How to design rovers?

[rabcor]

I was wondering how to best design a rover, in general is what i mean.

Whether i want a small or large rover, whether i want it to be fast or efficient, how to keep it stable, where and how to place the tires, etc, etc.i'm having a bit of a rough time making one from randomly putting together parts. I want to make a rover, launch it into space and drive it around on surfaces of other moons and planets.

The problem is that i don't know how to actually design a rover to begin with, and how could i bring it to the surface of other moons/planets? (i can get to the moons, but how to get a rover of any size there i have no clue)

[DerekL1963]

Search on "landing rover" or "land rover", there's a ton of threads... I've learned a lot about rover design just by studying the "show off your rover" thread.

[M5000]

Get the ground clearance you want. As in, mount the wheels somewhere so that the body will sit X distance off the ground. Rovers really don't need all that great of ground clearance. Then, put all the parts on, make your center of mass as low as possible, and your wheelbase as wide and long as possible. You want it to be slightly longer than it is wide, but not much. Like a car, kinda. The lower your center of gravity, the easier it will be to turn at higher speeds.

Also, four wheels is usually sufficient, but if you have a particularly heavy rover and you're going to a planet with high gravity like Eve, you might want an extra set or two.

[LtKraftKrackers]

well, i feel like i am not the best one to answer this question, but, the last 2 rovers i designed have worked pretty well. the first one was a medium size rover "capable" of holding three kerbals and on the mun surface, it reaches a top speed of 29 m/s. I pretty much started with a rover body (can be found in structure tab) and added on the top a 2x2 structural plaque... or sheet... wait.. ok here we go, an m 2x2 structural panel. this gave me a lot of space to play with on top. i added 3-4 cubic octagonal struts to put on a ceiling... bah i'm just gonna try to post a screenshot... ok so i cant post a screen shot... sorry i am so useless;.;

[Dunbaratu]

In low gravity environments like the Mun, rovers are VERY tippy. They hit the smallest bump and start going "air"borne, rotating in midair as they move, which can make them bounce badly and damage themselves. The basic rule of thumb is this: The smaller the gravity, the smaller the delta-V the craft can endure without tipping. You can find that a rover performs fine when tested on the launchpad but is very hard to drive on the Mun. Be aware the forces in all directions when building it. Think about what happens when you accellerate and when you brake. People often lose rovers to hitting the brakes too hard, simply because when the rover stops it tips forward and can flip end over on its back. Similarly if it's too narrow, you can't take any turns at speed or it will roll.

These are all common sense, but some things that are NOT common sense that it may help to know to avoid some easy newbie mistakes are:

1 - Rover wheels have a max speed listed. Never even TRY to get near that speed in a low gravity world. It's a bad idea. Far before you hit that max speed you'll have controlling problems from the bumping and bouncing about. Never go even as fast as 1/3 of max speed when you're in a low gravity setting.

2 - Rover wheels can become damaged from impacts and from going too fast for terrain (which, again, is less than their max speed listed). Once they become damaged you will find the rover utterly unresponsive to any command input INCLUDING hitting the brakes. Don't let this happen. I've lost rovers to this because I became unable to slow down on a slope due to wheel damage. The artwork for a damaged wheel is that it will look like it has patches of tread missing.

3 - Wheel damage can be repaired by a Kerbalnaut if the mission is manned. Walk the Kerbal to stand near the damaged wheel and if the Kerbal is close enough, you can rightclick the wheel and the menu option "repair wheel" will appear. This is not possible if the rover is unmanned so drive carefully for unmanned rovers.

4 - Although flipping is easy in low gravity, the low gravity also means the damage might not be too bad. There may still be enough of the rover left after a rollover to drive if you can just get it back rightside up again. Consider mechanisms to avoid rollover or to re-right the craft when it's on its back. I use landing gear on the roof that when activated lever the craft over sometimes. Watch a few old episodes of Robot Wars and look at the self-righting mechanisms used there.

[DoToH]

After doing as people above said, take a while to test your rover on kerbin surface... drive it fast and make some sharp turns. Keep in mind that any stability problem on kerbin will go worse and show up at slower speed in a low gravity environment. And, if your rover has any SAS module or pod with some torque force, switch to docking mode to drive it.

[Markus Reese]

On mobile so I cannot make a big post. Also much of it is covered. My quick two bits.

1. In vertical building, use the double symetry to attach wheels. Use small part rotation to position for alignment. Duplicate part wih alt click and add wheels for same size to ensure that they drive same direction.

2. For landing it, I like to use landing legs and not the wheels. It helps absorb landing shock.

3. The two seat lander capsule works great and is a fun lander. Fits wheels wide and stable.

4. For driving stability, lock steering on your rear wheels. Prevents overturning and rolls. Be careful braking to prevent nosing over.

When I am on my computer, I will upload my favorite rover to show better what I mean.

[N_Molson]

Add parts that resist to 80 m/s impact and use them as armor to protect frail parts. You can put landing legs on the top (but they have to be protected too) so that you can deploy them to put back the vehicle on its wheels after a rollover. Center of gravity is very important, I found that adding useless dead mass like RCS tanks under the chassis adds stability.

Wheeled vehicles need a significant gravity to work and keep grip, on bodies smaller than Mun you can consider using RCS-powered platforms or similar stuff.

Oh and about braking, see in the Action Groups menu, click on the rear wheels, and assign a key to brakes. That way you can brake only with the rear wheels, which prevents nearly all risk of tipping. KSP don't really take skidding into account, so that technique works. In real life doing so makes the vehicle uncontrollable.

Edited June 11, 2013 by N_Molson

[sauliukas]

Try my rovers for fun and might get inspiration for yours. Rather stable and hard to damage.

http://forum.kerbalspaceprogram.com/showthread.php/32924-0-20-Crawler-Heavy-Duty-Rover

[Markus Reese]

Oh. Great tip with the braking action groups. I believe there is one specific for braking as well. I am going to start rear wheel braking as well.