Mun Rovers - Unsafe at any speed ?

[Louella]

Hello

I have landed an autonomous (but crewable) rover on the Mun. http://i.imgur.com/6eCXbg0.png

The idea being to send an unpiloted mission carrying the rover, and later crewed missions to do more Science, with the rover.

However, I have found the rover to be somewhat... difficult to drive on the Mun... http://i.imgur.com/ij92wwt.png

I didn't think it was going all that fast... maybe 5 m/s

Ground testing of the rover was also somewhat dangerous, as a Kerbal who was testing the accessibility of the seat and the other controls of the rover, managed to roll the machine over while attempting to turn. I thought he was dead, as he was lying flat out on the runway, but "recover craft" seems like he was OK.

The aeroplane the Kerbal was using also rolled into the sea, I think he left the brakes off, but that's another story.

So, is it something that I need to change with the Rover design ? is the centre of mass too high ? Or is the munar surface just hazardous and more care and attention is necessary ? would it be the reaction wheels in the probe core that are making it unsafe to turn ?

I've noticed the lights don't reflect off the munar surface all the time, not sure why.

Any amusing rover/autonomous rover stories of your own ?

[Sovek]

disable the torque from the command pod, or re-map the rover controls.

[MiniMatt]

Try widening the track & lengthening the wheelbase a little - that one does look a little top heavy.

That said, the Mun has always been a bit dangerous for rovers and is particularly so now we have the extra (pretty) craters all over the place.

I tend to find (though hunch only) that keeping probe core torque enabled is helpful but the biggest benefit comes from switching to docking mode controls (the little button between staging and map). Disabling steering on the rear wheels can slow direction changes and lessen the rover's desire to roll at every corner. Self righting mechanisms such as RCS jets or landing legs are something to investigate.

Test extensively on Kerbin - something that's very hard to flip at KSC will generally be reasonably useful on the Mun but nevertheless quicksave often.

[billw]

5 m/s is fast: 18 kph. That equals the Apollo Lunar Buggy speed record! They were designed with 13 kph as the top speed...

[Louella]

Try widening the track & lengthening the wheelbase a little - that one does look a little top heavy.

I haven't yet unlocked a great many parts, and this was my first ever rover project in KSP

As you might be able to guess from my first pic, landing it right-side-up on the Mun took a bit of doing. Underside of the rover had a tiny fuel tank with 4 tiny rockets to lift it off the rest of the lander (assuming falling over counts as "landing")

5 m/s is fast: 18 kph. That equals the Apollo Lunar Buggy speed record! They were designed with 13 kph as the top speed...

"but the engineers in the vehicle assembly building said 20 m/s was the maximum speed!" was the test driver's report, I think...

I wonder... is there a celestial body that you can land on, that has such weak gravity that it's possible to accidentally drive a rover into low orbit ?

[katateochi]

Here are my tips for building fast Mun rovers;

1) never drive in staging mode. switch to docking mode. this stops your wasd controls resulting in torque from the pod (and you don't have to rebind keys)

2) wide wheel base and low profile.

3) make use of SAS, but be careful. When driving fast I constantly switch SAS on and off. If your travelling on level ground and then move to an incline then double tap SAS to adjust it to your new position.

4) RCS stabilisers. At speed the slightest change in terrain elevation will send you into the air. I use linear RCS ports aimed directly up around the center-of-mass of the rover. These act to push the rover down onto the ground (kinda like spoilers on a sports car!) I don't have them on constantly, but I keep tapping them and vary use depending on terrain. When your in docking mode ctrl (i think its ctrl, maybe shift, at work atm and cant check) will fire your upward facing ports. They also help the wheels' brakes by increasing your contact with the ground.

5) Set your wheels up. I tend to disable the brakes on the front wheels and disable steering on the rear wheels.

6) RCS brakes! If your going to go fast you need good brakes and the ones on the wheels are not enough. A forward facing linear RCS port helps a lot. I also have rear facing RCS for better acceleration.

This is one of my best (in terms of being stable at speed) rovers. It's stable at 50-55ms

This was made in 0.20 and used hinges so it could fold but that's not key to its stability. (this is it folding

Some things may be a bit different in 0.22 depending on the parts you have available but the basic principles are still the same. Muns got rougher so hitting such top speeds may be harder now.

edit

*snip*

I wonder... is there a celestial body that you can land on, that has such weak gravity that it's possible to accidentally drive a rover into low orbit ?

maybe on Gily? Thou I've not rovered on Gily yet. The trick would be not leaving the ground to soon.

Edited October 21, 2013 by katateochi

[Levelord]

I designed a Dune Bike that was capable of over 40 m/s on Duna. The trick I used was a decoupler suspension together with I-beams and the ruggerized rover wheels.

[katateochi]

I designed a Dune Bike that was capable of over 40 m/s on Duna. The trick I used was a decoupler suspension together with I-beams and the ruggerized rover wheels.

*picsnip*

oh that's cool. love the detail with the sensors and ladders being used to look like engine parts. Are those landing gears used as stabilisers or it that its kick stand?

[Sirrobert]

I wonder... is there a celestial body that you can land on, that has such weak gravity that it's possible to accidentally drive a rover into low orbit ?

No, for the same reason you can't get into orbit with a Spaceplane using only jet engines. At the moment you leave the atmosphere (or ground) your apoaps may be high up, but your periaps is still inside the atompshere (or ground, for the rover).

You can get into a balistic sub orbital trajectory though

[numerobis]

Or you can launch yourself to escape velocity and end up orbiting Eve.

[capi3101]

Katateochi's got the basics down for rover designs on other worlds (build them wide, build them low, SAS on, use docking controls). As for widening and lengthening the wheelbase, Modular Girder Segments work well for that purpose (and those are Starting Tier parts). They also have the advantage of having high impact tolerance.

Brings up another piece of design - encase your critical parts in other parts with high impact tolerance, like girder segments and structural panels; slamming them into the ground at 20 m/s won't be nearly as catastrophic as slamming that probecore or RTG into the ground at the same speed. If you can't encase them, at least build an outer shell that covers most of the angles at which that stuff could impact.

RCS as brakes...never considered doing that before. I wonder if ion thrusters could do the job too...

Obligatory Hellhound screenshots:

Edited October 21, 2013 by capi3101

[Louella]

Made some progress with things.

Here's a pic of a 100% successful deployment of a rover to Minmus

http://i.imgur.com/V7VUjzd.png

You can see the little rocket pack to lift the rover off the landing stage.

It's still a bit easy to roll the rover, especially in the lower gravity...

http://i.imgur.com/dYkRkA4.png

And here's the end result. Landing a crewed mission to drive around performing Science!

http://i.imgur.com/4aUJ9jq.png

Success \o/

[capi3101]

Glad to hear of your success. I will say that particular design looks a bit tall and narrow, but the important thing is that it works.

[mathew5502]

Hi, well i have a couple of videos showing driving my pretty sweet little rover (if i do say so myself) landing on the Mun and Minmus, decoupling and safely lowering to the surface from the landing module. If you wanna see here are the links...

[LordFerret]

My rover was a tad tall as well, but had a very wide and stable wheelbase... even on Minmus I was cruising around at 15-18m/s ('stopping on a dime' wasn't exactly an option however). In the picture below, the rover is working autonomously, but a later mission brought 3 crew to the site for science collection. I'll be using a revamped version for Mun exploration.

I should mention this was built all stock in v0.23.5

Design was inspired by a number of other folks' designs.

[Zylark]

My cute but rather large Munbuggy:

It handles really well. Front steering and rear braking. RCS thrusters for keeping it on the ground should it hit a bump, and also for braking when going downhill or give some extra oomph when going uphill. Slung underneath is an Advanced SAS module which doesn't see much use, but do add some much wanted weight and also keeps the vessel stable should it go flying for some reason - and turn it right side up if having an 'accident'. Structural panels all around to absorb any impact-forces in case of an unfortunate twirl.

Have been put to good use in my current career, and is my most sturdy rover built yet. It's not a speed racer though. I don't like driving it much above 6-7m/s.

Comes with glowing recommendations from Bob Kerman - the Stig of Mun!

Edited November 14, 2014 by Zylark

[Max Peck]

I designed a Dune Bike that was capable of over 40 m/s on Duna. The trick I used was a decoupler suspension together with I-beams and the ruggerized rover wheels.

https://dl.dropboxusercontent.com/u/16683090/KSP/screenshot73.png

Hi Levelord

I don't generally have time to play ksp, read all the forums and then have time to actually post stuff here.

However I had to make the effort after seeing that picture.

That is by far and away the coolest thing I have ever seen in KSP.

Damn good work :-)

[goldenpsp]

As you can see from the picture, I could get my unmanned Muni mining rover (karbonite) moving at a pretty good clip. I did have to be mindful that it did not slow don very fast and plan accordingly

[DeMatt]

(newbie showing off his rover)

(user showing off his rover)

(oldster showing off his rover)

(oldster showing off his rover)

Previous post in thread:

Glad to hear of your success. I will say that particular design looks a bit tall and narrow, but the important thing is that it works.

November 2013.

Holy necropost, Batman!