Need some help getting my ship into orbit.

[fwankman88]

Well I give up, I need some help getting my Imperial Class Star Destroyer into orbit. It's powered by 19 Rockomax "Mainsail" Liquid Engines. 12 of the engines are staged. The staged engines have two large fuel tanks each and the 7 main engines have 9 large fuel tanks. All of the fuel tanks are daisy chained together. There are about 50 RCS thrusters supported by 6 large RCS fuel tanks. In total there are 1200+ parts. I saw a similar ship posted, but it was photoshoped into orbit, powered by ion drives and looked a bit small... So i made mine three times bigger and i intend to get it up there under it's own power. I typically get her out to 100km where there in no atmosphere and start a turn for orbit; it's obviously a slow process. Any atmosphere and i lose control. Then I start my burn, but I can only push it to about 1/3 throttle, otherwise she spins out of control and the RCS ports cant keep up. The slow burn drains the rest of the fuel while I coast out to 300km and then gravity pulls me back down to re-entry.

I'm trying not just "add more fuel" so if any one have any bright ideas on how to keep it afloat or have more questions, please share!

[Dedjal]

Well, I usually tend to stick SRB's everywhere. Saves a bit of fuel, gets me a bit higher.

Or.... You could have a little fun... Start stacking beams underneath your ship, keep pushing your ship upwards as you add more and more beams. In the end your ship will be ready to launch, sitting in space, wobbling on a 70km ++ long beam stack. Do not forget a launch clap or something else to release your ship with. You do not want to carry around such a heavy tail, hehe.

[stupid_chris]

Hummm, the best thing you could do is try adding a few layers or asparagus staged double orange tanks on the outside. Your ship is huge, and to send this you must be ready to test your computer's CPU speed. You're gonna need a hell of a lot of parts. SRBs burn too slowly for the amount of thrust they give and will probably be more of a weight on this. As for the tail idea, it breaks a bit the fun and the point of launching this and you will have part generation problems. I don't recommend.

I see you already have outer boosters. I say try making two complete loops around your destroyer. I know skipper engines are more efficient but here you need a good TWR, so go with the mainsails. And for the in space control... You can try adding more RCS thrusters, it's really all you can do. Can you post a pick of the destroyer only in the VAB with the CoT and CoM showing? It might be a part of the problem depending on their position.

Edited June 2, 2013 by stupid_chris

[Dedjal]

Part generation won't matter as anything past 2 km isn't rendered.

And don't tell me, that after setting up asparagus tanks and so on, that you don't got some free space to slap on free SRB's

And is mainsail better than adding multiple engines? I use 9 engines under 1 orange tank.

[stupid_chris]

Part generation won't matter as anything past 2 km isn't rendered.

And don't tell me, that after setting up asparagus tanks and so on, that you don't got some free space to slap on free SRB's

And is mainsail better than adding multiple engines? I use 9 engines under 1 orange tank.

SRBs would be a dead weight on such a heavy vehicule, 12 of them would barely give up 100m/s, not worth the part count here. And yes, I know that engine clusters are more efficient, I use them pretty often. But here he has already more than enough parts, so we don't want to crash his computer, and mainsails will do the job if staged correctly.

And for the rendering, that's exactly the point. Having a ship so long the game can't render it all at once because it's more than 2.5km away is known to cause game crashes and major bugs. So yeah, I do not recommend.

[Dedjal]

well, then either hyperedit, edit a fuel tank to have insane amount of fuel or an engine to have insane amount of thrust. Only way to avoid adding more parts as far as I know. Could even remove parts then

[Merinsan]

Now I might be reading this wrong, but why are you getting to 300km?

I understand that it might not fly well in atmosphere, but surely you could start a gravity turn by about 60km, if not 69km. For a straight vertical launch, I'd cut engines once my apoapsis was 100km, then try burning horizontal, as soon as possible, ie before leaving atmosphere.

[fwankman88]

Now I might be reading this wrong, but why are you getting to 300km?

I understand that it might not fly well in atmosphere, but surely you could start a gravity turn by about 60km, if not 69km. For a straight vertical launch, I'd cut engines once my apoapsis was 100km, then try burning horizontal, as soon as possible, ie before leaving atmosphere.

If i turn off ASAS before 100km, I lose control. I start a horizontal burn at 100km, but it's basically useless because im not at full throttle and I run out of fuel and that's when i end up coasting up to an apoapsis 300. I obviously have some CG issues; that's what im working on right now. All of the tanks are set up asparagus style.

I just tried adding some more fuel and engines, but i believe im at the point where just adding more will be more problematic... I don't think im going to be able to do it without cheating/mods.

[fwankman88]

Can you post a pick of the destroyer only in the VAB with the CoT and CoM showing? It might be a part of the problem depending on their position.

Yeah sorry, just saw that question. Its a little subjective because they don't have the standard Front, Right, and Top views, but if you as me the CG is off just a little bit towards the control tower.

[stupid_chris]

This... Weird? Did you try turning the gimbal off on as many engines as you could? This might be the issue on the wild spinning, cause I just really don't see what else could go wrong .-.

[Barujin]

Instead of adding tanks above tanks, can you add the tanks to the sides and put engines on them? I'm guessing that you might get more stability that way (plus more thrust). When staged, you'll be able to shed the dead weight of those extra tanks, too.

[fwankman88]

I think I figured it out. I lose control because the top is too heavy.... so if I'm thinking correctly, I just need to add some more engines to the top to help support it and keep that weight pointing up. I'll keep your guys informed.

[fwankman88]

Ok, I did it. No mods.... just time and an absurd amount of boosters. I suppose there's no real way to prove that I didn't use mods except take my word for it. The launch took about 3 hours (judged by watching a movie and 4 episodes of Parks and Rec)

Pre-Launch: 1691 parts, 3389.8 tons

Burning for Orbit

Post-Orbit: 1122 Parts, 356.81 tons

View from the Bridge

Edited December 27, 2013 by fwankman88

[FlamedSteak]

Well, I must say, that is impressive.....you remembered to add a docking port so you can refuel it right?

[fwankman88]

Yeah, I have 4 docking ports. Although, I probably wont dock with it anytime soon. There will be way too much lag just getting close.