Noob needs rocket science lessons.

[Zhetaan]

@ArmchairPhysicist:

Have a look at @Pecan's excellent 0.90 Design Tutorial, Exploring the System.  I strongly suggest that you use the PDF (it in the OP) rather than try to read it on the forum; the tutorial predates the last big forum switch.

You'll probably find the most useful information in chapters three and five, especially five, because that covers the example Mun landers.

However, do note that this tutorial is for an old-enough version of KSP that just about everything needs to be tweaked to work in today's version.  For example, the 0.90 Nerv used LFO and for a lot of missions, you got better results with a Spark.  However, the important part is that the principles of design don't change much even after taking into account things such as reentry heating and an atmosphere that's made of air instead of mud.  With that in mind, you may find some ideas on how to get the result you want without feeling as though you are launching a full colony mission to the Mun for two hours.

Next, I have @Norcalplanner's equally excellent Cheap and Cheerful Rockets tutorial that is quite a lot more up-to-date.  It's still a bit outdated and has not seen a new post in over a year, but the designs there need much less tweaking.

Where Pecan's tutorial takes the form of a structured campaign, Norcalplanner's is more a set of rules of thumb illustrated with examples.  In other words, Pecan's tutorial gives instructions to duplicate exactly the example rockets and is intended for the complete beginner who starts knowing only which way is up but not how to get there, and Norcalplanner's tutorial is intended to guide one into building designs that fit the overall philosophy without starting from the same assume-you-know-nothing, take-by-the-hand position.

I will assume that you're much more at the level of Norcalplanner's tutorial given that you can reliably (albeit expensively) reach the Mun and return.  However, there is still good information to be gleaned from a 'back-to-basics' approach and I do not wish to deprive you of that.

Good luck with your designs.

[Blaarkies]

On 5/16/2017 at 6:27 PM, Spricigo said:

I pointed out "the best way to make it cheaper is to do the task at hand with minimal expense of resources". To exemplify it I strapped together some scientific instruments and a scientist in the smallest engine in the game and some fuel.  But all you noticed it's that it don't have a closed pod?

Yes,  I decided to not be able to collect the less valuable scientific experiment and halve the mass of the lander.  I consider a good trade, but if you consider a pod mandatory just include it,  add some fuel and another ant. Still a capable vessel for the task at hand weighting about 1,5t.

Anyway don't just say I'm bragging about my design, show an alternative or point what you think can be improved. I really will appreciate constructive criticism,  and even more if you contribution make me notice something I'm overlooking. 

Hehe i see now my message looked really offensive, i am sorry.
What i meant was that OP probably wants the easiest way to fix his design for a single ship landing. Your design does make a lot of sense, it can quickly farm the entire Mun of all science, but the player needs to be at least well versed in orbital rendezvous, EVA kerbals into the boarding seat, soft landings that do not require landing legs.

Those are easy tasks for players past 100 hours of total gameplay time, but think back to your very first docking attempt...i know i still did the same Small-Tank-On-Nerv mistake back then.

You are right, constructive criticism: I was bugged about missing the low science Crew Report, because completionists will need to re-land a lander can design again on all the binomes again (only if you really really want every piece of science). Other than that, it really does check all the boxes for an efficient lander.

For OP: Most of my ideas for a better design has already been said in this thread. But one lightbulb moment got me past this design phase. Get the KER (kerbal engineer redux) mod to show the dv per stage, or take 15 minutes on Wikipedia to understand dv and how to calculate it. Now, thought experiment:
- Add a single MK1 liquid fuel tank, with one NERV engine on it. Write down the total dv for that stage
- Add an extra MK1 liquid fuel tank to the previous design, and calculate the difference in dv it gives you
- Add another MK1 liquid fuel tank and calculate the difference that this one tank offers

1st tank -> +3764 m/s
2nd tank -> +2217 m/s
3rd tank -> +1518 m/s
4th tank -> +1122 m/s
* dv with ONLY tanks and engine. Lander as payload will decrease these numbers

See the diminishing returns on adding more tanks? It is good to understand how that is affected by adding/removing fuel tanks. So the problem is you have a very expensive engine with 3tons of mass, but it only runs through 2tons of fuel. So if you add another tank, you get up to 3764+2217= 5981m/s dv. That alone replaces the job of your poodle engine. 3 tanks give you 3764+2217+1518= 7499m/s dv, which can do the entire mission from kerbin orbit and back again with a huge margin for error. Remove the poodle and you save a lot of mass on the launch, needing a smaller cheaper booster.

Now comes the lightbulb. The fuel+engine segment has dv proportional to the amount of payload up top. So your bottom most stage has a payload which is the total mass of all the stages above it. The second stage has a payload the mass of everything above it, and so forth. You want this ratio between payload to engine+fuel segment to be balanced:
- Too little fuel and you are carrying many extra stages to make up for the dv.
- Too much fuel and you are losing due to the diminishing returns.

Besides that, always try to pick the smallest engine that can get the job done (due to Isp differences, that leads to an entirely different discussion though)

Edited May 18, 2017 by Blaarkies

[KingDominoIII]

sLook at your goals and build around them, cutting out unneeded parts. For example, my Mars I ship has these stats:

Passengers: 5 kerbals

Mission objective: Land on Duna, deploy sats, Ike landing

Vehicles: Surveyor M3 survey sats, Mars I mothership, M2 All purpose lander

Science: Surveyors

Prop: 1 Poodle, 8 NERVs

Fuel: 10,000 LF

500 OX

2000 MONO

28,000 ELEC

It was excessive, and I wasn't able to land on Ike or deploy my sats- I left them in solar orbit. My lander only reached orbit barely and I ended up having to cannibalize my old Duna station to reach my mothership. My trip consisted of burning at quarter thrust to prevent lurching due to my heavy lander. The mission was a mess. I rehashed the program and used a reusable lander. My new specs:

Passengers: 5 kerbals

Mission: Land on Duna, perform orbital science

Vehicles: Ares I mothership, Corona I lander

Science: Small science kit w/ thermometer, narrow band scanner, and barometer

Prop: 1 NERV

Fuel: 2000 LF

500 ELEC

40 MONO

This one was far smaller and suceeded. Corona was sent ahead, landed, and returned to orbit for future missions, and there were no logistics errors.

Keep it simple and look at your goals.