Author Topic: Lunar Module Walker?  (Read 4379 times)

Offline DecoLV

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Lunar Module Walker?
« on: 04/18/2014 03:53 PM »
There's might be a thread on this already, but I'm wondering if anyone has speculated on walking the Apollo Lunar Module. That is, articulating the landing gear and adding locomotion and guidance. There obviously wasn't time in the Apollo rush to do that, of course (Grumman stood it up barely in time)...but with Antares, MCT, etc. somebody must have done a few calcs for this in a LM 2....my bet is that it was not only do-able, but do-able at that time (1960s) given more time and $ available.

And it would have saved the money spent on the Rover.  ;D

Offline Jim

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Re: Lunar Module Walker?
« Reply #1 on: 04/18/2014 04:09 PM »
There's might be a thread on this already, but I'm wondering if anyone has speculated on walking the Apollo Lunar Module. That is, articulating the landing gear and adding locomotion and guidance. There obviously wasn't time in the Apollo rush to do that, of course (Grumman stood it up barely in time)...but with Antares, MCT, etc. somebody must have done a few calcs for this in a LM 2....my bet is that it was not only do-able, but do-able at that time (1960s) given more time and $ available.

And it would have saved the money spent on the Rover.  ;D

It would have been a non starter.  It would have added more weight and cost more than the rover and would have limited mobility.  For large landers, adding mobility isn't good thing.

There were studies for Surveyor and Viking, but they were small and light. 

See MSL for an example where the lander and rover were kept separate.

Offline JasonAW3

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Re: Lunar Module Walker?
« Reply #2 on: 04/18/2014 04:52 PM »
There's might be a thread on this already, but I'm wondering if anyone has speculated on walking the Apollo Lunar Module. That is, articulating the landing gear and adding locomotion and guidance. There obviously wasn't time in the Apollo rush to do that, of course (Grumman stood it up barely in time)...but with Antares, MCT, etc. somebody must have done a few calcs for this in a LM 2....my bet is that it was not only do-able, but do-able at that time (1960s) given more time and $ available.

And it would have saved the money spent on the Rover.  ;D

It would have been a non starter.  It would have added more weight and cost more than the rover and would have limited mobility.  For large landers, adding mobility isn't good thing.

There were studies for Surveyor and Viking, but they were small and light. 

See MSL for an example where the lander and rover were kept separate.

Jim,

     I WAS going to counter with small electrically powered wheels, but although they would mass a fraction and not be NEARLY as complex as articulated legs, they would still add too much mass with the additional wiring, the wheels, motors and power source for the electrical motors.
     During Apollo, mass was at such a fine marging, even the LEM's hull had to be made thinner to make the mass target.  (Essentially, the LEM was effectively a pressurized metal tent. Which is why I think an Bigelow hab moduleontop of a crasher stage, could work as a crew cabin on a new LEM design.)

Jason
My God!  It's full of universes!

Offline NovaSilisko

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Re: Lunar Module Walker?
« Reply #3 on: 04/18/2014 05:01 PM »
There were studies for Surveyor and Viking, but they were small and light.

I'd be very interested in hearing more about these studies... I know there was originally a small tracked rover planned for Surveyor, but I've never heard of making either that or Viking into a walker.

Offline Jim

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Re: Lunar Module Walker?
« Reply #4 on: 04/18/2014 05:03 PM »
There were studies for Surveyor and Viking, but they were small and light.

I'd be very interested in hearing more about these studies... I know there was originally a small tracked rover planned for Surveyor, but I've never heard of making either that or Viking into a walker.

I meant tracked and not walkers

Offline simonbp

Re: Lunar Module Walker?
« Reply #5 on: 04/18/2014 05:36 PM »
There were studies for Surveyor and Viking, but they were small and light.

I'd be very interested in hearing more about these studies... I know there was originally a small tracked rover planned for Surveyor, but I've never heard of making either that or Viking into a walker.

I meant tracked and not walkers

This, I think you mean.

Offline the_other_Doug

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Re: Lunar Module Walker?
« Reply #6 on: 04/18/2014 06:59 PM »
A few thoughts, here...

First, articulating a 4-legged lander is a lot more work than you'd think.  It would be very heavy and give you exceedingly poor mobility.  Remember that the descent engine didn't have that much ground clearance, either.  With something as relatively top-heavy as a landed LM, getting the engine bell caught on a big rock or stepping into the slick side of a 5-meter crater could flip you ass over teakettle.

Second, some studies for extended LM systems (specifically the LM Truck concept) looked into replacing the landing gear pads with tracks or wheel sets.  The worst scenario I saw for this kind of mod was that, with the four-point suspension of the LM by the landing gear, you could easily break any braking mechanism on your tracks/wheels with a hard landing on a slope and find yourself rolling merrily down the hill.. backwards... sliding and slewing around... until you catch up against a big rock.

Third, however, lighter and much less top-heavy unmanned landers have looked into landing directly onto wheels or treads.  I have seen studies of replacing the footpads on both Surveyor and Viking landers with tracked mobility units.  Had NASA flown a Viking 3/4 pair, it's quite possible they could have had some mobility.  The Surveyor proposal I saw, though, was an early Apollo support request for one (or more) Surveyors to land at the candidate site for the first manned landing.  The Surveyors would provide radar transponders allowing the LMs to land very precisely near them, and the mobility was provided so that the Surveyor could just "mow the lawn" driving back and forth along strips, taking very frequent IMU measurements of changes in slope.  This would have given the first Apollo landing(s) a topographic map of their landing site accurate to within centimeters.

They eventually decided that such detailed site surveys were not required to support Apollo.  (Also, who wants to be the first people to land and walk on the Moon, just to land at a site that is saturated in little tank tracks?)  But seeing as the only really serious proposal for adding roving capability to Surveyor was to provide that kind of (needlessly overkilled) Apollo support, I dunno how effective the track/tread units would have been for what we now think of as planetary roving.

-Doug  (with my shield, still not upon it)
-Doug  (With my shield, not yet upon it)

Offline simonbp

Re: Lunar Module Walker?
« Reply #7 on: 04/19/2014 05:07 AM »
And here's the Surveyor Rover design from Bendix.

Offline TrevorMonty

Re: Lunar Module Walker?
« Reply #8 on: 04/19/2014 08:51 AM »
One reason to make a lander mobile is to be able to move in and out of a hangar.

Offline Jim

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Re: Lunar Module Walker?
« Reply #9 on: 04/19/2014 01:33 PM »
One reason to make a lander mobile is to be able to move in and out of a hangar.

Why is a hangar needed?

Offline mmeijeri

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Re: Lunar Module Walker?
« Reply #10 on: 04/19/2014 04:18 PM »
Why is a hangar needed?

It's not needed, but it could be useful. For servicing for instance, or for long surface stays. The ULA horizontal lander concept had small wheels. Doesn't make it a rover, but I can see how small wheels could be useful eventually.
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Offline simonbp

Re: Lunar Module Walker?
« Reply #11 on: 04/21/2014 04:40 AM »
It's not needed, but it could be useful. For servicing for instance, or for long surface stays. The ULA horizontal lander concept had small wheels. Doesn't make it a rover, but I can see how small wheels could be useful eventually.

That lander had rather comically small wheels that were clearly designed by an aerospace engineer with zero experience with vehicles that don't land on nice paved runways... ;)

The Moon has 1/6 the surface gravity of Earth. So, any wheel or tread will have 1/6 the traction that it would have on Earth. Thus, you need to to increase the contact area with the ground quite a lot to have decent traction, either with more wheels, tank treads, or (in the case of Apollo) wire wheels that sink a bit into the regolith. Either way, all wheels/treads must be driven.

Watch the Apollo 16 "Grand Prix" below. Imagine how much worse it would be if the tires didn't dig into the dirt.


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