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Old 09-10-2012, 06:29 PM   #81
MannoFr

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i don't think einstein said it either. or wrote it.

;-)
But he did walk on the Moon!
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Old 09-10-2012, 06:31 PM   #82
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F=ma and a=F/m
I think what you actually need here are the basic Kinematic Equations...
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Old 09-10-2012, 06:31 PM   #83
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anyway enough of feeding trolls there is real science to look at.
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Old 09-10-2012, 06:32 PM   #84
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might not be tower bridge on second looking.
Hammersmith bridge.
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Old 09-10-2012, 06:33 PM   #85
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ta PJ. been 30+ years since i was last in london. and i never knew it well then.
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Old 09-10-2012, 06:36 PM   #86
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F=ma and a=F/m
So what is the force put out by four 0.25hp electric motors?
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Old 09-10-2012, 06:38 PM   #87
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ta PJ. been 30+ years since i was last in london. and i never knew it well then.
A tops book would be a collection of the Thames bridges at London since they have moved all over the landscape but started with a soldier and a govt person at a suitable crossing point.

Can they still close down the Central City of London? Used to be closed down every night, no one who wasnt a resident couldnt get back till the gates opened.
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Old 09-10-2012, 06:39 PM   #88
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So what is the force put out by four 0.25hp electric motors?
Better use kW as horses can't breath on the Moon.
No oxygen and all that sort of thing.

~0.75 kW is enough to move a thing like a small scooter at about 40 km/h.
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Old 09-10-2012, 06:42 PM   #89
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Better use kW as horses can't breath on the Moon.
No oxygen and all that sort of thing.

~0.75 kW is enough to move a thing like a small scooter at about 40 km/h.
My point ( admittedly obscure) was that HP is not a force so f=ma is a bit hard to calculate
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Old 09-10-2012, 06:42 PM   #90
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Better use kW as horses can't breath on the Moon.
No oxygen and all that sort of thing.

~0.75 kW is enough to move a thing like a small scooter at about 40 km/h.
Given the recorded top speed of the rover was 11 km/h seems quite reasonable.
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Old 09-10-2012, 06:46 PM   #91
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Compressive forces of weight will be much less on the Moon.

Contact forces in the event of a collision with an obstacle will be similar (at similar speeds). If the rover was less strong then this certainly implies that a collision at similar speeds would do more damage to the rover than a similar collision would do to a stronger Earth-based rover. Interestingly the linked article describes avoiding obstacles as one of the biggest challenges of driving the rover on the Moon.

The working to show what the typical forces involved in small bumps, how they compare in magnitude with the weight forces and what kind of collision would be expected to reach the strength limit of the rover seems to be missing.
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Old 09-10-2012, 06:50 PM   #92
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In no way at all does this support a faked landing.

If L_D is correct that the vehicles were not strong enough to operate on the Moon, then by his own claim they were not strong enough to operate on Earth.

There is footage of the lunar rovers operating so obviously they worked somewhere.

If it was faked then the vehicles would have to be stronger than claimed so they could operate on Earth.

A vehicle strong enough to operate on Earth would have no problems operating on the moon.

So it would seem that the only two real options are:

L_D’s understanding of physics is wrong.
The claim that the rovers could not work on Earth is wrong.
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Old 09-10-2012, 06:51 PM   #93
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Given the recorded top speed of the rover was 11 km/h seems quite reasonable. The ARES link back there [points] had the top recorded speed as 22km/h.
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Old 09-10-2012, 06:53 PM   #94
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The ARES link back there [points] had the top recorded speed as 22km/h.
Oops my error, Wiki had it at 11 mph, 18 km/h.
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Old 09-10-2012, 06:53 PM   #95
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The ARES link back there [points] had the top recorded speed as 22km/h.
Righto.
I thought they cracked a mighty 11 mph going downhill in it, once.
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Old 09-10-2012, 06:53 PM   #96
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Still with one astronaut only taking it to about 863 lb.
863lbs is still a shirtload for 1 hp, I don't have youtube on this computer but from memory there is footage of two astronauts in the rover (taken from the rover camera) and by all accounts the rovers performed well fully loaded.

The performance must be staggering for 1 hp electric motors and only 150lbs? HOLD ON TO YOUR HATS LADIES!



BTW, 1 hp is actually quite a low powered mobility wheelchair, they can come in up to 3hp.
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Old 09-10-2012, 06:58 PM   #97
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The link says that they could drive at 17km/h but that 22km/h was recorded once on A-16 so that may well have been downhill.
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Old 09-10-2012, 07:02 PM   #98
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863lbs is still a shirtload for 1 hp, I don't have youtube on this computer but from memory there is footage of two astronauts in the rover (taken from the rover camera) and by all accounts the rovers performed well fully loaded.

The performance must be staggering for 1 hp electric motors and only 150lbs? HOLD ON TO YOUR HATS LADIES!



BTW, 1 hp is actually quite a low powered mobility wheelchair, they can come in up to 3hp.
And given they have to be limited to a certain speed for safety reasons, seems obvious 1 hp can give you a fair bit of performance.
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Old 09-10-2012, 07:02 PM   #99
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Here's a man, call him maybe 1 kW or so, pulling a ~200 tonne jet.



Pretty sure he could pull a ~700 kg lunar rover even faster and/or further. Though only as long as he could hold his breath on the Moon.
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Old 09-10-2012, 07:02 PM   #100
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In no way at all does this support a faked landing.

If L_D is correct that the vehicles were not strong enough to operate on the Moon, then by his own claim they were not strong enough to operate on Earth.

There is footage of the lunar rovers operating so obviously they worked somewhere.

If it was faked then the vehicles would have to be stronger than claimed so they could operate on Earth.

A vehicle strong enough to operate on Earth would have no problems operating on the moon.

So it would seem that the only two real options are:

L_D’s understanding of physics is wrong.
The claim that the rovers could not work on Earth is wrong.
They built stronger 1g models for Earth testing, there was absolutely no need to do that because if the Moon rovers can't handle being driven fully loaded on Earth then they can't handle being driven full loaded on the Moon.
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