Author Topic: Apollo 11 Lunar Lander Pre-Launch  (Read 24470 times)

Offline JayUtah

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Re: Apollo 11 Lunar Lander Pre-Launch
« Reply #570 on: May 01, 2019, 04:25:09 PM »
Well, congratulations, you win at basic human decency. Here's your ticker tape parade...

The social engineering is a bit more subtle than that, I wager.  The unspoken addendum to the defense, "I've been kind and polite," is "...while you guys have not."  It's the age-old ploy of trying to soften an opponent's criticism by making it socially or morally undesirable to offer it.  His references to his own virtue are contrasted against shaming his critics for disrespecting someone whose views differ -- again, forcing the discussion to be about moral approbation rather than fact.  Seen in the light of it being no more sincere than a rhetorical ploy, I'm inclined more toward the "condescending and passive-aggressive" interpretation.  I don't give praise for insincere politeness.  If he's doing what amounts to calling me a bald-faced liar, then no apparent sweetness can be genuine.

Quote
Now, I agree that being polite and level headed in discussions on contentious topic is valuable skill, but it doesn't change facts.

Delivering factually bankrupt speculation and supercilious opinions coated in counterfeit sugar doesn't do it for me.  That's just the Dolores Umbridge version of politeness.
"Facts are stubborn things." --John Adams

Offline JayUtah

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Re: Apollo 11 Lunar Lander Pre-Launch
« Reply #571 on: May 04, 2019, 12:35:52 PM »
All right, Jr.  Let's momentarily table everything except LM stability with the plume deflectors added.  It's not the original topic of the thread, but it's the topic on which I think we've reached the clearest moment of truth.

You told us there was a "paper" that proved the LM was unacceptably unstable with the plume deflectors attached.  Specifically you told us that an unacceptable feedback mode would arise.  You also specifically invoked the special nature of a "paper" in conveying, via such exercises as peer review, a sense of rigor and reliability in its findings.  You then produced this document.

The first thing we noticed is that it was not a paper (as scientists use the term, and as you intended it to be received) but rather a technical memo circulated among the usual suspects.  (Circuit memos were the 1960s equivalent of today's email chain.)  At that point you needed to have conceded that the document did not convey the degree of authority you purported.  But you did not.  You asserted, without evidence, that you must have been thinking of some other documentary source, which you still have not produced.  No critic is obliged to consider evidence that the proponent merely imagines exists.  Further, we who know the science are skeptical such a document exists because we can ascertain via other means that the conclusion you purport that it reaches is precluded by other facts.

One of those facts is clearly presented in the document you did produce.  The dynamic properties of any freely moving and rotating vehicle are strictly governed by Newton's laws of motion.  Those laws can be considered quantitatively by linear algebra, which provides a way to represent various rotational phenomena as vectors and matrices.  (Tensors too, in many cases, but we don't need that just yet.)  The forces that arise naturally, and which we apply artificially, can be modeled as "linearized" elements (i.e., rendered as the constructs over which linear algebra is defined).  This includes the effect of plume deflectors.  It's not a mystery.  This is what the memo has done.  While the memo deals specifically with the case of the docked CSM-LM, it refers to mass properties in a way that applies also to the LM alone in all cases -- namely the location, direction, and strength of the force supplied by the plume deflector.  That is invariant.  What varies in the problem is where the  rigid-body center of mass lies.  The physical arrangement of any body limits where the center of mass can lie.  That in turn limits the extent and orientation of moment vectors.  This is as mathematically rigorous and inarguable as 1+1=2.

Linearized dynamics problems are not unique to spacecraft engineering, or even to engineering in general.  But they are not commonly taught in general education.  We do not expect a layman to have experienced them.  Therefore you can be forgiven for not knowing this technique exists, and for not understanding how it works.  But you should have conceded that you didn't understand the relevant topics.  But instead of doing that, you just double down on your claim.  If you don't understand how the mathematics work, and specifically how they constrain where the center of mass can be in order to result in positive feedback, say so.  Don't keep avoiding the issue and riding the current of ambiguity.  And don't keep whining about an improper standard of proof. If your claim is submissible to a mathematically rigorous level of modeling, then that is the standard that applies regardless of your desires otherwise.  Your ignorance of the standard or your inability to meet it don't somehow let you off the hook.  You don't get to reject the standard just because it rejects your desired belief.

You tried a handwaving rejoinder (i.e., lots of performance but no substance) alluding to what you felt was the inherent fragility of any free body's dynamic behavior, and of the reliability of the Apollo RCS system.  The former simply doubles down on your "different view" without addressing any of the contravening fact.  The latter was thoroughly investigated from the documented engineering responses to the occurrence.  We discovered that you egregiously misrepresented both the nature of the RCS failures and their ability to present a hazard and affect mission success.  This is excusable by itself, since it involves equipment and principles of operation that are not common knowledge.  If you don't understand the engineering implications of what you read then you should concede as much, especially when corrected by professional practitioners who do know the equipment.  But you did not.  Further statements from the trove your memo was drawn from cast doubts upon your interpretation.  These were brought to your attention, but you simply ignored them as if they didn't exist.

Not knowing things such as (a) what a "paper" is, (b) the difference between positive and negative feedback, (c) what mathematics and physics govern free-body stability, (d) how to read and properly interpret technical material, (e) what other principles and facts are presented in your sources -- all that poses a problem.  Your incidental behavior in these debates cannot fail to persuade your critics to create an interpretational canon for your case.  Your critics will apprehend that you really don't know what you're talking about, but that you are easily willing to bluff; that you are more interested in promoting your belief than in discovering the truth.  This canon inevitably colors how they receive your statements, even those you fully intend to be innocent and forthright.  All your pleas for lenience and your complaints against your critics will be heard under that canon and, as you have seen, dismissed as mere posturing.  You don't get to engage in that sort of behavior and then ask not to have to deal with its consequences.  If you want congenial home, don't [expletive] the bed.

The quantitative stability of the LM is a ruthless matter of fact.  Your "different view" to the contrary is irrelevant.  You need to warm up to the notion that things you might have an opinion on are, to the contrary, matters of discernible fact -- and that your concerns really do have objectively discoverable right and wrong answers.  The items in boldface above need special attention from you.  The answer could legitimately be, "I guess I don't understand the math well enough to defend my belief, so I withdraw the claim."  You don't get to pretend that your ignorance is a safe position from which to rationally continue believing something.  If you can't address the math -- and it's clear you can't -- then you have to actually admit that you're wrong.  You have no reason to ask for friendly debate from others if you are unwilling to do that in this case.  Ignorance of fact is simply not a valid point of view.

Come on, Jr.  Prove you're actually as honest and virtuous as you proclaim yourself to be.  Close out this topic like a man.
"Facts are stubborn things." --John Adams

Offline Abaddon

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Re: Apollo 11 Lunar Lander Pre-Launch
« Reply #572 on: May 04, 2019, 01:02:58 PM »
Come on, Jr.  Prove you're actually as honest and virtuous as you proclaim yourself to be.  Close out this topic like a man.
Wait a minute, do we know for a fact that gender even exists among trolls?

Offline JayUtah

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Re: Apollo 11 Lunar Lander Pre-Launch
« Reply #573 on: May 04, 2019, 01:51:59 PM »
Come on, Jr.  Prove you're actually as honest and virtuous as you proclaim yourself to be.  Close out this topic like a man.
Wait a minute, do we know for a fact that gender even exists among trolls?

Good point.  Regardless, I wondered whether the phrase sounded sexist.  "...like a man" to me means something regardless of gender, but it could be considered inherently stereotypical.  The sentiment I wish to express is to rise to the occasion, regardless of hardship.  Apologies if anyone is offended.
"Facts are stubborn things." --John Adams

Offline bknight

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Re: Apollo 11 Lunar Lander Pre-Launch
« Reply #574 on: May 04, 2019, 02:45:01 PM »
All right, Jr.  Let's momentarily table everything except LM stability with the plume deflectors added.  It's not the original topic of the thread, but it's the topic on which I think we've reached the clearest moment of truth.

You told us there was a "paper" that proved the LM was unacceptably unstable with the plume deflectors attached.  Specifically you told us that an unacceptable feedback mode would arise.  You also specifically invoked the special nature of a "paper" in conveying, via such exercises as peer review, a sense of rigor and reliability in its findings.  You then produced this document.

The first thing we noticed is that it was not a paper (as scientists use the term, and as you intended it to be received) but rather a technical memo circulated among the usual suspects.  (Circuit memos were the 1960s equivalent of today's email chain.)  At that point you needed to have conceded that the document did not convey the degree of authority you purported.  But you did not.  You asserted, without evidence, that you must have been thinking of some other documentary source, which you still have not produced.  No critic is obliged to consider evidence that the proponent merely imagines exists.  Further, we who know the science are skeptical such a document exists because we can ascertain via other means that the conclusion you purport that it reaches is precluded by other facts.

One of those facts is clearly presented in the document you did produce.  The dynamic properties of any freely moving and rotating vehicle are strictly governed by Newton's laws of motion.  Those laws can be considered quantitatively by linear algebra, which provides a way to represent various rotational phenomena as vectors and matrices.  (Tensors too, in many cases, but we don't need that just yet.)  The forces that arise naturally, and which we apply artificially, can be modeled as "linearized" elements (i.e., rendered as the constructs over which linear algebra is defined).  This includes the effect of plume deflectors.  It's not a mystery.  This is what the memo has done.  While the memo deals specifically with the case of the docked CSM-LM, it refers to mass properties in a way that applies also to the LM alone in all cases -- namely the location, direction, and strength of the force supplied by the plume deflector.  That is invariant.  What varies in the problem is where the  rigid-body center of mass lies.  The physical arrangement of any body limits where the center of mass can lie.  That in turn limits the extent and orientation of moment vectors.  This is as mathematically rigorous and inarguable as 1+1=2.

Linearized dynamics problems are not unique to spacecraft engineering, or even to engineering in general.  But they are not commonly taught in general education.  We do not expect a layman to have experienced them.  Therefore you can be forgiven for not knowing this technique exists, and for not understanding how it works.  But you should have conceded that you didn't understand the relevant topics.  But instead of doing that, you just double down on your claim.  If you don't understand how the mathematics work, and specifically how they constrain where the center of mass can be in order to result in positive feedback, say so.  Don't keep avoiding the issue and riding the current of ambiguity.  And don't keep whining about an improper standard of proof. If your claim is submissible to a mathematically rigorous level of modeling, then that is the standard that applies regardless of your desires otherwise.  Your ignorance of the standard or your inability to meet it don't somehow let you off the hook.  You don't get to reject the standard just because it rejects your desired belief.

You tried a handwaving rejoinder (i.e., lots of performance but no substance) alluding to what you felt was the inherent fragility of any free body's dynamic behavior, and of the reliability of the Apollo RCS system.  The former simply doubles down on your "different view" without addressing any of the contravening fact.  The latter was thoroughly investigated from the documented engineering responses to the occurrence.  We discovered that you egregiously misrepresented both the nature of the RCS failures and their ability to present a hazard and affect mission success.  This is excusable by itself, since it involves equipment and principles of operation that are not common knowledge.  If you don't understand the engineering implications of what you read then you should concede as much, especially when corrected by professional practitioners who do know the equipment.  But you did not.  Further statements from the trove your memo was drawn from cast doubts upon your interpretation.  These were brought to your attention, but you simply ignored them as if they didn't exist.

Not knowing things such as (a) what a "paper" is, (b) the difference between positive and negative feedback, (c) what mathematics and physics govern free-body stability, (d) how to read and properly interpret technical material, (e) what other principles and facts are presented in your sources -- all that poses a problem.  Your incidental behavior in these debates cannot fail to persuade your critics to create an interpretational canon for your case.  Your critics will apprehend that you really don't know what you're talking about, but that you are easily willing to bluff; that you are more interested in promoting your belief than in discovering the truth.  This canon inevitably colors how they receive your statements, even those you fully intend to be innocent and forthright.  All your pleas for lenience and your complaints against your critics will be heard under that canon and, as you have seen, dismissed as mere posturing.  You don't get to engage in that sort of behavior and then ask not to have to deal with its consequences.  If you want congenial home, don't [expletive] the bed.

The quantitative stability of the LM is a ruthless matter of fact.  Your "different view" to the contrary is irrelevant.  You need to warm up to the notion that things you might have an opinion on are, to the contrary, matters of discernible fact -- and that your concerns really do have objectively discoverable right and wrong answers.  The items in boldface above need special attention from you.  The answer could legitimately be, "I guess I don't understand the math well enough to defend my belief, so I withdraw the claim."  You don't get to pretend that your ignorance is a safe position from which to rationally continue believing something.  If you can't address the math -- and it's clear you can't -- then you have to actually admit that you're wrong.  You have no reason to ask for friendly debate from others if you are unwilling to do that in this case.  Ignorance of fact is simply not a valid point of view.

Come on, Jr.  Prove you're actually as honest and virtuous as you proclaim yourself to be.  Close out this topic like a man.

I was not offended by the comment.  In fact as opposed to some I don't use terms such as "xxxman" as gender enduring.  I know I'm a dinosaur from the past and don't wish any retribution from those who may be more politically correct than I.

I, as an engineer, don't have the teachings of an aerospace degree so I can't speak to the math required to solve these equations.  But since I'm not looking for fakery or fraud, I take for granted that the institutions involved in the Apollo program hired individuals that had those backgrounds to solve issues.  Sure they made mistakes, but not fundamental in nature, so that the missions were conducted as envisioned, addressing certain unforeseen problems as they flew.  jr if you read the missions you would have read they were not problem free and need solutions. to issues that cropped up.  Your videos of LM rendezvous with CM are a classic example of poor analytical skills.  From ALJ on Apollo 12:
Quote
142:03:49 Conrad: Lift-Off.
142:03:50 Conrad: And away we go.
142:03:52 Bean: Boy, did it fire.
142:03:55 Conrad: Yawing? Looks pretty good
142:03:56 Bean: [Garble] our descent stage - holding on.
142:03:58 Conrad: Looks good. ALSEP looks good.
142:04:01 Bean: [Garble] It didn't get the ALSEP.
Public Affairs Office - "Looking good."
142:04:03 Carr: Intrepid, Houston. Copy ignition; guidance looks good.
142:04:06 Conrad: Pitchover's looking good. Okay. Boy, you sure do [garble].
Public Affairs Office - "316 feet above the lunar surface."
142:04:15 Bean: Nice and quiet, isn't it?
142:04:16 Conrad: Firing like I don't know what.
142:04:18 Conrad: Mark.
142:04:19 Conrad: Thirty seconds. Thirty seconds; 177, 984.6, and out at 1900 feet.
Public Affairs Office - "1,594 feet above the lunar surface."
142:04:28 Bean: That's pretty good.
142:04:29 Conrad: We're on our way.
142:04:30 Bean: And at 1 minute, yaw right 20, Pete.
142:04:32 Conrad: Okay.
Public Affairs Office - "Velocity building up now, 264 feet per second."
142:04:38 Bean: Boy, there's that.
Public Affairs Office - "Coming up on 1 minute."
142:04:43 Conrad: Say again? Pitch program looks good.
142:04:50 Bean: Kind of wobbles around up here [garble].
142:04:51 Conrad: [Garble].
142:04:52 Carr: Intrepid, Houston. Looking good at 1 minute.
142:04:57 Conrad: Okay. We've yawed right 20. Keeping right down the pike.
142:05:02 Bean: Okay.
142:05:04 Conrad: What a nice...
142:05:05 Bean: Both tank pressures look good, Pete.
142:05:06 Conrad: What a nice ride!
142:05:07 Bean: RCS, right in there.
Public Affairs Office - "That's Conrad reporting they're going right down the pike."
142:05:10 Conrad: Yes.
142:05:11 Bean: Sure jumps every time those thrusters fire.
142:05:13 Conrad: Yes.
142:05:14 Bean: Flies smooth.[Garble] part of it.
142:05:20 Conrad: Mark, 1 plus 30, 745, 156. We're out at 9000 feet.
Public Affairs Office - "Presently 9000 feet above the lunar surface."
142:05:32 Bean: Too jumpy.
142:05:36 Conrad: Okay. It's just changing CG.
142:05:38 Bean: I know it. It's still smooth.

The RCS system on the LM corrected the changing CG, as Pete said, and it was a little "jerky"(my phrase), but not uncontrollable as jr would have us believe as he seems to believe.  No instability but controlled three dimensional movement.
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Offline Zakalwe

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Re: Apollo 11 Lunar Lander Pre-Launch
« Reply #575 on: May 04, 2019, 03:14:59 PM »
 Stealth flounce and hope for a fringe reset in 3,2,1........
"The strain of anti-intellectualism has been a constant thread winding its way through our political and cultural life, nurtured by the false notion that democracy means that 'my ignorance is just as good as your knowledge.' " - Isaac Asimov

Offline Dalhousie

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Re: Apollo 11 Lunar Lander Pre-Launch
« Reply #576 on: May 04, 2019, 07:13:54 PM »
Delivering factually bankrupt speculation and supercilious opinions coated in counterfeit sugar doesn't do it for me.  That's just the Dolores Umbridge version of politeness.

Excellent. I'll save that line.

Offline gillianren

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Re: Apollo 11 Lunar Lander Pre-Launch
« Reply #577 on: May 05, 2019, 11:20:46 AM »
Good point.  Regardless, I wondered whether the phrase sounded sexist.  "...like a man" to me means something regardless of gender, but it could be considered inherently stereotypical.  The sentiment I wish to express is to rise to the occasion, regardless of hardship.  Apologies if anyone is offended.

Not offended, but I'd suggest not using it.  Perhaps "an adult" would be a better version?  Because the whole point is that he needs to be responsible for his own actions, surely one of the important aspects of adulthood and something, I suggest, that I'm better at than any number of men.
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Offline JayUtah

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Re: Apollo 11 Lunar Lander Pre-Launch
« Reply #578 on: May 05, 2019, 11:24:46 AM »
Not offended, but I'd suggest not using it.  Perhaps "an adult" would be a better version?

Yep, there it is.  Thanks!
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Offline Jason Thompson

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Re: Apollo 11 Lunar Lander Pre-Launch
« Reply #579 on: May 05, 2019, 01:58:49 PM »
To save everyone digging around for earlier comments, this is what jr knowing wrote about this specific document. JR, I have pointed out where there are outstanding questions for you to answer in bold.

Hi Everyone,

Here is one of the MIT documents.

The document provided is a memo, not a paper.

Do you understand there is a difference between a paper and a memo, and concede that this document is not what you present it as?

Quote
I will try to dig up the much more in depth paper.

It is months later, so where is this 'more in depth' paper?

Quote
To be clear it states

"Due to the presence of jet plume deflectors on the LM descent
stage, the use of +X thrusting LM jets for pitch or roll attitude control
of the CSM-docked configuration will"  "cause a
serious control instability"

This is what it actually states, and I have highlighted the bits you failed to quote:

Due to the presence of jet plume deflectors on the LM descent stage, the use of +X thrusting LM jets for pitch or roll control will, for some mass loadings, cause a serious control instability if any -X thrusting jets have failed off or been disabled.


Why did you snip those out of your quote?

I have attached an image of the text from the memo as well.

As is made quite clear, this instability ony arises in certain cases, where a very specific combination of mass loading of a CSM-LM docked spacecraft and failed or disabled -X RCS jets occurs. This is not an inherent instability of the craft caused by plume deflectors as jr mischaracterises it by his selective quoting.

Quote
Further it goes onto state that less than ideal conditions will lead to a positive feedback loop that will cause

"the vehicle will spin uncontrollably
in the counter clockwise direction."

What it actually says is that in very specific circumstances (not 'less than ideal', which makes it sound like the circumstances under which stability is achieved are the anomalous ones) a positive feedback loop will result under automatic control.

The memo includes a diagram (also attached) and a very simple mathematical equation to describe the circumstances where this instability will arise. The equation is:

M+X = (89lb)D1 - (59lb)D2

M+X is the net rotational moment (clockwise in relation to the diagram) around the centre of gravity caused by a jet plume from the RCS jet on the left side of the diagram that impinges on the plume deflector, assuming the one on the right is not working. Treating the spacecraft stack as vertical with respect to the LM (so the CSM is 'on top of' the LM) D1 is the horizontal distance between the centre of gravity and the RCS nozzle (essentially half the width of the LM and to all intents and purposes a constant in this equation), and D2 is the vertical height of the centre of gravity above the plane of plume impingement on the deflector. Because of the changing fuel and consumable loads of the two vehicles during the mission, D2 is the variable.

It can be seen that if D2 is long enough then the result for M+X can be negative. In this case the spacecraft stack will actually rotate in the opposite direction than intended. Under automatic control of course the system would try to compensate by firing the jet more and hence increasing the rotation in the wrong direction.

JR, do you understand that the memo is referring to the stacked spacecratf only?

Do you understand that the instability only occurs if a -X jet is not working or has been disabled?

Do you understand that this instability only occurs under automatic control?


Now we can do a little bit of mathematics ourselves. If:

M+X = 89D1 - 59D2

It follows that M+X is negative (the condition under which the control instability occurs) only if 59D2 > 89D1. This can be re-written as D2 > (89/59)D1. 89/59 is near enough 90/60, or 1.5, so M+X is only negative where D2 > 1.5D1.

JR, do you accept that or not, and if not why not?

JR claims that this control instability must be worse for the LM in solo flight, but you can see from the mathematics that instability only occurs when the centre of gravity lies more than 1.5 times the horizontal radius of the LM RCS system above the plane of impingement of the jet plume on the deflector. This places it above the docking hatch of the LM, so you can see that this instability can only occur with the CSM docked.

There is also a graph (again attached) that shows the region of instability in terms of mass and centre of gravity and total spacecraft mass, and again you can see that the LM alone does not fall into this zone of instability. What's more, the zone outside the grey area is described as a zone of increased stability in the case of diabled or failed -X jets.

Fially, the memo finishes with an instruction on how the crew can avoid the instability by using manual control and siabling other jets to avoid it in the first place.

JR, do you accept that this instruction is included in the memo?

With all of this information in this one document, I expect JR to be able to show how it actually supports his contention of LM instability caused by the plume deflectors, or to concede it does neither.

JR, which of these will you do?

And here is the ink to the memo itself:

https://www.ibiblio.org/apollo/Documents/LUM117_text.pdf
« Last Edit: May 05, 2019, 02:01:50 PM by Jason Thompson »
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Offline bknight

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Re: Apollo 11 Lunar Lander Pre-Launch
« Reply #580 on: May 05, 2019, 03:02:59 PM »
Jason, I believe that jrk will not accept the premises and will continue to splash about in his CT contortions.  But excellent recount of what has been posted.  :)
Truth needs no defense.  Nobody can take those footsteps I made on the surface of the moon away from me.
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Offline molesworth

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Re: Apollo 11 Lunar Lander Pre-Launch
« Reply #581 on: May 05, 2019, 04:28:10 PM »
Thanks for the excellent summary of the "paper", aka memo, Jason.
Quote
To be clear it states

"Due to the presence of jet plume deflectors on the LM descent
stage, the use of +X thrusting LM jets for pitch or roll attitude control
of the CSM-docked configuration will"  "cause a
serious control instability"

This is what it actually states, and I have highlighted the bits you failed to quote:

Due to the presence of jet plume deflectors on the LM descent stage, the use of +X thrusting LM jets for pitch or roll control will, for some mass loadings, cause a serious control instability if any -X thrusting jets have failed off or been disabled.


Why did you snip those out of your quote?

I have attached an image of the text from the memo as well.
I'm actually surprised that JRK made such a blatant attempt to misrepresent the contents of the memo, since it was pretty much certain that it would be examined in detail.  However, it's not an uncommon tactic for hoax-believers.

The memo includes a diagram (also attached) and a very simple mathematical equation to describe the circumstances where this instability will arise. The equation is:

M+X = (89lb)D1 - (59lb)D2

M+X is the net rotational moment (clockwise in relation to the diagram) around the centre of gravity caused by a jet plume from the RCS jet on the left side of the diagram that impinges on the plume deflector, assuming the one on the right is not working. Treating the spacecraft stack as vertical with respect to the LM (so the CSM is 'on top of' the LM) D1 is the horizontal distance between the centre of gravity and the RCS nozzle (essentially half the width of the LM and to all intents and purposes a constant in this equation), and D2 is the vertical height of the centre of gravity above the plane of plume impingement on the deflector. Because of the changing fuel and consumable loads of the two vehicles during the mission, D2 is the variable.

It can be seen that if D2 is long enough then the result for M+X can be negative. In this case the spacecraft stack will actually rotate in the opposite direction than intended. Under automatic control of course the system would try to compensate by firing the jet more and hence increasing the rotation in the wrong direction.

JR, do you understand that the memo is referring to the stacked spacecratf only?

Do you understand that the instability only occurs if a -X jet is not working or has been disabled?

Do you understand that this instability only occurs under automatic control?


Now we can do a little bit of mathematics ourselves. If:

M+X = 89D1 - 59D2

It follows that M+X is negative (the condition under which the control instability occurs) only if 59D2 > 89D1. This can be re-written as D2 > (89/59)D1. 89/59 is near enough 90/60, or 1.5, so M+X is only negative where D2 > 1.5D1.

JR, do you accept that or not, and if not why not?

JR claims that this control instability must be worse for the LM in solo flight, but you can see from the mathematics that instability only occurs when the centre of gravity lies more than 1.5 times the horizontal radius of the LM RCS system above the plane of impingement of the jet plume on the deflector. This places it above the docking hatch of the LM, so you can see that this instability can only occur with the CSM docked.
Unfortunately JRK seems to avoid doing any kind of calculation, even one as simple as this, which leads me to suspect his understanding of maths and physics is very limited.  I've pointed out to him that the science and engineering beats any "feelings" and "expectations" every time, and challenged him to produce some mathematical basis for his claims, but I don't expect to ever see a response.

I suspect that's also the reason for the Gish-gallop - he's very quickly out of his depth on any topic, so has to keep changing tack.
Days spent at sea are not deducted from one's allotted span - Phoenician proverb

Offline JayUtah

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Re: Apollo 11 Lunar Lander Pre-Launch
« Reply #582 on: May 05, 2019, 06:54:41 PM »
I'm actually surprised that JRK made such a blatant attempt to misrepresent the contents of the memo[.]

Indeed.  I've been giving him the benefit of the doubt and suggesting merely that he doesn't understand the underlying science or procedure.  But there's always something suspicious about an author who knows exactly what to leave out.

Quote
I've pointed out to him that the science and engineering beats any "feelings" and "expectations" every time...

Some people simply don't want to acknowledge that the world works in that particular way, because they are not proficient with math and believe themselves instead to be highly intuitive.  In other words, they convince themselves that their common sense is finely honed to serve a variety of needs, even if a more objective and rigorous process disagrees.  I think this is why he so quickly shifts over into advocating "different thinking" and trying to shame people who don't appreciate the fresh, enlightened perspective he's bringing to the subject.

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I suspect that's also the reason for the Gish-gallop - he's very quickly out of his depth on any topic, so has to keep changing tack.

Because the ultimate goal is ego reinforcement.  He has to show that his "different thinking" method and layman's observation get the right answer on at least something.  When he fails to keep the discourse steered in the direction of "common sense" observation and intuition, he has to abandon that ship and try again.
"Facts are stubborn things." --John Adams

Offline Dalhousie

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Re: Apollo 11 Lunar Lander Pre-Launch
« Reply #583 on: May 05, 2019, 07:32:24 PM »
Because the ultimate goal is ego reinforcement.  He has to show that his "different thinking" method and layman's observation get the right answer on at least something.  When he fails to keep the discourse steered in the direction of "common sense" observation and intuition, he has to abandon that ship and try again.

And if he can prove himself right on one thing, he can convince himself he is right about the others.

Offline JayUtah

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Re: Apollo 11 Lunar Lander Pre-Launch
« Reply #584 on: May 05, 2019, 08:19:22 PM »
And if he can prove himself right on one thing, he can convince himself he is right about the others.

Yes.  He figures it might take him several tries, but "finally' he'll prove that his particular brand of deep thought trumps everyone else's sheepish book-larnin'.
"Facts are stubborn things." --John Adams