multi stage vs single stage.

[Stilgar2300]

Which do you prefer for a lander? Is one more efficient then the other? Ive tried both and while my two stage munlander is fun it seems pointless. Thoughts?

[Tortoise]

Whats the point of 2 staged lander?

[regex]

Whats the point of 2 staged lander?

It generally ends up being lighter overall.

[User Unrelated]

If designed right, a dual-stge lander than leaves the spent descent stage on the surface can be really convenient, and quite a bit more efficient.

I try to design them all the time, but always end up packing WAY too much fuel, and I usually end up having enough fuel to simply return on the descent stage, and completely ignore the top stage.

[xcorps]

That's how Apollo LEM/LM was designed.

Descent stage had 40,000n of thrust roughly, ascent stage had something like 15,000. Descent had 2200 Dv, Ascent had 2,500DV.

It's kind of pointless for KSP though, because sundries and samples aren't weighed separately.

[Jouni]

If the landing requires less than 2000 m/s of delta-v, staging is usually pointless. Beyond that, there can be noticeable efficiency gains.

[Sirrobert]

Depends on where I land.

Mun and Minmus have a simple 1 staged 3 radial engines design with about 2000m/s deltaV

This functions as transfer, lander, and return craft.

For Other planets and their moons, I'll use dedicated landers that detatch from the Transferstage on location, and if needed, those landers have their own stages.

However those stages are normal staged rockets with droptanks. I don't use Apollo style landers that leave parts on the surface

[Orionkermin]

I like a good crasher stage from time to time, like the N-1/LK block D. I find 2 stage landers difficult to build asthetically speaking, mostly due to engine and decoupler sizes.

[maltesh]

I almost invariably use single-stage landers. A single-stage lander means that the next mission doesn't need to bring its own lander, all it has to do is bring enough fuel to top off the the tanks on the lander the last mission left behind.

[Red Iron Crown]

I use single stage landers for simplicity and reusability reasons everywhere I can. Eve and Tylo get multistage designs because of their high delta-V requirements.

[cantab]

For the Mun and Minmus I generally use a single-stage lander, but may have it ditch unneeded parts on ascent - especially the jerry rigged girder legs I was using in early career mode, since they were heavy. I typically use a separate orbiter; don't think I've done a direct ascent mission with stock parts. (I just now did a direct ascent to Minmus with a ship using Near Future Propulsion, but then NFP makes silly amounts of delta-V practical.)

A 2-stage lander does have the appeal of leaving a landmark on the surface - but watch the debris cleanup doesn't get it!

Edited May 13, 2014 by cantab

[razark]

It depends on how you define "stage".

My recent landers have had a central core with the engine, fuel, and pod. Radial decouplers on the sides hold extra fuel tanks and the science modules. I'll land, do science, then hop to another location and do some more science. Once I'm done, I jettison the side pods, leaving them at the last landing site, and return in the central core. So how many stages is that?

[problemecium]

I always prefer single stage, whether it's landers, launchers, or anything else, because I have this obsession with not being wasteful of my free imaginary rocket parts. I will have the launcher and the "ship" that goes to the Mun or wherever be separate ships, or do any amount of orbital construction, just as long as I can theoretically get everything back when I'm done.

[Red Iron Crown]

So how many stages is that?

Two stages.

[razark]

Two stages.

Just for you, the next time I use it, I won't jettison the side pods.

[Dispatcher]

Depends on what your preferences are. I've tried both.

[Franklin]

I love modularizing everything if I can help it. The extra nth of weight decouplers add I feel are inconsequential to greater versatility if (when) something goes wrong and I need to re-think what I'm doing.

That said, every lander I make is one-stage with the capacity to be two-stage if (when) I mess up. Being able to decouple radial elements has saved me a few times with otherwise being unable to get back into orbit, or being too heavy to land safely.

[Landge]

I've tried both but my favorite lander is single stage. It can land and take off of any planet except Eve, Kerbin, or Tylo.

[Whirligig Girl]

3-stage Duna Lander. Stage 1 is in-flight/lander stage. Stage 2 is ascent stage, stage 3 is ascent stage and in flight stage.

[cantab]

Two stages.

I would say it's one stage, with drop tanks (and drop science modules). It's not the most authoritative source, but according to Wiki, "A multistage (or multi-stage) rocket is a rocket that uses two or more stages, each of which contains its own engines and propellant." So dropping a part that is just a fuel tank, just an engine, or neither a tank nor an engine doesn't count as true staging. Though the early Atlas rockets, which dropped engines but not tanks, were sometimes described as "stage-and-a-half".

[Blind Dead McJones]

I have thus far used a lander with radial attached engines that are onion staged. The reason I did that is because those parts also have the landing gear, so even if those engines are empty I can't drop them until I lift off.

Although so far I've only taken Kerbals to Mun and Minmus. And the reason it's staged is because of the aforementioned solution to widening the landing base. On those bodies, it still always has a ton of ∆V left over when I go back to Kerbin. So yes, I guess I have a two stage lander. Not because staging is necessary, but because it was too narrow otherwise.

[Brotoro]

In real life, Apollo was cutting things very fine to keep the weight of the moon ship small enough for the Saturn V to lift... so the two-stage design was needed. In KSP I can generally haul along plenty of extra fuel, so a single-stage Mün lander works fine... although I have done Apollo re-creations, which require a two-stage lander for accuracy.

But basically, for any of the low-gravity moons, I use a single-stage lander (with no drop tanks). So: Gilly, Pol, Bop, Minmus, Ike, Mün. These landers have the advantage of being reusable by just refueling them (as mentioned up-thread).

When I first landed on Duna, Laythe, Vall, Moho, Dres, and Eeloo, I used staged landers that either dropped side tanks or side tanks with engines on ascent (although for some of those targets I did not always need to drop parts). But I would handle any of those now with single-stage landers. I also now use SSTO rockets or spaceplanes to go up and down from Kerbin to low-Kerbin orbit.

Tylo and Eve I certainly tackle with multi-stage landers. In the case of Eve, MANY stages for ascent. In the case of my most recent Tylo mission (in progress), the lander uses drop tanks during descent AND staging during ascent to minimize the mass of the lander.

[magnemoe]

I would say it's one stage, with drop tanks (and drop science modules). It's not the most authoritative source, but according to Wiki, "A multistage (or multi-stage) rocket is a rocket that uses two or more stages, each of which contains its own engines and propellant." So dropping a part that is just a fuel tank, just an engine, or neither a tank nor an engine doesn't count as true staging. Though the early Atlas rockets, which dropped engines but not tanks, were sometimes described as "stage-and-a-half".

One Russian moon lander concept staged during decent then left landing legs on ground.

One of my standard Minmus landers for career uses single engine, four drop tanks with science modules and fuel together with landing legs.

Below the side modules I have extra drop tanks for going from LKO to Minmus and science modules for high and low Minmus, they are dropped before landing.

Now the version used in 0.235 refined this a bit more, its set up with extra landing legs so it can drop the two first tanks then fuel and science gear is use up.

On mun I uses an rover who can drop the wheels, side tanks and science.

[pantner]

I'm certainly no expert on the matter, only landed on Mun, Minmus and Duna.

Pretty sure all of mine have been single stage.

My Mun/Minmus landers have a FT400(?) with 4 of the smaller tanks around it for a larger landing base. Sometimes a 909 as the engine, other times the smaller ones (rockomax 447? im sure you know what I mean). One on each fuel tank (ie, 5) with the outer ones thrust limited to 50%.

My Duna lander started it's decent and dropped the transfer stage, leaving 2xnuke engines. I landed, took off and made it home with those.

Have considered 2-stage but never actually built any.

[Duke23]

Earlier in the tech tree my landers are 2 stage (or 3, but the 3rd stage typically only gets used if something goes wrong). I'll have the whole thing pushed out on a transfer stage, use the main outer engines on the lander for deorbit, landing, and at least half of the ascent / circularization. Then I'll drop all the empty tanks and head home on something minimal. This usually only applies to Mun and Minmus. Or for my first landing or two of a new save it's usually something small (no outer engines) that ends up cutting it close, maybe staging on the descent and using the final stage to touch down, ascend, and hopefully return home. But those don't bring any equipment, just a Kerbal.

Once I get docking ports and other useful stuff I usually make them single stage so I can take the lander out on a large reusable transfer ship, go down to the surface and do my business, then redock with the transfer ship and either top it off to hit another spot or take the whole ship wherever I'm headed next. Sometimes that "single stage" does include a backup plan though depending on the design, like the lander's command module having it's own small fuel tank and engine so I can dump everything and at least get to a safe orbit if I miscalculate and don't have enough fuel.