Author Topic: Were the Lunar Rovers faked?  (Read 279682 times)

Offline Jason Thompson

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Re: Were the Lunar Rovers faked?
« Reply #495 on: April 04, 2013, 06:51:32 AM »
Okay, a quick look around shows it is generally a force, so  I apologise for the obstinance and confusion.

Thank you.
"There's this idea that everyone's opinion is equally valid. My arse! Bloke who was a professor of dentistry for forty years does NOT have a debate with some eejit who removes his teeth with string and a door!"  - Dara O'Briain

Offline Jason Thompson

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Re: Were the Lunar Rovers faked?
« Reply #496 on: April 04, 2013, 07:03:52 AM »
And by the way I hope my reasoning is correct. I'm sure someone will correct me if I'm wrong, since I'm not an engineer.
"There's this idea that everyone's opinion is equally valid. My arse! Bloke who was a professor of dentistry for forty years does NOT have a debate with some eejit who removes his teeth with string and a door!"  - Dara O'Briain

Offline anywho

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Re: Were the Lunar Rovers faked?
« Reply #497 on: April 04, 2013, 10:05:54 AM »

So why are they applying a load? Because once it starts climbing a slope (which is what they are applying their conclusions on the rover's behaviour to), the weight of the vehicle is resisting the forward motion.

They could also extrapolate the results to acceleration rather than a slope if they wanted. How would they get a vehicle that requires pull coefficient of 5 to accellerate when all their testing shows traction failing at about 0.5?

Either way, if you want to only relate it to a slope then the results are still impossible for the rovers to operate on the moon, the results clearly show it could not start on or climb even the mildest of slopes.

Even if you get a rover going on a downslope and use momentum to keep it going over a flat area, once even a slight incline is needed to be driven up under the power of the rover (not momentum) then the test show the rover traction will fail.

If a pull coefficient of 5 is needed to drive the vehicle along the flat (ignoring momentum) then on even a mild slope it will be greater, and the test show the rovers can only sustain traction at around 0.5 or 0.6

Offline JayUtah

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Re: Were the Lunar Rovers faked?
« Reply #498 on: April 04, 2013, 10:11:30 AM »
So we should take the test results, that are specific to the lunar rover and lunar soil, then extrapolate those results to a locomotive...

No, you should have looked at how the comparable results are obtained and reported for locomotives, to help you arrive at your belated realization that you didn't know what the heck you're talking about.  You have a substantial lack of qualitative understanding about how to measure vehicle performance, stemming from a fundamental ignorance of basic physical principles.

You may want to revisit your claim that every engineer in the world is wrong and that you, decades later, seem to be the only one that has discovered the alleged impossibility of the LRV.
"Facts are stubborn things." --John Adams

Offline JayUtah

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Re: Were the Lunar Rovers faked?
« Reply #499 on: April 04, 2013, 10:24:38 AM »
They could also extrapolate the results to acceleration rather than a slope if they wanted. How would they get a vehicle that requires pull coefficient of 5 to accellerate when all their testing shows traction failing at about 0.5?

To accelerate at what rate?
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Offline Jason Thompson

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Re: Were the Lunar Rovers faked?
« Reply #500 on: April 04, 2013, 10:26:50 AM »
They could also extrapolate the results to acceleration rather than a slope if they wanted. How would they get a vehicle that requires pull coefficient of 5 to accellerate when all their testing shows traction failing at about 0.5?

Once again, the wheels are operating at a constant speed. The vehicle does NOT require a pull coefficient of 5 to accelerate. It can accelerate with any force and whatever speed it likes. F = ma. On a level surface it does NOT have to pull with a force equal to or greater than its weight or mass. You even said that yourself in an earlier post. Why are you now insisting otherwise?

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Either way, if you want to only relate it to a slope then the results are still impossible for the rovers to operate on the moon, the results clearly show it could not start on or climb even the mildest of slopes.

No, the results show that it can't run at that speed up slopes of about 25 degrees without slipping too much.

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If a pull coefficient of 5 is needed to drive the vehicle along the flat

Which it isn't, for reasons gone over so many times now I have to wonder if you're just being argumentative for the sake of it.
"There's this idea that everyone's opinion is equally valid. My arse! Bloke who was a professor of dentistry for forty years does NOT have a debate with some eejit who removes his teeth with string and a door!"  - Dara O'Briain

Offline Zakalwe

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Re: Were the Lunar Rovers faked?
« Reply #501 on: April 04, 2013, 12:16:22 PM »

Did you hear the one about the Irish Zamboni driver?

He wanted to take the Zamboni on a hill-climb, but he abandoned the idea when he couldn't find an Ice Hockey rink on a hillside.

^^Nice line in racism. What's for your encore? Pointing out that women are weaker than men? That all Muslims are terrorists?


An apology for making out that a nation's people are stupid and backward just because they happened to be born in a certain geography would be welcome. Especially as The Learning Curve report places the Irish education system ahead of Denmark, Australia, Poland, Germany, Belgium and the US (amongst others).
http://thelearningcurve.pearson.com/the-report
"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 nomuse

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Re: Were the Lunar Rovers faked?
« Reply #502 on: April 04, 2013, 12:19:33 PM »

So we should take the test results, that are specific to the lunar rover and lunar soil, then extrapolate those results to a locomotive, then extrapolate back to the lunar rover and declare that the rover can therefore far exceed what the tests show the limits are?

If you do a simulated test you do not have to extrapolate the results away from the rover and then back to it, you only have to look at the results directly.

...

No.

It's called a sanity check.

You test your method against a known quantity.  If it returns nonsense -- in this case, if your method tells you a locomotive can't work -- then you know there are problems with the method.

It is exactly the same as testing a tester, or calibrating a measuring device.  Before you trust it to tell you about an unknown, you check to see if it returns data in agreement with a known.
« Last Edit: April 04, 2013, 12:21:35 PM by nomuse »

Offline anywho

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Re: Were the Lunar Rovers faked?
« Reply #503 on: April 04, 2013, 12:32:52 PM »
They could also extrapolate the results to acceleration rather than a slope if they wanted. How would they get a vehicle that requires pull coefficient of 5 to accellerate when all their testing shows traction failing at about 0.5?

To accelerate at what rate?

Any rate. a (traction) pull coefficient of 5 is the minimum needed, the faster you want to accelerate the higher that will go.

Please note that when I am talking about pull coefficient or drawbar pull I am talking about the formula in the army test, so it is not a measurement of force, it is a measurement of the mass the wheel can pull before traction is useless.

The wheel has a 57lb load on it, on the moon it needs enough traction to pull 342lbs to accelerate, or 6 times the wheel load, which equates to a drawbar pull of 5.

They could also extrapolate the results to acceleration rather than a slope if they wanted. How would they get a vehicle that requires pull coefficient of 5 to accellerate when all their testing shows traction failing at about 0.5?

Once again, the wheels are operating at a constant speed. The vehicle does NOT require a pull coefficient of 5 to accelerate. It can accelerate with any force and whatever speed it likes. F = ma. On a level surface it does NOT have to pull with a force equal to or greater than its weight or mass. You even said that yourself in an earlier post. Why are you now insisting otherwise?

Once again for clarity, in the army test the pull coefficient is the amount of mass the wheel can pull (above and beyond it's own load) before traction becomes useless, it is not a force.

So yes, the wheel does not have to be able to pull with a force anywhere near its own weight to move, but it does have to be able to get enough traction to pull 6 times its weight. This equates to, using the army testing method, a pull coefficient of 5.

On earth the wheel only needs enough traction to pull it's own weight.

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Either way, if you want to only relate it to a slope then the results are still impossible for the rovers to operate on the moon, the results clearly show it could not start on or climb even the mildest of slopes.

No, the results show that it can't run at that speed up slopes of about 25 degrees without slipping too much.

No the results show the wheel has enough reserve traction to go up a 25 degree slope on earth only.

When the testing shows a pull coefficient of 0.5 before traction is too problematic, it is saying the wheel has enough traction to drive the weight on it plus 50% more (which is enough to get it up a 25 degree slope here on earth).

But on the moon it needs enough traction to drive/pull the weight on it, plus 500% more.

Do you see what i am saying?

A wheel on earth with 57lbs of weight on it has to have enough traction to drive 1/4 of a vehicle weighing 228lbs.

On the moon a wheel with 57lbs of weight on it has to have enough traction to drive 1/4 of a vehicle weighing 1368lbs.

 

Offline gillianren

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Re: Were the Lunar Rovers faked?
« Reply #504 on: April 04, 2013, 12:46:08 PM »
I don't know if the method I was adamant about is archaic, or if there was different criteria among different sectors.

Have you ever, here or elsewhere, just considered the possibility that you might be wrong?  This is not intended to be an insult.  It is a serious and legitimate question.  Have you ever, anywhere along the proceedings, considered the possibility of your own error?  If not, why not?
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Offline JayUtah

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Re: Were the Lunar Rovers faked?
« Reply #505 on: April 04, 2013, 01:26:13 PM »
Any rate.

Nope.

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...a (traction) pull coefficient of 5 is the minimum needed...

Nope.

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Please note that when I am talking about pull coefficient or drawbar pull I am talking about...

No, do not redefine things to make it seem like you were still right.

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Do you see what i am saying?

I see what you're trying to say.  I also see a lot of patient people, including myself, trying to explain exactly how your understanding is in error.  But what I don't see is any indication from you that you've considered that you may be wrong on a fundamental level.  And I don't see any interest from you in determining whether your understanding is correct.
"Facts are stubborn things." --John Adams

Offline Andromeda

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Re: Were the Lunar Rovers faked?
« Reply #506 on: April 04, 2013, 02:30:53 PM »
Funny how Anywho has focused on Jason...
"The most exciting phrase to hear in science, the one that heralds new discoveries, is not 'Eureka!' but 'That's funny...'" - Isaac Asimov.

Offline Jason Thompson

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Re: Were the Lunar Rovers faked?
« Reply #507 on: April 04, 2013, 02:44:21 PM »
Any rate.

Wrong.

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a (traction) pull coefficient of 5 is the minimum needed, the faster you want to accelerate the higher that will go.

Wrong.

F = ma. How many times do i have to write that formula down for you? Since F = ma, it follows that a = F/m

If I have a 100 kg mass I can accelerate it with any force whatsoever. If I apply 1 Newton force I can accelerate it at 1/100 m/s^2. If I apply 10 N of force I can accelerate it at 1/10 m/s^2. If I shove it with 1,000,000 Newtons it will accelerate at 10,000 m/s^2. There is NO 'minimum force' required to accelerate any given mass, ignoring all other factors such as friction, rolling resistance etc. The thing that determines minimum force is any force that acts directly to oppose the motion the wheel is trying to impart. Since the wheel is trying to move the vehicle forward, the limiting force has to be one that acts 'backwards'. Weight does not do that on the level surface. Weight acts straight down. There is NO lateral component of weight that opposes forward motion. Therefore, weight is NOT directly a limiting factor in accelerating a vehicle forwards at any rate. It does of course affect things like traction and static friction, but you certainly do not need to exert a force equivalent to its weight just to get the vehicle moving. Hence I can push a car.

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Please note that when I am talking about pull coefficient or drawbar pull I am talking about the formula in the army test, so it is not a measurement of force, it is a measurement of the mass the wheel can pull before traction is useless.

No, it really is not. That is YOUR erroneous conclusion. I have already explained, twice, what those numbers actually represent and how that test applies to reality.

Drawbar pull, anywhere, is the force available to pull a load after the vehicle has moved itself. That's what it is in all cases, INLCUDING this test. You can keep on saying it means something else here, but the authors of that paper would not agree with you.

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The wheel has a 57lb load on it, on the moon it needs enough traction to pull 342lbs to accelerate, or 6 times the wheel load, which equates to a drawbar pull of 5.

No it does not.

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Once again for clarity, in the army test the pull coefficient is the amount of mass the wheel can pull (above and beyond it's own load) before traction becomes useless, it is not a force.

Which bit of what I have written about what those numbers actually represent is not clear to you?

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So yes, the wheel does not have to be able to pull with a force anywhere near its own weight to move, but it does have to be able to get enough traction to pull 6 times its weight.

No it does not. It ONLY has to pull against its own weight when the rover goes up a slope and its weight, which is an acceleration itself, is acting against the force the wheel is applying to move the rover forward.

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No the results show the wheel has enough reserve traction to go up a 25 degree slope on earth only.

No, they don't.

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When the testing shows a pull coefficient of 0.5 before traction is too problematic, it is saying the wheel has enough traction to drive the weight on it plus 50% more (which is enough to get it up a 25 degree slope here on earth).

But on the moon it needs enough traction to drive/pull the weight on it, plus 500% more.

No, it does not.

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Do you see what i am saying?

Yes, but that does not make you any more right.
 
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A wheel on earth with 57lbs of weight on it has to have enough traction to drive 1/4 of a vehicle weighing 228lbs.

On the moon a wheel with 57lbs of weight on it has to have enough traction to drive 1/4 of a vehicle weighing 1368lbs.

And how much traction is required to drive that?

Stop trying to redefine already well-defined parameters to make your argument fit your conclusion. drawbar pull is a measure of force, FULL STOP. That force does not have to exceed the weight of the vehicle to move it along the surface, ever. That's why I can push a car, a tractor can tow an airliner and a train can tow several carriages.
« Last Edit: April 04, 2013, 02:48:26 PM by Jason Thompson »
"There's this idea that everyone's opinion is equally valid. My arse! Bloke who was a professor of dentistry for forty years does NOT have a debate with some eejit who removes his teeth with string and a door!"  - Dara O'Briain

Offline smartcooky

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Re: Were the Lunar Rovers faked?
« Reply #508 on: April 04, 2013, 02:45:16 PM »

Did you hear the one about the Irish Zamboni driver?

He wanted to take the Zamboni on a hill-climb, but he abandoned the idea when he couldn't find an Ice Hockey rink on a hillside.

^^Nice line in racism. What's for your encore? Pointing out that women are weaker than men? That all Muslims are terrorists?


An apology for making out that a nation's people are stupid and backward just because they happened to be born in a certain geography would be welcome. Especially as The Learning Curve report places the Irish education system ahead of Denmark, Australia, Poland, Germany, Belgium and the US (amongst others).
http://thelearningcurve.pearson.com/the-report

OK, I'll apologise to myself then?

No! Wait! That would be only a half apology, since I'm only half-Irish (mother's side, Kerry born and bred!!)

Sometimes a joke is just a joke.


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Offline Abaddon

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Re: Were the Lunar Rovers faked?
« Reply #509 on: April 04, 2013, 03:08:55 PM »

Did you hear the one about the Irish Zamboni driver?

He wanted to take the Zamboni on a hill-climb, but he abandoned the idea when he couldn't find an Ice Hockey rink on a hillside.

^^Nice line in racism. What's for your encore? Pointing out that women are weaker than men? That all Muslims are terrorists?


An apology for making out that a nation's people are stupid and backward just because they happened to be born in a certain geography would be welcome. Especially as The Learning Curve report places the Irish education system ahead of Denmark, Australia, Poland, Germany, Belgium and the US (amongst others).
http://thelearningcurve.pearson.com/the-report
I am Irish. I take no offence at it.