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Post by jupiter2 on Feb 22, 2007 11:14:50 GMT -4
35+ years after the fact this technology is still under research and development and it still cant be done.
Hogwash. The rocket stabilization problem was solved in the 1930s. Every rocket requires active stabilization.
Jay- im talking about vertical landing- not vertical takeoff.
As I said Jay you would have no link and no documentation of the LEM of 1969 being successfully tested.
Changing horses.
Not at all.
You asked for evidence of successful LLRV flights, wrongly believing that they were intended as the LM test flights.
Incorrect asumption. Its possible that some people might tend to believe that however. I asked for the Prototype LEM being successfully tested. AKA "the real LEM" used on the moon.
You specifically asked for it in hyperlink form, for whatever reason. I told you I was not aware of any links. But I did refer you to Spacecraft Films, which includes films of LLRV flights in their DVD. I referred you to the Dryden test center, where the flights took place. The curator there will be pleased to answer your questions and arrange for you to inspect the records of the flights.
I have seen the flight films. they are very good. But they are not solely rocket powered.
If you're asking for evidence of the LM test program, that's a different story. Start with Tom Kelly's Moon Lander, then I suggest you read Chariots for Apollo, which I believe is online at NASA. I have the print version, so I don't know the link. I'm sure one of my friends here has it in a bookmark.
This does not constitute visual documentation. Irrelevant to the question.
Did either you someone else mentioned it was tested in space? That is not helpful to NASA's problem since there was nothing to land on...
Apollo 11 tested the LM by landing it on the moon.
To use your own words - Hogwash. Look up the definition of a TEST. A test occurs before an event act is attempted, not during the event itself. Im suprised at this superficially dismissive answer.
All the other functions had been tested in previous missons or in ground qualification programs.
All except the landings you mean. And it is not correct that flight dynamics can only be tested faithfully in the presence of gravity.
Of course not. But a vertical landing tested faithfully in the prescence of gravity.would certainly produce better results
There is nothing to learn unless its done on a gravitional body.
What is your training in classical Newtonian dynamics? What is your personal experience in engineering test methodology? What is your personal experience in flight test methodology? I'm not prepared to accept this statement without an argument to support it.
My argument is simple logical one. To test thr Lunar Lander successfully you should have as close to the actual conditions as possible. Gravity is an essential aspect of those conditions isnt it, even ata 6 to 1 ratio to that of the moon?
This is because the continually changing center of gravity...
...and relatively top heavy craft like the LEM...
Top-heavy compared to what? Please show me your studies by which you arrived at the conclusion that the LM was top-heavy.
Maybe its those spindly legs. How much to they weigh?
The technology needed would have had to have included some form of reliable mechanical weight distribution compensation...
Straw man. Why do you think the solution to changing center of mass is redistributing the mass? That is by far the most complicated way I can think of to address the problem.
Just a guess. Im glad you see it as a problem however.
Off-axis thrust (i.e., thrust whos vector does not pass through the center of mass) creates a moment. The moment creates a rotation rate. You already have a means of detecting rotation and a means of intentionally causing rotation on your spacecraft. Why not simply correct the effect with your existing equipment instead of trying to correct the cause?
Come on. The gimballed axis thrust allowed for what.- 4-6 degrees of adjustment?. What good is that if youre doing cartwheels in space. Wasnt that what happened to "Snoopy"?
Plus the real LEM-. which you will never see being tested because all attempts failed
Whoa! Before you told us there was no evidence the LM was successfully tested. Now you're telling us you have evidence that the LM was tested, but that it failed the tests. I'd like to see that evidence, please.
If NASA has no film of it, that is evidence that no film of it exists. Simple deductive reasoning here.
The LM had no atmospheric effects to deal with.
But it certainly has plenty of other effects to deal with such as manuvering in the vacuum of space. Ask the Apoolo 10 crew how easy it was.
And it was not designed to be inherently dynamically unstable. It was designed to be dynamically stable. Hence the overall stability problem did not require an extensive computer solution.
Simplistic answer. The instability comes not from the design, but from outside forces working against it.
However, this issue is simplistic compared to that of modulating rocket engines and multiple thrusters.
Hogwash.
LM stability is a much easier problem to solve than stabilizing a high-performance aerodynamic vehicle. In fact, you can break it down to the same problem repeated in each of the three cardinal axes. The only source of unwanted moments is off-axis thrust.
Thats a pretty big source for you to be making it sound like a small problem isnt it?
The V-2 rocket had an active stabilization platform using analog controls. That was in the 1940s and resulted in highly accurate trajectories.
Please stop adressing vertical landing prroblems with vertical takeoff and flight trajectory proofs. Talk about changing horses.
Unfortunatley the real LEM had neither a mass gyro...
Yes it did.
...nor such multiple modulated thrusters.
Yes it did.
How many do you mean by miltiple thrusters? And where exactly was the gyro located?
The LEM successful documentation films have never been shown by NASA because they dont exist.
Grumman filmed a great deal of the LM design and development process. I've seen many of them. I don't have links to them and I don't know if they're online.
R + D is for the drawing board . Show me it doing a vertical landing and i will believe everything you say.
LM flight test footage is ubiquitous. I believe Apolloarchive.com might have some online.
They dont. How unfortunate. But that doesnt mean they didnt land on the moon. Please.
known as tIt is a common misconception that a rocket stability solution must incorporate the gravity vector. It does not. This misconception is he Pendulum Theory, and rocket engineers are forever having to explain why that's not right.
A flying rocket is a fully-consistent, self-contained rotational reference frame, regardless of whether it's flying in deep space or near a planet with gravity. Rockets do not "fall off" their thrust if they tilt too far to one side.
Robert Goddard discovered this the hard way. He originally thought the Pendulum Theory was correct, so his original rocket design put the thrust chamber above the center of mass. His rocket spun out of control. It did not self-correct, as Goddard had assumed it would. He went back to his physics books and did some more study, then slapped his forehead and realized that the relative position of the thrust and the center of mass, with respect to gravity (if any), is utterly irrelevant.
Goddard never worked on a rocket vertical landing problem that he could solve.
Now 35+ years later we are still waiting for a simple demonstration...
You're only waiting because you ignore the existing examples.
Im from Missouri Show me.
In rocketry vertical takeoff is the easy part. The difficult and so far impossible part is the descent landing.
I don't recognize you as an expert on rocketry.
You dont have to be a weatherman to know which way the wind blows do you?
Landing is indeed more difficult, but for reasons that have little to do with rotational stability. Ascent allows you to fire the rocket at full thrust. Landing requires a variable-thrust engine. We have those, but they are more finicky than simpler engines.
Indeed they are. Impossibly finicky.
What is needed is some kind of anti-gravity system...
No, just a correct understanding of physics.
Jay, your avoidance of real proof is understandable because you have none. Now if maybe we have finally figured out how to do it, maybe you or somebody can direct me to an actual film of any of the following succesful vertical landings ( I believe it the DCX program) done in the 90"s. If not fine, we'll get it right someday!
LAS CRUCES, N.M., June 20, 1994 -- Flight tests of the Delta Clipper- Experimental (DC-X) resumed today as the single-stage vehicle lifted off the flight stand here at White Sands Missile Range. The 8:42 a.m. MDT liftoff began the experimental flight vehicle's fourth consecutive successful flight.The DC-X reached an altitude of 1,500 feet, and then followed a curved ascent to a height of 2,600 feet, traveling laterally 1,050 feet from the take-off point. Then flight controls commanded the DC-X to reverse its direction of flight and climb to an altitude of 2,850 feet. Once over its landing pad the vehicle descended vertically and touched down 136 seconds after liftoff.
WHITE SANDS MISSILE RANGE, N.M., June 27, 1994 Today at 8:37 a.m. MDT the Delta Clipper Experimental (DC-X) single-stage launch vehicle executed a safe landing on the desert floor, following an anomaly which occurred at takeoff. An explosion of unknown origin took place at engine startup with subsequent damage to the DC-X's graphite fiber aeroshell. The DC-X, however, continued through its flight sequence with its avionics and engine systems performing normally, and liftoff was according to expectations. "We were 17 seconds into the initial launch and flight mode when Pete Conrad, DC-X flight manager, initiated the vehicle's emergency autoland sequence and it descended according to plan," said Paul Klevatt, McDonnell Douglas' DC-X program director. Total flight time from start of engines to landing was 78 seconds. "We are pleased the vehicle returned essentially intact so that it can be repaired and flown again," Klevatt added.
WHITE SANDS, N.M., May 16, 1995 The Delta Clipper Experimental launch vehicle (DC-X) climbed into the skies over the U.S. Army's White Sands Missile Range at 9:40.02 MDT today to resume a rigorous series of flight tests. The single-stage, vertical-takeoff, vertical-landing vehicle reached an altitude of 4,350 feet flying at a constant angle. During the ascent, the DC-X traveled 1,150 feet from the flight stand. The vehicle traveled laterally until it was positioned over its landing pad located 350 feet from the initial flight stand. The DC-X touched down approximately 123.6 seconds after liftoff. --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
P.S. Oh by the way 12 weeks ago the best space scientists and the best space entempreneurs in the world gathered to attempt (for a 2 million dollar prize no less) a successful vertical takeoff and landing demonstration of the "latest" rocket technology to vie for prize money. NASA is actually sponsoring this lunar lander prototype competition. They want to know how to do it too!
I believe its called Wirefly X Prize Cup held in Las Cruces, New Mexico. You can go to Space.com to view one pretty good but unsuccessful attempt on video.
A rocket-propelled craft called “Pixel” was the lone contestant out of Armadillo Aerospace of Mesquite, Texas. They tried and failed. but hey its only 35+ years after we already did it. Theyll be back this year 2007 to try again however. If after 35+ years you dont succeed theres always next year.
And youll never guess what company sponsored it- Northrop Grumman! You know the company that you keep pontificating (as the best authority on NASA I know) had already designed a succesful working Lunar Lander in 1969. Youd think some of these top scientific minds would just drag out the specs for the old LM used on the moon and grabbed the 2 million. Wonder why nobody thought of that.?
Its called the Northrop Grumman Lunar Lander Challenge. The rules are so simple even a caveman can understand them. The rules call for a rocket-propelled craft with an assigned payload to climb vertically, reach a defined altitude, fly for a pre-determined amount of time and then vertically land on a target that is a fixed distance from the liftoff point.
After remaining at that spot for a period of time, the vehicle must re-fly, stay aloft for the same amount of time, then land again on its original launch pad.
So much simpler then flying a jet, yet no one can do it.
I believe Ive made my point clear enough Jay.
I do hope you can show me where I am being ignorant of the "facts" or the "laws of physics" here. I no its a tall order but Im pulling for you. Just dont call me ignorant anymore. I know alot more that you are giving me credit for. I didnt "come to a gunfight with a knife" if thats what you think.
Now, what do you know about this and where am I listening to the wrong people?
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Post by Grand Lunar on Feb 22, 2007 11:46:34 GMT -4
Jupiter2,
The priciples behind a powered landing and takeoff are similar. The only difference is the amount of thrust applied.
In a powered descent, the thurst is set to simply keep the craft from falling down to the ground, or to let it fall at a controlled rate. In powered takeoff, the thrust it set to counteract the force of gravity and accelerate it into orbit.
The LM's descent engine could do just that. At full power, it could blast the LM into orbit. On approach, it merely was throttled down for a controlled rate.
Now, tell me why the Surveyor, Viking, DC-X, and Blue Origins craft do not count toward successful powered descents?
And as mentioned to you, a powered descent on Earth is more difficult than it is on the moon. More thrust is needed, plus the atmosphere adds complications.
For your purposes, the Surveyor flights would be more applicable to the discussion. Explain why you are not considering them in your arguments.
Maybe my dictionary is incomplete, but for "test", there is nothing saying that it is conducted before an event is attempted. Consider STS-1 through 4. These were the test flights for ths space shuttle. They were conducted in the same light as Apollo 11; that is, they preformed the steps that an operation mission would preform. Explain why those missions are referred to as test mission but Apollo 11 is not.
Being pedantic, it's difficult to tell when you quote Jay and when it is your text. It makes it hard to read. Somehow, you should mark the text apart. You can use the quote function, or set it in italics, bold, or other fonts.
The rest I leave to my collegues.
From the tone of your replies, it seems unlikely that you "want to believe" and more like "I don't understand, therefore it's phony". If you did "want to believe", you would ask questions as to how the problems you believe were solved, and by which methods, rather than acting like you know something that qualified individuals don't, and making erroranous assumptions.
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Post by LunarOrbit on Feb 22, 2007 12:10:18 GMT -4
First of all, Jupiter2, I would like you to learn how to use the quote function of the forum. Your post is really hard to read because you do not properly distinguish between what you are quoting and what you are saying. It's really simple, just surround quotes with the following tags: [quote]Quoted text goes here[/quote] im talking about vertical landing- not vertical takeoff. The vehicle is stabilized the same way whether it is taking off or landing. Except the moon. Testing the LM in space was the only way to test it. How would you suggest they do it? Do you believe the space shuttle is a hoax? It was tested for the first time by launching it into low Earth orbit with two astronauts aboard. Sometimes the only way to test something is to just do it. You may consider it dismissive if you want, but it's the truth. How would the legs, which are at the bottom, make the LM top heavy? Are you aware of the RCS thrusters mounted at key points around the vehicle? They help maintain the LM's attitude. Or that they haven't put it online. See the image I linked to above. There are four groups of four RCS thrusts mounted around the LM's ascent stage. I guess the fact that the gyro isn't shown in that images means it doesn't exist, eh? That's your logic. Variable thrust engines are impossible? I guess that means the Space Shuttle is fake too. Hmmm... a variable thrust rocket. I thought those were impossible? Maybe because this competition is taking place on Earth and not on the Moon. The LM was designed to land on the Moon, so anyone copying the LM system for the competition would fail.
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Bob B.
Bob the Excel Guru?
Posts: 3,072
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Post by Bob B. on Feb 22, 2007 12:13:56 GMT -4
35+ years after the fact this technology is still under research and development and it still cant be done. Nonsense. It was done 1966-68 with Surveyor, 1966-75 with Luna, 1969-72 with Apollo, and 1976 with Viking. It has also been done here on Earth with the LLRV/LLTV, the DC-X, and other vehicles, though there is really little use for the technology on Earth. Jay- im talking about vertical landing- not vertical takeoff. Makes little difference. The stability problem is essentially the same. Incorrect asumption. Its possible that some people might tend to believe that however. I asked for the Prototype LEM being successfully tested. AKA "the real LEM" used on the moon. The fully assembled LM (not LEM) was tested in space, thus image documentation is very limited. However, there are pictures and video of these missions in the Apollo archive if you bother to go look for it. The manufacturer of the LM also produce video documentation of most of the component testing that took place on Earth. If you want to see this documentation then go do your own research -- we are not your lackeys. Come on. The gimballed axis thrust allowed for what.- 4-6 degrees of adjustment?. What good is that if youre doing cartwheels in space. It prevents you from doing the cartwheels in the first place. But it certainly has plenty of other effects to deal with such as manuvering in the vacuum of space. Maneuvering in space is actually a fairly simple problem.
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Post by Data Cable on Feb 22, 2007 13:45:54 GMT -4
I asked for the Prototype LEM being successfully tested. AKA "the real LEM" used on the moon. Make up your mind, are you talking about a prototype, or a vehicle which actually performed a mission? [emphasis mine] Interesting. Previously, you complained that the LL*Vs weren't "rocket powered." After we've corrected you on this, you now complain that they aren't solely rocket powered. You've revealed how mobile your goalposts are. Now, ignoring the fact that the jet engine was only producing thrust approximately equal to 5/6ths of the vehicle's weight, why does it matter if the descent propulsion as produced by a jet or a rocket? Thrust is thrust. Perhaps because the Harrier is capable of vertical landing, and it's jet powered, so you have to narrow the window of acceptable evidence in order to maintain your "it's never been accomplished" claim. Show us visual documentation of a new submarine being tested before it is put in the water. Of course. How do you propose the ability of the LM to land on the moon be tested other than landing it on the moon? You keep demanding footage of the LM landing on Earth, but that's not a valid test, is it? Why is testing under 6 times the gravity of the intended landing site and in an atmosphere "faithful?" Exactly our point. Testing at a 1 to 1 ratio of lunar gravity is even closer to actual conditions, isn't it? Especially with no atmosphere to create drag, crosswinds, and such. What would cause it to do cartwheels in space to begin with? And why do you ignore the RCS thrusters, the primary means of orientation adjustment? But you said the attempts failed. How do you know this unless you've seen film of the tests? And this directly contradicts your claim that the LM was never tested. "Maneuvering in the vacuum of space" is most decidedly the absence of "other effects to deal with." No drag, no friction, no unpredictable wind gusts, just pure newtonian physics of action and reaction. What "outside forces" are there to "work against it" in a vacuum? What do you think would be a source of off-axis thrust to a vehicle in a vacuum other than it's own propulsion systems? Here y'go: Apollo 11Apollo 12Apollo 14Apollo 15Apollo 16Apollo 17You will be held to this pledge. I found it in 5 seconds by punching "Delta Clipper" into Google Video, and so can you. Also look up "Blue Origin." And see above for footage of 6 successful vertical landings performed from '69-'72. We will, if and when it is warranted.
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Post by Alliterative Andy on Feb 22, 2007 14:01:09 GMT -4
Wow, I had a lot of trouble discerning who said what in Jupiter’s last post, too. From what I can tell, Jupiter3 is responding to some of JayUtah’s rebuttals in reply #475 of this thread. To help make it a little easier to parse, I’ve reconstructed the reply portion of his post as follows: The blockquotes contain the excerpts taken from reply #475, where the quoted material is Jupiter’s initial claims, and regular text is Jay’s rebuttals. Otherwise, unquoted text comprises Jupiter’s responses. ***
Hogwash. The rocket stabilization problem was solved in the 1930s. Every rocket requires active stabilization.
Jay- im talking about vertical landing- not vertical takeoff.
Changing horses.
Not at all. You asked for evidence of successful LLRV flights, wrongly believing that they were intended as the LM test flights. Incorrect asumption. Its possible that some people might tend to believe that however. I asked for the Prototype LEM being successfully tested. AKA "the real LEM" used on the moon. You specifically asked for it in hyperlink form, for whatever reason. I told you I was not aware of any links. But I did refer you to Spacecraft Films, which includes films of LLRV flights in their DVD. I referred you to the Dryden test center, where the flights took place. The curator there will be pleased to answer your questions and arrange for you to inspect the records of the flights. I have seen the flight films. they are very good. But they are not solely rocket powered. If you're asking for evidence of the LM test program, that's a different story. Start with Tom Kelly's Moon Lander, then I suggest you read Chariots for Apollo, which I believe is online at NASA. I have the print version, so I don't know the link. I'm sure one of my friends here has it in a bookmark. This does not constitute visual documentation. Irrelevant to the question.
Apollo 11 tested the LM by landing it on the moon.
To use your own words - Hogwash. Look up the definition of a TEST. A test occurs before an event act is attempted, not during the event itself. Im suprised at this superficially dismissive answer. All the other functions had been tested in previous missons or in ground qualification programs. All except the landings you mean. And it is not correct that flight dynamics can only be tested faithfully in the presence of gravity. Of course not. But a vertical landing tested faithfully in the prescence of gravity.would certainly produce better results
What is your training in classical Newtonian dynamics? What is your personal experience in engineering test methodology? What is your personal experience in flight test methodology? I'm not prepared to accept this statement without an argument to support it.
My argument is simple logical one. To test thr Lunar Lander successfully you should have as close to the actual conditions as possible. Gravity is an essential aspect of those conditions isnt it, even ata 6 to 1 ratio to that of the moon?
Top-heavy compared to what? Please show me your studies by which you arrived at the conclusion that the LM was top-heavy.
Maybe its those spindly legs. How much to they weigh?
Straw man. Why do you think the solution to changing center of mass is redistributing the mass? That is by far the most complicated way I can think of to address the problem.
Just a guess. Im glad you see it as a problem however. Off-axis thrust (i.e., thrust whos vector does not pass through the center of mass) creates a moment. The moment creates a rotation rate. You already have a means of detecting rotation and a means of intentionally causing rotation on your spacecraft. Why not simply correct the effect with your existing equipment instead of trying to correct the cause? Come on. The gimballed axis thrust allowed for what.- 4-6 degrees of adjustment?. What good is that if youre doing cartwheels in space. Wasnt that what happened to "Snoopy"?
Whoa! Before you told us there was no evidence the LM was successfully tested. Now you're telling us you have evidence that the LM was tested, but that it failed the tests. I'd like to see that evidence, please.
If NASA has no film of it, that is evidence that no film of it exists. Simple deductive reasoning here. The LM had no atmospheric effects to deal with. But it certainly has plenty of other effects to deal with such as manuvering in the vacuum of space. Ask the Apoolo 10 crew how easy it was. And it was not designed to be inherently dynamically unstable. It was designed to be dynamically stable. Hence the overall stability problem did not require an extensive computer solution. Simplistic answer. The instability comes not from the design, but from outside forces working against it.
Hogwash.
LM stability is a much easier problem to solve than stabilizing a high-performance aerodynamic vehicle. In fact, you can break it down to the same problem repeated in each of the three cardinal axes. The only source of unwanted moments is off-axis thrust. Thats a pretty big source for you to be making it sound like a small problem isnt it? The V-2 rocket had an active stabilization platform using analog controls. That was in the 1940s and resulted in highly accurate trajectories. Please stop adressing vertical landing prroblems with vertical takeoff and flight trajectory proofs. Talk about changing horses.
Yes it did.
Yes it did.
How many do you mean by miltiple thrusters? And where exactly was the gyro located?
Grumman filmed a great deal of the LM design and development process. I've seen many of them. I don't have links to them and I don't know if they're online.
R + D is for the drawing board . Show me it doing a vertical landing and i will believe everything you say. LM flight test footage is ubiquitous. I believe Apolloarchive.com might have some online. They dont. How unfortunate. But that doesnt mean they didnt land on the moon. Please. known as t It is a common misconception that a rocket stability solution must incorporate the gravity vector. It does not. This misconception is he Pendulum Theory, and rocket engineers are forever having to explain why that's not right.
A flying rocket is a fully-consistent, self-contained rotational reference frame, regardless of whether it's flying in deep space or near a planet with gravity. Rockets do not "fall off" their thrust if they tilt too far to one side.
Robert Goddard discovered this the hard way. He originally thought the Pendulum Theory was correct, so his original rocket design put the thrust chamber above the center of mass. His rocket spun out of control. It did not self-correct, as Goddard had assumed it would. He went back to his physics books and did some more study, then slapped his forehead and realized that the relative position of the thrust and the center of mass, with respect to gravity (if any), is utterly irrelevant. Goddard never worked on a rocket vertical landing problem that he could solve.
You're only waiting because you ignore the existing examples.
Im from Missouri Show me.
I don't recognize you as an expert on rocketry.
You dont have to be a weatherman to know which way the wind blows do you? Landing is indeed more difficult, but for reasons that have little to do with rotational stability. Ascent allows you to fire the rocket at full thrust. Landing requires a variable-thrust engine. We have those, but they are more finicky than simpler engines. Indeed they are. Impossibly finicky.
No, just a correct understanding of physics.
Jay, your avoidance of real proof is understandable because you have none. Now if maybe we have finally figured out how to do it, maybe you or somebody can direct me to an actual film of any of the following succesful vertical landings ( I believe it the DCX program) done in the 90"s. If not fine, we'll get it right someday! *** Thus ends, from what I can tell, Jupiter’s direct responses. Jupiter3, you seem to have some trouble attributing materiel to its sources. It would seem to me that if you’d like to be taken seriously here, you should at least take the time to cite your material in a clear way. Without some sort of method to do this, it is hard to tell if you are being intellectually honest or not.
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Post by sts60 on Feb 22, 2007 15:02:21 GMT -4
The real problem is that jupiter2 presumes to lecture everyone here about rocketry, and about the role of the LLxVs, and about sound engineering test principles, and other various issues of fact and judgment, despite apparently having no relevant training or experience, and apparently having done no self-education on the issue.
He's spent less effort really researching the issue than others have spent formatting his posts to make them legible, yet he makes proclamations like "[variable-thrust engines are] impossibly finicky" with Olympian self-assurance and in the same breath tell us not to call him ignorant!
"Discovery, Houston, go at throttle-up..."
But what's really funny is that the LLxVs, which jupiter2 seems to believe existed because he can Google up some video clips, used variable-thrust rocket engines themselves. They were so "impossibly finicky" that the LLxVs only had over 200 successful flights.
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Post by gillianren on Feb 22, 2007 16:02:01 GMT -4
To be fair, I would like to point out that "spindly little legs" don't look like they'd weigh much, therefore making the bottom light, which would make the top heavy.
I'm not saying I believe this, mind you; I'm saying that's what it looks like.
But do allow me to add my voice to the "make it clearer who's saying what" cries, and thank you Andy for trying to clarify.
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Post by Jason Thompson on Feb 22, 2007 17:04:57 GMT -4
As I said Jay you would have no link and no documentation of the LEM of 1969 being successfully tested.
No links just means something is not online. The internet is not yet the repository of all human knowledge. And documentation you were referred to. Your arbitrary definition of what constitutes a test is the problem, not lack of documentation.
Incorrect asumption. Its possible that some people might tend to believe that however. I asked for the Prototype LEM being successfully tested. AKA "the real LEM" used on the moon.
Apollos 5, 9 and 10 tested a flight configured LM in space. Apollo 11 was the final test.
I have seen the flight films. they are very good. But they are not solely rocket powered.
On the contrary. The flying training vehicle used a jet to counter 5/6ths of the vehicles weight in order to simulate lunar gravity effects, but all the descent control and attitude control was then done using rocket motors.
Did either you someone else mentioned it was tested in space? That is not helpful to NASA's problem since there was nothing to land on...
But it does help them test everything that will be used to land the LM. I do not need to stick a jet engine in an aircraft to see if it works. NASA does not need to land the LM to see if all its systems work as they are supposed to.
To use your own words - Hogwash. Look up the definition of a TEST. A test occurs before an event act is attempted, not during the event itself. Im suprised at this superficially dismissive answer.
So tell me how they test aeroplanes then. Do they not get in them and fly them? How do they test cars? Do they not get in them and drive? Boats are tested by putting them in water. Submarines are tested by submerging them. How did they test the shuttle? They flew it in space. The only way to test hardware’s ability to perform a function is to actually get it to perform that function, therefore the only way to finally test the LM’s ability to land is to actually land it.
All except the landings you mean.
The landing depends on all the other functions. What about the landing itself makes a difference to how the descent engine works, or the attitude control thrusters, or the radar?
My argument is simple logical one. To test thr Lunar Lander successfully you should have as close to the actual conditions as possible. Gravity is an essential aspect of those conditions isnt it, even ata 6 to 1 ratio to that of the moon?
But you can’t test the LM on Earth because it simply could not use its rocket to support its weight in Earth’s gravity. Nor can you simply put in a rocket 6 times more powerful to hold it up against Earth’s gravity because that will introduce new stresses and strains to the structure that it was never intended to cope with. If the rocket gives enough thrust it will work against lunar gravity exactly as intended.
This is because the continually changing center of gravity...
Please look at the diagrams and show us how much the centre of gravity would change in the LM. It is one of the most stable rocket powered vehicles ever made because of the distribution of weight around the engine combustion chambers rather than directly above them.
Maybe its those spindly legs. How much to they weigh?
Not good enough. If you claim the LM is top heavy then you back that claim up. Those spindly legs are attached to a rather large descent stage, and those legs project out to the sides not below the vehicle.
The technology needed would have had to have included some form of reliable mechanical weight distribution compensation...
The body of the LM was solid and unchanging, and the fuel and oxidizer tanks were mounted such as to distribute their weight evenly across the centerline of the LM. Since fuel and oxidizer are depleted in tandem, how is the mass distribution changing during flight in any way other than directly upwards during the descent phase as the descent stage empties? How is the weight distribution changing at all during ascent?
Come on. The gimballed axis thrust allowed for what.- 4-6 degrees of adjustment?. What good is that if youre doing cartwheels in space. Wasnt that what happened to "Snoopy"?
Yes, and what do you know, they cancelled their cartwheel using the available systems.
If NASA has no film of it, that is evidence that no film of it exists. Simple deductive reasoning here.
That is not what you said. You said the tests failed. You cannot simultaneously claim no film of the tests exists and that you know the results. Neither, frankly, do I believe you can justifiably claim that no such film exists anyway, since I highly doubt you have scoured the record to any great degree.
The LM was tested in space. Apollo 5 was unmanned, therefore no film but plenty of telemetry. Apollo 9 and 10 tested them, and they were filmed to the degree permitted by the cameras available. Apollo 11 filmed its descent from the LMP window.
But it certainly has plenty of other effects to deal with such as manuvering in the vacuum of space. Ask the Apollo 10 crew how easy it was.
Oddly enough, that’s just what NASA did, and you know what, they reported that the LM handled well and that they foresaw no problems with actually landing it on the next mission.
The only source of unwanted moments is off-axis thrust.
Thats a pretty big source for you to be making it sound like a small problem isnt it?
It’s not a small problem, but it is the only problem. It is considerably easier to engineer a solution to one problem when you don’t have others to deal with too.
How many do you mean by miltiple thrusters? And where exactly was the gyro located?
How do you presume to judge the capabilities of the LM when you don’t even know what control systems it had?!
The LEM successful documentation films have never been shown by NASA because they dont exist.
Cobblers. The film you want to see does not exist because no such test was performed, nor is it justifiable. However, there is a VAST archive of film of the LM being designed and built, and in flight. Just because you haven’t been able to find it on Google doesn’t mean it doesn’t exist. The film is not generally circulated because it makes for some very dull viewing if you’re not an engineer with an interest in the subject. Demand for circulation just isn’t there, but if you ask for it from the people who have it you’ll probably be given it. That’s how real researchers work.
R + D is for the drawing board . Show me it doing a vertical landing and i will believe everything you say.
Every single lunar landing was filmed, and that film is freely available online.
Jay, your avoidance of real proof is understandable because you have none.
Let’s qualify that. Jay has no proof that you want because such proof does not exist, and lengthy and patient explanations have been given as to why this is. It is not suspicious if someone can’t satisfy your expectation of proof if your expectation is flawed to begin with.
Now if maybe we have finally figured out how to do it, maybe you or somebody can direct me to an actual film of any of the following succesful vertical landings
And what if you are told that film is not online?
That’s a legitimate question that I would almost go as far as to demand an answer to. If you cannot accept that some stuff is not to be found on the internet there is little point in continuing to discuss such things.
P.S. Oh by the way 12 weeks ago the best space scientists and the best space entempreneurs in the world gathered to attempt (for a 2 million dollar prize no less) a successful vertical takeoff and landing demonstration of the "latest" rocket technology to vie for prize money. NASA is actually sponsoring this lunar lander prototype competition. They want to know how to do it too!
I believe its called Wirefly X Prize Cup held in Las Cruces, New Mexico. You can go to Space.com to view one pretty good but unsuccessful attempt on video.
A rocket-propelled craft called “Pixel” was the lone contestant out of Armadillo Aerospace of Mesquite, Texas. They tried and failed. but hey its only 35+ years after we already did it. Theyll be back this year 2007 to try again however. If after 35+ years you dont succeed theres always next year.
And youll never guess what company sponsored it- Northrop Grumman! You know the company that you keep pontificating (as the best authority on NASA I know) had already designed a succesful working Lunar Lander in 1969. Youd think some of these top scientific minds would just drag out the specs for the old LM used on the moon and grabbed the 2 million. Wonder why nobody thought of that.?
Why do you think that a competition involving private enterprise groups is in any way comparable to what Grumman could do with a government funded contract? After remaining at that spot for a period of time, the vehicle must re-fly, stay aloft for the same amount of time, then land again on its original launch pad.
So much simpler then flying a jet, yet no one can do it.
And yet infinitely more complex than a lunar lander because vertical motion and hovering in one spot is scuppered by wind effects that no-one has to factor in when designing something that operates in a vacuum. How many more times must this be explained before you actually get it?
I believe Ive made my point clear enough Jay.
And I believe you are either a sock puppet of someone else who has been here or else you are someone who has come over from another board with a personal vendetta against Jay. There seems little other explanation for your ability to single him out for your criticism from your very first post, nor your apparent refusal to acknowledge the rest of the people offering you answers to your questions. Why don’t you leave Jay alone and deal with the rest of us, or is your sole purpose to try to make him look bad?
Just dont call me ignorant anymore.
But you are ignorant of such fundamental things as how the LM reaction control thrusters work or even where they are, yet you claim to be able to judge that the LM couldn’t do what it was said to have done.
I didnt "come to a gunfight with a knife" if thats what you think.
Then I ask you to explain why you singled Jay out right from the start. This board is a group forum. Jay is one member.
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Post by Jason Thompson on Feb 22, 2007 17:12:47 GMT -4
To be fair, I would like to point out that "spindly little legs" don't look like they'd weigh much, therefore making the bottom light, which would make the top heavy.
I'm not saying I believe this, mind you; I'm saying that's what it looks like.
Whilst acknowledging the second line of your post, I would like to say that it is not 'being fair' to say that on a drawing the legs look like the might be light. This is a common mistake from conspiracy theorists who presume to judge an object's abilities and characteristics by looking at it, or worse by looking at a picture of it.
My standard response is to ask anyone if they think the harrier looks like a vehicle that can take off vertically or fly sideways and backwards....
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Post by PhantomWolf on Feb 22, 2007 17:53:28 GMT -4
It doesn't matter where the legs are, it matters where the combustion chamber throat is, and that's buried in the center of the Descent Stage.
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Post by JayUtah on Feb 22, 2007 17:54:35 GMT -4
Jay- im talking about vertical landing- not vertical takeoff.
I know you are, but in terms of the rocket's rotational stability they are equivalent cases.
Gravity is irrelevant to rotational stability. This follows inexorably from the definition of center of gravity in Newtonian dynamics, as I explained in my response to someone else. Robert Goddard verified this principle empirically for rockets. Your intuitive belief to the contrary is simply wrong.
I asked for the Prototype LEM being successfully tested.
But what exactly do you mean by "prototype LM"?
It's hard to pin you down on what you mean. And I surmise that's because you came here to validate a preconceived belief that we had no "real proof" for a valid, tested LM. Hence the shifting goalposts: you're trying to exclude each new bit of proof so your belief remains true.
You offered the LLRV as a straw man. You said it was intended to be the LM prototype, then gave reasons why it wasn't a valid one. After we pointed out that the LLRV wasn't supposed to be an LM prototype, you tried a few rhetorical gymnastics to maintain it was. Now you seem to have backpedaled.
I consider all the LTAs, and LM-1 through LM-4, as prototypes of one kind or another. LM-5 was an operational LM according to how it was built; but it was flown in a flight-test context, thus it can also be considered a prototype.
But you categorically reject early LMs as prototypes. You arbitrarily expect that a prototype must differ significantly from the "real thing" or perhaps that test missions must appear obviously different from operational missions. I don't know where you're getting that. I don't agree with it. It sounds like you're defining "prototype" according to whatever you need not to exist. And you've reached the point of begging the need for some other kind of vehicle in a valid test program.
I have seen the flight films. they are very good. But they are not solely rocket powered.
Irrelevant. Rocket engines and jet engines propel vehicles according to the same physical principles. Your empty distinction just ignores applicable evidence.
This does not constitute visual documentation. Irrelevant to the question. (emphasis added)
Shifting goalposts. You're desperate not to have this question answered so that you can continue to argue from silence.
Look up the definition of a TEST.
I'm well acquainted with engineering test methodology. It's my job. I don't, however, recognize you as an expert in it. I'll keep my own counsel on what is a valid test and what isn't.
A test occurs before an event act is attempted, not during the event itself.
NASA considered Apollo 11 the flight which the landing capability of the LM would be tested. No one is obliged to agree with your characterization of it as "the event itself" -- if by that you mean some previous test flight should have occurred.
I'm suprised at this superficially dismissive answer.
It is neither superficial nor dismissive. You simply wish to believe Apollo 11 was something other than it was so that you can pretend something significant should have preceded it.
Here is the entire set of mission objectives for Apollo 11
All except the landings you mean.
Correct. The ability of the LM to proceed from an altitude of 10,000 feet to the lunar surface, and to ascend from the lunar surface to an altitude of 10,000 feet was tested for the first time on Apollo 11 using LM-5. That was Apollo 11's primary mission objective. Operational Apollo missions began with Apollo 12.
The historical significance of Apollo 11 is remarkable indeed, but it is entirely collateral to the engineering objectives for which the mission was flown.
But a vertical landing tested faithfully in the prescence of gravity.would certainly produce better results
Let's clarify.
You seem to say rotational stability is the show-stopper. Or in other words, the LM would be more rotationally unstable and prone to tumbling if gravity were acting on it, so it was unwise to attempt a landing on the moon without first testing the LM's stability in gravity.
Obviously I disagree that rotational stability depends on gravity. But I don't intend that to mean that once you have a rotationally stable spacecraft, you've solved all the landing problems. The LM pilot still has to deal with gravity, just not as a rotational factor; it's still a force pulling him in a certain direction. But that's a pilot training issue. You don't have to put an actual LM in an actual lunar gravity field in order to acquaint the pilot with sink rate and altitude.
I'm not prepared to accept this statement without an argument to support it. My argument is simple logical one.
All arguments attempt to use logic. Some arguments additionally require accurate, specialized knowledge that serve as premises to the argument. You attempt to argue logically, but in the process you propose statements whose truthfulness is a matter of study and experimentation in classical dynamics. You cannot assert the correctness of your argument without proving the truthfulness of the premises on which it is based. Since you've tacitly admitted you don't have the appropriate knowledge, we naturally question whether you know your premise is true.
To test the Lunar Lander successfully you should have as close to the actual conditions as possible.
The question is not that simple.
Yes, fidelity is the basic tenet of test methodology. But from that it does not follow that every condition present in or absent from the test affects the fidelity of the test. Some are irrelevant to the outcome.
If classical dynamics -- which has accurately predicted the physical behavior of objects for 400 years -- tells us that gravity has no effect on rotational stability, then that's how we know that manueverability tests of the LM in Earth orbit will accurately measure the manueverability of the LM as it hovers over the lunar surface. It is not necessary to perform that test again in gravity.
Devising a feasible and valid test plan is precisely about knowing which variables affect the outcome of some test and which do not. It is also about knowing which variables apply during operation and which do not. It is most certainly not about broad, sweeping assumptions of relevance.
Here you're telling us that we have to duplicate the intended operational environment as closely as possible. Yet for some reason you think duplicating it on Earth, in Earth gravity, in atmosphere is somehow a faithful test. Let's say your test flight failed because there was a gust of wind. Since the LM wasn't design to deal with air, that flight would tell you nothing about whether the LM might have flown correctly without air.
If you want to duplicate the intended operational environment of the LM as faithfully as possible for the actual landing, fly it in 1/6 gravity with no air. That's how LM-5 was tested on Apollo 11.
The fidelity of the prototype matters too. If the test procedure is cumulative, the final test prototype will have to exhibit all the significant properties of the actual flight article. And that means it will be largely indistinguishable from the flight article. LM-5 was used as the final prototype, but it was a fully-functional LM for all intents and purposes.
Gravity is an essential aspect of those conditions isnt it...
No. Gravity is irrelevant to rotational stability in a free body. Since that was a premise of your logical argument, your argument fails logically because its premise is false.
Maybe its those spindly legs. How much to they weigh?
I asked for your calculations, not "maybe". Analyzing the mass properties of a composite object is not a matter of casual inspection of photographs of it.
Since it's clear you have undertaken no study to support your allegation that the LM was top-heavy, I reject it as unsupported. I further emphasize that the location of the center of gravity does not affect rotational stability.
Just a guess.
No, just a straw man. Your belief depends on the premise that rotational stability is impossible. To buttress that belief, you propose a completely impractical solution and imply that's the only way it could be solved.
Im glad you see it as a problem however.
No, you misunderstand. I'm using the engineering definition of "problem". When an engineer identifies something as a "problem" he is simply talking about some complete and consistent set of objectives and constraints. He is not identifying a situation for which there is no solution.
For example, an engineer may speak about the "problem" of knowing how much gasoline is in a car's tank. That implies an objective (present the operator with accurate, real-time information about the fuel quantity). It implies some constraints (do not introduce any ignition hazard; do not move the tank to an awkward location; etc.). His use of the word "problem" doesn't suggest he's stumped, or that it's a particularly difficult thing to do. There are a number of potential solutions: weight transducers on the gas-tank mount, electrical quantity transducers in the tank itself, an inspect port.
So when I speak about the "problem" of rotational stability, I'm by no means agreeing with you that it's intractable, or even particularly difficult. In fact, I maintain that the problem has been solved for approximately 70 years and that a variety of feasible straightforward solutions are available to the designer.
The gimballed axis thrust allowed for what.- 4-6 degrees of adjustment?
DPS gimballing was not the only means of changing the LM's attitude. Plus, you beg the question that 6 degrees of deflection is insufficient.
Wasnt that what happened to "Snoopy"?
Yes it went out of control, but not because of inherent vehicle instability or because of some outside influence. The pilots selected the wrong guidance platform by mistake. The digital autopilot therefore got the wrong idea of where the spacecraft was supposed to be pointing, and fired the reaction control system to reorient the spacecraft to its "correct" attitude. The pilots disengaged the autopilot and regained control manually, again by firing the reaction control system jets.
If the passenger in your car reaches over and yanks your steering wheel hard over, that's not proof that your car is uncontrollable.
Now you're telling us you have evidence that the LM was tested, but that it failed the tests. I'd like to see that evidence, please. If NASA has no film of it, that is evidence that no film of it exists. Simple deductive reasoning here.
No, fallacious attempts at deductive reasoning. First, absence of evidence is not evidence of absence. Second, saying there is no evidence the LM passed a test is most certainly not the same as being able to assert it failed the test. If you claim the LM failed some test, you have the burden of proof to provide direct evidence of the test and direct evidence of the failure. That burden is not satisfied by an argument from silence.
But it certainly has plenty of other effects to deal with such as manuvering in the vacuum of space.
What exact effect does the "vacuum of space" have on the rotational stability of the lunar module?
Ask the Apoolo 10 crew how easy it was.
The incident on Apollo 10 was not caused by any outside factor. It was caused by a misconfiguration of the guidance system that resulted in an uncommanded change of attitude using the vehicle's own manuevering system. It was corrected in a matter of seconds by commanded changes using the same system under manual control. Nothing associated with vacuum was a factor in this incident.
The instability comes not from the design, but from outside forces working against it.
What exact outside forces? How exactly do they affect the rotational stability of the LM?
You mentioned gravity, but that's irrelevant. Gravity does not affect rotational stability.
You mentioned vacuum (or conversely, air). But you seem to imply that air is required as a medium by which to exert control. That's certainly how aircraft work, but only because we have chosen to exploit the benefits air provides. It's not true because any rotational stability solution requires air. Aircraft require air only because we designed them (not inappropriately) to require air. We can certainly build aircraft that use an RCS for rotational stability. The Harrier is an example. But for ordinary aircraft that's impractical. Aerodynamic control surfaces are far simpler and more efficient.
But since we can't use control surfaces in space, we use an RCS. That's by no means the only solution that would work; we could use gyrodynes instead. But because gyrodynes provide only rotational control and the LM would also need translational control, the RCS solution (which provides both) kills two birds with one stone. And it's by no means true that RCS systems or gyrodynes are somehow less effective or harder to build and operate. So saying that rotational control is intractable without the presence of air is pure hogwash.
Air is instead a nuisance to rotational stability because it moves around and changes an object's attitude unpredictably. Yes, it provides a medium by which aerodynamic control can be achieved, but it also provides the primary need for such control. The LM does not have to deal with attitude changes resulting from moving air around it, so its attitude-hold problem is simpler.
You say the LM was "top-heavy" implying that its mass properties are to blame for its instability. Now you say outside forces acting on the LM made it unstable. Which is it? Or is it a combination of the two?
Thats a pretty big source for you to be making it sound like a small problem isnt it?
Begging the question.
Please stop adressing vertical landing prroblems with vertical takeoff and flight trajectory proofs. Talk about changing horses.
They are equivalent problems.
You clearly have no understanding of dynamics. Yet you maintain that your beliefs predicated on misunderstanding those principles must somehow be correct and defensible.
How many do you mean by miltiple thrusters?
Two pair in each axis, plus four in the hover translation axis. Have you paid much attention to the LM's appearance? The steering jets are rigged prominently on the ascent stage.
And where exactly was the gyro located?
In the LM's Inertial Measurement Unit (IMU), located above the astronauts' heads in the cabin ceiling of the ascent stage. In addition there were strap-down gyros for the backup guidance system attached to various places in the ascent-stage frame. You could have found this out from any number of searchable online sources. Why did you assert that the LM had none before you checked whether it did?
Goddard never worked on a rocket vertical landing problem that he could solve.
Goddard proved that gravity was irrelevant to the rotational control of a rocket. Therefore the presence, absence, or movement of the rocket through a gravity field is irrelevant to maintaining rotational stability. Where the problem of vertical landing is described as a rotational stability problem, gravity still does not affect the solution to that problem.
Im from Missouri Show me.
You were shown.
In Kansas, where I grew up, we have another saying: "All hat and no cattle." That pretty much describes your approach here.
You dont have to be a weatherman to know which way the wind blows do you?
No, but you do have to be one to know correctly why it does. Just because some questions can be correctly answered by untrained observation doesn't mean all can be. And just because you think a question is straightforward doesn't mean it is. If I ask you which way the wind blows and you point the wrong direction, that's enough evidence that it's not as easy as you think to figure out.
Science exists precisely to compensate for the errors of presumptive intuition.
Indeed they are. Impossibly finicky.
Tell that to the designers of the SSME. We've been operating powerful, human-rated, variable-thrust rocket engines successfully for more than 20 years with only one operational failure (non-catastrophic) in more than 300 operational firings. They are somewhat more complicated than fixed-thrust engines, but not "impossibly" so. You're assertion is rejected empirically.
Jay, your avoidance of real proof is understandable because you have none.
Get real. You came here intending to show at all costs that we had no "real proof" for the LM's viability, because that's what you wanted to continue believing. No wonder then that you say you've failed to find any, even though you've been moving goal posts as fast as possible trying to redefine "real proof" according to what you suspect we can't provide. Do you really think you're fooling anyone?
You want to skip to the chase. You asked for documents; we can't provide it; therefore you win. Instead we're showing that you're asking in some cases for something you only presume should exist, and in other cases for things you've already been given but choose to ignore.
I do hope you can show me where I am being ignorant of the "facts" or the "laws of physics" here.
Those demonstrations were given and repeatedly ignored. It is too late in the game to sweep your arrogance under the rug. If you'd like to apologize, retract your claims, and instead start asking honest questions, then perhaps we can re-engage this discussion on a more productive footing.
Just dont call me ignorant anymore.
It's not anyone's fault but your own that you pretend to have knowledge you don't have. When you smugly contradict knowledgeable people under that pretense, you're going to be dismissed as ignorant. Not knowing what you're talking about has consequences.
I know alot more that you are giving me credit for.
You get credit for any correct knowledge you can display. But you also get a debit for being stubbornly wrong.
Now, what do you know about this...
A whole lot. I've been an engineer in this field for more than 15 years.
...and where am I listening to the wrong people?
I have no idea what your sources are. I can only tell you where you're either wrong or making an assumption. It's up to you to identify who gave you that wrong information and decide what to do about it.
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Post by Alliterative Andy on Feb 22, 2007 18:03:02 GMT -4
Here's another point concerning rocket powered VTOL that I, a relatively unknowledgeable fan of Apollo, realized was that the competition vehicles are actually attempting to do things which the LM was not designed to do.
The LM was designed to first land as a whole unit, and then the ascent module would later take off. The competition vehicles are designed to first lift off, and then land as a whole unit.
You dont have to be a weatherman to know which way the wind blows do you?
But you do have to have some knowledge of meteorology in order to understand what the weatherman means when he says "southerly winds." If you don't, it behooves you to learn, rather than pretend that you know and claim that he is wrong.
So, what does "southerly winds" mean?
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Post by svector on Feb 22, 2007 18:24:39 GMT -4
Can any of you Apollo gurus identify the cylindrical silver object seen reflected in the window in my video at approx. 2:06? It also appears at 3:17. Are these pressure suit connectors? www.youtube.com/watch?v=_SRV7elUFjoAlso, how easy or difficult would it have been to see the LM through one of the CSM side windows (1 or 5), while they were docked?
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Post by PhantomWolf on Feb 22, 2007 19:00:45 GMT -4
im talking about vertical landing- not vertical takeoff.And it's already been pointed out that the Delta Clipper was highly successful (until someone forgot to plug in the helium line to one of the legs.)
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