Rover brakes ineffective

[barfing_skull]

I'm trying to design a rover, as a fuel tanker, that could easily move a little ways between ships. I'm starting on drilling ore and refining it, using KAS (because docking sucks on the surface).

Anyway, I've built the following rover. It seems to be able to land itself on Kerbin, so I figure on lower gravity bodies it should do better. However....the brakes are almost totally ineffective. It'll move itself out just fine, and stop by reversing the motors, but the brakes barely slow it. Is that a product of the weight (as you can see, 61t)?

Any tips at getting better braking out of this?

Cheers,

-BS

Edited May 5, 2015 by Claw

[zekes]

Can't you turn them up? Or can you just reverse power to stop?

But yes I did notice a drop in braking force.

[arkie87]

I'm trying to design a rover, as a fuel tanker, that could easily move a little ways between ships. I'm starting on drilling ore and refining it, using KAS (because docking sucks on the surface).

Anyway, I've built the following rover. It seems to be able to land itself on Kerbin, so I figure on lower gravity bodies it should do better. However....the brakes are almost totally ineffective. It'll move itself out just fine, and stop by reversing the motors, but the brakes barely slow it. Is that a product of the weight (as you can see, 61t)?

Any tips at getting better braking out of this?

Cheers,

-BS

http://i.imgur.com/ILQMSZV.jpg

Breaking force is proportional to local gravity (friction is proportional to weight). You will only slow down at approximately 1 local g. On Mun and Minmus, that is quite slow...

EDIT: on review, it appears you are talking about breaking on Kerbin...

Edited May 4, 2015 by arkie87

[impyre]

I suspect those large wheels produce more torque when active than their brakes do... I'd try throwing it in reverse.

[Geschosskopf]

Anyway, I've built the following rover. It seems to be able to land itself on Kerbin, so I figure on lower gravity bodies it should do better. However....the brakes are almost totally ineffective. It'll move itself out just fine, and stop by reversing the motors, but the brakes barely slow it. Is that a product of the weight (as you can see, 61t)?

Any tips at getting better braking out of this?

Any rover big enough to need the "Ginormowheels" is going to have a boatload of momentum so will take a while to stop even from its top speed of about 13m/s. I find it useful to use reverse thrust while braking with such monsters.

Be advised, however, that these big wheels have like zero traction on on low-gravity worlds, no matter how heavy the rover. I just tried using them with a large ore miner on Ike that weight 67 tons fully loaded and only 4 wheels, so the ground pressure was pretty high. Still, the thing would slide sideways down even the gentlest of slopes, and accelerated uncontrollably if pointed up or down the slope, despite both brakes and opposite thrust.

So I'm inclined to believe that these wheels are pretty much useless.

[Supernovy]

Does the braking force change depending on whether steering is locked? I know the big wheels don't have individual steering, but tank steering, but I can't remember if they have a steering tweakable on them.

[Claw]

It's a bug with the way the wheel torque tweakable was reworked. If you are not opposed to add-ons, I have built a fix for this in my stock bug fixes: http://forum.kerbalspaceprogram.com/threads/97285

The specific piece you need from the download is the "ModuleWheelFix" folder (which you can place into your GameData folder).

Cheers,

~Claw

[Chaos_Klaus]

Do you actually hold B to use the brakes? If you just go backwards, you will only slow down and that takes more time.

[katateochi]

It's a bug with the way the wheel torque tweakable was reworked. If you are not opposed to add-ons, I have built a fix for this in my stock bug fixes: http://forum.kerbalspaceprogram.com/threads/97285

The specific piece you need from the download is the "ModuleWheelFix" folder (which you can place into your GameData folder).

Cheers,

~Claw

Claw, you are a absolute legend!! Thanks!

Do you know if wheels are supposed to be weaker in 1.0.x or is that related to this?

[Claw]

Claw, you are a absolute legend!! Thanks!

Do you know if wheels are supposed to be weaker in 1.0.x or is that related to this?

I don't think it was intentional. It looks like the code was modified for landing gear but unfortunately borks rover wheels.

Unless that isn't what you mean by "weaker."

Cheers,

-Claw

[Geschosskopf]

It's a bug with the way the wheel torque tweakable was reworked. If you are not opposed to add-ons, I have built a fix for this in my stock bug fixes: http://forum.kerbalspaceprogram.com/threads/97285

The specific piece you need from the download is the "ModuleWheelFix" folder (which you can place into your GameData folder).

Cheers,

~Claw

Much obliged. Thanks +1

[barfing_skull]

Yeah, I was testing on Kerbin only. Reversing power does work there, but I find brakes more useful as you don't need to worry about shooting off in the other direction. Yes, the B key was continuously pressed.

I was pondering first taking this thing to Mun. I suppose another approach would be to use the smaller ruggedized wheels, just more of them. Those ones, to me, seem to have the most traction.

Good to know about the braking bug. I'll look at the mods, I've got a few already.

This is another one of those instances where I wish I could 'simulate' different gravity situations on Kerbin without actually sending a craft to the target body. I wanted the same thing to test engines in Eve's atmosphere....

Thanks all for the help.

Cheers,

-BS

[katateochi]

I don't think it was intentional. It looks like the code was modified for landing gear but unfortunately borks rover wheels.

Unless that isn't what you mean by "weaker."

Cheers,

-Claw

I meant that they seem to break (get punctures) more easily than before. I have a very lightweight rover that could easily handle being jumped off the launch pad in 0.90.0 without the wheels breaking, but in 1.0 the wheels break much more easily (just going up the small ramps nearby at 20m/s breaks them). (I know, rovers aren't meant to be jumped, but that was my test course to see what it could handle).

[SlabGizor117]

If your question is answered, remember to mark it as such, it helps us to know whether we need to reply.

[Claw]

I meant that they seem to break (get punctures) more easily than before.

Ah...I hadn't noticed this yet. Hmm, I can't imagine that was changed either, but I will take a look and see if there is something that can be done to toughen them up a little. Was this with or without my fixes?

Cheers,

-Claw

[katateochi]

Ah...I hadn't noticed this yet. Hmm, I can't imagine that was changed either, but I will take a look and see if there is something that can be done to toughen them up a little. Was this with or without my fixes?

Cheers,

-Claw

That was in a pure stock install without your (awesome) fixes. The wheels in question are the TR-2L ruggedized wheels on a very small (< 2 ton) rover. In previous versions the wheels hardly ever broke (as the rover was so light). If you could toughen them up that would be great!

Also, do you know if the complete steering lock that happens above ~35m/s is intentional?

[Beowolf]

I don't think it was intentional. It looks like the code was modified for landing gear but unfortunately borks rover wheels.

Unless that isn't what you mean by "weaker."

Cheers,

-Claw

"Borks" is a polite way to put it. I was using stronger words as my little rover went cross-country skiing across Duna...sideways.

Thanks for the patch!

[Claw]

Also, do you know if the complete steering lock that happens above ~35m/s is intentional?

I would guess no, it's not intentional. I haven't experienced a "steering lock" myself at those speeds, but I have seen the wheels skidding. They still move though. Is that what you mean?

"Borks" is a polite way to put it. I was using stronger words as my little rover went cross-country skiing across Duna...sideways.

Thanks for the patch!

Haha. Hopefully the patch helps a bit. I did increase the traction some. And you are welcome.

Cheers,

-Claw

[katateochi]

I would guess no, it's not intentional. I haven't experienced a "steering lock" myself at those speeds, but I have seen the wheels skidding. They still move though. Is that what you mean?

It's not a skidding thing, it's as if steering gets completely disabled above a certain speed and then suddenly gets re-enabled as you drop below that speed.

This is my very simple rover for testing this; (in a 100% stock install, the only change is to keybindings so that in docking mode W also does translate forwards)

At that speed (39m/s) I'm still able to steer, you can see the rover tipping slightly. obviously if I was to steer hard it would roll right over, but little steering adjustments can still be made.

Then just after at 40m/s the steering suddenly locks out. In this pic im holding down steer left and the rover does nothing (there is a very very slight movement, but it is not enough to change course at all)

Them I let go of the throttle while still holding the steering, the second the speed drops below 40m/s steering is re-enabled and (not surprisingly) the rover flips.

I'm guessing this is to do with the way steering is reduced at higher speeds. That is a fine mechanic, but this is a very sharp cut off and means at 40+m/s you have no way of adjusting the rovers heading.

I hope this is a bug as you say. If it's an intended safety feature it actually makes things worse; obviously steering hard at speed will make you roll, but you could still make little adjustments. This means that you are inclined to hold down the steering hard and then when it suddenly kicks back in you are bound to flip.