Noob Needs helpwith my design.

[Nervustwitch]

I have been trying to build a rocket that can get me to the mun and land then return,but I have been having trouble.

I have built a couple that get me to the mun and home but not enough fuel to land me.So I tried looking on youtube and found a design that similar to what I have built and his got him to the mun without any problems.

In the vid when he drops the boosters and about 7500m he still has over half his fuel in the 7 remaining rockets and that carries him to 30,000m+,mine only do for about maybe 20,000.I tried copying what he did in the vid but nope.

here is the vid:

http://www.youtube.com/watch?v=0dtpLLhLbN8

my design,not much differnt:

[700NitroXpress]

I'm assuming this is for career mode. You can get there without fuel lines, however, it's best if you unlock fuel lines first and then build a rocket that uses asparagus staging. There is an insane amount of science that you can get just from flying around Kerbin.

[Taki117]

In the video, as he approaches something called Terminal velocity, he throttles down to keep his speed below terminal velocity. Try that and see if it helps, and if I wasn't on my phone I would be of more help...

[Dave Kerbin]

The delta-v shown in the screenshot is definitely short. To go to the Mun I would put it roughly at 4500 + 1000 + 1600 + 200 (7300).

Looking at your screenshot (I can't really see everything clearly, photobucket shrinks and compresses images terribly) I am wondering what it is you have between the lander's T400 fuel tank and the lander's LV909 engine. It's something dark with landing legs and solar panels attached to it. That extra weight on a late stage could be having a big effect.

[Dave Kerbin]

In the video, as he approaches something called Terminal velocity, he throttles down to keep his speed below terminal velocity. Try that and see if it helps, and if I wasn't on my phone I would be of more help...

Even with throttling the Engineer Redux screenshot is showing just over 6100 m/s total, and that's in a vacuum. Flown perfectly that rocket could make a safe touch down on the Mun with some fumes left in the tank, no return trip possible. I think some of the modifications have increased the landers weight and thrown everything else off.

[Respawn]

Judging from your stats display, you start off with 2.22 TWR, I'm guessing you're wasting alot of fuel fighting drag when you pass about 1000m after launch.

I don't use MJ but I bet there is an option for limiting thrust to terminal velocity, if not try gradually throttling down until you're out of the densest part of the atmosphere,

or until you drop the solid rocket boosters, whatever comes first. Then throttle back up to full.

However if that's not your problem then I would consider rebuilding the entire rocket. It does not look very efficient.

[RSwordsman]

With six SRBs, they should be almost enough to lift that thing with a respectable TWR all on their own. You could try giving the liquid engines just a little bit of juice to maintain course* and acceleration rate (I've found about 2-2.5 m/s^2 is good with FAR at least) and that should significantly extend the life of your first couple of stages.

*It looks like you're using LVT-30s, which don't have thrust vectoring. Is it possible to switch to 45s? IMO there is hardly ever a reason that the 15 extra thrust units of the 30 are worth the loss of gimbaling capability.

[Nervustwitch]

Where you talk about at the legs,that was a small tank,I removed it and the nose cones.The launch stages are now exactly like the vid.The lander is similar but I added a decoupler between the Jr. and the lander stage engine and fuel.

What is a better way to post a screen shot?

What can I do to make this work?

Also i do now have fuel lines but I do not know how to do asparagus staging,I've tried it once but it was a HUGE failure.I have looked for a how to own it but I get kinda confuses.Could use some info or a link to a really good how-to.

Thx for the help,still trying.

After the changes

Tried a different host

[Nervustwitch]

Also I dont really use the Mechjeb for flying just mainly for info,but I did tick the box in MJ for terminal V and it did the same thing.

I also tried the 45's but im getting almost the exact same results.

yeah I figured its not very efficient but Im trying to learn.

[Nervustwitch]

Ok I finally figured out asparagus staging but that didnt help that rocket setup at all.

Ok so I guess its start over and I have no idea what to do.

Is my lander good or a bad setup?

My lander mass is 5.34T,count the lander engine and fuel tank for return.As for the stages I', lost,been at for I dunno how long now.Im very determined but it is starting to wear on me trying to figure this out.

[DeMatt]

First thing to note is that the video you mention was done in KSP v0.22, as he's spamming the Science Jr. (it was made single-use in v0.23). Secondly, he's using the steerable AV-R8 Winglet, rather than the fixed AV-T1. Thirdly, he only put one FL-T400 tank on his lander, so the extra FL-T100 (or whatever it is) is Not Necessary. Fourthly, he's launching from about 50 metres above the launch pad - not much, but with the other differences possibly enough to account for the difference in your launch profile.

So, since I for one don't think he built a very good rocket, suggestions for further improvement:

• Remove the 6 SAS modules on the intermediate stacks (but leave the single SAS in the center). You don't need 'em. Use LV-T45 engines at the bottom if you're desperate for steerability.
  
• Cut down on the number of solar panels. One ring of four ought to be plenty.
  
• Cut down on the number of landing legs. Four is good, six is probably overkill.
  
• Replace the two FL-T400 fuel tanks in the second-to-last stage with one FL-T800.
  

And most importantly... go to Minmus instead. While it's a bit harder to match orbits, it's a LOT easier to land on.

--------------------------------------------

...I just noticed. Why do you have TWO sets of decouplers in your stage #4, between the six intermediate stacks and the single center stack? You should only have ONE set of decouplers.

I'm betting that you put the two rings of decouplers on, to hold the two layers of fuel tanks... but because you did that, the upper fuel tank in each intermediate stack is not actually connected to the lower fuel tank - and you're thus forced to jettison it, unused.

That would account for the "missing" half-a-stage's-worth of fuel you mention.

To fix this, just put in one ring of decouplers, attach one set of fuel tanks to the decouplers, then be sure to attach the second set of fuel tanks to the first.

Edited February 3, 2014 by DeMatt
Odd staging spotted.

[MarvinKitFox]

At 6117, your total delta-v is just not enough.

Realistically, you need 4500 to get to orbit, 2000 or so to get to Mun and back, leaving you nothing to land by.

You need to beef up your launching stage a lot, or better trim your final payload mass a bit.

Mind you, the displayed dv looks a bit slim... Check DeMatt's suggestion above, that maybe your design didnt match fueltanks correctly, and is only access half your first stage liquid fuel?

Hints:

Lose the ladder. On Mun, Minmus, the eva pack provides ample ability to enter&leave your capsule.

Less legs. 6 legs is very overkill. Rather invest in an extra gyro, to keep you upright on landing. I'm usually good with 3, or 4.

Your lander, at 2000m/s delta-v, has a bit more oomph than it need. Especially of heading to Minmus instead of Mun.

Your starting TWR of 2.22 (will go up to about 3.6 at burnout) is too much. Air drag losses will be horrid. You want first stage to run something like 1.8-2.5 TWR.

Edited February 3, 2014 by MarvinKitFox

[Nervustwitch]

Ok I think I got it.

I redesigned a lot of it and now getting in orbit with plenty of fuel to spare.

I learned the Asparagus Staging and made a huge difference for me now.

Also Demat I did not know that about the decouplers,that was most likely a very bad mistake.I have learned alot tonight about ship design,Im not having to much issues setting a basic orbit and getting to the mun.

Yeah I figured the 6 SAS was not needed

I'm not sure why i thought I needed all the solar panels,but I have fold out ones now.

I figured 6 legs was overkill but thought that it might help with being new to this,will try 4 instead.

I also trimmed down the lander a bit.

I will be trying Minmus 1st

Thank you everyone for all the help and info,was very helpful.

Here is the new design and I would and opinions about it or what I could improve.

[Nervustwitch]

At 6117, your total delta-v is just not enough.

Realistically, you need 4500 to get to orbit, 2000 or so to get to Mun and back, leaving you nothing to land by.

You need to beef up your launching stage a lot, or better trim your final payload mass a bit.

Hints:

Lose the ladder. On Mun, Minmus, the eva pack provides ample ability to enter&leave your capsule.

Less legs. 6 legs is very overkill. Rather invest in an extra gyro, to keep you upright on landing. I'm usually good with 3, or 4.

Your lander, at 2000m/s delta-v, has a bit more oomph than it need.

Your starting TWR of 2.22 (will go up to abotu 3.6 at burnout) is too much. Air drag losses will be horrid.

I really appreciate all that info but a couple things I no nothing of:

Extra gyro?

TWR,I do not know what that is or means at all or really the delta-v.

Remember i am very new to this and ver willing to learn but I just do not know how or where to find out about all this.I have basically just used game tuts and some youtube to learn.

As for beefing up the landing stage,what am I missing.Bigger engine? I am only using the one with I think 50 thrust. Do I need bigger?

Where would be a good place to find alot of this info collected in a single place or web site.I try looking here in the forums but there is just so much to look for and I dont know what would be considered beginner or advanced info.I kjnow Im needing the basics need to know kind a stuff.

Edited February 3, 2014 by Nervustwitch

[MarvinKitFox]

Last bit of advice.

There is no need to keep your Goo canisters, Science jr. on your return craft.

Land, do your science, then eva to the science instrument. You can extract the data, carry it to your capsule. Then the instrument is just dead weight, and can be abandoned on the surface.

Either mount them on a decoupler, or use a seperate return stage that carris just the bare minimum needed to return.

Extro Gyro: == another sas or reaction wheel, to increase the electric-steering-ability of your lander. It doesnt matter if your legs are placed solid, if your balance is stronger than gravity!

TWR: thrust-too-weight ratio. At TWR 1.00, your rocket gives just enough thrust to hover. At 2.21 as yours starts, It can zoom upwards fromt he launchpad at 1.21 gravities acceleration.

When TWR of your launching stage is too high, you get too much speed while still in thick air, thus lose a LOT of speed to air friction. Best is to keep your speed at or a bit less than terminal velocity, this means TWR at launchpad should be 1.8 or so...

Beef up launch, not land stage! I mean, your first+2nd stage total not really enough. If might be that tank misalign mentioned earlier.

Your lander has a fine engine, it could just use a bit of a diet on the unneeded extras. (but not bad, really)

P.S.

If you have never done it before, expect to crash on your first landing. and the next 15 or so. It is not really that difficult, but everything happens SO FAST.

F5 and F9 will be your friends here, for quicksave and quickload.

Edited February 3, 2014 by MarvinKitFox

[Nervustwitch]

Last bit of advice.

There is no need to keep your Goo canisters, Science jr. on your return craft.

Land, do your science, then eva to the science instrument. You can extract the data, carry it to your capsule. Then the instrument is just dead weight, and can be abandoned on the surface.

Either mount them on a decoupler, or use a seperate return stage that carris just the bare minimum needed to return.

Yeah I just learned that I could get the data out by playing around with them on Kerbin a bit,so I will fix that.I have been really wanting to slim down the return stage but wasnt sure what I can and cant drop.

Thx again everyone.

[SRV Ron]

Your design is very similar to my Career Mode one. With fuel lines and braces as shown, you will get a stable efficient flight that can take your probe or Kerbal anywhere in the Kerbal system. You don't need the fins as the bracing will stabilize flight. Place a T-45 on the core and use T-30s on the asparagus boosters.

[SRV Ron]

This demo one made Mun landing and back;

If you design a similar lander to use with your existing launcher, you should have plenty of fuel, as shown in my demo, to land and return from Mum or Minmus.

Do Minmus first to get some experience on landing and returning.

The same design with landing parachutes, with flight experience, practice, and finding the correct direct transfer window, can do a Duna mission.

[ShadowDragon8685]

There's just not enough dV in your designs. To quote Jeremy Clarkson: POWER!

Refer to this. Bookmark it. Hell, I'd be glad if someone made a mod to display this DV map in-game.

That second vehicle of yours has a total dV of 6,588. To get to the Mun and land, you need a minimum of 6,250. You're cutting that to the wire for a one-way trip, forget about any inclination changes and Kod help you if you come down in nasty terrain (which the Mun has a lot of.)

With that rocket, returning to Kerbin might as well as much of a fantasy as the Starship Kerbaprise rolling on by to beam up your poor stranded Kerbonaut.

First off, mods or no mods? I assume you're okay with modding, since you're using MechJeb. My advice: Get KW Rocketry. Their engines are much better. By which I mean they are more specialized, not that they are simply overpowered compared to stock. And they have better sounds, too, less OH GOD EAR ****!

Once you've done that, basically divide your rocket into two sections: Launch and Mission. Build the Mission stage first, though it will itself be divided into transfer and lander stages (more on that later.) Assume you're starting from the very edge of LKO (you won't be, set MechJeb to at least a 100km, preferably a 200km launch,) and count up your dV requirements. 680 + 180 = 860 to do your Hohmann transfer to the Mun, 80 to correct, 230 to circularize.

Plan for the worst. And by that I mean plan your transfer stage to get all the way to a circularized orbit of the Mun and then turn around and go home without jettisoning anything. So count it back again: 230 + 80 to get back to Kerbin's SOI, 180 + 680 to get to low orbit.

That gives us a number of 1,170. Don't stop there, though, if you're making a shot at one of the satellites of Kerbin, you want an inclination change buffer. Make it at least 1,500, preferably 1,800 or better, and no matter what you do, if you find yourself cutting down to the mathematical wire, turn around and head home. You don't want to find yourself planning impromptu rescue missions.

Now, your lander stage itself will need a lot of dV. Fortunately, it's light, so what would barely qualify as an engine and fuel supply for a transfer stage qualifies as beefy for a lander. The bare minimum, for a Mun landing, is 1,160, unless it's a one-way trip. Again, see my advice about not planning impromptu rescue missions: It's very possible for a planned two-way trip to become a one-way trip by accident. "We ran out of fuel" should not be one of those accidents, however, so plan that stage with at least 1,500 dV again. You may want to hop up and have a look at another biome.

And lastly, the launch stage. Once everything's together, this sucker should have a minimum of 4,500 dV. You won't need much buffer on this, if you're using MechJeb, since it can put you into the orbit you want on exactly 4,500 dV with a ridiculous degree of accuracy. If it doesn't have 4,500, you're automatically scrubbed.

Ideally, you want light-weight, high-atmosphere-ISP engines. You won't be in atmo the entire time, of course, but again, don't cut it down to the wire: if you have 4,500 atmo DV, you definitely have all the DV you need to get into orbit.

So, build it from the top-down. Build your lander stage first, and don't plan on bringing any part of the damn thing home. It is fully possible and practical to build a lander capable of landing from low Munar orbit, doing a few biome-change hops and then returning to the mothership as a single stage. There are advantages and disadvantages, though the biggest advantage is that if you do so successfully, you can easily vamp the lander's fuel tanks and RCS tanks for any remaining fuel. Every little bit helps, especially when you don't actually have to bring the lander's mass home with you.

Okay, you're planning to fly the satellite of your choice (more on that later.) You're going to go down, do some Science (Science!) and come home. Ideally, you want to bring a lot of Science with you. You know what you don't need to bring back? Those heavy goo containers, and those even-heavier Science Jr. materials bays. I didn't realize that at first and made a stupid lander designed to take off, do science, return to the mothership, transfer the kerbonaut back, and then jettison the landercan and fuel tanks, leaving the Science Jr. and goo tanks still attached.

You can leave those on the Munar surface to increase your DV. attach them radially, have your Kerbonaut cuddle up to them, rightclick on them, take the Science out of them,get back in and discard them. You also don't need landing legs on your return trip, so if you're going to decouple something, might as well attach the things you won't be needing to the heaviest things you won't need. So build it low, squat, radialize the engines and radialize the Science! bays onto the engine pylons, and radialize the goo onto the Science bays, along with the lander legs. If you're so inclined, of course. It's just my way, but I like to plan my landers and mission stages as if everything is going back with me. Remember, the only cost to taking fuel home with you is the cost of going up in the first place, and fortunately the Kerbal race are so space-happy that KSP currently enjoys unlimited funding. (Enjoy that while it lasts.)

So, the short version: Build from the lander down. The lander needs 1,500 dV. The transfer stage needs 1,500 as well, though I wouldn't go without 1,800 minimum myself. And the launch stage needs 4,500. If you don't meet these numbers, don't launch. Or if you do launch, use a probe core in there somewhere and have your learning experiences without a Kerbal's life on the line. You can always do what the Apollo program did, take it one step at a time, test each step and come home before moving on to the next.

Now, my personal trick for launching heavy payloads? It's as simple as it is reliable. Build out, not down. Radialize, radialize, radialize. Six identical rockets firing at once will give you far, far more dV than those six firing in sequence, jettisoning when the stage above them is complete. And if you have to use a dozen or two dozen fuel stacks to get you up, so be it.

Also, keep it simple. People here swear by asparagus staging and mixed engines. I'll have none of that, personally. If it works for you, go for it, but my strategy is identical engines connected rigidly all the way. Even if it lags, so what? You've got MechJeb, input lag and lag in general are no concern of yours. Launch the sucker at the sky, set of MJ to auto-stage if you attached SRBs (just remember that SRBs are bottom stage only,) and go make tea if you have to.

One other thing: that much mass doesn't adjust its course easily if your only sources of control are fins (which do no good whatsoever above the atmosphere,) and the reaction wheels in the mission and lander stage. Put some reaction wheels in the lower stages. KW has a nifty one that can be radialized around a Rockomax fuel tank as two halves though using regular old inline reaction wheels works just as well.

Lastly, launch from as high up as possible. Attach rocket holders to the bottom of your rocket, hold shift or control (I forget which does which; alt copies the part,) as you click on the bottommost bit of your rocket, lift it as high up in the VAB as you can, attach the rocket holders, set them to decouple when the first stage launches. It's not much, but every little bit helps!

And don't forget to check "Limit to terminal velocity." Going past terminal velocity isn't doing your DV any favors, even if getting atmospheric re-entry effects going up is hella sweet.

Edited February 3, 2014 by ShadowDragon8685

[Kerba Fett]

2 tips for you; if you havent already done it, try Minmus first. It only takes about 100 more dV to get there, but a lot less to land and get back to orbit.

Second, use jet boosters for your initial ascent. If you've got the bi couplers unlocked you can put a pair of jets and a fuel tank with some intakes to replace each SRB. They only work up to 20 km, but you're probably not getting anywhere near that with the SRB's anyway. (note: you need to turn the jets about 45' to put a pair on a bicoupler)

[Nervustwitch]

Wow alot of info here.

Ok I havnt done much today but with the current setup in the last pic I posted I have got to a 80k m alt Kerbin orbit with almost half fuel left in the center stage,just before the lander stage.Now I havnt left orbit yet but ShadowDragon says that I most likely not gonna make a landing.If I still have that much fuel in the center stage before lander shouldnt that be more than enough to get to Mun/Minmus? then drop center stage to use my lander stage?

My lander stage is using the engine with 50 thrust and the and the fuel tank you see in the pic,is that enough to land with and return on either Mun or minmus?

With having that much fuel left before my lander stage I'm not understanding why he says that its just down to the wire.

Thank you again everyone for all the help,I feel Im finally making some progress here.

Edited February 3, 2014 by Nervustwitch

[Nervustwitch]

Well I finally did it and it wasnt too hard,had more trouble trying to work out the nodes more than anything and got about 600 science.

All I did was add a SRB stage to it my last version and some RCS rockets for some control.

I am also very surprised that my very first landing attempt was almost perfect.As I was coming down I gave the lander a lil too much power and started going back up,so I flipped it upside down and throttled up a bit to get in the downward direction and then had to flip it back over to land on the legs.!st attempt sat down very easy,no crashes or Kerbal loses....lol. and the landing was on a slope to boot.

[Taki117]

Well I finally did it and it wasnt too hard,had more trouble trying to work out the nodes more than anything and got about 600 science.

All I did was add a SRB stage to it my last version and some RCS rockets for some control.

I am also very surprised that my very first landing attempt was almost perfect.As I was coming down I gave the lander a lil too much power and started going back up,so I flipped it upside down and throttled up a bit to get in the downward direction and then had to flip it back over to land on the legs.!st attempt sat down very easy,no crashes or Kerbal loses....lol. and the landing was on a slope to boot.

PIC SNIP

YAY! One thing to note though, you could have just not flipped your lander and instead let gravity pull you back down. I know it sucks having to wait, but it saves fuel, and hassle (Can't exactly flip on the mun, you fall too fast) A bit of advice for your lander: build out, not up. What you have now is fine, but I wouldn't go much taller. You can put fuel radially attached to your science junior and run fuel lines from the tanks to an engine on the bottom of the junior to get more dV and a more stable lander.

[Liowen]

While I do not have a picture of the rocket I am using on my career mode I do have to say that one is a bit over kill. Mine does not use asparagus staging, but it has 4 srb and 4 outer thrusts and one center, with the center piece staying all the way to Mun with fuel left. I will get a picture of it soon as I need to finish the video of the Mun Mission, been too busy to do it right now.

[Nervustwitch]

YAY! One thing to note though, you could have just not flipped your lander and instead let gravity pull you back down. I know it sucks having to wait, but it saves fuel, and hassle (Can't exactly flip on the mun, you fall too fast) A bit of advice for your lander: build out, not up. What you have now is fine, but I wouldn't go much taller. You can put fuel radially attached to your science junior and run fuel lines from the tanks to an engine on the bottom of the junior to get more dV and a more stable lander.

Yeah I dont a tall lander.Im trying to picture the fuel and engine design you suggest but I cant really get what is meant.You add tanks and engines to the side of the junior,the fuel line is throwing me off by what you mean.

Thx for help.