Delivering Rovers

[AlexinTokyo]

I'm playing about with rovers, and I've pretty much managed to get to the stage where I can build them and drive them around KSC without blowing them up or crashing them into anything important.

I'd now like to try driving them elsewhere, but I cannot get a good handle on how to 'deliver' the rovers to where I need them.

Basically, I need to know:

• How to design a rocket that can deliver a rover.
  
• How to attach a rover (pre-designed, most likely) to the rocket.
  
• How to detach the rover in a drivable state.
  

My first goal is to drop a rover and a Kerbal onto the northern ice sheet, drive to the pole and place a flag there.

Any advice would be very much appreciated.

Edited March 11, 2014 by AlexinTokyo

[NGTOne]

What you're after is a skycrane. Basically, design a small rocket package using symmetry that has a reversed stack decoupler (so it now decouples up, rather than down like normal) in the middle, then paste your rover onto that decoupler. Make sure your rocket package has a TWR of greater than 1 on your destination body, that the engines are clear of the rover body (or else they won't produce any thrust), build a launch system, and you're good to go. You can use this technique to deliver anything from rovers to buildings to multi-hundred-ton mobile bases to any body you can think of.

It's usually better to build the skycrane around the rover, rather than building the rover as a subassembly. That lets you surface-attach decouplers to your rover, which gives you a lot more flexibility in designing it, and greater margin for change if you need it.

[AmpsterMan]

This is a good question, one which I think would require more specifics on how your rovers are designed.

Generaly, there are two ways to carry a rover; either you just mount it to the top or side of your rocket, or you build your rocket around it.

[juanml82]

For low gravity bodies, I dock the rover on top of the final stage, put several 24-77 rockets (the radial ones), and use those to land. The fuel tanks become part of the rover. You can also add landing struts to absorb the impact or help it stand up if you land in a slope and it lands on a side. For Kerbin, you can attach some parachutes on top. Basically: you have your final stage (the one making the burn out of Kerbin's SOI and wherever you want to go). On top of that, you have a docking port point up. Docked to that, you have a docking port pointed down, which is at the bottom of your rover. Or you can turn the rover upside down and the docking port can be at the top of the rover. You land with the rover.

Or you land with your final stage and the rover just has enough fuel or use monopropellant to be detached, it moves away from the final stage (it should be at, let's say, 10 meters away from the surface) and land.

Here's a screenshot of two of my rovers, on Minmus

And a similar one to the one in the background, out in space

The rover at the forefront can reload its tanks from the kethane miner on the right, take off from Minmus and refuel ships on Minmus orbit. The one in the background it's a more conventional rover, but it can also land and orbit on it's own. And the smaller rover could also be stacked on top of the bigger one. Designing a heavy lifter capable of lifting both at once it's another matter though.

If you don't want to add engines, you'll need to put it at the bottom-center of the lander. I don't have an image right now, but it would work roughly like this:

The lander has four fuel tanks/engines around it, where you also have the landing struts. Instead of a centerline engine, you have some part (a command module, a fuel tank, an structural fuselage) at the center-center or top center where the four fuel tanks connect. And below that structural part, attached by a docking port, you have the rover.

Once you land, you undock. The rover should fall just a few meters, so it won't break anything on a low gravity world. Make sure the space between the tanks/engines/landing struts is wide enough for the rover to go through.

[AlexinTokyo]

Thanks for the responses.

I'll see what I can do about a skycrane for my polar expedition this evening.

I'll try and put up some pics, so it'll be easier to see what I may be doing wrong

[SpaceGremlin]

Here's a small Mun rover mission I did to look for a flat spot to start mining kethane.

The descent stage works fine under stock SAS, but I used Throttle Controlled Avionics for better stability.

[Zephram Kerman]

For your northern ice sheet mission, you could simply drop it in there by parachute. Make the rover and parachute your top stage, fly a rocket over your target site, stage and open the parachute.

[celem]

Attaching the things to the rocket is the struggle for me, but i'm forced to streamline due to the FAR mod. Fairings like SpaceGremlin uses above will help if thats the case (nice delivery system btw Gremlin).

If you are using stock aerodynamics then you can get much more boyscout and will get away with strapping them onto the sides if you like. Realism starts to slide but its certainly viable, just be sure to balance or send symmetrical pairs of rovers. I used to use a central lander with a pair of rovers strapped to it radially (and horizontaly). Once the lander was down and settled the rovers were released to drop to the surface (about 2 m in my design). I used decouplers to spit the rovers off and they all landed just fine (make sure their brakes are off).

I cant seem to find pics of it deployed though I used this a lot for a while. Heres a launchpad test.

The decouplers impart a bit of horizontal V so the rovers continue to roll once they land, more pronounced on low-g airless worlds, only time I broke a rover doing this was on Eve. I've got double decouplers on there mainly so the rovers can clear their docking ports once deployed.

Lately i've gotten into the habit of rovers beneath the lander between the legs. That way they can move base components around by driving back under them and having the base section drop its legs to land back on the top port of the rover

Edited March 10, 2014 by celem

[Geschosskopf]

I'd now like to try driving them elsewhere, but I cannot get a good handle on how to 'deliver' the rovers to where I need them.

Basically, I need to know:

• How to design a rocket that can deliver a rover.
  
• How to attach a rover (pre-designed, most likely) to the rocket.
  
• How to detach the rover in a drivable state.
  

My first goal is to drop a rover and a Kerbal onto the northern ice sheet, drive to the pole and place a flag there.

Well, if you're going to move the rover with a rocket, there are 2 basic ways of attaching the rover to the rocket: vertically or horizontally. Vertically means the front end of the rover is pointing up when on the rocket. Horizontally means the rover's nose is pointing at the horizon when on the rocket (although the rover could be upside down with the wheels pointing up instead of down). This is a matter of personal taste. Horizontally attached rovers are easier to land at the destination although they often look ridiculous on the Launchpad due to their blantant disregard for aerodynamics. So some folks prefer to do vertical attachment, which complicates the descent somewhat.

In either case, it's usually best to build and save the rover in the SPH because this allows putting the wheels symmetrically on both sides. Then exit the game and copy the rover's file from the SPH to the VAB folder. In the process, edit the 4th line of the craft file from "type = SPH" to "type = VAB". This makes it so when you revert the flight, it goes to the VAB instead of the SPH.

Now, if you want a horizontally attached rover, the rocket required obviously depends on the size of the rover and what else you want to send there in the same mission. If the rover is fairly small, you can put it under a lander and bring them down as a unit with the rover between the lander's legs. Once at the destination, you can release the rover and drive it out from under the lander. OTOH, if the rover is too big for that, or is itself a mobile lander, then stick it on the nose of the rocket. Big landers like this can be mounted wheels up atop the rocket, but this means all its command parts (capsules or probe cores) will be upside down during launch, which results in explosions. To avoid that, put a probe core in the last booster stage that's facing up and remember to set "control from here" to that probe core before launch.

With vertical rovers, you also need a "control from here" probe core in the rocket itself. But the real issue with vertically attached rovers is getting them balanced for the rocket's thrust. The rover's CoM needs to be at or very close to the centerline of where the rocket will attach to it or the rocket won't fly straight when pushing the rover up. Rovers are inherently imbalanced this way due to having wheels on the bottom, so you sometimes have to finagle parts (or the attachment position of the rocket) around to get the CoM where it needs to be. A little offset isn't that big a deal because during flight, control surfaces, torque, and RCS can correct for that, but try to make it as small as possible.

If the rover isn't going down attached to a lander, you now have the issue of how to get it down by itself. For this, the rover needs rockets and/or parachutes. The main question here is whether you want these descent devises to remain on the rover once it lands, so it can take off again. If you don't want to keep them, then attach them with separators or decouplers. It's safer to drop these parts once you're safely on the ground but it's more dramatic and entertaining to drop them just barely above the ground with the rockets still burning so they fly off and crash skycrane-style.

In either case, however, one of the most important things about landing rovers is protecting the wheels. If the rover hits the ground on its wheels and is falling too fast, 1 or more of the tires will pop. So, you either need enough rockets/parachutes to land like a feather, have a Kerbal ride the rover down to fix any flats, or put lander legs on the rover, land on them, then retract them once down.

[Dwight_js]

I personally like to make my rovers modular so that they pack nicely on the rocket and then assemble them at the destination. I've stacked a lander can and a science jr. module on top of each other - both had 4 wheels and a docking port on their side. They could each drive on their own, but were tall and tippy in low gravity. Once they were linked up I had a kind of Mun truck with eight wheels - lander can in the front pulling the science module behind.

I've also had a smaller rover that was split in two and hung off the sides of my Mun lander, attached via a docking port. Just like above, once on the Mun, I dropped the rovers off the sides of the lander and moved them into place so they docked together forming a long, eight-wheeled rover.

[magnemoe]

Here is one way.

This is an probe lander with wheels, the upper tank is to take it from circulate into Mun deorbit.

This medium sized rover can be docked with the lander and flown to another location

[Jimbimbibble]

I see that you're not opposed to using mods, so I would suggest using Kerbal Attachment System. It includes winches and other parts you can use to help you lower the rover to the surface. It's also just a really cool mod.

[Wooks]

Can I interest you in one of my VTOL rover carriers? Download link and instructions here: http://forum.kerbalspaceprogram.com/threads/70145-VTOL-Flatbed-Carrier-Hermes-and-companion-Rover-Marathon

Of course this kind of transport works only in planetary bodies with atmosphere.

[Tank Buddy]

This is a skycrane of mine: It is lightweight and has a high TWR. Just slap it on top of a rocket and jettison said rocket before landing.

[juanml82]

Can I interest you in one of my VTOL rover carriers? Download link and instructions here: http://forum.kerbalspaceprogram.com/threads/70145-VTOL-Flatbed-Carrier-Hermes-and-companion-Rover-Marathon

Of course this kind of transport works only in planetary bodies with atmosphere.

That's cool. I guess it could be adapted for vaccum, although with a limited range

[MarvinKitFox]

Here's my solution:

The base is a lander, carries three rovers on detachable/re-attachable vertical mountings.

Rovers align correctly, then the base kneels down on the staggered legs to pick up the rovers.

As a bonus extra, the rovers can *pick up* and drive the base to a more desireable landing location.

There rovers are 99.97% collision-proof, those buggy bumpers are rated at 1000m/s impact.

An abundance of gyros make them self-righting, of course, and are also handy for the occasional bulldozer work, righting tipper-over escape pods, tumbleweeding up 80degree slopes, etc...

(sorry, this album is very much under construction yet, few comments and some redundant images..)

Javascript is disabled. View full album

[Cerberus738]

Here is a crane i sent to the mun. i believe it's around 50ton at least 40 ha ha ha. the engines on the front and back fall off after landing and then i have a crane!! it uses the fuel in the tank which would need to be refilled before using it as a crane as that's the counterweight.

[HafCoJoe]

When I first started creating rovers, I built a lander with a rover directly under its center and with 3 engines on the outside. This way it can land straight down and then just detach the rover below it (assuming the rover can drive between the engines - See my "Mishap on the mun..." if you want to see some pics of what I did).

After you have a lander, flip it over! And then build a rocket under it.

[LostElement]

Scott Manley has a video about it.

[Landge]

There's no one way to build and attach rovers to launch boosters as you can see by all the excellent builds posted here.

One of the easiest ways you can build them is in the SPH for testing. Once you have a design you like, go into your SPH folder in the saves folder.

Copy the craft file over to the VAB folder. Then open the file using notepad. Find the line that says... type = SPH and change it to type = VAB.

From the game's Space Center, click on the VAB and load your rover. Clicking on the cockpit will reorient itself into the vertical position.

From here you can continue building the other stages.

One of my fav early rovers once I unlocked wheels that was attached with docking ports.

It's VTOL capabilities can land and return to orbit and land back on Kerbin all on it's own or redock with the command module to refuel and land on other biomes.

One of my proudest achievments. Testing through to completion of my 1st successful rover to land on Tylo... that is without the exploding into pieces part. It took about about 6 or 8 reloads.

Javascript is disabled. View full album

Edited March 11, 2014 by Landge

[Lohan2008]

[AlexinTokyo]

Thanks all for the awesome advice. It has definitely got my head in the right place.

Managed to drop a rover at about 81 degrees north, so it's only a bit of a drive to place a flag at the pole.

Oh, and thanks SO MUCH for the trick of moving a craft from the SPH to the VAB. That is beyond helpful.

One thing; the axis of symetry in VAB after loading the craft was really wonky; is this a known problem, or did I screw something up?

<pics tomorrow, or when I get round to it.>

[Cerberus738]

The symmetry gets wonky if you have parts horizontal in the vab and vertical in the sph. It should be fine if you turn the rover root part to default orientation (spacebar). Course that might screw with the way you want to launch it. I found it much easier to build the rover as a sub assembly and then build a lift vehicle and mount the rover to it. It's a lot of work to rebuild though. One mod I really like is the 'root select' one. You can build any vehicle and then attach some throw away part. Set it as the root and then you can easily save your vehicle as a sub assemblyrready to be lifted!

[Geschosskopf]

Oh, and thanks SO MUCH for the trick of moving a craft from the SPH to the VAB. That is beyond helpful.

One thing; the axis of symetry in VAB after loading the craft was really wonky; is this a known problem, or did I screw something up?

If you move a ship from SPH to VAB, it's generally best not to mess with that ship in the VAB other than attach boosters on the bottom. Don't try to add any parts to the moved vehicle itself, except the ends of struts from the booster. The SPH-built vehicle retains SPH symmetry which doesn't work in the VAB.

I'm sure you've noticed that the 1st time you open the SPH-built thing in the VAB, it starts out in SPH position, facing out the door close to the floor, but as soon as you move it up off the floor, it rotates to point up. This is fine and normal, and if you're doing things vertically oriented, you can just build the rocket under it. But if you want the rover horizontal in the VAB, then you have to manually put it back that way by shift-clicking on a part and hitting W.

Now, if the rover is supposed to go between a lander and the rocket, so you have to build rocket on both top and bottom of the rover, things are a bit more complex. In this case, it's often best to do like Cerberus said and do the rover (all but its probe core/cockpit) as a subassembly. That way, you build the lander in the VAB, add the rover subassembly under it, then build more rocket below.

[AlexinTokyo]

OK, so from 81 to 90 degrees north is more than 'a bit' of a drive

Anyway, I promised pics, so here they are:

Launch of the Polar Explorer.

Burning in hot over the polar ice. This is the updated version that actually managed to land properly.

Landed and personnel carrier detached. Manned up and ready to go.

Scooting North.

Looks like he's having fun

Pole pic to be added when I arrive.