Is it possible to actually make a stable, safe-to-drive rover?

[Hour Hero Yes]

I was experimenting with Mun rovers last night and had one that wasn't any taller than one of the smaller structural girders, very low center of gravity, and I must've killed my poor three Kerbalnauts about 20 times trying to go 3k on the moon.

All the tiny elevation changes and bumps mean that 9 times out of 10, one side of the rover lands first after a bump and flips like an Olympic gymnast. Is there anything to do to counteract this? I disabled rear wheel steering, had RCS pressing me downwards, didn't go over 15m/s, let go of the pedal while landing from mini-jumps, etc.

[capi3101]

Switch to the docking controls and turn on SAS if you have a probe core available. The docking controls alone help. If you have a Reaction Wheel on your rover, so much the better. Was driving around a rover on Mun just last nice with this configuration; it flipped over just once, and only because it caught some serious air going over the edge of a crater lip.

[MockKnizzle]

Re-map your rover controls to something besides WASD (my preference is IJKL, since I don't normally have RCS on my rovers), or turn off control pod torque, or use docking mode.

[zerotwo]

Define "Stable and safe"?

With six of the new wheels and minimum weight I can get rovers going 21+ m/s, that's 120+ kph (80+ mph) in something that weighs under 2 metric tons.

If you are going along in a vehicle with a higher centre of mass, at 120 km/h or more, and you hit a bump, you are going to go flying.

That aside... A good option is to spread the weight out as far as possible, when the front wheels hit a bump they decelerate and the rest wants to keep moving, causing the flip, wider or longer vehicles will be more stable.

You can also lock the rear wheel steering and shut off the front wheel drive for agility on flat ground.

The safest rovers do not attempt to move their top speed except on a flat.

[Darren9]

There's some alternatives to the stock wheels that have better suspension and a tendency to slide more rather than dig in and flip, it makes driving much more fun. Take a look at RollKage and TT's Multiwheels.

[Lheim]

Actually, I've a question myself: The new wheels. Am I the only person that they ALWAYS clip into the ground for?

[allmhuran]

Wider wheel base helps.

This one, for example, has rather a wide wheel base and I found it to be a very pleasant drive. Tank drifting is fun:

[Bean]

The best I could do is about 30m/s (108kph), faster than that I had to add RCS to keep it upright during jumps, can sustain 40m/s when I'm concentrating. Took me a lot of iterations to make sure nothing breaks when it goes flipping.

[annallia]

I find that a heavier rover works well for me. My current Mun rover has 8 wheels and weighs in at just over 2 tons. Of course it also helps if you go slow, keeping it around 12-15m/s is very safe on the mun (for mine). I did have it up to 28 but hit a bump and flipped it, fortunately it managed to land right side up.

[Tiron]

Not entirely: Due to imprecisions in the terrain, or somesuch, there are sections of terrain that will make your rover bobble about like crazy, and generally act like it's barely touching the ground at all. This makes it very hard to design a stable rover, because when you hit one of these, it bounces all over the place and steers more or less randomly, and becomes very prone to flipping over entirely.

[Hour Hero Yes]

What does docking mode do to help steering? And can I overcompensate with wheel size, like using the huge industrial wheels so I could set the center of gravity beneath their "axels"?

[capi3101]

By default, the controls for staging mode (i.e. normal view) affect a craft's attitude. That is to say, the W/S keys control pitch, A/D controls yaw, and Q/E controls roll. You don't want a rover attempting to pitch if you can at all help it. By switching over to docking mode, the controls by default affect translation instead of attitude. W/S keys become translational controls (forward and backward) and the A/D keys translate left and right. The benefit is that the game isn't interpreting your commands as an attempt to change the attitude of the rover (i.e. it won't think you're making a deliberate attempt to roll over the rover).

IJKL are the default translation keys in staging mode; I don't know if they work without RCS thrust engaged though. I've never tried that.

[Darren9]

Docking mode deactivates the reaction wheel/SAS rotating torque that you'd get with WSAD in staging mode, if you've got some fitted it can be enough to flip or at least help flip a rover. The huge skid-steer wheels stop turning at around 16m/s IIRC and are slow and heavy. As mentioned a wide design with low center of gravity will help the most but the stock wheels have high friction and that's bad in low gravity. The only way to go fast without disaster though is get some low friction wheels.

[SkyRender]

The best vehicles for roving are designed to be fairly wide, long and symmetrical, just like how real-world cars are designed. Here's a good example of a very stable but simple rover:

At a glance, it almost looks like a car that's had the frame removed. It also has a ton of free space on it, meaning if you use mods, you can load it up with stuff like the Kerbal Attachment System and make it a proper utility vehicle.

Of course, how you drive is also important. A stable rover is well and dandy, but if you handle it poorly, it won't do you a lick of good. Some of the most common driving problems and how to deal with them:

Going airborne! - Drive slower! There's a safe speed limit for most planets and moons, and it's slower than you might think. Make good use of your brakes to stay below that speed. For the Mun, it's between 10 and 15m/s, depending on rover stability.

Fishtailing! - In KSP, this tends to happen due to a mix of uneven terrain and imperfectly-set wheels. Try to make sure your wheels are always set evenly, and reduce your steering to only front-wheel or rear-wheel drive by disabling steering on the offending set. You can't prevent fishtailing completely, which leads us to...

Rollover! - Rollovers are easy to deal with, if you know how. You just have to be okay with stopping after and re-obtaining your bearings. Turn into the direction of the rollover (so if you're tilting left, turn left, for example). As you reach stable ground again with all four wheels, stop the turn and start hitting the brakes. Do not try to brake while you're in the midst of a rollover!

Spinning through the air! - Worst-case, you start a rollover just as you hit an edge, and you start spinning through the void. Turn SAS on and start turning against the spin, and try to keep your front wheels up as you do. You want to land roughly flat, but if you can't land flat, always land with your rear wheels more down than your front. Front-first will cause you to flip forward, and that's really not good (obviously).

So! That should hopefully help. Above all else, practice! Practice design, practice driving, practice safety maneuvers, just plain practice everything! You can't get better at responding to problems if you never run into them, so the occasional failure is a good thing. It'll make you a better rover driver, in the end.

[Xeldrak]

I spent some time, driving about ~20km on the Mün today. My tips are:

• Have a Kerbal on board to fix tires
  
• Map your rover controls on your numpad, now you can drive with you right hand and should you lift of control you postion with your left hand
  
• Have an ASAS module on board otherwise the tip above won't work
  
• Have RCS on board, it's much more efficient in .21 and with ASAS it will even keep your rover from fliping over if you perform full braking
  
• The usual stuff - low center of mass, large track and wheel base
  

[Starwaster]

wow just had a waking nightmare reading this thread... a nightmare involving driving a rover on Gilly... (just had my first successful landing there... probably would have gone easier if I'd had more than 8kg of left in the tanks for rcs)

[Jean Deaux]

"shameless plug" for my Nina