The right Rover for the right situation

[Yorou]

Hello again. You guys are awesome and thanks for all the input on my part limit/performance thread.

This time, I would like to discuss Rover. I find that the part descriptions for the wheels is lacking and I couldn't find much online. So my question is; other than obvious aspect (IE: weight and size of rover or cargo) how should one choose the wheel type in relation to the gravity of the astral body it will be used on?

[magnemoe]

I use the rugged wheels most of the time even if optimized for low-g worlds, the old balloon tires might be better in some settings but are more fragile.

The tiny wheels are nice for tiny probes but are pretty hopeless for large low g worlds.

[BlueCanary]

The rugged wheels are tougher, use less power, and accelerate faster to a higher top speed than the non-rugged ones. The only reason I can see to use those ones is looks and the slightly smaller size being more convenient on certain craft.

The small wheels are painfully slow and the massive ones are painfully glitchy even by KSP wheel standards and are also slow and hard to steer so I rarely use them at all.

[keeper]

The only times i've used the ginormas ones was with very heavy "rovers" about 40t, but they handle the weight better.

Most if not all my rovers are with the rugged wheels, i try to get at least 3 wheels per side. Only the middle wheel with motor, no steering. The two outer sets of wheels no motor, with steering helps balance ALOT on low g worlds

[vixr]

There is a mod that has tank treads (5 sizes) that are awesome...

Edited August 26, 2015 by vixr

[Mikki]

Make sure that one of your engineers is able to fix the broken wheels, when it comes to a serious mission...

No matter how cautios you are driving, something will break sooner or later...

This truck is able to land/ ascend by itself on smaller celestial bodys (Monoprop engines), i suggest to make rovers with a lower CoM, but not in this case:

[Fearless Son]

The rugged wheels are tougher, use less power, and accelerate faster to a higher top speed than the non-rugged ones. The only reason I can see to use those ones is looks and the slightly smaller size being more convenient on certain craft.

Given that rovers can accelerate beyond a speed at which they can safely collide with surfaces, the additional acceleration and top speed of those wheels is not always desirable, particularly on rougher or lower body surfaces where the rover is prone to catch air if it crests a ridge too quickly or tries to make too sharp a turn or too aggressive a breaking maneuver.

It would be nice to have a few more tweakable options for rover wheels to fine-tune their performance envelope for what you need the rover to do.

[BlueCanary]

Given that rovers can accelerate beyond a speed at which they can safely collide with surfaces, the additional acceleration and top speed of those wheels is not always desirable, particularly on rougher or lower body surfaces where the rover is prone to catch air if it crests a ridge too quickly or tries to make too sharp a turn or too aggressive a breaking maneuver.

It would be nice to have a few more tweakable options for rover wheels to fine-tune their performance envelope for what you need the rover to do.

I find that on a rover especially designed for toughness, particularly with a suspension system added, the off road wheels are very tough to the point of being able to ford the admin building swimming pool at 20m/s, whereas the normal wheels would shatter if you tried that at anything above 10m/s. But then again I completely agreeabout the difficulty turning and braking, it's made especially bad by the extra ground clearance from the slightly bigger wheels.

Tweakable options would be great, I really hope that's one of the things they put in the 1.1 wheel overhaul. Until then you can avoid going too fast and avoid having to hold down W all the time by using trim - assuming W is your rover wheel forward key, hold down Alt+W until going at the speed you want.

[Hagen von Tronje]

Generally I find it's less about where you're putting the wheels and more about what vehicle you're putting them on. I also think their potential applications are fairly obvious by looking at them, with the note that rugged wheels are more or less a direct upgrade to balloon wheels (better wheel, more power efficient), though balloons are perfectly servicable.

But it's worth mentioning that landing gear constitutes a whole other class of wheel that can be perfectly viable on rovers. In particular, landing gear are ideal for high speed "land ships" that pretty much sail over the ground on external thrusters, and also great when you need a wheel to be a point of abusive or high speed contact, and some landing gear can be deployed as well making it a viable option for moving parts on a stock rover.

If you find yourself dissatisfied with the wheels and thinking about mods, first try Claw's bugfix for wheel brakes, a lot of folks find this gives them just the thing they needed to be acceptable.

rovers can accelerate beyond a speed at which they can safely collide with surfaces

Are you sure?

Build a rover like this:

- 4 rugged wheels, all motors engaged, all touching the ground level with each other

- 2 small wheels, turned facing to the front, motors disengaged. This is to act as a bumper

Drive this into the side of the VAB at 25m/s, the top speed for rover wheel motors. The small wheels should survive the impact, they will have flat tires but not be destroyed. An engineer can then repair them and you can repeat the experiment indefinitely so long as you repair the wheels. Even if you don't repair it might take you a few tries to get one to explode.

I've had countless rover fails by now but I've yet to have a single rover wheel be permanently destroyed unless the entire vehicle was pretty much annihilated in the impact. They're pretty durable parts so far as that goes.

Edited August 26, 2015 by Hagen von Tronje

[Fearless Son]

Are you sure?

Yeah, I am sure. It is not just a matter of the strength of the wheels themselves, though that can certainly be a big factor in some circumstances. But even the toughest wheels will not stop a rover from breaking chunks off itself if takes a bad spill at speed. The wheels might be fine, the scientific apparatus, antenna, batteries, and docking ports might get wrecked though. Yes, there are ways of building more stable rovers where that is less likely to happen, but other design constraints can limit one's ability to take advantage of that. If it needs to fit in a cargo bay, for example, that will limit how wide the base can be.

Hence why I really want tweakables for fine-tuning the rover performance. Some mission profiles might allow for greater acceleration, some might demand lower.

[BlueCanary]

Yeah, I am sure. It is not just a matter of the strength of the wheels themselves, though that can certainly be a big factor in some circumstances. But even the toughest wheels will not stop a rover from breaking chunks off itself if takes a bad spill at speed. The wheels might be fine, the scientific apparatus, antenna, batteries, and docking ports might get wrecked though. Yes, there are ways of building more stable rovers where that is less likely to happen, but other design constraints can limit one's ability to take advantage of that. If it needs to fit in a cargo bay, for example, that will limit how wide the base can be.

Hence why I really want tweakables for fine-tuning the rover performance. Some mission profiles might allow for greater acceleration, some might demand lower.

Depends what your rover is built of, and how. My pickup truck (shameless plug, I know ) is built so in most impacts all that will contact the ground is 80m/s impact tolerance structural parts, and the chassis is built exclusively of those parts, and as a result it can survive having the VAB blow up underneath it and is safe in pretty much all rollovers. You just need a tough chassis so the rover will remain driveable no matter what, a rollcage to keep breakable parts away from the ground in rollovers and maybe a bumper (even just the wheels extending out in front) to protect from head on impacts and the rover should be fine.

[Hagen von Tronje]

Yeah, I am sure. It is not just a matter of the strength of the wheels themselves, though that can certainly be a big factor in some circumstances. But even the toughest wheels will not stop a rover from breaking chunks off itself if takes a bad spill at speed. The wheels might be fine, the scientific apparatus, antenna, batteries, and docking ports might get wrecked though. Yes, there are ways of building more stable rovers where that is less likely to happen, but other design constraints can limit one's ability to take advantage of that. If it needs to fit in a cargo bay, for example, that will limit how wide the base can be.

Hence why I really want tweakables for fine-tuning the rover performance. Some mission profiles might allow for greater acceleration, some might demand lower.

Kind of moving the goalposts from "beyond a speed at which they can safely collide with surfaces," isn't it? My experiment demonstrates precisely that they can safely collide with a surface at their own top speed. If you're using an antenna as the bumper, then kerbals on EVA exceed the top speed for safe impact on that.

But to be honest I'm a little surprised acceleration would be an issue, at least in terms of wanting to turn it down. Either analog control or just tapping keys seems to do a pretty good job, no? Though to be sure I'm in favor of any and all additional tweakables, though I'd personally prefer things like ride height, stiffness, etc, as I think that would do a lot more for customization to the vehicle/terrain.

[Wjolcz]

Rovers aren't really worth bothering with before 1.1. I cried a lot when I found out how bad the wheels are on less than 1G bodies. Probably should work fine on Eve or Laythe, but after trying to achieve anything with them on Duna I gave up sending rovers anywhere else.

[magnemoe]

I find that on a rover especially designed for toughness, particularly with a suspension system added, the off road wheels are very tough to the point of being able to ford the admin building swimming pool at 20m/s, whereas the normal wheels would shatter if you tried that at anything above 10m/s. But then again I completely agreeabout the difficulty turning and braking, it's made especially bad by the extra ground clearance from the slightly bigger wheels.

Tweakable options would be great, I really hope that's one of the things they put in the 1.1 wheel overhaul. Until then you can avoid going too fast and avoid having to hold down W all the time by using trim - assuming W is your rover wheel forward key, hold down Alt+W until going at the speed you want.

Remember going Jeb with an rover on Mun, that is looking for maximum airstime.

Very simple design, three of the structural plates some octagonal struts to get wider wheelbase, 6 rugged wheels, two seats, power and some science.

My main problem was that kerbals was knocked out of seats in the high speed landings and had to eva back to rover to fix the wheels, then I went out of fuel for the eva packs

If you want speed keep weight down at all cost, heavier rovers break up far to easy.

- - - Updated - - -

Rovers aren't really worth bothering with before 1.1. I cried a lot when I found out how bad the wheels are on less than 1G bodies. Probably should work fine on Eve or Laythe, but after trying to achieve anything with them on Duna I gave up sending rovers anywhere else.

Why will 1.1 change this? Has been a bit out of the loop.

I always use rovers doing the final grinding of science on Mun. pod with small equipment bay, small fuel tank an engine, then four fuel tanks on radial decoplers with wheels on. science and power on this for balance.

drop tanks below the outrigers to get from LKO to mun surface or on last mission an service module for refueling and doing multiple landings.

Mun has one spot with 7 biomes within 10 km and multiple 3 biome places.

Probe rovers are nice for contracts.

Yes rovers on low g worlds like Minmus don't work well and here you also don't use much fuel but on other places they are nice.

[Castille7]

There is a mod that has tank treads (5 sizes) that are awesome...

http://i105.photobucket.com/albums/m236/vixr/screenshot3_zpsqqatao4k.png

http://i105.photobucket.com/albums/m236/vixr/screenshot16_zpsy89m4ztr.png

Man these are sweet!!!

[Wjolcz]

Why will 1.1 change this? Has been a bit out of the loop.

Don't remember exactly, but they will be better.

[BlueCanary]

Remember going Jeb with an rover on Mun, that is looking for maximum airstime.

Very simple design, three of the structural plates some octagonal struts to get wider wheelbase, 6 rugged wheels, two seats, power and some science.

My main problem was that kerbals was knocked out of seats in the high speed landings and had to eva back to rover to fix the wheels, then I went out of fuel for the eva packs

If you want speed keep weight down at all cost, heavier rovers break up far to easy.

http://forum.kerbalspaceprogram.com/threads/132305-Xtreme-Quadbike-Unstoppable-unless-you-re-a-brick-wall-or-any-kind-of-sharp-turn

Uses 4 ruggedized wheels, takes 30 metre, 50m/s+ jumps on Kerbin without any issues whatsoever. I wonder what the difference is between my designs and yours that causes this. The only times I ever have kerbals knocked out of seats is when they are squished against the ground in rollovers, and a rollcage solves that easily.

[Belphegor]

i use the balloon wheels on small unmanned rovers, the kind small enough to put multiple of them on the same rocket. usually with the soul purpose of doing a surface scan

and the rugged ones for everything else. i only used the biggest wheels once but that was a 20 ton landship that needed a lot of ground clearance

[BlueCanary]

http://forum.kerbalspaceprogram.com/threads/132305-Xtreme-Quadbike-Unstoppable-unless-you-re-a-brick-wall-or-any-kind-of-sharp-turn

Uses 4 ruggedized wheels, takes 30 metre, 50m/s+ jumps on Kerbin without any issues whatsoever. I wonder what the difference is between my designs and yours that causes this. The only times I ever have kerbals knocked out of seats is when they are squished against the ground in rollovers, and a rollcage solves that easily.

EDIT: Maybe it's the octagonal struts, they are relatively easy to break. Also what kind of ground clearance do you have? And what kind of suspension? Using a springy Vagani-style suspension can help prevent wheels breaking quite well, check out MajorJim's RAGE Buggy, it uses the fragile balloon tires but can still do crazy off road stuff because of the suspension.

EDIT 2: The only time I use the balloon wheels is for aesthetic reasons. Other than that, they're slow, and I'm impatient and just too lazy to wait for them to speed up.

[Hagen von Tronje]

If you want speed keep weight down at all cost, heavier rovers break up far to easy.

...

rovers on low g worlds like Minmus don't work well and here you also don't use much fuel but on other places they are nice.

Ironically, heavy rovers work marvellously on Minmus.

The reason rovers are hard to deal with on low g bodies is because they have poor traction; poor traction is countered with downforce, which can come from downthrusters/RCS or it can come from just having a bunch more mass, so long as you keep the COM low. You can prevent most of the flipping by merely having a low COM (wide wheelbase) but only downforce will give you traction for more...sporty performance, though cornering you'll always want to either go slow or have downthrusters. The nice thing is that downthrusters and "more mass" are one and the same goal, just carry fuel tanks for both ballast and for fueling downthrusters and you'll find Minmus's gravity is just a number.

Minmus also has nice natural highways built into it. You should be able to do top speed on all flats at x4 physics warp no problem as long as you are careful about heading changes, making any two craft landed on the same flats accessible to one another risk-free if you have a rover active. This can be a handy thing if you have shipwrecked crew or a craft out of fuel as you can count on being able to reliably cross the flats in really short time spans to save them. Plus, most of Minmus's terrain is reasonably smooth, the slopes are gentle compared to mountains elsewhere and there are no craters.

I am curious about the 7 Mun biome spot though! That sounds like a real find!

Maybe it's the octagonal struts

It is. They have a pretty low structural strength, actually. Better off bolting wheels directly to structural panels IMO.

Edited August 27, 2015 by Hagen von Tronje

[Just Jim]

This is my newest rover, "Kirby", landed on Laythe yesterday. I built this one heavy and tough with I-beams and steel plates. It has 4 rugged wheels, a wide wheel-base, and very low CoM. Oh, and it's using a Mk2 Probecore..... I'm hoping the improved pitch torque will help keep her from flipping when braking. Only using front-wheel drive motors, and mostly just the rear wheels for braking.

Although it was originally designed for the Mun, it tore up the Laythe Dunes... and at one point was doing 50 m/s going down hill, hit a bump and got some air without flipping or blowing a tire!!!!

I was tickled pink when she landed and just kept on going.

This is by far my most successful rover.

[Falkenherz]

I just came home from an extended rover trip on Mün (uh, wait...). It was a science-rover for a 4-man-crew.

While the uphill speed was undewhelming due to only four wheels and a heavy mass rover (sometimes only 3m/s at 45 degree slopes), I was able to go downhill at top speeds of ~40m/s, and take high jumps with an impact vertical velocity of ~12m/s.

But not with the baloon rover wheels. I rather use landing gear to that purpose. The baloon wheels broke everytime I was over ~14m/s and just bumping over ridges. I am not sure how the ruggedized version is going to fare, but if you want to cheese the game, always combine with landing gear.

Edited August 27, 2015 by Falkenherz