How to improve traction on rover wheels?

[THX1138]

I'm having problems with a small rover going downhill on Duna. The brakes are ineffective, apparently due to the lack of friction. Could a landing leg at the back be deployed to drag across the surface or is that just going to flip me over when it catches on something? I suppose another couple of wheels would help.

[Crusher48]

Try making the rover heavier so that it has more downward force from gravity and thus more traction.

[maceemiller]

could you place something heavy like a battery on top of each wheel? Just a thought ive had even if its wrong

[katateochi]

Since 1.0 rover wheels seem to have weaker brakes (and seem to break more easily). But traction has always been an issue. What I've done in the past is use RCS thrusters; have thrusters that point up and a couple pointing forwards which you can fire (and some facing backwards if you like speed).

It used to be that the controls for docking mode where set up perfectly for this by default, but since 1.0 I've had to reconfigure key bindings bit to keep this working. You need to enable the wheel steering keys to work in Docking(translation) mode, and disable pitch and yaw controls in Docking(translation). Then set W and S to be translate forward and back and Lctrl and LShift to translate up and down (respectively) in Docking(translation) mode.

Then when you drive in docking mode if you switch on RCS while holding W your rear facing RCS will give you a boost, or while decelerating (S) will fire you forward facing ones and to increase your traction hold down Lcrtl to fire the upward facing ones.

[Jaeleth]

Duna has a reasonable gravity, a little more weight should do the trick. In lower grav. environments, like minmus, just try hopping around using wheels only for small relocations, like getting under a fuel truck.

for extra speed i'd go for a back facing engine, ion engines are great for this since they provide slow, controllable, acceleration and very long burns with little fuel.

if you want a fast rover make them heavy, flat, wide, and low CoM, like a formula 1 race car

if you put weight on the wheels the brakes "B" will always work, but braking with the engine is always very innefective unless under heavy weight / gravity.

beware on travelling over ground at high speed. Depending on the rover above 20m/s requires your full attention at the terrain in front of you, near or above 40m/s almost always spells disaster.

[arkie87]

Duna has a reasonable gravity, a little more weight should do the trick. In lower grav. environments, like minmus, just try hopping around using wheels only for small relocations, like getting under a fuel truck.

for extra speed i'd go for a back facing engine, ion engines are great for this since they provide slow, controllable, acceleration and very long burns with little fuel.

if you want a fast rover make them heavy, flat, wide, and low CoM, like a formula 1 race car

if you put weight on the wheels the brakes "B" will always work, but braking with the engine is always very innefective unless under heavy weight / gravity.

beware on travelling over ground at high speed. Depending on the rover above 20m/s requires your full attention at the terrain in front of you, near or above 40m/s almost always spells disaster.

More weight shouldnt help. Friction is proportional to the normal force. The more you weigh, the more friction you get, but also the more mass you have, so your acceleration will not and cannot change.

More wheels wont help. The more wheels you have, the less weight is on each wheel.

Your acceleration is always related to the local gravitational constant. No getting around that (unless you use RCS or engine to provide extra downward force).

The maximum angle uphill (or downhill) you can go at steady speed is related to the coefficient of friction of the wheels ONLY and not dependent on gravity, number of wheels, weight, mass, etc... http://physics.bu.edu/~duffy/semester1/c6_measuremus.html

Edited May 4, 2015 by arkie87

[Gaarst]

Best braking with rover wheels in pre 1.0 was achieved by actually breaking and going backwards at the same time.

Don't know if this still works since 1.0 though...

[monophonic]

More weight shouldnt help. Friction is proportional to the normal force. The more you weigh, the more friction you get, but also the more mass you have, so your acceleration will not and cannot change.

More wheels wont help. The more wheels you have, the less weight is on each wheel.

Your acceleration is always related to the local gravitational constant. No getting around that (unless you use RCS or engine to provide extra downward force).

The maximum angle uphill (or downhill) you can go at steady speed is related to the coefficient of friction of the wheels ONLY and not dependent on gravity, number of wheels, weight, mass, etc... http://physics.bu.edu/~duffy/semester1/c6_measuremus.html

That is true, for completely rigid bodies. Which is the kind I suppose KSP is simulating. Once elasticity in the form of tire and terrain deformations come into play, however, higher mass starts to increase your energy losses. I believe that is why people think adding mass to rovers would increase drag. Because it seems to in the real world. (Seems to because the actually increased energy loss is not from drag as defined by physics but from the deformation losses.)

[arkie87]

That is true, for completely rigid bodies. Which is the kind I suppose KSP is simulating. Once elasticity in the form of tire and terrain deformations come into play, however, higher mass starts to increase your energy losses. I believe that is why people think adding mass to rovers would increase drag. Because it seems to in the real world. (Seems to because the actually increased energy loss is not from drag as defined by physics but from the deformation losses.)

Rolling resistance does increase with mass for non-rigid bodies. However, does KSP simulate it (i'd be impressed if it did). Regardless, rolling resistance still cannot increase breaking force above what is possible from static friction...

[jarmund]

I've seen a lot of people utilize upwardsfacing engines or RCS translating downwards to stick to the surface. In addition, it should be noted that the wheel types have different friction rating.

Also, as this is Duna, you might want to try to add:

[Claw]

These are all good and valid tips. However, I'd like to also mention that there is a bug with the current wheels which causes rover wheel braking to be very poor. If you are not opposed to addons, I have a fix for this in my Stock Bug Fixes.

http://forum.kerbalspaceprogram.com/threads/97285

The specific fix you are looking for in the download is called "ModuleWheelFix"

Cheers,

-Claw

[FlyingPete]

One thing which I found worked well on Minmus was to use the reaction wheel's torque to lift the rover onto two wheels. This meant you could actually use the brakes rather than locking the wheels, and likewise go up hills without spinning the wheels.

[Jaeleth]

More weight shouldnt help. Friction is proportional to the normal force. The more you weigh, the more friction you get, but also the more mass you have, so your acceleration will not and cannot change.

More wheels wont help. The more wheels you have, the less weight is on each wheel.

Your acceleration is always related to the local gravitational constant. No getting around that (unless you use RCS or engine to provide extra downward force).

The maximum angle uphill (or downhill) you can go at steady speed is related to the coefficient of friction of the wheels ONLY and not dependent on gravity, number of wheels, weight, mass, etc... http://physics.bu.edu/~duffy/semester1/c6_measuremus.html

Now that you mention, what you say makes sense, however, experimentation showed me that a big truck is easier to control on, say, minmus, than a light rover, whatever reason, maybe the type of wheel i was using?

as for a work around, a rear pointing engine will produce more acceleration than a downpointing one, since the downpointing one will only increase downforce, thus limiting accel. to the electric engine's capabilities while a back pointing one will increase speed beyond the rover's electric engine capabilities, sometimes, way beyond driver's capabilities too... on the other hand, a downpointing engine will increase controllability. On duna one could even try a spoiler, although i don't know if the low atmosphere density is to make such thing even feasible.

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That is true, for completely rigid bodies. Which is the kind I suppose KSP is simulating. Once elasticity in the form of tire and terrain deformations come into play, however, higher mass starts to increase your energy losses. I believe that is why people think adding mass to rovers would increase drag. Because it seems to in the real world. (Seems to because the actually increased energy loss is not from drag as defined by physics but from the deformation losses.)

ah... Ha! Maybe you just given an explanation to my previous question , in a way...

the truck i drive on minmus is, actually, NOT rigid... It has a midsection that tends to bend when I brake and it increases enormously the braking power. It was an unintended effect, since i had the midsection designed that way in order to refuel small probes that moved below it to access a docking port. On high gravity environments I have to brake slowly or the whole thing flips over from stored elastic forces sudden release.

now this just gave the idea of a catterpillar-like truck, moving like a snake... Over rough terrain