Issue with my lifter

[Shawarmakriger]

So, I've been working on a semi-heavy lifter for getting big stuff into orbit.

Problem is, once I launch, when I drop the first stage of liquid rockets, it hits the center column rocket and it breaks off.

This is in the VAB, you can see that I've made some space between the columns to avoid this issue.

Removed the SRB's so you can see a bit better

And the result, most unfortunate for poor Bill

Any tips? They are nowhere near each other and I'm using Sepratrons, but do I need to put them even further away?

Thanks in advance.

Edited August 11, 2014 by Shawarmakriger

[O-Doc]

The usual problem is that the sepratrons are overheating your central engine. The easy way to avoid that is to throttle down a bit before decoupling those liquid fuel boosters.

[Master Tao]

Or reposition your Sepratrons. Try vertically centering them on the outside of the booster, nozzle up. They'll push your boosters down and away without twisting them so much that they hit your central stack.

[Red Iron Crown]

You're experiencing the radial decoupler bug introduced in the most recent version. There's a partial fix for it here.

[DrMonte]

Do not use "Sepratron" for stage drop. If this is required that means that you've already made a mistake somewhere and are covering consequences.

[Wanderfound]

Those are very heavy boosters; they need a good kick to get them clear. If the top is rotating in to strike the core, move the Sepratrons up so that they push the top away. And, as mentioned above, move them out a bit so that the Sepratron exhaust doesn't damage the core.

If you place the Sepratrons right, you won't need to space out the boosters.

And yes, there is a bug at the moment that makes the radial decouplers direct their force lower than it should be. But even without the partial bug fix mentioned above, properly placed Sepratrons will negate the problem.

Incidentally, once you get the hang of Sepratrons, you can do all sorts of tricks with them. You can get your discarded boosters to do pretty acrobatics as they fall if you place them right.

[kStrout]

Always try to have the center of mass of your booster be below the "center of ejection". Try adding another decoupler higher up on the booster, and they should turn away from the rocket.

[Oafman]

Move the boosters lower, so they have less time to fall inwards before you are clear of them

[Shawarmakriger]

All right, I've been messing around a bit with the sepratrons, removed some and moved others - and I think I've got it to work, at least for now. Thanks a bunch!

[MarvinKitFox]

One trick you can try...

Have your whole vehicle rotating when staging.

The centrifugal 'force' will make the dropped boosters fall OUT not DOWN.

[SRV Ron]

Try to mount the boosters centered to the decoupler. Brace evenly above and below. Keep in mind that fuel lines also act as braces. Do not be turning your ship when you stage. If done right, the burned out boosters should slide straight down without hitting anything. Sepetrons, if needed, in pairs angled away from the center fuel tanks. And, if done right, you can mount the boosters much closer to the center core.

This all slid off with no issues of hitting or rotating. No braces or sepratons were used. The rocket, a low cost test the heavy Poodle escape Kerbal test and radical decoupler while escaping Kerbal. Two for one mission.

Edited August 11, 2014 by SRV Ron