Land propulsion - Tracks, or tires?

GraemeSkinner · 2004-03-02 04:48:33

I'm in favour of to start with a half wheel, half track vehicle. Using tracks for the propulsion and wheels for steerings. How would a hovercraft type vehicle work in the Martian gravity/atmosphere, then you don't have to worry about the tyres freezing and breaking or tracks coming loose. A downside to the hovercraft would be it kicking up dust - but not being an expert on such things (having only built a small one that you can not ride ) I don't know how much dust they create when hovering.

Shaun Barrett · 2004-03-02 06:27:51

Has anybody really had a good look at the rocks on Mars? I've been amazed at how many of them are extremely sharp and jagged, at least close to craters (ejecta, I suppose).
It's difficult to imagine riding a bike through some of these places and I can visualise some of the rocks being very effective at getting wedged into metal tracks and even stopping a tank!

If we're going to explore untravelled regions of Mars using wheeled vehicles, I tend to favour oversized wheels made of the toughest metal mesh we can produce. I think the bigger the wheels the better to facilitate progress over sharp boulder fields and to minimise the weight/unit area on soft sandy terrain.
Even though tough, the mesh will need to be very flexible to avoid tearing. But carry at least a couple of spares if you're going very far into unknown territory! I don't think you'll be getting very good mileage from even the most rugged Goodyear mesh tyres!

For more frequently travelled routes, I think there'll be no substitute for bulldozers to clear the way. I imagine they'll need to be heavy to get any useful traction in the 0.38g, so I suggest we we use heavy metal tracks for them. In Dr. Zubrin's book, "Entering Space", I seem to remember him pointing out that steel production on Mars will be quite straightforward and I can see no reason why we can't pour the liquid metal out in the open to produce track links and connecting pins etc.
Flexible and durable hi-tech mesh might need to come from Earth initially, though.

Why am I discussing tyres anyway?!!

Palomar · 2004-03-02 07:54:19

Has anybody really had a good look at the rocks on Mars? I've been amazed at how many of them are extremely sharp and jagged, at least close to craters (ejecta, I suppose).
It's difficult to imagine riding a bike through some of these places and I can visualise some of the rocks being very effective at getting wedged into metal tracks and even stopping a tank!...
Why am I discussing tyres anyway?!!

*Yep, I've noticed those rocks and boulders even from the Viking images...yipes.

I think I mentioned somewhere previously that vehicles on Mars should be outfitted with the equivalent of snowplow blades. Push them rocks right out of the way!

Why are you discussing tyres, Shaun? Well, I think men tend to discuss matters such as these more than persons of my gender.

--Cindy

GraemeSkinner · 2004-03-02 08:48:37

*Yep, I've noticed those rocks and boulders even from the Viking images...yipes.
I think I mentioned somewhere previously that vehicles on Mars should be outfitted with the equivalent of snowplow blades. Push them rocks right out of the way!
Why are you discussing tyres, Shaun? Well, I think men tend to discuss matters such as these more than persons of my gender.

A snow plough type attachment would only be useful if the rock was not too well buried, I can see it working on surface boulders and the like but many of them we're only seeing the tip of the iceburg.
They could use a light metal alloy as a wheel and tyre in one if it had suitable groove marks and maybe offset insert of rubber (or similar). You'd need pretty good suspension to go with it though or the ride would be fun!

Palomar · 2004-03-02 09:06:13

*Yep, I've noticed those rocks and boulders even from the Viking images...yipes.
I think I mentioned somewhere previously that vehicles on Mars should be outfitted with the equivalent of snowplow blades. Push them rocks right out of the way!
Why are you discussing tyres, Shaun? Well, I think men tend to discuss matters such as these more than persons of my gender.
A snow plough type attachment would only be useful if the rock was not too well buried, I can see it working on surface boulders and the like but many of them we're only seeing the tip of the iceburg.
They could use a light metal alloy as a wheel and tyre in one if it had suitable groove marks and maybe offset insert of rubber (or similar). You'd need pretty good suspension to go with it though or the ride would be fun!

*Yes, I see your point.

Time to whip out the gamma-ray guns and blast those obnoxious rocks to smithereens instead!

A ride like that might be fun...on an empty stomach.

--Cindy

Shaun Barrett · 2004-03-03 01:38:28

Hi Cindy!
Yeah, I know the average guy find tyres and wheels and engines and vehicle performance figures more interesting than the average girl does. We have 'car chromosomes' which the female of the species often lacks!
I was just copying your earlier comment because I thought your surprise and exasperation, at finding yourself involved in a discussion about something which holds no interest for you, was really quite amusing!

Sometimes things like that just tickle me, I guess.

sethmckiness · 2004-03-04 00:06:59

I know the U.S. Navy has operated C-130 aircraft in Antarctica when temperatures have been as low as -60 F and the only problem they had with their tires was that they would freeze to the ice at times.

LC-130s use Skis, the C-141s use tires on a runway that is iced over.

I don't think that tires being brittle should be an issue. If you want to use tires, then you should be able to design a tire that is functional from 100 to -100 celsius. look at Motor Oil. Who would have thought you would get 5w-50 50 years ago.

Anyway, I think tracks have their advatages over tires. If you want to go fast, I would recomment tires, if you want to go slow, probably tracks. But, I believe in the KISS principle. Keep it simple stupid.. Lol. The less complex it is, the less likely it is to break. It is usually quite a bit less expensive as well.

sethmckiness · 2004-03-04 00:08:50

I know the U.S. Navy has operated C-130 aircraft in Antarctica when temperatures have been as low as -60 F and the only problem they had with their tires was that they would freeze to the ice at times.

LC-130s use Skis, the C-141s use tires on a runway that is iced over.

I don't think that tires being brittle should be an issue. If you want to use tires, then you should be able to design a tire that is functional from 100 to -100 celsius. look at Motor Oil. Who would have thought you would get 5w-50 50 years ago.

Anyway, I think tracks have their advatages over tires. If you want to go fast, I would recomment tires, if you want to go slow, probably tracks. But, I believe in the KISS principle. Keep it simple stupid.. Lol. The less complex it is, the less likely it is to break. It is usually quite a bit less expensive as well.

dicktice · 2004-03-04 08:31:56

I'd like to hear from the hovercraft community, first, before commiting myself.

GraemeSkinner · 2004-03-04 08:45:32

I like the hovercraft solution, but then I like hovercrafts! You never know all these ideas may be out the window by the time we get a manned mission - they may have come up with an anti-grav unit and we won't have to worry about brittle tyres; slow heavy tracks; or dust from hovercrafts.

melkor · 2004-03-09 12:01:23

Forgive an ignorant social-science type, brand-new to this forum, but...isn't the Martian atmosphere too thin for a hovercraft to work?

Rxke · 2004-03-09 12:55:15

I was thinking the same thing... But also lower G's, so maybe with a turbo-hoovercraft? How efficient are thes things?

dicktice · 2004-03-09 13:41:03

I like the hovercraft solution, but then I like hovercrafts! You never know all these ideas may be out the window by the time we get a manned mission - they may have come up with an anti-grav unit and we won't have to worry about brittle tyres; slow heavy tracks; or dust from hovercrafts.

Don't bet on it, the same old rough and ready engineering solutions will be the order of the day for as long as you live, so let's hear some creative ideas along these lines from you. Nobody is an expert on this subject right now.

dicktice · 2004-03-09 13:47:34

I was thinking the same thing... But also lower G's, so maybe with a turbo-hoovercraft? How efficient are these things?

The use of an airbag to compress the Mars atmosphere with the turbine and store it (like a bagpipe does) for discharge under control in the form of pressure-jets for hovering.

Brian Hanley · 2004-03-09 13:51:24

Hardly matters. What is your power source?

Engineering requires engineering the whole thing. So start there, and then think about what you can run using that power source. That's why Zubrin's hoppers are such a good idea.

Shaun Barrett · 2004-03-10 00:28:09

As far as hovercraft are concerned, I think Graeme Skinner's point about dust may be important. If we're going to start our own home-made dust storm every time we drive anywhere, blasting fines into every crevice of every building and machine in range (including the hovercraft itself), or perhaps even blinding the hovercraft driver in a huge cloud of dust, is it worth it?

A second point may be the hovercraft skirt. As you know, the skirt travels in close proximity to the ground. On Earth, we use hovercraft mainly over relatively smooth terrain and over open water or marshes; they've never really caught on as a means of transport over rougher country. How would the skirt stand up to the kind of jagged razor-sharp ejecta fields we've seen on Mars?
Even the relatively smooth martian lowlands, such as Chryse and Utopia, have been shown to be quite rugged by the Viking lander photographs. It may be that there are few places on Mars where a hovercraft would be suitable.

Perhaps I'm being overly pessimistic? ???

Byron · 2004-03-10 06:22:53

As far as hovercraft are concerned, I think Graeme Skinner's point about dust may be important. If we're going to start our own home-made dust storm every time we drive anywhere, blasting fines into every crevice of every building and machine in range (including the hovercraft itself), or perhaps even blinding the hovercraft driver in a huge cloud of dust, is it worth it?
A second point may be the hovercraft skirt. As you know, the skirt travels in close proximity to the ground. On Earth, we use hovercraft mainly over relatively smooth terrain and over open water or marshes; they've never really caught on as a means of transport over rougher country. How would the skirt stand up to the kind of jagged razor-sharp ejecta fields we've seen on Mars?
Even the relatively smooth martian lowlands, such as Chryse and Utopia, have been shown to be quite rugged by the Viking lander photographs. It may be that there are few places on Mars where a hovercraft would be suitable.
Perhaps I'm being overly pessimistic? ???

I don't think you're being overly pessimistic, Shaun. I think trying to operate a hovercraft on Mars would be inpractical, if not impossible. For one thing, how would you clear the boulder fields in one of these things, which would hover a half meter (at the most) above the ground? And the dust, too...that would certainly be a no-no, especially around the entrances to the habs... ???

I think vehicles with oversized flexible tires (probably made of a fiber mesh material) would work best...like the lunar rover of the Apollo missions. I say stick with what you know is most likely to work in a given situation, in keeping with the "KISS" principle...

B

Shaun Barrett · 2004-03-10 06:54:49

Point well-taken, Byron!
There's a lot to be said for the 'K.I.S.S. Principle'!

GraemeSkinner · 2004-03-10 09:15:25

I think the first task would be to decide what you want the vehicle for, what you will be doing in it, how far you want it to go per day, will it be required for a multitude of tasks or just moving a couple of people from A to B etc. Then you have to decide what form of propulsion you'll be using, and only then should you consider the way of getting the propulsion to the surface to move the craft/vehicle.
I'd consider the first manned transportation crafts to be a multi-tasking vehicle that carries both people and supplies/equipment, and could double as an 'overnighter' for longer explorations away from the base. And in keeping with the K.I.S.S. principal power it with a known reliable source, and use large mesh wheels to cope with the rugged terrain.
Now if someone could design a craft capable of flying in the Martian atmosphere/gravity with the characteristics of a Harrier Jet that would certainly overcome the rough terrain, and it would give the occupants a good range to travel each day - though I'm not sure how jump jet technology would work up there (thinking out loud so to speak )
Graeme

dicktice · 2004-03-10 09:47:45

Well, perhaps the term "hovercraft" carries too much baggage with it. I was thinking more along the lines of the jet-levitated moon buggy in the film "2001" which skimmed over the Moon terrain in vacuum, and then imagined the combined advantages of having an atmosphere, however thin, and only one-third the weight. Compressing the Martian air, before directing it downwards under piloted control came next. Powering the rig wouldn't be any more of a problem than for other forms of land locomotion. The speed with which you could get around should even contribute to its km/watt-hour efficiency. Dust around the habitat entrances could be avoided by coming down some distance downwind, and driving closer on wire wheels. What's wrong with that?

Brian Hanley · 2004-03-10 09:58:30

That sounds pretty close to the solid fuel hoppers from "The Case For Mars"

dicktice · 2004-03-10 10:11:30

Great, but I don't have the book. Would you mind doing a short description of the "hopper" to show the comparison? [I wonder why this topic doesn't appear on "New Posts"?]

Brian Hanley · 2004-03-10 10:34:29

Heavens! a Mars Society member that hasn't read it.

Here's a pdf I found on the web.

[http://www.nw.net/mars/docs/mobility.pdf]http://www.nw.net/mars/docs/mobility.pdf

Dook · 2004-04-26 20:41:04

How is a hovercraft going to fly over an area that is covered in large rocks? Of all the pictures I have seen of mars only one shows a sandy area, the rest is nothing but medium sized rocks. Hovercraft can't operate there. Also, navy LC-130's skids have tires, the skids support the aircraft on ice/snow and the tires are used for runway landings. The tires survive the cold temperature well enough for the aircraft to land on them when it returns home.

Hazer · 2004-04-28 11:11:14

Well...Thanks all for the suggestions on land propulsion.

One the hovercraft idea, you might have problems with the density of the air on Mars. It wouldn't be dense enough to support the craft, unless you blasted it downward at VERY high speeds.

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#26 2004-03-02 04:48:33

Re: Land propulsion - Tracks, or tires?

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