a good idea they did. And I believe they're right. The AGS probably could get you down. Nobody'd ever let you do it, though."

Jones - "You guys had been through your landing, John and Charlie had been through theirs..."

Scott - "And, as long as something will keep that vehicle stable...The LLTV landings were manual landings, and the LLTV was a great trainer. I mean, boy, am I glad we had that, because it gave me confidence that I knew what I was doing on the Moon, and I didn't have to think about things. I didn't have to consciously program myself to do things. I was automatic. So, my feeling was, if you can land the LLTV, you can land a LM. And if the AGS will just keep the sucker straight, you can get it down, manually. But you're not going to do that, mainly because, if you lose the PGNS, you're not going to land. That's the way it is. So you go into it that way. One of the things we did do was to cut the rendezvous in half, Jim and I. And they used it on 14, because our experience on Apollo 12 enabled us, when we got to 15, we were already up on the curve."

"When you're in the (LMS) simulator - and I'm sure Gene and Jack did the same thing - after a while you need some variety. I mean, there are all the normal emergencies and you can do all that stuff. So let's see what else we can do. Jim and I worked on cutting the rendezvous by one rev and helped them develop a quick rendezvous. And we got that done early on in 15, so they used it on 14. But I'm sure Gene and Jack, when they got in there, went through all their stuff. They were up on the curve, so 'Let's see if we can land on the AGS.' Great idea. Sure, you probably can. But we didn't do that."

Jones - "The LLTV. It was a solo vehicle. You didn't have an LMP standing there next to you feeding you information of any kind. What kind of instruments did you have?"

Scott - "Essentially the same as on the LM. Same kind of descent rate and altitude."

Jones - "Instruments surrounding a window?"

Scott - "Let me see. Yes, it was as high a fidelity as you can build on the Earth. You know, we started out with four LLTVs and ended up with one (because three were lost in crashes). And, every time one crashed, the hue and cry from management was, 'Get rid of those damn things, what good are they?' But we (astronauts), as a group supported the idea a hundred percent because, again, you've got to do things as real as possible before you get into the lunar situation."

Scott - "I remember when Pete came back and I had a couple of conversations where I asked him, 'What do you think about the LLTV?' And he said 'Boy, that's the thing to have.' So, when my turn came, I was absolutely insistent. 'You've got to fly this thing.' I could probably have gone to the Moon and landed without doing it, but I certainly wouldn't have had the comfort or the confidence."]

Jones - "Was the LLTV more or less stable than the LM itself?"

Scott - "Well, in what way? You couldn't abort. You run out of gas and you crash. And it also put you on the line. And it also enabled you to stretch yourself. In other words, when I flew the LLTV, I never landed it where I was supposed to land. When I got down to where I was comfortable I could go where I was supposed to go, I pushed myself on to a secondary landing point, so could learn how to do that. I never had to use it, but it was a great opportunity to push things out to the edge under a controlled situation, with supervision, with people watching you, on a normal day where you didn't have all these other things going on. So you could push yourself out there without taking a big risk. And that's why I thought it was a marvelous machine. Hell of a challenge. A tough thing to fly. Landing on the Moon: I don't care what anybody says, that's damn hard. I mean, that takes real aviation. That's flying! And I think all the things we got prepared us to do that. And I was very comfortable."

Jones - "If you look at the list of Commanders, six of the seven (Jim Lovell included) assigned to make landings had Navy training. Everyone but Dave Scott."

Scott - "You're one of the first people I've ever heard observe that."

Jones - "And they had carrier experience. And Gene told me that he thought landing on the Moon was easier than a night carrier landing"

Scott - "And I think he's probably right. But go ahead."

Jones - "Had you ever done anything like that and is the fact that there were six Navy-trained guys due to the luck of the draw or did the carrier experience have anything to do with it?"

Scott - "Luck of the draw. Absolute luck of the draw. On the other hand, I think that they benefited from their carrier experience, because I do think it's hard. I've never done it but, golly, I know those guys real well and Dick Gordon (who was a Navy flyer) and I rotated backup and prime, backup and prime and we live across the street from each other and I flew with Dick a lot. Dick and I have lots and lots of yarns, together, let me tell you. And I know that the carrier landings at night are hairy mothers. They're tough. And I think that was valuable experience for those guys and I'd wish I had it. And I think it might have been tougher for me to learn how to land the LLTV without having had the experience of carrier landings."

"And I agree with Gene. Not that I can make a comparison from personal experience. But I can tell you that landing the LLTV was lot harder than landing any airplane I ever landed. But, as for who got to go, that was luck of the draw. As you well know...People say, 'Why did they pick Armstrong first? Oh, he was a civilian.' No, it was luck of the draw."

Jones - "He was in the rotation."

Following 124:44:11:
Scott - "One of the problems getting close to launch date was trying to get everything in - to do everything the last day. Which you couldn't possibly do, because there were so many things. You wanted to run through all the important things the day before launch, but you couldn't; so they had to be prioritized. And I don't recall what the priorities were."

Jones - "Flying the spacecraft, I would imagine."

Scott - "Yeah, but that got cut off reasonably early, just because we had to get down to the Cape. 'Flying the spacecraft', to me, means flying the LLTV. The (fixed-base) simulator was easy. The simulator becomes pretty ho-hum after a while."

Jones - "That's interesting to know."

Dave made his last LLTV flights on July 2nd, three and half weeks before launch.

Scott - "And the value of the simulator, at this point, was in integrated simulations with Houston, not in the individual things, because we'd had so much with Jim and I running through procedures that it was coming out our ears by now. So, what we do is a tune up on landing the LM. If we need any training at this stage of the game, we're not ready. The last month, the last two months, in terms of LM simulator time was probably minimal. 'Cause, by then, we should have been up on the (learning) curve."

"But running it with Mission Control was very important, again, because of getting all the players involved up to the very last minute. You have to think of the rest of the team, in terms of the Control Center and the Backroom and whatever. And what you really want is those people involved the day before the launch. So you've got to look at the bigger picture of what you do the last day or the last few days. And, probably the most important thing is to have the team practice before you go. And, hopefully, the individual things, like flying the LM simulator...If we weren't ready two months before launch, we really hadn't done our job. Because we've had plenty of time for that."

Jones - "Especially having backed-up 12."

Scott - "Especially having backed-up 12. Now, the LLTV is a different thing because its a real-time, dynamic vehicle, so you want that as close to launch as you can."

Jones - "Did you get to fly the LLTV before the (Apollo) 14 launch."

Scott - "I flew it during 12, as the backup Commander, and I don't recall when I flew it last before the flight. Some time reasonably close (July 2nd). And we also had one final (geology) field trip, close to the launch (a visit to Gray Mountain, Arizona, on 25 June 1971). Again, get everybody involved, keep us tuned up geologically speaking. So the real challenge was packing everything in, but not having too much, and having enough leisure time to do some thinking and to sort of cool it before launch. You don't want to go out and run a marathon the day before you race a marathon."

Jones - "Two weeks before, maybe, but not the day before."

According the Apollo 15 Training Log, Dave started training for the mission on 9 December 1969, about a month after Apollo 12 flew. He made his first LLTV flight (since the end of Apollo 12 training) on 16 February 1970 and made a total of 15 flight up to 22 June 1970. Apollo 13 splashdown was on 17 April and, because of the need to assess the reasons for the explosion in the Apollo 13 Service Module, both Apollo 14 and 15 were going to be delayed for many months. Apollo 14 splashdown was on 9 February 1971, with the Apollo 15 launch scheduled for 26 July. Dave resumed flying the LLTV on 28 April and made 18 flights, with the last on 2 July.

Scott - "It's just like a football team or a basketball team. You've got to peak at the right time."

Following 102:46:23 (A11):
In response to a 1997 question about his experience with the LLRF, Apollo 15 Commander Dave Scott offered the following: "Ah yes, the LLRF -- what an experience! The LLRF was indeed a large Erector-Set structure at Langley (Research Center) that operated much as you indicated. It was intended to provide LLTV-type training without the risk and cost - although it must have cost a bunch! However, it was actually used very little compared to the LLTV for several reasons. I tried it several times and found it to be negative training, albeit well-intended. The major problem for me was the lag in response to control inputs. Even though they had some feed-forward loops and, at the time, some sophisticated control modes, the system could just not compensate for a vehicle swinging from a cable. Thus, the very short systems lag in a very dynamic and tight loop was just enough to confuse the human response -- which for LLTV-type flight was probably on the order of 0.2-to-0.5 seconds from input to expected output. It was an impressive-looking rig though! Should be a reasonable amout of documentation on the LLRF in the Langley files; and some of the old-timers should have some good stories,. It was very important to Langley (as were a number of other Apollo-support activities, such as docking), and the structure may even still be there!"

Apollo 16 Commentary

Following 104:28:39:
Young, from the 1972 Technical Debrief - "When we redesignated to the south, we must have had 30 degrees of (left) yaw and took it back out. At that Sun angle, we could see the rocks (through the dust) all the way to the ground and I think that was a great help. From 200 feet down, I never looked in the cockpit. It was just like flying the LLTV (Lunar Landing Training Vehicle); your reference is to the ground outside. You had another thing that nobody has ever remarked about before, and that was the shadow. I really didn't have any doubt in my mind how far above the ground we were with that shadow coming down (that is, getting closer to them as they approach the surface). I had no scale of reference to the holes; but, with the shadow out there in front of you and coming down, it really takes all of the guesswork out of it. For that kind of Sun angle, if the radar had crumped, I don't think you'd have had a bit of trouble in just going right in and landing just like a helicopter. First, we could see the thing (rocks and other surface features) all the way to the ground; second, the shadow was right there to help you with the rate of descent. When Charlie says 'you stopped and you're hovering', there wasn't any doubt in my mind that I was hovering. I could look out the window and see that we're hovering just like a helicopter. We were well into the dust - maybe 40 or 50 feet off the ground - when we were doing that."
Following 104:30:46:
Young, from the Mision Transcript - ":Man, I could see the...all the way to the ground. Just like flying the LLTV. Piece of cake."

Apollo 17 Commentary

Following 112:59:25:
Cernan - "Although there is nothing quite like the real thing, flying the Lunar Landing Training Vehicle (LLTV) had been a step toward realism from "flying" the stationary simulators. In the LLTV you had your butt strapped to a machine that you had to land safely or you didn't make it. It still wasn't landing on the lunar surface, but it gave you a feel for what the actual landing would be like. Similarly, in simulator training we'd had a TV picture of a (large) model of the landing site that was good enough that, when we pitched over during the actual landing, I felt like I'd seen the landing site before. I won't say that I totally felt like I'd been there before, but I felt like I'd seen that valley before, three dimensionally. So it was a very comfortable feeling to know we were right where we expected to be."
Following 113:42:32:
Cernan, fromm the Mission Transcript - "Gordy, let me comment about the handling of the bird. After you once fly it (the LM) around in orbit a little bit, you get accustomed to the thrusters, and it came back to me quite a bit from (Apollo) 10, anyway. And you get a feel for acceleration and deceleration as well as the attitude-hold capability. And, really, the response, even with a heavy descent stage near the surface, is phenomenal. Responded exactly in the direction I wanted, held attitude very good. And, let me tell you, the LLTV(Lunar Landing Training Vehicle) played no small part in this landing as far as I'm concerned."

Schmitt - "As I recall, everybody was eventually supposed to go through LLTV training, but they were barely able to qualify all of the Commanders. All of us did get helicopter training as a precursor to the LLTV."

Cernan - "The reasoning behind giving only Commanders LLTV training, as best I can remember, was a combination of time, cost, and, quite frankly, safety. All the lunar module pilots wanted to fly the LLTV, strictly from a piloting point of view. When I was a lunar module pilot, I wanted to fly it. But, because we didn't have plans to land on Apollo 10, there wasn't any point in either Tom Stafford or I training in the LLTV; and, even for the actual landing missions, quite frankly, there was no need for LMP LLTV training. It would have been nice gravy to put on a chicken fried steak if the LMPs could have flown it as well as the Commanders; but, in reality, there was no need. There were two people to train for each flight anyway: the Commander and the Back-up Commander; and that pretty much took up all the time that was available. There were also some very real safety issues. We started out with four training vehicles, I believe, and we ended up with one. Joe Algranti (a NASA test pilot) ejected out of the first one. He was heading our aircraft operation before Neil ever flew the LLTV. And then two other people had to eject. So I was the last to fly the last one. It was a very unstable vehicle."

In all, Bell Aerosystems, Buffalo, NY built five LM trainers of this type for NASA. Two were an early version called the Lunar Landing Research Vehicle ( LLRV ). Neil Armstrong was flying LLRV-1 on May 6, 1968 when it went out of control. He ejected safely and the vehicle crashed. A later version was called the Lunar Landing Training Vehicle or LLTV and three were built. Two of these were lost in crashes on December 8, 1968 (LLTV-1 piloted by Algranti) and January 29, 1971 (piloted by Stuart M. Present). Both pilots ejected safely. The LLTV was a more accurate LM simulator and Gene is correct in saying that only one (NASA vehicle 952) was available for Apollo 17 training.

Cernan - "The LLTV gave us training in the critical final phases of the descent, from 500 to 700 feet on down. It had a J85 jet engine which, basically, maintained a constant thrust - based upon the weight of the vehicle - and took away 5/6th of the weight. That put you in a simulated lunar one-sixth gravity environment. You had sets of RCS thrusters, just like the lunar module, to control attitude; but, in addition, you had two other, vertically-mounted, hydrogen-peroxide-fueled 'lift' rockets that were capable of handling the extra one-sixth of the weight above the five-sixth that the J85 removed. They let you control how fast you went up or went down. To fly a descent, you'd use the lift rockets to fly yourself up to about five hundred feet. Then you'd start a forward trajectory and pick a landing point a few thousand feet down a runway. The key was to practice, and to get familiar with the dynamics of a six-degree-of-freedom machine. The more experience you got, the more you could displace yourself; or you'd give yourself errors; or, as you developed proficiency, instead of flying right straight down the runway, you could move over in the grass somewhere and put yourself in a position where errors were established before you started."

"The LLTV was inherently less stable than the LM itself; and we also had to contend with gusts of wind that could cause problems. But, LLTV training was very valuable because it really put your tail out on the line. It was not a simulator you could make a mistake in and then reset. If you made a mistake, you busted your ass, quite frankly. It also really brought home the uniqueness of the problems that you get with six degrees of freedom. By six degrees of freedom, I mean that not only could you roll, pitch, and yaw the vehicle and change your thrust direction because of the main engine, you could also use the RCS thrusters and move it laterally up, laterally down, laterally left, laterally right, laterally fore, or laterally aft. You had a combination of all those things to do when you landed a lunar module, and that is why the LLTV was so realistic. It was a great training device, one of a kind and probably never will be seen or used again. The 'flying bridge'. The ugliest thing in the world; but it was an ingenious idea and an ingenious design, and I don't know how else you could have ever put yourself in a one-sixth gravity flying environment, with rocket engines, here on Earth, and still have six degrees of freedom. Helicopters are just vertical flying machines, and they were nothing like this at all."

Also used in training and in the development of the landing systems was the Lunar Landing Research Facility - shown here with Neil standing in front of the LM mock-up. The facility consisted of a large, overhead gantry which allowed the cable-suspended LM mock-up to be moved forward and down - or up and back - in response to pilot input. The figure consists of a set of multiple exposures showing the mock-up as it comes in for a landing. A view from behind and one from the side show the vehicle approaching touchdown. Note that the 'craters' are painted on the flat tarmac. Both images are frames captured by Ken Glover from a 16mm film of a training session in late June 1969 with either Neil or Buzz as the pilot.

In 2002, I was reminded that the Apollo 15 Training Log shows that, on 24-25 March 1970, Jack was at Langley AFB using the LLRF. Although the Apollo 15 Prime and Back-up crews were not announced until 27 March 1970, the training log shows Jack's first Apollo 15 training session was a LM Radar Briefing on 27 October 1969. Dick Gordon, the Back-up Commander, didn't join Jack in training until 3 April 1970, following the conclusion of the Apollo 12 PAO tour.

Schmitt, from a 2002 e-mail - "As I remember, that was my only use of the LLRF at Langley and I had several runs during those two days. Originally, LMPs also were going to check out in the LLTV. Development and test delays and having the LLTV operational long enough to train CDRs, however, prevented this from happening."

"Al Shepard told me in January 1970 that I would soon be assigned to a back-up crew and that I should start stealing some simulator time. I had already been doing this for many months and just increased the level of activity to scheduling time whenever the MSC or KSC, CSM or LM simulators were available. In fact, this was the reason that I was at KSC rather than Houston right after Apollo 13 launched - the simulators were available. That meant that when the Apollo 13 explosion occurred, I immediately began to work with the KSC simulator operators to develop and test navigation and engine burn procedures we thought 13 would need as well as test those developed at MSC."

"The simulator operators at both MSC and KSC were great and spent a lot of time with me as I learned the various systems and subsystems as they were presented in the two cabins. I also scheduled a lot of time with the contractor training personnel that understood the details of the various CSM and LM systems. I worked alone until Dick Gordon, Vance Brand and I began to work as a crew, probably after Apollo 13 returned, the 12 crew was free of post-flight activities, and the Apollo 15 prime and back-up crews were assigned internally. April 1970 sounds about right as my memory is that we trained for 15 months for the July 1971 launch of Apollo 15."

Note added 13 December 2005: Journal Contributor Brian Lawrence adds that, based on unconfirmed but seemingly plausible postings to sci.space.history, "In December 1966 Deke Slyton assigned six guys to do the initial testing of the LLRV. They were the CDRs and LMPs of the early crews who might have been assigned to flights with an LM. They were Borman/Anders, Conrad/Williams, and Armstrong/Aldrin. Williams made one - possibly two - flights in February 1967 before the training was put on hold for a year. He died in an aircraft accident in October 1967. Starting in February 1968 the other five men got their chance. When Neil ejected from LLRV #1 (6 May 1968), he had made 21 flights while Pete had made 13. The other three (Borman, Anders, Aldrin) had made 18 flights between them. When flights resumed in June 1969, there was no time for any of the LMPs to fly the vehicle."

Following 118:31:01:
Cernan - "I had a firm idea in my mind about how I wanted to land. I wanted to bring that thing down as quickly as possible and then, when we got down within the 50 or 60 feet range, slow down to two or three per second and maintain two or three feet per second and a little forward velocity of a foot or so per second forward. You learned very quickly in the LLTV that if you tried to get it down at about one foot per second, all of a sudden you started hovering, or maybe you put a little bit too much thrust in and you started going up a little. So I tried to keep going down."

 

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