multi stage vs single stage.

[KerbMav]

To reuse a transfer vessel for another mission it would have to be restocked with supplies and fuel, cleaned, thoroughly checked, overhauled and repaired.

Landing the whole thing to do so would have required protection for reentry and loads of parachutes - additional weight needing more fuel and also even more expensive gear.

Every kilogramm of equipment raises the fuel requirement, making everything heavier and requiring a bigger launch vehicle.

There was no space dock back than like we have ... not even today really ... ISS might be used to dock a transfer vessel and a lander might be parked in lunar orbit, although for maintenance reasons it would be better to bring it back too. But it all comes down to: is it feasible and secure enough?

[Rus-Evo]

If I want to reuse a multi stage lander I just make sure the next mission brings a small dockable tank to be the first stage (I put docking ports on the top and bottom of landers).

[aleis]

Just add wheels and a solar panel to your decent stage and it feels much more useful.

If you don't see the need or effort required in designing it

[AmpsterMan]

In haver come to the conclusion that there are different reasons for prefering one design over another.

For all Mun-like bodies, the single stage is the most mass efficient. The mass of decouplers and engines are too large compare to the mass of what is left behind (landing legs? Science experiments?) It also has a distinct advsntage of lower part count and lower complexity. The doenside however is that piloting needs to be precise and one will potentially be using the same engine for different jobs (these last bits are minor though)

Conversely, a two stage has a significant advantage over the single stage, flexibility. By being able to design a "seperate craft" one can fine tune for whatever conditions you will be facing. Furthermore, as was mentioned before, the peace of mind that comes from not having to ration fuel can help greatly as well. Also, leaving a small base on Mun looks cool as a reminder of where you have been.

I beleive it is important to remember that this is mainly for for Munlike bodies. Duna and Laythe require different craft. Vall, Eelloo, and Dres may also benefit more from the fuel savings of a two stage. Eve and (forgot the airless, huge moon) are on leagues of their own.

I quite like that the most efficient way of landing on Mun is also the easiest. It means that your first time player won't have to know how to rendezsvous, dock, or worry about staging. He'll be able to land with a big ship and the just leave and head for home. Mun provides the base level by which all other bodies are measured. It's truly a wonderful case of balance through careful design.

Edit: I must use this qualifier: since 0.18, all of my missions have included a rendezvous. If one were to attempt a direct ascent, the multistage approach has more traction.

Edited May 14, 2014 by AmpsterMan

[Vahal]

I used to built single stage landers, but they were quite huge to pack the fuel to finalize transfer, manage descent, land, sometime land to another biome - several time - and finally go back to Kerbin. Then i started to use fairing from NovaPunch and even inside the 5m those big ass landers didn't fit so I started to make Apollo clone:

*lifter with fairing to send the vessel to stable orbit

*vessel is command commule +lander module

*command module is used for transfer then when vessel is on stable low orbit, lander is undocked

*lander... lands and does its job. All data are stored inside lander pod

*lander takes of, uses the remaining fuel and the landing stage is jettisoned and lander becomes return capsule who rendez vous with command module

*all science datas and remaing fuel are transfered to command module and remotely deorbited with RCS since monopropellant is'nt needed anymore.

*command module is used to make the transfer back to Kerbin, everything is jettisoned from the pod except the parachutes of course after reentry.

What I found is that single stage lander needs less parts (obviously) but is a lot more heavy and massive since you have to transfer, land and bring back all the package. atm I land a little 7t lander when before my standard lander weighted around 40t and they both have the same science tools onboard. Single stage are simpler to build since you don't have to manage the weight and dV ofr each stage, if you build a 2k/2K dV staged lander it's just useless so you have to make them the lighter and smaller as possible with security margin cause it's not good/fun to push your capsule during 45min. A single stage lander just requires your lifter can bring it to orbit and the vessel has enough dV to come back. Plus the fact you don't have to place everything carefully to avoid ejection failure and bringing back useless parts. One stage lander is also easier to fly since you don't have to rendez vous, dock and other stuff that makes newbies having nightmares waking up and screaming "we're going too fast! Jeb slow down!". You go to orbit, go to your target, land, lift of, go to orbit, come back to kerbin and land with chutes. I have to decouple my lander, land it, bring the return capsule to orbit, rendez vous and dock it with command module, transfer science, ditch the return capsule, bring back the command module to Kerbin. But I foudn this damn more fun and by the way safer. My first landing stage hadn't enough fuel and Jeb promised to a 400m/s lithobraking, but, I ditched the landing stage, and used the return capsule to go back to command pod and avort safely the mission, with a single stage lander I guess I would have some problem when trying to come back to Kerbin.

[technicalfool]

Mun, Minmus, Gilly and similar? One stage.

Duna can be one or two stages. Generally two, and parachutes help a lot (even on Duna).

Anything heavier, at least two stages. That said, I haven't done anything heavier with the 0.23.5 parts yet.

[Jouni]

Basically we have several classes of planets and moons:

1. Gilly. The landing requires so little delta-v that bringing a lander is inefficient.
   
2. Minmus, Pol, and Bop. Landers require 500-1000 m/s, depending on the mission, so multi-stage landers are pointless.
   
3. Mun, Dres, and Eeloo. Typical landings require 1000-2000 m/s, which can be efficiently achieved with single-stage landers.
   
4. Duna, Moho, and Vall. We're now in the 2000-3000 m/s territory, so multi-stage landers can be useful.
   
5. Kerbin and Laythe. At 3000-5000 m/s, single-stage landers are possible. Without jet engines they'll be inefficient.
   
6. Tylo. With 5000-7000 m/s, single-stage landers are still possible but inefficient.
   
7. Eve. Multi-stage landers are obligatory without mods.
   

Achieving a 2000 m/s delta-v target with chemical rockets requires that 40-50% of lander mass is fuel. With nuclear engines, the fuel fraction drops to the 20-25% range. With numbers like that, multi-stage landers are pretty much pointless.

Things change, if we increase the target to 3000 m/s. With chemical rockets, fuel must now account for 55-65% of lander mass in a single-stage lander, making multi-stage landers borderline useful. With nuclear engines, we're still in the 30-35% range.

At 4000 m/s, multi-stage landers clearly become efficient. A single-stage lander with chemical rockets must be 65-75% fuel, which doesn't leave too much room for the payload. With nuclear engines, the fuel fraction is still only 40%.

[Redshift OTF]

My tylo lander is 3 stages which brings the weight down to 10 tons.

[merendel]

Most of lower gravity targets I use a single stage lander. Some of my designs to include an emergency stage, basicly a FLT100 with the small roco under it. This "Stage" is rarely used and is mostly for those times when I cut my dV margins too close and had insufficent fuel to make orbit or return home. Frequently it will get jetisoned along with the rest of the craft if I'm doing a capsule only return or remain intact if the whole ship is returning.

Once I have docking ability I often design a reuseable lander where just the landercan/pod gets docked on top of it with a science package attached. The mission crew docks with the lander, refills if needed from the transfer stage, does the landing and reorbit, redocks with transfer stage and returns leaving the lander in orbit for the next mission. Transfers may happen at an orbital station if I've sent one to that location. If I sent a science lab the science package will be built into the lander frame itself and reset there with only the data being returned with the pod.

[Vaporized Steel]

I recreated apollo styled mun landings once. It's actually very hard to design a decent/ascend(LEM) and CSM module in the Kerbin / mun transfer configuration without packing any of the stages with to much fuel. I was forced to use the smallest Oscar B and Round 8 Toroidal tanks with adequate fairings for prettyness to pack the stages with just the right amount of Delta V to make the design have any purpose. Although this mun styled landing was fun it's absolutely pointless. I haven't tried real solar system yet but I'm sure a apollo styled mun landing will make alot of sense in the earth / moon configuration.

[SRV Ron]

To use a multi stage lander, such as this design from the demo that could also land and return from Duna, requires a good sized rocket using asparagus staging.

After launching this standard staging design, I had sufficient fuel in the second stage to orbit and crash it in Minmus. The third stage made a landing and return with lots of fuel left.

[Geschosskopf]

For early-game, 1-shot, "grab the Science! and get home" trips, I almost always use a crasher stage. Crasher stages are cool. They act as radar altimeters in the external view (at least for a while) and they provide entertaining fireworks. So I suppose technically these are 2-stage landers.

However, from the mid-game on, it's all single-stage because of reusability. Either I'm systematically plundering all Mun/Minmus biomes with 1 lander paired with a Mobile Lab in orbit, or I'm building a permanent presence at another planet. To me, mere exploration is pointless unless you follow it up with expansion and exploitation. And this requires a means of regular transfer of stuff between Kerbin and elsewhere, which without Extraplanetary Launchpads is really only possible with 1-stage landers.

[harop23]

Mk2 Landeis very useful with single Kerbal. As its large window that allows a view to the outside and ground. Edited June 19, 2014 by harop23

[awsomejwags]

I generally use 2 stages because the decent stage looks cool beside my flags and also, why take your landing legs with you?

[karolus10]

For moon lander/orbiter (3 crew on surface and back) I had one simple, but effective design.

This both (lander will go back to propulsion stage and spend lander stage before leaving back to kerbin) stages are more than enough to reach mun surface starting from 80km parking orbit around kerbin and came back to Kerbin.

Edited June 5, 2014 by karolus10

[teal'c]

I think it's fun to design minimalistic 2-stage landers. Also, with Procedural fairings they can look quite cool:

[nobbers12345]

I don't see what the issue is.

I just use a 27 stage ARM asparagus lifter to get off the moon.

[magnemoe]

I have used a three stage Minmus lander, 4 stages if you count the drop tanks used to take it from LKO to Minmus deorbit.

Its designed to land 8 times on Minmus, main reason to drop stages is to remove used goo and material labs.

[Felsmak]

I always build my landers with two stages. I want to make sure the aliens know I got there first.

[Stilgar2300]

I don't see what the issue is.

I just use a 27 stage ARM asparagus lifter to get off the moon.

I want to see wackjob do this

[Taki117]

I use a single stage for most things. I Do have a hybrid for Duna in the works. (It will make it back to orbit, but will drop the unneeded Service Module when it's done.)

[Othuyeg]

I often end up using my transfer stage for deorbiting and tuning the landing spot. Then I only need a tiny amount of dV in my actual lander for landing.

[No one]

Before I completed the tech tree, I would jettison all the heavier science equipment before taking off. Now that I've completed it, the goal is no longer to get science, but to get all the science, and only one copy of the data is allowed if I jettison the heavier equipment.

So one stage for most stuff, but if I ever land on Tylo I'll probably use multi-stage because of the delta-V required. Same for if I land and return from Eve, Duna, or Laythe.

[Dat_Spacewaffle]

1 stage landers, I've never really landed on anything other than, the mun, minimus, and kerbin. so, I really dont need to go designing Apollo style landers.

[Tortoise]

I usually use a single stage just to get into orbit, then multiple stages in space.

Unless its really heavy.