Lander Design? Have I done it wrong all along?

[Rocket Farmer]

So I guess I would consider myself a pretty decent KSC player. I have landed on pretty much all the bodies and have come back from most of them (no Tylo, Moho or Eve returns yet).

I was working on a different lander. Something nuke powered that could hop to a lot of different moon biomes (aiming for 6000+ DV for lots of hops) plus do some slightly higher no atmosphere bodies. Anyways I was incorporating something nice and compact around the nuke engines and came across the age old problem of having to figure out ladders when a thought struck me.

Why not put the lander can at the bottom of the lander (not the top)? It allows me to make a perfectly square block of lander without anything sticking out the top wrecking the balance (I can store 6 materials bays up there for samples). Also no pesky ladders and no need for Jeb jet packing either.

Anybody ever try this? My Launchpad tests seem to show it working fine (Jeb has a door right at ground level) but I am wondering about how the landers take the forces etc. Really so far my biggest hang-up with the design has been tat its esthetically horrible (which doesn't bother me too much) and ethically questionable (the lander can is squished between 2 nuke engine exhausts). Otherwise so far its seems viable.

[Merinsan]

That's an interesting idea. I've never considered doing it before.

The thing I would worry about would be smashing the lander can on the ground. You'd have to be careful to go slow enough when landing. I like to have landing legs to absorb impact myself.

I seldom use the lander can also. Normally I use cupola or the 3 man pod.

[Markus Reese]

I have done that sometimes as well. Alot more since transfering and placing crews is easier. When I do it, I have my main drive portion high on the rocket with the lander underneath it and it's drive engines radial. Keeps it low and wide. With the can, I actually have a top mounted fuel tank that pre-fills the radials. Jettison it away when getting low.

[FlamedSteak]

I've done plenty of landers with 4 radially attached engines in order to lower the centre of gravity.

The biggest issue you run into is the additional weight, which means reduced efficiency, which means more fuel to compensate, which means a bigger booster at launch. I also tend to underestimate my fuel use when I do them. Pretty well much all of my rescue missions are the result of an underfueled 4 engine lander.

[rodion_herrera]

I've done plenty of landers with 4 radially attached engines in order to lower the centre of gravity.

Something like this perhaps?

Tried lots of lander designs, and this is the best one I've made so far--when two are docked, it basically is an orbital station, and you get to carry six Kerbals enroute to some planet/moon. Granted, it takes a lot of juice to get it to orbit, but as a lander, the lower CoG really helps. In keeping with the topic, I'll be modifying this design to allow an "undercarry" assembly for a rover--my previous solution was the usual on-top, and yes, totally ungraceful.

[FlamedSteak]

Nice, I love that design. My concepts are similar but a lot cruder in their execution.

I tend to spread out the radial tanks with struts to widen my footprint, that way there's less chance of flipping. This one was a bit of a failure, I forgot to take off the parachutes after using it on a duna mission, and probably didn't need eight legs on it. Suffice to say, the whole debacle was underfueled and these Kerbals remain trapped on Eeloo forever in Version 0.20

Also I meant to mount the 1x6 solar panels but put the 2x3's on by mistake. Which meant the kerbals couldn't get out of the capsule with all 3 solar panels deployed......live and learn.

Edited October 23, 2013 by FlamedSteak

[Tommygun]

This one used the old crew tank at the bottom with a large fuel tank on the top and radial aerospike engines on the sides..

I did this for an atmospheric Eve landing. It has a small rocket motor at the bottom under the capsule for the deorbit burn.

[Spaps]

Something like this perhaps?

IMAGE

Tried lots of lander designs, and this is the best one I've made so far--when two are docked, it basically is an orbital station, and you get to carry six Kerbals enroute to some planet/moon. Granted, it takes a lot of juice to get it to orbit, but as a lander, the lower CoG really helps. In keeping with the topic, I'll be modifying this design to allow an "undercarry" assembly for a rover--my previous solution was the usual on-top, and yes, totally ungraceful.

Well, this looks like a good and stable lander. I was going to go to Duna today (in search for ribbons) and now I know what lander I will use! Thanks.

[GraviTykillz]

Ive been doing this

[Dunbaratu]

The only problem with the idea of putting the lander can on the bottom is that you need to be a LOT more gentle when landing directly on the can then when landing on lander legs. Lander legs can support a much harsher landing than landing right on the bottom of the can can.

[rodion_herrera]

Another option is skycrane style--release the rover from the bottom of the lander a few meters from the surface and hope it survives the impact (maybe add LV1Rs for cushioning). The lander of course needs to hover, so you have to be sure that you fire the engines at precisely the right moment...then tilt away from the rover's landing spot and land a few meters away. Sounds like a challenge This is how I might implement my lander modification.

[Kasuha]

I've been using this for ages.

All it needs are a few struts holding the can to the tank above.

Note: the screenshot is from Laythe but it's not strong enough to return from it. It is strong enough to return (to orbit) from anything but Eve, Tylo, and Laythe.

[Seret]

I generally try to make my landers wide, rather than tall. So for the Mun the lander can is the only central component (with maybe the engine under it if I'm not using radials). My other components like tanks are arranged radially around the lander using fuel lines if need be. That gives me a nice low C of G and a wide base for my landing legs.

So yes, I routinely put the can at the bottom. Often my problem is mounting the legs high enough so that I don't have a 10ft drop out the door.

[Kulebron]

i always made my landers flat to not tip over on slopes.

[Skorpychan]

Generally, I stick the lander can on top because they're lighter than the fuel tanks. Center of mass!

[SaturnV]

I'm not doing this because most lander can can only survive 6m/s~8m/s impact, I strongly recommended you add a girder/I-beam/struct panel (80m/s impact safe) underneath it, or use command pod instead (14m/s~50m/s)

[Seret]

I'm not doing this because most lander can can only survive 6m/s~8m/s impact, I strongly recommended you add a girder/I-beam/struct panel (80m/s impact safe) underneath it, or use command pod instead (14m/s~50m/s)

Or maybe some legs?

In my experience too much lateral velocity is more often the problem than too much vertical, since the vertical can be more easily controlled. Can't say I've ever had a lander come down hard enough to impact the underneath. A bit of tippage on touchdown is pretty routine though, and having your torque near your C of G helps control that.

[AmpsterMan]

I've put a lander can at the bottom before. Main reason I don't do it anymore is because it ruins my sense of verisimilitude.

I think my most clever design to date has been a two stage that was a lander and Rover in one.

[Tuupertunut]

This message can be deleted. Or do I have a way to delete this on my own?

Edited October 23, 2013 by Tuupertunut

[Tuupertunut]

I made this a while ago:

It is a Mun lander with lander cans underneath and fuel on top of it. There are no radial engines but two stack mounted ones next to the cans. It has no ladders because you can jump high on Mun but they can be easily added.

[Dave Kerbin]

The only problem with the idea of putting the lander can on the bottom is that you need to be a LOT more gentle when landing directly on the can then when landing on lander legs. Lander legs can support a much harsher landing than landing right on the bottom of the can can.

You also need to be very gentle with any parachutes. With the can on the bottom it might detach and fall to its doom when the chutes deploy.

[KvickFlygarn87]

If you are to use nukes (or any gimbaling engine for that matter) make sure to put the engines below CoM or your steering will be inverted.

[Kulebron]

I made this a while ago:

It is a Mun lander with lander cans underneath and fuel on top of it. There are no radial engines but two stack mounted ones next to the cans. It has no ladders because you can jump high on Mun but they can be easily added.

I was trying this "legitimate" option to put two cans side by side, but they were clipping with neighbors, and eventually I chose metal plates and trusses.

[jduchock]

I did this back in .21 with a fuel tank on top of the crew pod, four engine configuration, cross fuel fed. it looked a bit like a spider or a bug but it worked perfectly.

NOTE: build your lander alone and put it on the launch pad to gauge your lander leg clearance before putting it on your delivery system. That way you have no surprises when landing. Dont forget to add kethane gear and you should be set for moon hopping...

Cheers !

[FlamedSteak]

Generally, I stick the lander can on top because they're lighter than the fuel tanks. Center of mass!

I endorse the physics in this post. Putting your tanks above your capsule is going to cause you a lot more instability issues making landfall.