Simple/Realistic rocket construction

[SirDoombox]

So far constructing realistic (Note: Not with 30 million boosters at the bottom) has turned up nothing of value. You seemingly cant make it in such a way that it has enough power to fully escape the Kearths gravitational pull.

For example...

This elegant yet simple and lightweight design gets to a certain height before it starts to flip uncontrollably. Even with the S.A.S modules activated and the 'D' key held down it just cant go any higher.

I'm no rocket scientist but surely having 10 boosters all jammed around a single booster held together with one small decoupler can't be stable enough to get off the ground, yet it seems it's the only design which can actually make it out of the Kearth's gravitational pull.

Is there anyone here who has constructed a realistic looking rocket that has proved succesfull?

[EatThePath]

Real world orbital rockets generally are multi-stage, have strapped-on boosters, or both.

The Delta rockets for example.

Single stage to orbit is generally a bad idea, and generally solids go on the bottom, not on the top.

[cjameshuff]

My best rockets have been relatively realistic ones. Real rockets have larger fuel tanks and larger/more engines, denser fuels/solid boosters on the earlier stages, and stack together identical boosters for a first stage that can lift more mass, and it's a formula that seems to translate well into Kerbal Space Program.

You've got a first stage that's just a big hydrogen fuel tank and engines (or that's what they look like, I've no idea if their mass and thrust are set sanely for it) with a single solid motor on top...nobody builds rockets like this.

[SirDoombox]

As I said, I know barely a thing about rockets in any way.

So all I've got here is what I understand from common sense.

So if I strap two solid boosters on the sides for stage one, use the main liquid fuel engine for the rest of the flight once they run out of fuel?

If you could post a simple design and I'll learn from that

[EatThePath]

Off the cuff I'd point to my Goldberg2, it even has a

The first stage is three liquids fueled by two tanks each, and with two solid rocket boosters each. All of these fire at the same time, but the staging is set so you can eject the solids once they're empty while still firing the liquids. You want to do this whenever possible. Then a stage of three single-tank liquid rockets, and finally a stage of one single-tank liquid rocket. Pepper in SAS modules as necessary.

[Soldats]

You might wanna check out my 'Delta IV' too, it doesn't use any SRB's but its based on an actual design (hint: look at molo's linked picture and click on mine for the rocket file)

She flys wonderfully can achieve both escape velocity and orbit, if I had symmetry she would fly perfectly straight and I would need all those damned SAS's.

Very simple rugged two stage rocket really though I do have a version that has a bunch of SRB's strapped on that isn't as 'realistic' but gets it about another 500 m/s of escape velocity.

I love simple designs tbh even though I build complicated ones too the simple ones always seem to out perform the ridiculous ones.

[RayvenQ]

My attempt at a working American style shuttle launcher, yes, I know the shuttle isn't in the right place, but this way it allows you to detach the shuttle and have it stay with you until you get it into a position you want since you arent allowed to assign something as the command module.

[molo]

Rayven, mind sharing the shuttle file?

[RayvenQ]

Sure,

http://www.freefilehosting.net/shuttle

Though you may have to fiddle with the Shuttle and the Radial Decoupler in the stage bar, as it can sometimes go back to what it was before.

Essentially, move the shuttle icon and the radial decoupler icon to the very top.

when it detaches from the main fuel tanks, you have a thurster to help guide you, although, unless you turn off SAS and then rotate 180 degrees, it's damn hard to fly in aything but going straight up.

You also need the shuttle and SundayPunch's parts from here:

http://mod.gib.me/kerbal/mods/

(shuttle is inder Gibbed)

[dm1940k]

What Ive found to work best so far is a two-stage rocket, the first consisting of a tri-coupler with a solid-fuel booster on each port. That is attached by decoupler to the second stage. Starting from the top, the second stage consists of a parachute, the command unit, 2 fuel tanks and a liquid fuel engine. It's basically a copy of the original Apollo designs. Though it can't reach escape velocity, it got me over 16 km up on its first run and all I had to do to keep it pointing up was hold down the SAS button. I'd say start small and add things, keeping them when they work and tossing them when they don't. Some of my best rockets have been little one fuel tank liquid engines. By the way I'm not using any addon files, just KSP 0.82. Hope all that rambling helps.

[dm1940k]

Just a quick update. I broke 36.7 km a minute ago using a variation of the above rocket configuration above, but it had 3 fuel tanks instead of 2. May break gravitational pull with a 4th fuel tank.

[illectro]

I've got that design (3 srb followed by single Liquid Fuel engine with two fuel tanks) and I can get mine way up past 270km - when you ignite your liquid stage be sure to throttle up the engine, in my install my throttle starts at 50% which isn't enough to counteract gravity when pushing 2 tanks.

[dm1940k]

Agreed, I keep my engine at 100% power until I reach about 1km/s then Ill turn it down to the point where the speed remains constant, not increasing or decreasing. This helps save fuel and get me a little higher.

[CannotIntoSpace]

I like designing very simple rockets too. Of course, I only use stock parts. After hours of testing, I finally got this:

http://kerbalspaceprogram.com/forum/index.php?topic=78.msg2003#msg2003

[atlas_again]

parachute

CC

coupler

LFC

LFC

LFR

coupler

SAS

Tricoupler

LFC LFC LFC

LFC LFC LFC

LFR LFR LFR

This is my most efficient base design so far. Simple, able to achieve great altitude, and able to orbit. Im sure you've all made something similar but it is a simple design thread... Any feed back on the design? Im having problems adding rockets to jump it further into space. Ive circled it with liquid and SRB before but the weight thrust ratio is off and is of limited use.

[Supraluminal]

parachute

CC

coupler

LFC

LFC

LFR

coupler

SAS

Tricoupler

LFC LFC LFC

LFC LFC LFC

LFR LFR LFR

This is my most efficient base design so far. Simple, able to achieve great altitude, and able to orbit. Im sure you've all made something similar but it is a simple design thread... Any feed back on the design? Im having problems adding rockets to jump it further into space. Ive circled it with liquid and SRB before but the weight thrust ratio is off and is of limited use.

I've been using a very similar base design, but with up to four liquid fuel tanks per stack with good success. In straight-up escape-velocity testing, 3-tank stages outperform 2 tanks, and 4 tanks are even better still by a small margin. I haven't tried 5-tank stages yet, but I suspect that's pushing the fuel-to-engine ratio too high. Stability might become a problem as well; it's already slightly wobbly at 4 tanks.

I do find that an initial solid booster stage is helpful for getting off the ground with this design - I have a ring of 9 of them right around the top of the bottom liquid stage and 3 attached to the bottom engine nozzles. Each booster gets its own SAS module on top. That's enough to gain a couple kilometers of altitude and about 100m/s of initial speed, and it's pretty stable to boot.

I've been twiddling with attaching more boosters, but without much success. I'll probably try to stick some more liquid engines onto the sides just for kicks, but in general I haven't found that approach to work very well either.

[atlas_again]

Ah ok. Thank you very much.

[ijuin]

When you get to 5 tanks you are better off separating it into multiple stages (e.g. a 2 tank stage on top of a 3 tank stage). This is because the empty fuel tanks still have mass, so the 4 empty tanks will be hauled along while the 5th one is being used. At the point of 5 tanks, the dead weight of the tanks exceeds the weight of just having a separate engine for the upper 2 tanks and throwing away the lower 3.

[Supraluminal]

When you get to 5 tanks you are better off separating it into multiple stages (e.g. a 2 tank stage on top of a 3 tank stage). This is because the empty fuel tanks still have mass, so the 4 empty tanks will be hauled along while the 5th one is being used. At the point of 5 tanks, the dead weight of the tanks exceeds the weight of just having a separate engine for the upper 2 tanks and throwing away the lower 3.

That makes sense! I wish component weights and stuff were displayed in the in-game UI. I'd rather not have to dig around in the config files and wiki for that kind of info when I'm building a rocket.

[Johno]

Soldats, I love your Delta IV!

It already flew well, but I have made a couple of modifications which have made it even better.

1) I deleted all but one of the radial boosters and re-built it using the symmetry widget.

2) I separated the top fuel tank from the rest of the core stack and added an engine and a decoupler. The remainder of the core is now the orbital insertion stage, and the top part has become an orbital maneuvering system.

Now only my piloting skill (or lack thereof!) stands between me and my first orbit. Already had a couple of successful sub-orbital flights!

[mixinghoney]

i did tried , but didnt worked :-\

[Skivster]

After multiple times, I finally managed to get my rocket into space. Fairly easy I'll post my craft design in this post. So I don't have to double post.

[Moach]

it is possible to design a rocket that reaches orbit without using 'cheat' parts or any other manner of trickery

first thing you wanna do, is ensure it's stable - wobbling about like a snake only wastes fuel and precious delta-V - then, if you're using solid boosters, try to set 'em up in a way that you don't blast off too fast right after launch... there's a lot of atmospheric drag at low altitude, and it'll limit your speed - so for a rocket with 4 radial-mounted boosters, it might be best to stage them in a way that they fire 2 at a time

you'll get less vertical speed at the beggining, but you'll have more burn time and less energy loss from drag

warning - rockets can get very skittish when you rig them like this - it takes some fine flying (and Jebediah-like nerves) to pull this off

there are other ways to do it... but then, it's up to you to figure them ot :thumbup:

[foamyesque]

One of the keys is to be really ruthless about extra weight. SAS modules impose big performance penalties: don't use them if you can avoid it.

The fact that the launchpad is sticky is really annoying, though.

[cray]

You've got a first stage that's just a big hydrogen fuel tank and engines (or that's what they look like, I've no idea if their mass and thrust are set sanely for it) with a single solid motor on top...nobody builds rockets like this.

No, they haven't actually been built, but the Delta IV got pretty close by using a H2/O2 first stage with a small cryogenic kick stage and (on some payloads) a solid third stage. A strong case can be made that a shuttle external tank with 6 SSMEs can make an SSTO ascent with 20-25 tons payload. And since solid motors are popular in third stages as 'kick motors,' the design isn't all that weird.