Help Request

[Commander Dax 4]

I am still fairly new to the game, I managed to get jeb to the mun, but he's out of fuel. I have tried time and time again to create a design that can get him home. If anyone could help me out, it would be appreciated. I don't have a large amount of tech unlocked yet, so my request is to help me out with a rocket that can get there and at least get him back into munar orbit without running out of fuel. I really need to get jeb home. Thanks. 

Current Tech Tree:

 

Edited September 1, 2016 by Commander Dax

[FullMetalMachinist 712]

1 hour ago, Commander Dax said:

I usually fly to around 10,000 feet and pitch to 45 degrees,

If you mean that you are going straight up until you get to 10km, then suddenly pitching over to 45 degrees, that's bad, and you should stop. 

That was the old way of doing it, but a little more than a year ago the aero model in the game changed, and it's really inefficient to do it that way. 

Instead, you should perform a gradual gravity turn, starting with a small turn to the east almost immediately, and then continuing to slowly turn. The big milestones that most people generally agree on are roughly: 45 degrees by 10km, 35 degrees by 20-25km, 20 degrees by 35km, and horizontal by 50-60km.

[Snark 14,363]

Welcome to the forums! 

Moving question to Gameplay Questions.

Can you post a screenshot of a rocket that you used for your attempt?  That will make it easier for us to give specific suggestions on how to improve it.

[Commander Dax 4]

Well I don't exactly have a rocket anymore, I threw away my design I used to get there, and the others i've tried. I was hoping someone could post a picture of one of their rescue ships with this tier of technology. I have enough fuel to get there, but landing is where I start to run out.

[The_Rocketeer 1,507]

Howdy Commander Dax

Can u give us bit more of an idea of your experience level? Have you returned from the Mun before or is this your first ever landing? There are some folks around here that can do it incredibly cheap, but for most entry-level players their ships would be useless. Low-tech noob-proofing is also kinda tricky tho - difficult to answer, I know, but what I'm trying to learn is how confident are you in your own ability to return to Kerbin from Mun efficiently?

[Snark 14,363]

1 hour ago, Commander Dax said:

Well I don't exactly have a rocket anymore, I threw away my design I used to get there, and the others i've tried. I was hoping someone could post a picture of one of their rescue ships with this tier of technology. I have enough fuel to get there, but landing is where I start to run out.

 

Broadly speaking, there are two categories of problems that you can run into when trying to accomplish a task in KSP:

1. Design issues
2. Piloting issues

Either or both of these could be your problem.  Without knowing anything about what you're actually doing, it's very hard for us to give advice.  For example, if you're having significant piloting issues (which you could have, without knowing it), then somebody handing you a design wouldn't necessarily help you.

Here's my suggestion:  Go ahead and build a Mun ship, give it your best shot.  Then post a screenshot here, along with a description of your flight profile:  how do you get to LKO?  how do you transfer from LKO to Mun?  how do you land on the Mun?  how do you take off again?

That will really help us to help you.  Not only does it give us a starting point from which we can offer helpful critiques, but also, just from reading what you've provided, that will help calibrate us to your general level of KSP understanding and knowledge, which will better enable us to tailor our advice to what you need.

(And that holds true with asking for help in general in the KSP forums.  It's almost always easier to get an answer to "Here's how I'm trying to do X, what am I doing wrong?" than it is to just ask "How do I do X?")

[Commander Dax 4]

Sorry for taking a minute to answer, my experience level is practically nothing. This was the first time I went to the mun, he got stuck there because of fuel. I made this rescue ship, but it only has enough fuel to get into munar orbit, then de- orbit, but not enough to land. 

This is it: I usually fly to around 10,000 feet and pitch to 45 degrees, then when im higher I usually pitch to 80 or 90 degrees. (although my velocity doesn't actually get to 90 degrees, just my pointer on the navball.)

 

Edited September 1, 2016 by Commander Dax

[Snark 14,363]

Thanks, that helps.

First:  I'd suggest adjusting your staging to take off on the SRBs alone.  The Thumpers are plenty big enough to lift a craft that size.  You can probably even dial down the thrust limiters on them to give your craft a reasonable TWR-- aim for 1.5 or so.  Set your staging so that the liquid engine kicks in when you jettison the SRBs.

Second, it looks to me like you're using a Reliant.  Replace that with a Swivel, it has better vacuum Isp (and you'll be in mostly-vacuum by the time the SRBs burn out).

Third, you probably need some additional design tweaks, because that ship looks like it may be a bit light on dV overall for a Mun landing.  But the above tweaks will do for starters.

Are you bumping up against a part-count limit?  Could you, for example, put a Thumper below your liquid fuel engine, then put your radial boosters around that?  Then your staging sequence would be:  radial SRBs, then center SRB, then the liquid-fuel engine.

Also, how's the piloting?  When you reach 10 km altitude, how fast are you going, and at what angle?

[Commander Dax 4]

Ok I think I built it how you wanted, I have the radial SRB's set to 1.5 thrust to weight. Did I do it how you thought? Or should I change something else?

 

[Chiron0224 96]

It looks a little top-heavy to me.  I would remove a tank or two from your second stage.  Also a word of advice about engines and it may have already been covered.  The bigger the engine the more powerful, but the less fuel efficient.  So big bangin' engines are good in atmo but once you are in space the much smaller engines help the fuel go farther.  Also don't underestimate the amount of fuel it takes to land and take off again.  When I get home I'll take another look at your tech tree and see if I can come up with a design or some suggestions.  Oh, and put a probe core on it so it can fly out to Jeb without a pilot (otherwise where is he going to sit once it gets there?).

Also this image pretty much sums up how I feel right now

 

 

Cause we are going to get Jeb home no matter what! Failure is not an option here folks!

[Commander Dax 4]

I feel the same way, and it has a probe core on the very top, ill remove a tank or two, and check back periodically for when your home. 

[Snark 14,363]

Let's take it one step at a time.  I dunno that it's "top-heavy", give it a whirl and see how it does. 

Yes, Dax, that's pretty much exactly what I was suggesting.  For a bit of minor convenience, you can collapse your staging sequence-- for example, you can put "ignite the center SRB" into the same stage as "fire the radial decouplers".

Did you replace the Reliant with a Swivel?

How does it fly for you?  And back to the question of piloting:  what's your speed and angle when you're at 10 km altitude?

[Signo 298]

I would "pull down" a little bit the radial boosters, otherwise it might be flip prone.

And I would add some "beef" (in terms of fuel, if you are using a Terrier you are more than covered about "boom") to the lander if you want to get back home.

[Commander Dax 4]

I only really need to get him off the surface and into munar orbit, after that It wouldn't be that big of a deal to retrieve him.

[FullMetalMachinist 712]

6 minutes ago, Commander Dax said:

I only really need to get him off the surface and into munar orbit, after that It wouldn't be that big of a deal to retrieve him.

Are you sure about that? Have you done orbital rendezvous before? 

I only ask because earlier you said that your experience is "practically nothing", and rendezvous & docking is generally considered one of the hardest things in the game. 

I don't mean to sound like I'm talking down to you or anything, I just don't want you to get in a situation where you thought it would be easy, and it turns out not to be. 

[Commander Dax 4]

I have done an orbital rendezvous before, one of my past attempts involved refueling using a secondary ship over the moon, I managed to dock them and refuel, but things went downhill on the landing. And it's fine, I am way below your level, but thats why im here. 

 

(btw @Snark, It's probably because of my piloting, but I have enough fuel to land, but I doubt it will be enough to take off. And I did put the swivel. Plus I also condensed the staging like you asked.)

Edited September 2, 2016 by Commander Dax

[James Kerman 2,622]

Another place you can find fuel savings is in landing.  I used to be really conservative when landing and waste a lot of fuel.

If you are mod friendly most of us use informational mods to determine Delta v when building our vessels.  I can't really live without Kerbal Engineer Redux these days (I played without this for the first 6 months or so basically guessing how far my vessel will go - very hit and miss.  KER gives you a baseline figure for how far you can go in meters per second on top of lots of other information).

 

[Commander Dax 4]

Im open to mods, i'll check it out. @James Kerman

 

P.S. (It's getting late where I am, I'll be back tomorrow, if you guys come up with anything just let me know.)

btw My steam name is Dax (pic is astronaut), if anyone needs to message me for some reason.

See you tomorrow, thanks for the help.

Edited September 2, 2016 by Commander Dax

[Chiron0224 96]

One more Apollo 13 reference, just couldn't help myself.

http://imgur.com/a/Nfc3D

 

Anyhow, I'm going to fire up KSP now and work on the problem a bit.

[DD_bwest 154]

from what i see you have 52 science?   have you flown by kerbol yet?  by that i mean left kerbins soi.   if you havent.  maybe send a pod with val quickly leaving soi and come back.  you would be able to get enough that you unlock the prupolsion and get the smaller spark engine. landers become much easier to design

[Snark 14,363]

2 hours ago, Commander Dax said:

I have done an orbital rendezvous before, one of my past attempts involved refueling using a secondary ship over the moon, I managed to dock them and refuel, but things went downhill on the landing.

Okay, that sounds like it may be an issue around efficient vacuum landing-- there's a skill to develop.

What you want is a "suicide burn"-- try searching the forums for that term, you'll find a lot of helpful guides.  The basic idea is to wait until the last possible second, then slam on the engines full-throttle and keep 'em that way until the ship comes to a halt right when it reaches ground level.

The tricky part is judging exactly when that "last possible second" actually is, thus the name of the maneuver. 

There are mods that can help with that, or you can do it in stock.  Here's a technique you can use that doesn't require any mods at all:

The other thing is, when you're in orbit around the Mun and you want to head down to the surface, don't do a big burn while in orbit that sends you dropping steeply downwards.  Instead, do a much lighter burn so that your  "impact point" is way downrange, so that you're approaching the surface at a shallow angle.  It's more efficient that way.

[Chiron0224 96]

Alright! I built something that can do it but I didn't just want to post it on here in case the point was not to just give you the craft but rather give advice.  Here's something that helped me do this though: I made sure my first stage was bangin'!  The second stage and the lander are fairly straight forward on my design but my first stage is pretty strong.  Not sure if I could have done it more efficiently since I am really bad about over building my rockets.  Anyhow, more boosters!

[Commander Dax 4]

Im back everyone, day 2 of my task, i'll take all of the new replies into consideration, and let you know my results.

[Commander Dax 4]

Update Breaking News:

I managed to get Jeb into orbit of the moon, I believe I can manage to do a rendezvous and bring him home, but if not i'll probably be back for more advice. 

[Chiron0224 96]

We're rooting for you Dax!  Bring our boy home

[Commander Dax 4]

I'll report what happens as soon as I finish