Problems with large rover.

[c4ooo]

I just built a fairly big rover (160 tons), and am having lots of problems with it.

My issues are:

1) I am quite puzzled by the fact that turning (A/D key) requires more electricity than going forwards/backwards.

2) Probably linked to issue #1, going acceleration is very poor when i go backwards/forwards,; however, turning has much greater acceleration. I could go forwards faster by spamming A/D then by holding down 'W'.

3) Rover gets stuck very easily and can't go up hills.

In the above picture, i was not able to climb onto the launch pad. However when i spamming A/D it went up fine.

In this picture the rover is stuck between the two raised platforms, i can't go backwards or forwards, nor can i turn.

 

A few things i should note:

1)The 4 horizontal wheels on the back are disabled.

2)I have plenty of electricity

and 3)I am in 1.2 prerelease. 

 

Thanks

[Aegolius13]

One possible issue is that by design, those big wheels don't turn by, you know, turning.  Instead, they turn by having one set rotate forwards and the other set rotate backwards, kind of like you would see on a tank track.  As a result, they're not supposed to be able to turn well at speed, since that does not play well with one wheel set going backwards.  Not sure how this play with the "disable steering" option, but I'm guessing you may want to leave at least the front and back pairs with steering on.

As far as going up hills, I'd try messing around with the traction control and other tweakables.   But you may just be running into the infamous wheel issues; no clue if those have improved in 1.2.  

[YTNewneo]

With a big Rover like that you really have to think of it more as a Tank than a Car while building it. That means i would keep ALL wheels active and only disable the steering on the middle ones, and maybe even ad another pair to make it more like the tracks of a Tank. 

Also if this behemoth has it's center of Mass offset to the front or back it could very well be that your wheels are not getting enough traction while traveling up/down, because the wheels loose a bit of contact with the surface. 

[Sharpy]

First, don't build any heavy rovers in 1.1.x

The wheels are broken, everyone knows it. They semi-work for lightweight stuff. They don't work for heavy stuff, period.

You want that thing to drive across the crawlerway - that's one of hardest challenges for heavyweight rovers. 160 tons? I wonder why the crawlerway hasn't exploded yet.

From what I see - what tasks you set to it - the mass it carries and the terrain it crosses, in full Kerbin gravity - it performs great. You just aren't satisfied with 'great' - you demand miracles.

[DrLicor]

On 19-9-2016 at 10:07 AM, Sharpy said:

First, don't build any heavy rovers in 1.1.x

 

 

Left top of the screen, you can see the relay icons from 1.2  

[Sharpy]

57 minutes ago, DrLicor said:

Left top of the screen, you can see the relay icons from 1.2  

Oh, okay. The point stands though - 160 tons across the crawlerway -

This thing has a payload mass of 160 tons. It's not loaded to full capacity in the photo.

Try to imagine it doing the shenanigans you want your rover to do.

[c4ooo]

Yep time in 1.2 (I said this in the original post )

My goal was to build a large rover that could traval long distances, from biome to biome.

Iirc there was a video of a similar planet exploration probe on YouTube that worked fine, except in older versions and probably with much smaller mass.

[Sharpy]

@c4ooo Yep, the rover can be BIG, but it can't be very HEAVY.

The huge wheels are actually quite useless, because for the mass they are supposed to support, all other structural joints begin failing and the wheels are the only thing that remains unbroken when your rover hits a bump.

I did my own share of heavy rovers.

This was one of my first attempts:

As you see, a total massacre resulting from driving off the runway. Thankfully Squad reinforced MK3 joints shortly after. Still, huge wheels vs heavy rover.

This was a different attempt - a fuel truck for a Minmus base. Ruggedized wheels.

Note: all wheels broke, but none broke off. The truck fell apart on all weak joints, and the runway exploded - all a result of plain, careful driving the truck off the runway.

That was the first "prototype" of a fuel truck, and despite the problem seen above, once landed on Minmus, it appeared to be vastly overpowered.

I added a second, simpler variant.

STILL way overengineered, and the multiple tanks were bothersome.

I don't have the screen of the third, final variant, but it was extremely simple. Just the largest Kerbodyne tank, with a probe core, battery and Klaw on one end, Poodle on the other end, four ruggedized wheels stuck directly to the tank, two solar batteries and four Twitches, that were more than enough to lift the full truck off Minmus. Simply put, Kerbin gravity is deadly. If your rover is meant for Mun, Ike or Duna, take less than half of what Kerbin needs. For Minmus, cut the requirements by 5 or so.

 

And this is my recent project - after I disabled Autostrut which was making it impossible.

The ore and fuel tanks are empty - yet. The rover was getting way too twitchy and floaty with them full, but I expect 1.2 will help against that. Already the wheels are "skipping". Of course with autostrut, the "carriages" don't follow the terrain.

And then...

The gantry was able to carry 20-ton items with zero effort. I could have done with some 4 less wheels - one central pair, and four for stability, but they really don't hurt, and give it a better acceleration. Of course nothing of that would be the case on Kerbin.

And the flatbed had no problem with such payloads either, other than half a kilometer of braking distance after it reached 20m/s.

For Minmus, really, four ruggedized wheels is all you need for about all applications. If you plan to take your rover to Eve - then you may consider other solutions... but also consider their weight once they get there.

 

[Just Jim]

1 hour ago, Sharpy said:

Yep, the rover can be BIG, but it can't be very HEAVY.

Agreed. I have a heavy rover I named the chariot:

On the Mun it's performance is amazing, and I was able to circumnavigate it with ease. But on Kerbin it's garbage, especially after 1.1, and can't climb even a small hill because of the weight.

[adsii1970]

 

@Just Jim: Reminds me of the Armadillo from the movie, Armageddon.

[c4ooo]

Nice rovers

I have a small(er) rover working, but i'm wondering how to get all the science from the rover and bring it back to kerbin. (I'm in sandbox so i don't mind impractical builds like this but i still want the rover to be useful in career/science  ).

On a side note, @Just Jim, how long did it take you to circumnavigate the mun? O.O Even with timewarp i would image it would take multiple hours? 

[Just Jim]

37 minutes ago, c4ooo said:

On a side note, @Just Jim, how long did it take you to circumnavigate the mun? O.O Even with timewarp i would image it would take multiple hours? 

Several days off and on in real time. 
But I don't want to derail this thread, so if you want to see the whole thing, I went into great detail in Emiko Station starting at chapter 44: