Landing Trucks

[FictionXVI]

Hello everyone!

Quick question here. How do you land trucks on various worlds. By truck I mean a tank on its side with wheels. I have tried many things but haven't seemed to have had much luck with it really. So if you could shoot me your ideas/tips or whatever that would be fantastic. If you have any pictures that would be even better. I hope I'm not asking for to terribly much haha.

Thanks

FictionXVI

[Sirrobert]

You need a tank with docking port on top (in the middle). With this I mean: If the fuel tank were to stand on it's wheels, the docking port looks at the sky.

You can than dock your lander (with a docking port at the bottom, and engines on the side) to this port, and land it directly on the Mun. Or wherever you want it. Now undock, and take off with the lander

This vid has a good example:

[Johnno]

I normally land bigger stuff (be it vehicles, bases, etc) with rockets on multiple sides around the payload. Normally easiest if your payload is symmetrical, otherwise you have to adjust your landing rockets to the proper distances from center of mass.

Here's an image of my kethane rover during Mün landing, so you can see what I mean. The tanks and engines stay on so it can lift off if necessary, but you can just as well attach tanks/engines to the sides with decouplers, like the picture further down.

[Tw1]

My technique so far has been to attach engines of the sides, with the extended radial decoupler. They must be exactly around the centre of mass, or you'll have bad problem.

[Pulstar]

There are four ways I found to do this, the vertical landing "tipper" aproach, the landing "coathanger" assembly, the middle-engine approach and the skycrane. Unfortunately my screenshot folders seems to be empty of examples.

One vital hint, always add a probe module on the carrier rocket and right click on it to "control from here". Saves a lot of trouble if the rover is upside down during launch and transit or if it is sideways compare to the rocket.

In all you first build a truck (I usually build tankers out of a the big rockomax 32 tank), then you copy the craft file from the SPH to the VAB folders to build the carrier rocket and landing things using the symmetry in it.

"tipper" - you attach a decoupler with landing legs, either regular ones or ones made out of girders ("I-beams")+flat panels and not-rockomax minonodes, at the bottom of the rover. Make the base as wide as possible, if you have parachutes always attach them to the top of the rover with a decoupler so that the rover orients itself with the legs being down when they open. Engines and fuel tanks can go to the bottom or top depending whichever is easier to place (usually bottom). What you do is you place the legs in an X shape so that you can tip the rover into one of the empty spaces betwen the legs (rotate the legs in the VAB using shift+rotation keys to do this). Decouple, tip the rover, decouple whatever was attached to the front of the rover. Usually the mass of the wheels shifts the CoM so that it falls in the right direction properly. If you use deployable landing legs you can only the front pair to retract and thus tip over the rover to fall on it's wheels. Risky for heavier vehicles and high-g planets, although you can use small radial engines attached to the front decoupler to slow down the falling front so it doesn't get damaged.

Coathanger - you land the rover oriented horizontally but hanging from an assembly with landing legs and engines. Basically a scaffolding, but with enough area to fit the rover and allow it to drive out. Once it lands you just decouple it and drop it below, you need enough room between the wheels and the ground so that the assembly takes the force of the landing impact but not too much so the drop isn't big. Decouple dropping it below and drive away. Using this usually means the rover is launched upside down when on top of the rocket.

middle engine - you build a tanker rover (or one using hithiker modules for kerbal transport) using two tanks or hithiker pods with a 6-way hub between them right in the middle. Use that to build your engines right at the CoM of the rover, using decouplers or not if you want to drag the engines around after landing. Use the same central node to add a lander leg assembly using structural parts connected to that node.

sky crane - find the center of mass of the rover on it's roof, attach a radial decoupler there, now attach a radial attachment node on it, build fuel tanks, probe pod (important!) ASAS, engines, legs and all the other rocket parts on top of that radial node. Just space out the engines so their exhaust doesn't damage the rover. You land the rover using "control from here" on the skycrane, similar to the coat hanger but you land using the rover's wheels and after you land you decouple and fly the skycrane away crashing it at a safe distance.

[BubbaWilkins]

There are four ways I found to do this, the vertical landing "tipper" aproach, the landing "coathanger" assembly, the middle-engine approach and the skycrane. Unfortunately my screenshot folders seems to be empty of examples.

One vital hint, always add a probe module on the carrier rocket and right click on it to "control from here". Saves a lot of trouble if the rover is upside down during launch and transit or if it is sideways compare to the rocket.

In all you first build a truck (I usually build tankers out of a the big rockomax 32 tank), then you copy the craft file from the SPH to the VAB folders to build the carrier rocket and landing things using the symmetry in it.

"tipper" - you attach a decoupler with landing legs, either regular ones or ones made out of girders ("I-beams")+flat panels and not-rockomax minonodes, at the bottom of the rover. Make the base as wide as possible, if you have parachutes always attach them to the top of the rover with a decoupler so that the rover orients itself with the legs being down when they open. Engines and fuel tanks can go to the bottom or top depending whichever is easier to place (usually bottom). What you do is you place the legs in an X shape so that you can tip the rover into one of the empty spaces betwen the legs (rotate the legs in the VAB using shift+rotation keys to do this). Decouple, tip the rover, decouple whatever was attached to the front of the rover. Usually the mass of the wheels shifts the CoM so that it falls in the right direction properly. If you use deployable landing legs you can only the front pair to retract and thus tip over the rover to fall on it's wheels. Risky for heavier vehicles and high-g planets, although you can use small radial engines attached to the front decoupler to slow down the falling front so it doesn't get damaged.

Coathanger - you land the rover oriented horizontally but hanging from an assembly with landing legs and engines. Basically a scaffolding, but with enough area to fit the rover and allow it to drive out. Once it lands you just decouple it and drop it below, you need enough room between the wheels and the ground so that the assembly takes the force of the landing impact but not too much so the drop isn't big. Decouple dropping it below and drive away. Using this usually means the rover is launched upside down when on top of the rocket.

middle engine - you build a tanker rover (or one using hithiker modules for kerbal transport) using two tanks or hithiker pods with a 6-way hub between them right in the middle. Use that to build your engines right at the CoM of the rover, using decouplers or not if you want to drag the engines around after landing. Use the same central node to add a lander leg assembly using structural parts connected to that node.

sky crane - find the center of mass of the rover on it's roof, attach a radial decoupler there, now attach a radial attachment node on it, build fuel tanks, probe pod (important!) ASAS, engines, legs and all the other rocket parts on top of that radial node. Just space out the engines so their exhaust doesn't damage the rover. You land the rover using "control from here" on the skycrane, similar to the coat hanger but you land using the rover's wheels and after you land you decouple and fly the skycrane away crashing it at a safe distance.

Or VTOL style, place engines symmetrically in such a manner that the combined thrust vector is centered on the vertical axis with the Center of Mass.

For instance, Truck in route to Mun:

Trucks on surface:

The trick landing both of these is that you have to remember that your points of reference for control are the cab, but your thrust is 90degs off. In both cases, I had just enough fuel in the booster stages to do an initial retrograde burn within 50k of the Munar surface bringing velocity down to under 100m/s. At that point I would decouple the stage and orient the craft via surface heading/orientation using mechjeb (could do manually, but too much work). At that point, you just monitor your altitude and adjust thrust to maintain or slow the craft down. These trucks can not survive a landing impact greater than 5m/s.

[Tw1]

One other way I've seen done is with a platform beneath the rover. This can double as a "heat shield". After landing, the rover is undocked or decoupled and driven off.

The last rover I landed used a modified variation of the "Tipper" I called the Tilt and eject. More suited to lighter vehicles, or very low gravity landings.

Like so:

So there you go.

Tilt and Eject.

VTOL style.

Sky Crane.

Middle engine.

Coat-hanger.

Tipper.

Platform.

Seven techniques. Choose wisely.

Edited July 1, 2013 by Tw1

[Pulstar]

The trick landing both of these is that you have to remember that your points of reference for control are the cab, but your thrust is 90degs off.

Hence why I put a probe core on a decoupler at the CoM oriented properly and select "control from here" in the right-click menu, although docking ports can also be used for this. That also helps with docking if you put one on top of say a spaceplane rather than at the front/back. It shifts the Nav Ball to reflect the point the vessel is pointing at relative to the horizon and prograde/retrograde from it's perspective.

I personally dislike using more than a single pair of centrally-mounted VTOL engines since it's hard to align them with the CoM unless you use copy-pasted sections. But it is also an option.

[BubbaWilkins]

Hence why I put a probe core on a decoupler at the CoM oriented properly and select "control from here" in the right-click menu, although docking ports can also be used for this. That also helps with docking if you put one on top of say a spaceplane rather than at the front/back. It shifts the Nav Ball to reflect the point the vessel is pointing at relative to the horizon and prograde/retrograde from it's perspective.

I personally dislike using more than a single pair of centrally-mounted VTOL engines since it's hard to align them with the CoM unless you use copy-pasted sections. But it is also an option.

That's a good trick, and I hadn't really thought if it. This configurations definitely take a lot more finesse and testing to get balanced.

[Tw1]

I personally dislike using more than a single pair of centrally-mounted VTOL engines since it's hard to align them with the CoM unless you use copy-pasted sections. But it is also an option.

My trick is to install them as one of the last things, replacing the other engines with groups of parts that together are of similar length and weight. Then line them up using the centre of thrust marker.

This doesn't make then perfect though, you still need to be using the ASAS for anything more than short bursts, or they will slowly roll the ship, or rover.

[Flixxbeatz]

As for large rovers (trucks, mobile bases, etc), it's preferable to land them on their own power (either incorporated to the rover or a detachable one)

[Pulstar]

Here, I made some screenshots to illustrate what I meant:

Middle engine:

Coathanger:

Skycrane:

Tipper:

Edited July 1, 2013 by Pulstar

[Geschosskopf]

A variation on the tip-and-eject thing. This ain't a truck but it shows the idea, and something similar would probably work for your truck. This was built for Duna with everything you see here doing all the burns from LKO to landing, hence the big delivery vehicle, which is OK to destroy in the process because it's not coming home anyway.

Basically, the rover was held in place with a KAS winch. The rocket landed on the engine nozzles and then I extended the gear legs. It had 1 mounted low on the "top" side to tip it over and 1 reversed mounted high on the "bottom" side to break the fall. After some dramatic explosions and breakage, I just unhooked from the winch and drove away.

Note the rocket has one of the circular robot brains just below the cup of the fairing. This is where I flew and landed the rocket from. The rover has its own brain sitting on the floor of the chassis for driving it.

[rob_dray]

What I would do is strap your vehicle onto the side of a large-enough rocket with parachutes on where your going. You could also fashion it into a part vehicle-part lander.

[rob_dray]

Strap your vehicle to the side of a rocket...