This is how I roll.

[Mihara]

I haven't seen anyone seriously do this in KSP yet, so I suppose it might be interesting to some.

If you read up on asteroid research missions, in particular, Hayabusa and Phobos 2, you will notice that these planned to use rather unorthodox rovers, or more precisely, hoppers, meant for very low gravity environments. Instead of using wheels, they are essentially a wheel -- the rover rolls on it's outer surface by turning inertial control wheels inside itself. Neither of the two saw actual use -- Phobos 2 got lost, Hayabusa actually completed it's mission but lost the rover.

Well, today I set out to determine if the method works in KSP, because that would be just the thing to drop on Gilly or Bop. Turns out making a micro-rover like this from stock parts is not a problem. It rolls just fine even on Kerbin, as long as you don't make it heavier than about 0.25t. Just get it to fall on the side, hold down the roll button, and off it goes. Amusingly, while keeping the core on consumes power, rolling itself does not.

The most annoying problem was making it stop busting the solar panels against the ground -- while the panels look fine, after just a few touches they report as broken, so you can't exactly roll on them. Eventually, I ended up with this thing, which weighs 0.06t without a scientific payload, gets up to 1.5m/s on Kerbin, up to 2.6m/s on the Mun, and I suspect that with skillful rolling on Gilly, one could get it to escape velocity. You need to turn off clipping to squish the solar panels inside the cage.

It would probably work best by making a custom part for it -- the actual hoppers are way smaller and lighter than the smallest and lightest KSP parts, so it's kinda too far out of scale. With the tendency of small and light parts to fall through the terrain mesh and die, I'm not sure it would even work -- but I guess the method is usable as is.

[Deadpangod3]

Great design

For some reason when I saw the pic I thought "ERMAGHERD ITS GLOWING!!! KILL IT WIT FIRE!!!"

[Psycked]

LOL! classic!

[Mihara]

For some reason when I saw the pic I thought "ERMAGHERD ITS GLOWING!!! KILL IT WIT FIRE!!!"

That's MechJeb's unearthly light. It could be a battery glowing, but with it's energy requirements, just a battery isn't enough to get it to last through the night, and is dead weight during the day because it's power consumption does not depend on what it's doing and is fully satisfied just by one panel. MechJeb gets royally confused by rolling across the surface this way, apparently, at least the 'surface' window stops showing anything.

[Deadpangod3]

How come for me mech-jebs light is red?

[Mihara]

How come for me mech-jebs light is red?

It's green for the "active" mechjeb and red for the "inactive" ones. When there's more than one MechJeb on your ship for whatever reason, only one of them is green, others are red. When there's crew on your ship, all MechJeb lights are red.

[Vanamonde]

Can rolling rovers be steered? Driven uphill? Parked? It's an interesting idea, but how practical is it?

[Mihara]

Can rolling rovers be steered? Driven uphill? Parked? It's an interesting idea, but how practical is it?

Steered: You're still free to rotate the core in all directions, tilting it along the other axes steers it, though it's easy to oversteer. It's actually slightly faster when it's tumbling head over heels rather than rolling, but is less steerable this way because it spends more time flying. Just releasing the button actually makes it stop, barring friction against the ground or lack thereof.

Driven uphill: Yes, depending on how steep is the hill. From the testing I've been able to do (the idea is just a few hours old in my head) they're at least as capable of it as the lightest wheeled rovers. But they don't have wheels to bust.

Parked: Flip onto the flat end and turn on SAS. With the rover's very low mass, it can keep it parked while it's standing tilted on the edge, even.

The only drawback that I see is low maximum speed, 7.2km/h is not particularly fast. Still faster than kerbals running though. I suppose, with the use of off-center RCS thrusters, one could get them to very high speeds.

[Kerba Fett]

Check out the Jebcorp M209 sphere probe if you want to try rolling rovers.

It's spherical and has fuel enough to take off from Kerbin, fly to the Mun, and land. You then tip to the side and roll on the yaw axis using q and e.

If you try to roll along the pitch or roll axis, it will still move, but bounces as its a bit bottom heavy.

You could probably also use the Wayland Egg pod the same way.

[Limited Infinity]

I love this! I had make my own.

Introducing the Pangolin Class based off Mihara's design, or as the Kerbals call it, the Spin Cycle Vomit Car:

The command pod has more torque and I was able to make one that can go 4.1 meters per second. It has room for 2 Kerbals and it can climb the ramp back onto the VAB launch pad.

Unfortunately the MkIII has limited power generation and won't rover for long. The MkI performs nearly as well but is heavier with the generators.

Edit P.S.:

Steering is very twitchy as it uses roll for forwards and backwards and yaw to turn, but left and right flop as it rolls.

I tried adding SAS for more torque, but alas it only added weight and slowed it down

Edit: P.P.S: (last one. Promise )

The Pangolin MkV Solar panels for unlimited day time rover and just as maneuverable and same room for 2 as the MkIII.

Edited May 14, 2013 by Limited Infinity

[Mihara]

Omg, what have I done, poor kerbals.

[DerekL1963]

Try using the docking mode controls like you would for a regular rover...

[Mihara]

I tried adding SAS for more torque, but alas it only added weight and slowed it down

As a side note, in current version at least, SAS modules definitely do not add rotational torque, even though most descriptions say they should. As far as I can tell at all, the only torque they do add only goes into stopping rotation when you turn on SAS, (maxTorque) but rotational toque that goes into actually turning the ship only and exclusively comes from pods. (rotPower and linPower parameters in part.cfg).

[Noticeably FAT]

Does that mean you could add rotPower and linPower parameters to the SAS .cfg file and get them acting as they should? Or will that just make the SAS fight itself?

[Mihara]

Does that mean you could add rotPower and linPower parameters to the SAS .cfg file and get them acting as they should? Or will that just make the SAS fight itself?

I'm pretty sure it shouldn't make SAS fight itself, but whether this does anything at all or not depends on which object (as in software object, not a part) in the object tree actually handles the rotPower/linPower parameters. If it's CommandPod only, nothing will happen. If it's some other object that both CommandPod and SASModule objects inherit from, it will work. I'm not that deeply aware of KSP internals, I'm afraid.

[flux.faraday]

I decided to try this out. Copied the SAS Part file, changed some names, checked the log:

(Filename: C:/BuildAgent/work/812c4f5049264fad/Runtime/ExportGenerated/StandalonePlayer/UnityEngineDebug.cpp Line: 43)

Warning: Variable rotPower not found in SASModule Module!

(Filename: C:/BuildAgent/work/812c4f5049264fad/Runtime/ExportGenerated/StandalonePlayer/UnityEngineDebug.cpp Line: 43)

Warning: Variable linPower not found in SASModule Module!

It looks like those variables are not attributes added to the ship as a whole, rather they are handled by the part's module and SAS doesn't do that. The resulting part worked like a SAS, but didn't have any additional characteristics.

Nice probe design, BTW. I love it!!

[ChrisC177]

I know this thread is a few days old, but I had the same thought about SAS, and have found that you can change it to basically be identical to a probe part, but with no usage of electric charge, which then means the rotational power will work. I also increased the mass, just as a form of balance. I can't seem to post attachments, I guess because either I don't have enough posts, or it's just not allowed in the forums, so I'll put the additions I used for it here, and you can just copy and paste it into a copy of the SAS module config file.

CrewCapacity = 0

category = Pods

// --- SAS parameters ---
rotPower = 20
linPower = 20
maxTorque = 20
Ki = 0
Kp = 5.0
Kd = 3.5

MODULE
{
	name = ModuleCommand
	minimumCrew = 0

	RESOURCE
	{
		name = ElectricCharge
		rate = 0
	}
}
}

Obviously some is just changing what's already there, and some is adding it in. Hope this helps anyone! Sorry if I've done this post really badly.

[MBobrik]

looks like my TumbleWeed experimental rover. Don't have the sshots here, but it reached 4.1 m/s on Minmus. I abandoned the concept because it was unsteerable. To change direction in a controlled way one had to make a full stop.

[Mihara]

looks like my TumbleWeed experimental rover. Don't have the sshots here, but it reached 4.1 m/s on Minmus. I abandoned the concept because it was unsteerable. To change direction in a controlled way one had to make a full stop.

For something meant to be dropped from an ion-powered probe onto an asteroid, it's a drawback you can probably live with.