Trying to build a re-usable rover system, but everything explodes?

[foamyesque]

So I'm poking at KSP again for the first time in a while, and it seems there's been some changes to either wheel physics or docking packing that's made a lot of my old cargo-bay rover systems break. In general the idea is that there'd be a docking port at one end of a Mk3 bay that a rover would nose on-to to clamp on to a mothership of some sort, which would then fly the rover somewhere else for it to deploy, rinse and repeat.

 

However, on undocking from the ports now, it appears the spring in the wheel suspensions go absolutely batty and blow apart not only the rover but potentially the ship that's supposed to carry it around. I've seen wonky wheels launch stuff weighing substantial amounts hundreds of metres into the air on deployment.

 

Has anyone else tried a similar architecture or have some tips on how to do this? I'd really like to be able to use a rover in more than one spot.

[Guest]

Version 1.3.1 is plagued by a nasty physics bug related to wheels. I haven't seen this exact manifestation but it sounds like it could be related. It triggers if you switch to the tracking station and back.

I suspect your specific problem is triggered by badly calculated surface intersections between the cargo bay and the wheels; if something's inside another surface but shouldn't be it sometimes gets violently ejected. I also haven't tried recovering rovers with cargo bays, although I have tried recovering regular spacecraft with cargo bays (works) and rovers with other means, e.g. a lander with a docking port which then picks it up, but with no cargo bay involved at that point (also works). 

In your shoes I would try to figure out if it's possible to pick up the rover so that picking it up also lifts it off the ground, for example by placing the port just a little bit too high, so it lifts up the rover when it docks. If you're lucky it's just that right now it's just a little too low, and docking pulls the rover down, which triggers the bug when you undock.

[foamyesque]

I've been fiddling with the docking port positions for some time and haven't yet been able to produce one that will allow a dock/undock sequence. Unfortunately using rockets to adjust height, or non-cargobay solutions, aren't going to work for this particular mission, since it's headed to Eve. The ports can have the wheels visibly clear of the floor of the bay in build mode (and decouple from initial construction without issue), but after redocking to them, and then undocking... boom. Occurs even if I have spring strength cranked to minimum, too.

[Guest]

That's unfortunate.

I'm curious about this now though and will attempt it later today. I'll report back.

PS. Have you tried using the Klaw?

[XLjedi]

I have experienced the same thing but have managed a very workable solution with my patented Untied Technologies Overhead Gantry (UTOG) safe transport system!  I've also built a number of "UTOG" compatible rovers/craft of various types that are mission ready. 

Here's a short mission video that illustrates the concept:   (notice how the fuel truck is equipped with lift jacks for docking) 

Additionally, I have also  been developing a Mk 2 "Engineering Bay" system for transporting smaller rovers.  Although I have not yet published the associated craft, I do have this video to show how it works:  (no wheel clipping issues if there's no floor to clip)

 

Edited January 17, 2018 by XLjedi

[Guest]

I tried this. 

It's definitely a wheel clipping issue. If I move the docking port low enough that the rover is able to re-dock, it bounces. If I move it high enough that it doesn't bounce, it won't be able to dock.

It might be possible to design a rover that doesn't do this, but it would have to be very narrow, so narrow that its wheels fit entirely on the flat part of the cargo bay.

As a proof of concept, I did manage to make a dockable rover by adding landing struts: I drive up to the port and when it bounces against it vainly trying to dock, I lower the struts which raises the rover high enough and it snaps into place.

 

[dangerhamster]

Not using 1.3.1 (still on 1.3) ATM but when having problems with wheels interacting with the cargo bay using the Buffalo Rover hitch I raised the target hitch slightly and raised the capture range slightly. This seems to work.

Edited January 17, 2018 by dangerhamster

[foamyesque]

9 hours ago, Brikoleur said:

PS. Have you tried using the Klaw?

 

No, primarily because I need fuel flow, and as far as I recall the Klaw does not allow that. It's also a bit bulky.

[XLjedi]

3 minutes ago, foamyesque said:

 

No, primarily because I need fuel flow, and as far as I recall the Klaw does not allow that. It's also a bit bulky.

I have no problem transferring fuel on my fuel truck using the claw...  (see video above)

And if you sink it into the craft/rover it's not too bad; actually looks pretty good on the fuel truck I think.

[XLjedi]

5 hours ago, Brikoleur said:

As a proof of concept, I did manage to make a dockable rover by adding landing struts: I drive up to the port and when it bounces against it vainly trying to dock, I lower the struts which raises the rover high enough and it snaps into place.

Yes it works, although I abandoned your idea of attaching to a wall because it was too limiting on the type/shape/size of rovers that I wanted to create.  I have some rovers that are quite large and would bend down if stuck to a rear wall when gravity is applied.  Others are designed such that attachment at front or rear is impossible.  It really left me no other choice; overhead attachment was the only viable solution for Mk3 cargo bays.   

So I use "lift jacks" to raise the rover to the overhead gantry.  I have an airdrop utility truck, a fuel truck, a mobile ISRU, an amphibious rover, a submarine... and they are all UTOG compatible.  So far, I also have 3 large transport craft all with the same gantry system installed.  The rovers are interchangeable between transport craft covering air/sea/space, all I had to do was maintain consistency on the gantry height.    

I have an SSTO that can drop off mobile ISRU vehicles on various moons to establish a network of mobile refueling points.  I can pretty much put any type of rover I want on any planet now and easily retrieve them and/or repack for the next location.  I may even take my submarine on a mission to Laythe in the near future. 

In some cases I use landing struts, for others retractable gear works better.  I found with retractable gear the craft briefly bounces up upon retracting; so it both docks and stows the gear in one action.  My submarine uses this method and the retractable gear allow it to maneuver 'carefully' on land to load/unload.

I also prefer to start missions at the KSC with the mission rovers separate from the transport vehicle and I load them up on the runway, perform the mission, return and unload them.  Which may not be everyone's style of gameplay but I seem to enjoy the loading/unloading part.

Here's a cool airdrop mission to the Island Base to deliver supplies:

You can tryout all these craft if you like and do the same missions... 

They're available for download in the "My Designs" link in my signature below.

Edited January 18, 2018 by XLjedi

[foamyesque]

I'd be interested in that mobile ISRU design, if you could post a picture. It's one of the things I'm working on; my current build looks like this:

 

 

The canted drills allow it to thread the eye of the needle of a cargo ramp, getting down to ground level w/o clipping through bits. That way it can still operate whilst docked in the cargo bay.

 

Gotta be careful when roving, though. Likes to roll :v

Edited January 18, 2018 by foamyesque

[XLjedi]

All of the craft are in the "My Designs" link in my signature below... 

This is the RLV-21 (RLV = Roving Logistics Vehicle) "Magic Hat" mobile ISRU and it turns the SC-20 Monarch SSTO into a SSTA.  It doesn't just convert ore to fuel, it's also a mobile power plant with dual Gigantor solar arrays and the "Hat" is a LD Relay Antenna. 

...and this is how it works with the Monarch SSTO: 

I can either leave the "Magic Hat" on a low gravity moon to serve as a mobile refueling outpost.  ...or reload it and move on to the next planet.  Another advantage to the overhead gantry method is that it allows you to ALWAYS be able to drive straight into the cargo bay.  As opposed to having to back-in if the docking port was located at the rear of the rover.  You'll find that you will always want to drive straight in, it's much easier. 

I also have several rovers that are compatible with this system...  notice the UV-14 Barracuda submersible and the RV-17 rover in the blueprint above.

https://kerbalx.com/XLjedi/RLV-21-Magic-Hat

https://kerbalx.com/XLjedi/SC-20-Monarch

As far as controlling rollovers on low gravity planets...  My rovers are rather large and I typically include reaction wheels in the design to manage roll.  You just need to be aware that the ability to adjust for roll is there as you drive it around.  In your design, your wheel base does not have to be that narrow.  You can see in my designs what I view as the optimum wheel base width for large Mk3 rovers.

You have to "thread the needle" with your rover because you're not designing your transport craft to accomodate loading/unloading.  Since I'm dealing with larger sized rovers, I've designed my transport craft with auxiliary wheels and struts to allow them to "sit" or "squat" to reduce the loading ramp entry angle.  It would not be possible to get the RLV-21 up a Mk3 cargo ramp otherwise.  The idea is to keep the deployed cargo ramp and loading bay area a straight line, and tilt the whole craft so the ramp touches the ground.  I'm guessing at 3.1M, my typical rover is taller than what you have, but it fits easily in the cargo bay and there's still room for the overhead gantry. 

Edited January 18, 2018 by XLjedi

[DrLicor]

17 hours ago, Brikoleur said:

I tried this. 

-snip-

As a proof of concept, I did manage to make a dockable rover by adding landing struts: I drive up to the port and when it bounces against it vainly trying to dock, I lower the struts which raises the rover high enough and it snaps into place.

-image snip-

 

This is actually a very smart "solution" for storing rovers when you don't them to glitch or break. Whenever it's on a platform of a propulsed landing unit or in a plane, thanks for enlightening me.

  

[linuxgurugamer]

1 hour ago, XLjedi said:

All of the craft are in the "My Designs" link in my signature below... 

This is the RLV-21 (RLV = Roving Logistics Vehicle) "Magic Hat" mobile ISRU and it turns the SC-20 Monarch SSTO into a SSTA.  It doesn't just convert ore to fuel, it's also a mobil power plant with dual Gigantor solar arrays and the "Hat" is a LD Relay Antenna. 

...and this is how it works with the Monarch SSTO: 

I can either leave the "Magic Hat" on a low gravity moon to serve as a mobile refueling outpost.  ...or reload it and move on to the next planet. 

I also have several rovers that are compatible with this system...  notice the UV-14 Barracuda submersible and the Rv-17 rover in the blueprint above.

https://kerbalx.com/XLjedi/RLV-21-Magic-Hat

https://kerbalx.com/XLjedi/SC-20-Monarch

As far as controlling rollovers on low gravity planets...  My rovers are rather large and I typically include reaction wheels in the design to manage roll.  You just need to be aware that the ability to adjust for roll is there as you drive it around.  In your design, your wheel base does not have to be that narrow.  You can see in my designs what I view as the optimum wheel base width for large Mk3 rovers.

You have to "thread the needle" with your rover because you're not designing your transport craft to accomodate loading/unloading.  Since I'm dealing with larger sized rovers, I've designed my transport craft with auxiliary wheels and struts to allow them to "sit" or "squat" to reduce the loading ramp entry angle.  It would not be possible to get the RLV-21 up a Mk3 cargo ramp otherwise.  The idea is to keep the deployed cargo ramp and loading bay area a straight line, and tilt the whole craft so the ramp touches the ground.  I'm guessing at 3.1M, my typical rover is taller than what you have, but it fits easily in the cargo bay and there's still room for the overhead gantry. 

How do you make those images?  I love them

[XLjedi]

3 minutes ago, linuxgurugamer said:

How do you make those images?  I love them

I make those blueprints for all the craft that I post to KerbalX.  Otherwise, how would anyone know the intended mission role?

I do get asked that question a lot though...   I s'pose I could post a tutorial on how I do it exactly, if interested?

[DrLicor]

@linuxgurugamer, I think with the help of (your) Kronal Vessel Viewer and some nice photshop skills.  

 

@XLjedi, whoops, answers at the same time :), but a tutorial would be nice. Always wanted to make such blueprints, just haven't figured out how.

Edited January 18, 2018 by DrLicor

[XLjedi]

1 minute ago, DrLicor said:

@linuxgurugamer, I think with the help of (your) Kronal Vessel Viewer and some nice photshop skills.  

@linuxgurugamer

Oh WOW!  Yesm, I do use KVV for my blueprints!   ...and thank you for it!  Didn't realize that was your mod.  It's wonderful! 

Although, now that I know you created it, you realize I'm going to suggest upgrades that would make my blueprint work far easier.  ;-D

I've also noticed some bugs introduced to KVV as a result of the last 1.3.1 upgrade.

[foamyesque]

I'm kind of surprised the wheelbase you've got on that thing doesn't catch on cargo ramps or bay walls, @XLjedi. Maybe I can widen mine.

Otherwise, you've certainly given me some very interesting ideas -- I *really like* the interchangeable overhead gantry system. Have you tried it on Eve, specifically? Does the higher gravity impact anything?

[XLjedi]

29 minutes ago, foamyesque said:

I'm kind of surprised the wheelbase you've got on that thing doesn't catch on cargo ramps or bay walls, @XLjedi. Maybe I can widen mine.

Otherwise, you've certainly given me some very interesting ideas -- I *really like* the interchangeable overhead gantry system. Have you tried it on Eve, specifically? Does the higher gravity impact anything?

Nope... the system works fine.  Download a few of the 6x6 rovers I have at KerbalX and try driving em into the transport plane.  I've spent a fair amount of time testing for optimal wheelbase for both ease in loading and actual drivability on the ground and pretty much used the same base 6x6 chasis for at least 3 of em...  The Gator, the fuel truck, the Umvee pickup, and the ISRU all use the same wheel base width.

I mean Eve though?  ...do you really think you're gonna load up a big rover (heck any rover) and return?  A one-way rover ticket inside a rocket designed around a Mk3 cargo bay drop-n-forget mission is most likely where you'll be.

 

[foamyesque]

If I wanted to, I think *could* build something to return the rovers -- it's already returning 4 dudes --, but no, once they're on Eve they're on Eve forever. They aren't necessarily going to be in the *same place* on Eve, though; the idea's to biome-hop via ISRUing a big rocketplane. A prior iteration had the ISRU integrated into a bomb-bay style of cargo bay, which would be jettisoned in-flight on the final liftoff, but cost in aerodynamics for opening the bay and flying near-level long enough to get the thing out the doors is harsh and it also made taking off more difficult. The idea behind the rover approach is to be able to wheel the thing off beforehand and avoid all those issues.

 

The undocking/redocking thing is because I'd like to have my non-ISRU rovers be able to bomb around wherever I land, then reattach for travel to the next stop.

Edited January 19, 2018 by foamyesque

[XLjedi]

Well if you can make something to bring back one of my rovers from Eve let me know!  ...I haven't gotten that far yet.  LOL

I have however gone into hyperedit and made the gravity on the KSC runway equal to Eve's 1.7 multiplier and the rovers load and dock the same as any other planet.  I was suspicious at first thinking the jacks might compress with the larger gravity factor.   I actually had more trouble driving up onto the stupid KSC runway (that incline is pretty aggressive) than I did loading and docking my fuel truck onto the cargo plane.

[foamyesque]

3 hours ago, XLjedi said:

Well if you can make something to bring back one of my rovers from Eve let me know!  ...I haven't gotten that far yet.  LOL

I have however gone into hyperedit and made the gravity on the KSC runway equal to Eve's 1.7 multiplier and the rovers load and dock the same as any other planet.  I was suspicious at first thinking the jacks might compress with the larger gravity factor.   I actually had more trouble driving up onto the stupid KSC runway (that incline is pretty aggressive) than I did loading and docking my fuel truck onto the cargo plane.

 

This actually got me experimenting and I have a proof-of-concept for the ascent; I hyperedited it to Eve and did a flying start at ~90m/s & 1.5km altitude to avoid having to deal with landing stress.

(Note: KER is not processing the drop tank dV correctly. Dunno why)

Working out how to land it, get it through entry, get it to Eve, or remove the rover once in orbit are left as an exercise for the student.

 

[foamyesque]

@XLjedi: I have built a version of your overhead gantry, which works pretty nicely. But I've noticed something irritating: After I run through a dock/undock cycle, my rovers wheels will not steer to anything close to their full extent; it basically triples my turning radius. Have you encountered the same thing?

[Guest]

Coincidentally, I came up with a mission that requires a rover system that can be transported by plane. Here's my first iteration:

The bounce issue manifests on this design also, so it's not just cargo bays. I managed to tame it by very careful positioning of the docking port and going with ruggedised rover wheels, no need for an overhead gantry. As an extra safety measure, I have an engineer flying the plane, so in case one of the wheel breaks he can fix it.

As you can see, I decided to go with a flatbed design rather than trying to design everything to fit in the cargo bay.

[XLjedi]

7 hours ago, foamyesque said:

@XLjedi: I have built a version of your overhead gantry, which works pretty nicely. But I've noticed something irritating: After I run through a dock/undock cycle, my rovers wheels will not steer to anything close to their full extent; it basically triples my turning radius. Have you encountered the same thing?

I've noticed it occasionally...  IIRC, I've fixed it by either trying the "Control from Here" option on a few different parts, and in the case of my mobile ISRU unit, if I deploy and retract the landing gear it seems to fix it for some reason?  Maybe try deploy/retract the gear or landing struts that you are using for lifting the rover.  Not sure about your wheel placement and if a narrower footprint on the rover is more prone to the problem or not?  Maybe even a game save and reload?  ...although, in 1.3.1 those can be deadly to units on the ground.