Large rover wheels

[martinborgen]

I just accepted a contract to build a station duna, on wheels.

I fiddled around with an idea of a mobile refinery, but i couldn't get a design that seemed plausible. The first desing was basically am upright 126 ton mining lander but had weels. The wheels broke almost immediatly on testing at kerbin. (three times the G, I know, but I think it might be similar performance on duna due to wobbling anyways. ).

The second was a lay-down verision, that would have to perform a tilt manouvre after or before landing (I've done both), but I generally find the problems with these to balance the darn wheels, and get the thing to orbit. I am lacking inspiration of wheel bases. What do you use them for, what configuration, and so on?

[Kelderek]

For those contracts I usually land on struts and retract them to set the whole thing on wheels, allowing for contract completion. It helps to find a nice flat place to land, and build your ship wide instead of tall to make the landing more stable.

[SpacedCowboy]

I can't really suggest any designs for you, however I can tell you one thing not to do. Do not employ the small landing gear in your design. I had a similar contract to put a base on the Mun "with wheels" so I slapped on the small landing gears and whatever other stuff the contract stipulated. The mission went well, landed on the Mun, and did the ten second wait, only to find out the contract did not consider the landing gears as wheels! Result?,,, Fail. Now this was in the .90 version so it may have been changed. Regardless, make sure all required equipment has that little green check!

[moronwrocket]

Here's one I built for the Mun in 0.90. I guess it follows the "build it tall and fall over" philosophy. If a few tires break, you can use engineers to replace them. This model has some side-mounted rockets to liftoff for long-range exploration. Some "Mun Patrol" glamour shots are included as well.

For Duna, with the new parachute physics that keep them open/attached until you stop vs the old style of disappearing when you touched down, I think you could setup a drop that landed already tilted somewhat (offset parachutes, or lots of SAS), and use the chutes to drop slow enough that you don't break wheels/URD. But I haven't visited Duna myself yet, so YKMD (Your Kerbals May Die).

I suggest installing Kerbal Construction Time or Hyperedit to test your Duna descent before sending your system there.

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[martinborgen]

Interesting. I built a big behemoth today, an upright towering thing. It has enough TWR to lift from duna (I think, depends on atmosphere and poodles), I hope it's enough to lift from duna to orbit (no mods or calculations here). Will check by comparing with my current duna lander.

[problemecium]

The most likely explanation I see, based on what seems to happen with others around here, is that you're landing too hard. What is your touchdown speed, i.e. your vertical speed just as the wheels hit the ground? For most things not on lander legs this needs to be less than 6 m/s, and when there are tires involved the slower the better.

[martinborgen]

Oh, this is moving on the pad. I haven't gotten the thing to duna yet.

[xtoro]

Do you mean the huge xl wheels? Here's my minmus vtol rover:

Some tweaking, landing legs and chutes might make it work on duna. But you'll need larger vtol engines to take off again.

[Spatzimaus]

It's doable.

Back in olden days (0.23ish), I'd send this 300-ton rover to Mun:

It was a mobile Kethane miner, using a number of parts from other mods. But, the wheels were stock, so it'd work for your contract. The downside was that it was only designed as a 1-man rover, but had the capacity to hold far more. I tweaked the design a bit, but I did this in three or four separate versions so I know it's workable.

I later switched to even larger rovers, and that necessitated the use of caterpillar treads from a mod:

That's a 600-ton megarover in the background (default crew of 3, but can hold 9), and a 25-ton smaller rover (also a kethane refinery) in the foreground. The smaller rover uses stock wheels, but it doesn't have enough crew for those contracts. I highly recommend using treads, though, simply because of the fact that they don't rip themselves apart under even minor shears. (They do have a very poor top speed, though. That huge rover tops out at about 12m/s; those 5m KW fuel tanks are really heavy when loaded.)

Honestly, though, all of those base construction contracts are simple because of one simple flaw: a lander qualifies, as long as you stick any necessary parts (docking ports, antennae, wheels) on the side as necessary. The wheels don't have to touch the ground, the ports don't have to be reachable, etc., they just have to be on the craft (even inside a cargo bay).

In my career I'm still in the second tier of techs, and I've got a 7-man lander (3-man pod plus hitchhiker) that I use for quick astronaut training. (One trip to Mun or Minmus with Jeb piloting, and POOF, a half-dozen level 2 kerbonauts!) I stick a couple extra parts on it, and suddenly it's completing my orbital station contracts as well for big money. I'm just about to send it to Duna and Ike for HUGE profits, as soon as I unlock the LV-N for my transfer burn.

[AbacusWizard]

In the past (version 0.25, I think) I set up a surface outpost on pillars that had a detachable rover underneath (connected by docking clamps). Since the rover and outpost count as one vessel when docked, would that count as a "base with wheels" at the time it lands?

[martinborgen]

Interesting desingns! However, while I also made similar ones, the problem I find is to make them get off the launch-pad! Just because I find it's so hard to balance a long rover, with all the wheels on one side, and with aerodynamics and whatnot.

[Halo_003]

Interesting desingns! However, while I also made similar ones, the problem I find is to make them get off the launch-pad! Just because I find it's so hard to balance a long rover, with all the wheels on one side, and with aerodynamics and whatnot.

Solution for that:

[xtoro]

Interesting desingns! However, while I also made similar ones, the problem I find is to make them get off the launch-pad! Just because I find it's so hard to balance a long rover, with all the wheels on one side, and with aerodynamics and whatnot.

I use fairings

This is what's inside the fairing:

And since I'm using huge mk3 parts, the wheels hardly shift the CoM so it doesn't really matter.

Edited May 18, 2015 by xtoro

[Landge]

I haven't gotten to the big stuff yet on 1.02, playing career mode, to get a feel for the attachment strengths of the XL rover wheels and Mk3 tank parts (pretty flimsy in 0.90 so I didn't use them). For the XL wheels, throw struts, crossbraced between the rocket body and the end of the wheel's support beam. You can't start the strut on the beam but you can end the strut there.

You can see where I strutted the wheels together here (click on pic for link to full size)...

As far as landing with them and staying in one piece, It is best to keep your vertical speed below 10 m/s. 5 m/s is better.

The advantage with landing with wheels over legs is you can make a rolling landing where legs would catch and flip you over. Just keep your forward speed under 30 m/s.

This is a video I made landing on Duna in 0.90 without the aid of landing legs or parachutes. This was my attempt at making a landing Mass Effect Mako style.

[AbacusWizard]

I was able to fix the center of mass problem by attaching several of the big structural cubes on a girder on the opposite side from the wheels as a counterweight, with a decoupler so I could snap it off during re-entry.

[Spatzimaus]

Interesting desingns! However, while I also made similar ones, the problem I find is to make them get off the launch-pad! Just because I find it's so hard to balance a long rover, with all the wheels on one side, and with aerodynamics and whatnot.

Back in the old souposphere days, here's how I launched my huge 600-ton rover:

Basically, the rover itself was close enough to symmetry on both axes that a mounting point under the center connector would stay balanced. The huge (12000-ton) stack of rockets below the rover was an SSTO launcher (fully recoverable, other than the fuel of course), and once in orbit the skyhook on top would draw fuel from the rover's tanks for the rest of the trip. (After landing on Mun and refilling all of the fuel tanks, the skyhook detached and flew up to Mun orbit to act as an emergency fuel depot.) With the new atmosphere model, that sort of design might have a bit more drag than it used to, but it should still work given the raw power of the booster.

[martinborgen]

I just love the Idea of two rovers! But I'm afraid my CPU don't.

Here's my rover solution, but I don't know how to embed.

http://imgur.com/a/L8Tda

[xtoro]

I just love the Idea of two rovers! But I'm afraid my CPU don't.

Here's my rover solution, but I don't know how to embed.

http://imgur.com/a/L8Tda

That works too! Just don't make a turn too sharp

[Spatzimaus]

Here's my rover solution, but I don't know how to embed.

Not a bad design, although it's a bit top-heavy. You might roll if you try to make a turn too fast, or go up a steep slope. I'm currently trying out a large, flat design so that this isn't an issue.

When you're at your imgur page, and you click on an image, one of the options on the right will be the "BBCode" entry: (img)http://i.imgur.com/whatever.png(/img) (except brackets instead of parentheses). That's the one you want to copy for embedding on boards like this.

[martinborgen]

That works too! Just don't make a turn too sharp

Not a bad design, although it's a bit top-heavy. You might roll if you try to make a turn too fast, or go up a steep slope. I'm currently trying out a large, flat design so that this isn't an issue.

When you're at your imgur page, and you click on an image, one of the options on the right will be the "BBCode" entry: (img)http://i.imgur.com/whatever.png(/img) (except brackets instead of parentheses). That's the one you want to copy for embedding on boards like this.

Haha, thanks. Well, that brings the ultimate question - why would I need to go anywhere?

[xtoro]

Haha, thanks. Well, that brings the ultimate question - why would I need to go anywhere?

Well, my rover for example is a mining/refining ship. So I might not land exactly where the good ore is, but I don't have to worry much because I can just drive there.