How to land Large tall objects in low gravity

[zeedesertfox]

How does one land a large, tall, skinny object on the mun? I have the landing gear spread out, and the only thing so far that ive noticed is that it cant land on hills. At all. The object in question is about 5 main sails tall. Give or take a few meters.

[exbyde]

can you post a screencap of what you're trying to land?

[zeedesertfox]

http://cloud-2.steampowered.com/ugc/882986344243084970/FD6C28079591B0C416F8A4405792230D229C6647/

http://cloud-2.steampowered.com/ugc/882986344243082130/C4649C054B3DF31C63510B9CCD5B47237E1DDDAB/

http://cloud-2.steampowered.com/ugc/882986344243083057/D6AA479AC6F8B79EB7750A03E67CABBF5F9E3482/

Its designed to ferry kethane from the mun, to a LEO space station and back.

[SiliconPyro]

First, rotate it so the landing gear is as close to right under those engines as possible. If you draw lines from landing gear to landing gear (in this case a square) you don't want anything outside that square. Of course this means parts in the engine wash of your nukes, which is not good. I would bring the engines in by about 50% if you don't want to rotate them. Do that and it should be much more stable.

Any reason the engines are so high? The lower they are, the easier it'll be to balance when you touch down.

[Panichio]

I would lower the engines to put the center of mass further down, and make them closer-in so that the weight isn't so far out. Alternatively, building out instead of up is another possibility. It's a unique aspect of KSP.

[zeedesertfox]

Well, its landed. Gotta do modifications though, so i'm sending a new one up soon. If the landing gear is under the engines, it....it burns funnily, and starts spinning, uncontrollably. Mechjeb doesn't help fix it. Building out isn't an option here, as if you notice there is a docking port on the bottom, so it has to dock with my space station, which will be a tight and difficult dock already. Thanks for the quick input gentlemen. Any advice on landing? ( Mechjeb isn't accurate enough, and it was just sheer luck and a lot of quick saves to get this one down).

[NoMrBond]

You could put the landing struts further up the ship, high enough that the landing gear still hits first (lot of clearance visible), but a bit higher than they are now

You could also put more than one landing gear on each of those struts at the bottom

Edited June 30, 2013 by NoMrBond

[zeedesertfox]

I might just do that. Raise the legs, lower the engines and better yet, ditch the idea of having this thing land, and ship kethane to it from a refinery. This things big enough that I can just make it into its own refinery. Will 6000+ delta V be enough to go from LEO, to the mun, land, take off, and dock? I can dock rather well, I'm just not very fuel efficient.

[NoMrBond]

Quick mock-up

I don't have Kethane installed so I didn't have a kethane tank (assuming that's what the green one at the bottom is?)

Edited June 30, 2013 by NoMrBond

[Flixxbeatz]

Just make the base wider and you'll have no problems.

[zeedesertfox]

That's beautiful *wipes tears*. But how did you get 3 Landing struts on one area? Oh, and yes, its the largest kethane tank available at 16,000 units of kethane. Not sure what the conversion rate is though.

[entaran]

Basically it's way easier to just rotate where the leg is by 90 degrees and put a second one. So instead of folding out in line with the struts, they are at 90 degrees in two directions making a T at the end of the strut.

It will make it a whole lot more stable.

Also you should seriously consider tilting those engines to fire inwards at 5 degrees. It increases stability out of sight.

[entaran]

I quickly remade the ship with stock parts more or less. It's totally overkill, it's got WAY too much fuel (6.2k d-v unladen... you could do a kethane transfer off the moon to low orbit like 4-5 times between refuels!) Also I illustrated the tilted engine concept, took off yoru too many RCS thrusters (ones in the middle are acutally BAD) and copied your monoprop. I also lowered the centre of mass and thrust so it's way more stable and illustrated the landing leg concept.

You'll need to add a KAS attachment port or quantum fuel transfer thing to actually fill it but yeah. Craft file is below if you want it or want to play with it. I took your design cue's and optimised a bit rather than showed you a different design that I use There's probably too many struts but it doesn't wiggle at all and I'm sure someone else could further optimise it.

The root part is the kethane tank.

Kethane Tug Craft File

[NoMrBond]

You can get three landing struts on the end pretty evenly with angle snap

Javascript is disabled. View full album

Getting them vertically aligned is a bit of a pain, but as long as they're pretty close, the weight of the ship should be such that it won't matter.

Edited June 30, 2013 by NoMrBond

[zeedesertfox]

Im amazed how supportive the KSP community is, even at these late hours. Thank you gentlemen

[Skorpychan]

I hate to burst your bubble, but isn't landing the transit stage a bit inefficient?

Why not just have a smaller ship to transfer the fuel to a station, and have the transit ship move things without having to land?

That way, you can have a practical, easy-to-fly lander, and you don't waste fuel hauling around stuff that has to be landed. All it has to deal with then is the initial launch from kerbin, which I'm guessing it does as it is.

[CleverClothe]

First, rotate it so the landing gear is as close to right under those engines as possible. If you draw lines from landing gear to landing gear (in this case a square) you don't want anything outside that square.

That will not make a difference at all. This is a simple physics problem. You need the line between your CoM and the center of the gravity well to pass inside the area of your landing gear. If that line is outside you WILL fall over. Having a lower CoM makes this easier.

[zeedesertfox]

Sorry to bring this thing back to life but. I modified it to the forums specifications, and added on some more parts. I somehow manged to reduce the Delta v capacity from 6000+ to around 2000. I didnt pay heed to this, and now its stuck in orbit around kerbin, out of fuel and loaded with kethane, with no converter. Any advice on how to redesign this thing so that it has more than enough delta v to do what is required? Sorry for bringing a dead thread back to life, but I didnt want to start a new one.

Yours- ZDF

[Mr. Scruffy]

check the external fuel lines

[zeedesertfox]

I checked. With out the fuel lines, its around 1000. With the fuel lines its around 3000. before the modifications suggested by the forum, it was 6000+. Any who, it flys beutifully (for a behemoth), and could just use more fuel.

[NoMrBond]

In terms of immediate salvage of the current vessel, can you manually transfer fuel from the central tank to the outer tanks stacked with the engines, or is the central tank also empty?

[Mr. Scruffy]

yeah, check all tanks... try to figure in what sequence it´s getting used and most importantly if everything is getting to the engines! If so, and the difference remains: Any version changes between the design and the flight? Staging?

[zeedesertfox]

There is ZERO fuel in the current craft, the fuel lines are working properly. I removed some batterys to save weight, added a few solar panels instead, and 4 heavy converters to the base of the craft. That may have had an impact.

[NoMrBond]

You can't use the included heavy converters to make more LF/O?

Sorry I'm not familiar with the Kethane mod

[zeedesertfox]

I could. cept I kinda...Didnt attatch them to the craft. I got one attatched to the space station. I thought the craft could make it to the space station, but...*shrugs*