[0.20] 2 better and more realistic wheels for the Kerbals who are still alive

[zitronen]

Hi guys,

Having tried the stock rover wheels, I decided they are not very realistic. They simply have too much grip, and will not slide no matter what. Since the KSP uses the stock unity wheel physics (which sucks), I realized the only way to change the grip values is to make my own wheel from scratch. I know a little bit about vehicle dynamics, and can design stuff in CAD, but have zero unity, modelling and texturing experience. It took me 2 days to learn blender and unity get the thing working and couple more days to tweak the friction curves which is just bonkers in unity.

These wheels will skid at full torque (great for doing donuts), they will slide when you push them over peak friction, so you will be able to counter steer drift around the launch pad like a pro. Suspensions (0.3m travel) and dampers are set up for a medium sized rover (pictured below) on Kerbin, but also tested to work great on the Mun, just don't park on a slope!

This is just a normal part, no plugins required, just put it in the gamedata folder.

Added NEW Wheel!!! A smaller 0.5m wheel for probes and Kerbal Karts with working double wishbone suspension and shock absorber.

0.5 m wheel for 0.5-2T rovers (with 4 wheels)

1.0m wheel for 2-5T rovers (with 4 wheels)

Crater hopping on the Mun at 38m/s

It's not quite finished, I'm rubbish at texturing, and I still need to make a broken wheel model. I would like to get some feedback on whether you guys think the performance is more realistic though.

Direct download of the old original version here: https://sites.google.com/site/zitronfiles/FWheel.zip

License:

CC BY, attribution appreciated.

UPDATED:

I have increase grip significantly after studying corning acceleration G forces and sliding friction on slopes. They should now be more realistic but also more likely to flip your top heavy rovers.

Direct download of pack of both wheels: https://sites.google.com/site/zitronfiles/ZWheel.zip

*Edit now links to both models of the wheel

Edited August 22, 2014 by zitronen
Updated description and link

[KhaosCorp]

Kerchelin, that gave me a giggle, they look good so far, ill give em a spin

[EnterElysium]

I'll have to check these out, wheels have always bugged me a little. Plus 'Kerchelin'. That sold me.

[Talisar]

Kerchelin, that gave me a giggle, they look good so far, ill give em a spin

I see what you did there

[earth]

texturink is fine to me. But normal maps would be a good addition to you racing masterpiece

[Darren9]

Certainly more fun than the stock ones Maybe you could add a slick and a knobbly variant, one with a slightly higher grip level than the other? They seem to slide very easily at the moment - not that that's really a bad thing though.

[ghost010]

I get the need.... ,the need for..........SPEED! hahah

nice man,i was planing to do a car body for KSP some time,ill be sure to use these wheels.

[zitronen]

Do you guys think it needs more grip? I can make one with say 20% more grip if you want, bear in mind more grip = easier to flip over. I can work on the texture and model a bit more later, but I really want to get the handling right.

[Kenobi McCormick]

Oooooh. I'm trying these out right now. They look awesome, and the ability to do donuts is attractive to ay the least.

Any plans for probe and truck sized versions? Not necessarily new models, just resized ones with retuned suspension and traction settings?

Edit: After a bit of testing I've found out that A: I absolutely adore these things, and B: The CFG tuning is a bit off. What I've changed:

Braketorque. These slide, so I see no reason not to put enough of this to lock the tires up. Changed it to 2500.

Steering lock. Because they slide, steering too much at speed will jsut result in under/over steer instead of a rollover. Plus I've had a few spins that could have been easily corrected if I had more steering lock at that speed. So I turned this up across the board. Slow speed is up to 35 degrees, high speed is up to 25 degrees. I use a 360 pad to drive rovers so it isn't a problem for me to manually steer less than that.

Torque. The initial value of 2500 is good, but I felt the value dropped off way too quickly. Mine stay at peak torque until 30m/s, then slowly taper off. At 50m/s they're still putting down 1250. This gives my rather light(Under 2 tons) medium sized space car a top speed of about 45m/s, which is perfect.

What I'd like to change but cannot:

Spring rate. My medium sized rovers are incredibly lightweight, and as a result there isn't much action from the suspension. These feel to me to be tuned for 4-6 ton rovers, not 1.5 ton rovers. I'd turn the spring stiffness and dampening down quite a bit for them. Or maybe make a second "Type R" version with the lighter tuning for lighter medium sized rovers.

Sizing. As mentioned before some gokart and truck sized versions with varying stats would be great as well. I could handle scaling them through part.cfg, but not changing the springs rates to suit the different types of vehicles.

Traction. The sideways grip is about spot on I think, but forward bite leaves much to be desired. Even with my 360 pad every takeoff is full of wheelspin. That might just be because of how light my rover is, but I'd still like more forward bite. Maybe another 20%. But leave the side bite alone, again, I feel that's spot on. It's still possible to traction roll but you really have to eff it up to do it, and that's about right.

Edit 2:

Powerslidepowerslidepowerslidepowerslide

Certainly more fun than the stock ones Maybe you could add a slick and a knobbly variant, one with a slightly higher grip level than the other? They seem to slide very easily at the moment - not that that's really a bad thing though.

If only we could differentiate the surfaces. The slicks would work best on the runway, or other bodies like the runway, while the knobbies would slide like mad on those surfaces and dig in firmly on dirt and loose rocks.

Edited June 2, 2013 by Kenobi McCormick

[automcdonough]

Excellent.

I've started a few threads about the wheels and the strange friction tuning, the inability of them to slide. They didn't get anywhere.

Slapped them on my rover, so far I love them. I'll have to try it out on mun.

Edited June 2, 2013 by automcdonough

[KhaosCorp]

Honestly I think they need more grip (or as was mentioned before have knobbed/mudtire variant with more grip and a little less slip). The drift mechanics is great fun, and unlike other tires that slip with these its possible to power steer into the slide, for more controlled drifting. I just cant get over how easy things flip with these tires.

One of my little test vehicles (sorry I didn't take a pic, maybe ill rebuild it and snap one) flipped while skidding on the run way...was only goin 7m/s, and it was not an issue of top heaviness. The cart in question had wheel base almost double total ride height, that just don't add up to me.

I think you really got a good thing going here. Some other variants with tweeked values would be brilliant and take this mod from great to awesome!

But please, I beg, no matter what changes ya make, keep the Kerchelin, that's good stuff!

[genericevildude]

These are amazing, like others have said you should make different sizes, or atleast ones with the suspensions tuned to different weight classes of rovers

[automcdonough]

my rover i can't get to flip, even going up to 60mps and cutting the wheel. I can't imagine how you pulled it off at 7mps with a wheelbase like you describe.

[Panichio]

Thanks for doing this. The other thing that was annoying me was because the original wheels couldn't slide, rovers would just tip over a lot.

[K3-Chris]

Has no brakes and doesn't seem to work at all on the mun, can't go up any kind of incline, just slides down hill, otherwise very nice work, though they seem very similar to TT's wheels, albeit not running on fairy dust

[zitronen]

Hi guys,

Thanks for the feedback.

I agree the brakes need to be stronger, luckily that is one value you can change yourself in the cfg file. Other values in the cfg are also a bit conservative. While I also drive with a controller I had to make sure it doesn't get too difficult to drive at 40m/s for people using keyboards. Change the config files to fit your style!

Auto & Kenobi, your rovers in the pictures are definitely too light for the suspension, I wish there was some way to adjust it in the game like the procedural wing thing but I don't know how to do plugins. I will make a new version with spring rates reduced by 3 times for lighter things. At least for heavier rovers you can just put more wheels on.

As far as grip level is concerned, currently the lateral and tractive friction curves are identical. The problem is the unity (physx??) friction curves don't make any sense, the values you put in don't work the way you'd expect from reading the documentation. In fact I'm pretty sure there's something wrong with them. Getting things working is very much trial and error, it doesn't help that unity doesn't show you what the curves look like or even what units the values should have. Also Kenobi do you get too much wheel spin no matter how much throttle? It should bite more if you reduce the torque. Too much torque will easily push past the peak friction and break loose. It would be nice if there was some feedback like smoke or tire sound to let you know when you pushed it too much, but again that will require plugins.

For the models, I was thinking maybe one more bigger and wider wheel for more grip, and a smaller and narrower wheel with less, what do you guy think? Obviously "Kerchelin" is staying, that goes without saying!

Chris I don't know what you mean don't work at all on the Mun. They will have less traction on the Mun, but since the mass of your rover stays the same you will get much less acceleration, but they definitely work. Make sure you are not running out of power, these wheels are very power hungry. There's nothing I can really do about sliding down hills, squad needs to implement some kind of surface based friction. Even though the Mun has less gravity, you'd expect the wheels to dig in more in to the loose surface.

Another thing to note is the lack of rolling resistance, on the Mun there is no air to slow you down, without rolling resistance you can just basically coast along forever at 40m/s.

[itsme86]

These tires are tons of fun! Thanks!

[Weatherman159]

these wheels are very power hungry.

You're not kidding. When I first tested them out, I thought they didn't work very well, not realizing each wheel takes more than 4 of the new 0.20 ones. Been having great fun with them once I added MOAR POWER.

[Lindy]

Great wheels, I love them! Being a Yupper I'm used to driving on ice, so the amount of slip is no big deal. Too bad Unity is making it a PITA to tweak the grip ( a tiny bit more would be nice )

[Kenobi McCormick]

Auto & Kenobi, your rovers in the pictures are definitely too light for the suspension, I wish there was some way to adjust it in the game like the procedural wing thing but I don't know how to do plugins. I will make a new version with spring rates reduced by 3 times for lighter things. At least for heavier rovers you can just put more wheels on.

Heh, perhaps with tweakables in later versions of KSP you can put different spring rates in the menu.

As far as grip level is concerned, currently the lateral and tractive friction curves are identical. The problem is the unity (physx??) friction curves don't make any sense, the values you put in don't work the way you'd expect from reading the documentation. In fact I'm pretty sure there's something wrong with them. Getting things working is very much trial and error, it doesn't help that unity doesn't show you what the curves look like or even what units the values should have.

I took one to Ike and found it absolutely impossible to get stopped. With the brakes absolutely locked the thing slid forever and absolutely refused to sit still. We definitely need more forward bite on these things.

Some testing on Minmus is appropriate I think? If itt'l sit still on Minmus' slopes we'll be able to use 'em on most bodies no problem.

Also Kenobi do you get too much wheel spin no matter how much throttle? It should bite more if you reduce the torque. Too much torque will easily push past the peak friction and break loose. It would be nice if there was some feedback like smoke or tire sound to let you know when you pushed it too much, but again that will require plugins.

I might tinker with the torque values a bit more. I'm kinda in the mind to copy them and make a 'hotrod' variant with an absolutely bonkers torque setting that'll never hook up at all, which I'll use for hooning about the space center, and edit the one I have now for actual use with..maybe 1750 torque instead of 2500?

For the models, I was thinking maybe one more bigger and wider wheel for more grip, and a smaller and narrower wheel with less, what do you guy think? Obviously "Kerchelin" is staying, that goes without saying!

My sentiments:

Size 0: Wheel diameter about 0.15m. For gokarts, tiny unmanned rovers and the like. Resembles a golf cart tire, with similar performance envelope. A srs bzns small tire, if you will.

Size 0 Type R: Pulled off a racing ATV. Same size as Size 0, but with loads of power, for screwing around and doing donuts.

Size 1: Same size as the Rovemax M1, roughly the same speed, but able to slide instead of instaflipping. A general purpose rover tire.

Size 1 Type R: This should be a racing slick, high speed stuff. Possible to use as aircraft landing gear as well?

Size 1.5: Same mesh we currently have, but with more grip and less speed.

Size 1.5 Type R: The wheel you have out right now.

Size 2: A large truck tire. Biiiig, 2m in diameter. Narrow. Heavy. Slow. But unbelievably strong with loads of grip, for use on large mining equipment, fuel trucks, mobile bases and the like.

Size 2.5: A size 2 dual wheel setup, for the rear of a truck.

Size 3: A monster truck tire.

With that sort of variety of wheels there's no limit to the sorts of rovers we'd be able to build using Kerchelin tires.

You're not kidding. When I first tested them out, I thought they didn't work very well, not realizing each wheel takes more than 4 of the new 0.20 ones. Been having great fun with them once I added MOAR POWER.

I've found that two MML RTGs will power one wheel just fine.

Edited June 4, 2013 by Kenobi McCormick

[zitronen]

Update: The link on the first post now links to the updated part

I deliberately changed things a lot so we can find the sweet spot easier

Unity:

Increased peak traction force by 60%

Increased peak lateral lateral force by 20%

Reduced spring rate by 3.3 times

Reduced damper by 3.3 times

CFG

Increased brake torque to 1500

Decreased initial torque curve to 1000 (too much for the increased traction otherwise!)

I just realised that my rover in the first post was 13T fully loaded!! Now the wheels should be best for 2-5T rovers.

Kenobi there's no way I have enough time to make all those!! I like the golf cart wheel idea, I think I'll work on that next. I also would like to find out how to get animated suspension linkages so we can have a double wish bone suspension. It's just cosmetic so that may need to wait.

[zitronen]

I took one to Ike and found it absolutely impossible to get stopped. With the brakes absolutely locked the thing slid forever and absolutely refused to sit still. We definitely need more forward bite on these things.

Some testing on Minmus is appropriate I think? If itt'l sit still on Minmus' slopes we'll be able to use 'em on most bodies no problem.

I not really sure what I can do about the lack of traction on low G planets until they add some surface material properties. I mean you have like 1/20th of the traction, even less when you are travelling at 40m/s since the orbit speed is so low. If I increase traction by 20 times to compensate it will instaflip at KSC. I would say skidding on low G planets is actually more realistic, it's what you'd expect given they all have the same smooth surface.

As far as sliding down a slope, when you are sitting still I think physx's static friction stuff kicks in to prevent you sliding around, that **** is as mysterious as the Kraken! I don't how what they do and how to change it at all.

[Kenobi McCormick]

Update: The link on the first post now links to the updated part

I deliberately changed things a lot so we can find the sweet spot easier

Unity:

Increased peak traction force by 60%

Increased peak lateral lateral force by 20%

Reduced spring rate by 3.3 times

Reduced damper by 3.3 times

CFG

Increased brake torque to 1500

Decreased initial torque curve to 1000 (too much for the increased traction otherwise!)

I just realised that my rover in the first post was 13T fully loaded!! Now the wheels should be best for 2-5T rovers.

Sweeeeet

Kenobi there's no way I have enough time to make all those!! I like the golf cart wheel idea, I think I'll work on that next. I also would like to find out how to get animated suspension linkages so we can have a double wish bone suspension. It's just cosmetic so that may need to wait.

If I could texture for crap I'd pitch in. I could make the models, I've got a basic grasp of Blender and it's not too much to learn how to refine models, but I am beyond terribad at anything remotely artistic. Which includes texturing.

[Talisar]

Sweeeeet

If I could texture for crap I'd pitch in. I could make the models, I've got a basic grasp of Blender and it's not too much to learn how to refine models, but I am beyond terribad at anything remotely artistic. Which includes texturing.

I feel your pain. I am trying to improve my texturing, but it's a long process for me. I end up increasing poly count by adding detail to models that could have been done through texturing if I only had the skill.

As a side note, zitronen, every time I see this thread I get that song stuck in my head again, thanks for that

[Kenobi McCormick]

I feel your pain. I am trying to improve my texturing, but it's a long process for me. I end up increasing poly count by adding detail to models that could have been done through texturing if I only had the skill.

Hah, and I can't even do a better texture than mapping solid colors to various parts of the mesh. I never have been able to draw worth a damn, not as a kid not now, not with crayons nor with GIMP.