How do you handle radial decoupling?

[Duckytrask]

Specifically, when you have boosters connected on the sides of the rocket, do you ever run into a problem where they crash into the next/middle stage?

If so, how did you deal with this?

I personally put one of those Separatrons at the top and have them fire.

[cpast]

I've used Separatrons; before I used RealChute, I slapped radial parachutes on them (a radial parachute's insta-open behavior under stock means it's actually a very good way to slow the boosted while the rocket climbs away).

[regex]

Seperatrons all day, even before the bug.

[Sidereus]

I find the bigger the boosters, the less you have to worry about it, provided the rockets aren't too tall. Probably because they're so massive they don't spin as much, and instead fall cleanly away.

If I do have a problem, I use Separatrons on top. That works well. I've also experimented with using Launch Escape Towers, and while it works (so long as you don't have a very wide upper stage, anyway; the boosters will often shoot up and away from your ship), they're a bit heavy.

[Yukon0009]

For me the sepatrons are mounted on the core.

[Randazzo]

Specifically, when you have boosters connected on the sides of the rocket, do you ever run into a problem where they crash into the next/middle stage?

If so, how did you deal with this?

I personally put one of those Separatrons at the top and have them fire.

If the decoupler is near the boosters COM, they'll drop pretty much straight away. If they are too high, the lower end of the booster will swing towards your stack and probably hit it. If they are too low, the upper end of the boosters will swing in and probably hit it.

If you can't get them centered, then yeah, separatrons.

[Varsi]

If the decoupler is near the boosters COM, they'll drop pretty much straight away. If they are too high, the lower end of the booster will swing towards your stack and probably hit it. If they are too low, the upper end of the boosters will swing in and probably hit it.

If you can't get them centered, then yeah, separatrons.

Doesn't quite work like that. With liquid fuel boosters the COM is very low but they still hit the ship nose first even when the decoupler is higher. This only happens in atmosphere tho.

I always thought this was due to decoupler causing drag and pulling the nose at the ship.

I also use sepratrons (two per booster to throw them nicely away) to stay safe.

[Randazzo]

Doesn't quite work like that. With liquid fuel boosters the COM is very low but they still hit the ship nose first even when the decoupler is higher. This only happens in atmosphere tho.

I always thought this was due to decoupler causing drag and pulling the nose at the ship.

I also use sepratrons (two per booster to throw them nicely away) to stay safe.

Must work for me by magic I suppose.

[Varsi]

Must work for me by magic I suppose.

Does sound interesting if it doesn't happen to you. We must be doing things somehow differently I guess.

[Randazzo]

Decouplers slightly above COM (was supposed to be centered, but I was off)

Decouplers below COM

If the booster is heavy enough it won't clear the main stack. Where you place them matters.

Edit: I removed fuel from the boosters in the second test so I didn't have to stare at it as long. The behavior remains the same. I do not know what effect it would have in a vacuum but that's probably not an issue for a booster.

Edited February 27, 2015 by Randazzo

[Varsi]

Decouplers slightly above COM (was supposed to be centered, but I was off)

If the booster is heavy enough it won't clear the main stack. Where you place them matters.

Edit: I removed fuel from the boosters in the second test so I didn't have to stare at it as long. The behavior remains the same. I do not know what effect it would have in a vacuum but that's probably not an issue for a booster.

I need mods for them to work like that

I'll post pictures of how they work for me once I get back home (not in a few hours) unless someone else does that first.

[Randox]

I usually try to have it so the boosters nose out a tad on ejection. It's a lot safer than having them nose in (been there, done that). I'll add sepratrons to heavier boosters if they aren't getting pushed far enough away to avoid pants soiling. I also usually place the boosters so the engines are mounted a little lower than the central engine(s). This ensures that pushing the top of the boosters out wont cause the bottoms to collide with the rocket.

[Corw]

Sepatrons also look good Determine the centre of mass for empty booster and place 2 sepatrons there. Works every time.

[Streetwind]

Guys, there is a known issue with radial decouplers that's been present for a few versions now. It makes whatever it is attached to them rotate inwards at the top and hit the rocket nose-first. Unsure how Randazzo manages to dodge it, but it's a thing that happens. Separatrons do help, but it's annoying nonetheless, and very much not working as intended.

In fact, not only is it officially acknowledged to be a bug, but there's even a community fix available for download. Look up Claw's Stock Bugfix Modules. Even if you run no other mods at all, those are absolutely worth having precisely because they fix annoyances such as this, and others

[maltesh]

TT-70 radial decouplers. In general, they provide sufficient separation from the central stack that I've never needed to use separatrons to avoid boosterscrape since 0.16, even with the largest radial boosters.

[Xaver]

You can stop all engines before decoupling and burn slowly after it. So your relativ velocity to the boosters isnt that high.

Not very efficient but it works.

[Axelord FTW]

I use the snub separatron (no idea from which mod).

With Tweakable Everything, I set the ejection force of the decouples to 0 (even with the bug fix).

I don't have pictures of me using radial decouplers but I have something near enough.

Also, it's cool.

I usually set it up so it looks like this. In this case, stack découplers but it's the same, really.

[tg626]

Real rockets use sepratrons - well, not sepratrons but small solid rocket motors, to push the booster clear of the main craft. The key is knowing where the COM of the booster will be when it is jettisoned.

I build up a booster alone in the VAB - use "RCS Build Aid" to show me where the COM is and to place the Sepratrons. Once I see where they need to be I "eyeball" Sepratrons onto the same location in the VAB on the actual rocket I'm building.

2 Sepratrons will easily push the booster directly sideways with NO rotation save for some roll (spinning along it's long axis) if I'm already doing my gravity turn.

[Jouni]

Since 0.24.2, radial decouplers have been broken at speeds below 750 m/s. No matter where you place them, the tip of the decoupled booster will hit the rocket and probably destroy it. Stock Bug Fix fixes the problem, but it also "fixes" the feature, where the decoupler applies no force, if the booster is strutted to the rocket in a certain way. For me, the fix is worse than the bug, because radial decouplers without any ejection force are almost always a better choice.

My primary solution to the problem is to use large enough boosters. If they keep burning past 750 m/s, decouplers work perfectly. With smaller boosters, I use sepratrons.

[Cirocco]

I use seperatrons, like the vast majority of people. Normally I place them just above the CoM of the full booster so that they don't flip too hard, but I do like the idea of mounting them on the main stack rather than on the booster. That would ensure that you only push long enough to get the boosters clear and avoid possible over-flipping and it also gets rid of the damage the seperatron exhaust causes to the main stack. Good idea that.

[eddiew]

Claw's Stock Bugfixes are your friend! Radial decoupling that doesn't come back to bite you in the butt

[Superfluous J]

I use the bug fix mod so they actually get pushed away from the rocket, and if that doesn't have enough oomph (99% of the time it does) I use sepratrons, usually thrust limited down to about 25 percent.

[Random Tank]

I use Claw's fix for the decouplers, so they actually work correctly, but I also use seps to push then away for safety's sake. I still find it ridiculous that the decoupler bug has been left in the last 3 version of KSP, even when there is a community made mod that fixes it (which shouldn't even have to exist), and it still hasn't been fixed by the devs. Apparently it's about 20 lines of code to fix it. *facepalm*

I use the snub separatron (no idea from which mod).

The little ones called Snubrutrons are from Ven's Stock Part Revamp; cute little things

Real rockets use sepratrons - well, not sepratrons but small solid rocket motors, to push the booster clear of the main craft.

What are sepratrons if not small solid rocket motors?

[magnemoe]

Guys, there is a known issue with radial decouplers that's been present for a few versions now. It makes whatever it is attached to them rotate inwards at the top and hit the rocket nose-first. Unsure how Randazzo manages to dodge it, but it's a thing that happens. Separatrons do help, but it's annoying nonetheless, and very much not working as intended.

In fact, not only is it officially acknowledged to be a bug, but there's even a community fix available for download. Look up Claw's Stock Bugfix Modules. Even if you run no other mods at all, those are absolutely worth having precisely because they fix annoyances such as this, and others

Yes, I use a lot of the long SRB and its hyper annoying, worse than before then they didn't have any eject force if you used struts.

Another problem is that the seperatrons tend to rotate the SRB more than pushing it out, probably as its hard to place it correctly, however seperatrons on each side also generates spin, the decopler might cause this too.

An fin at the bottom reduce spin and give outward drag, add a seperator angled 30 degree upward seems to work, you don't need it to move far away from the core just enough to not hit.

Large liquid fuel boosters are more predictable probably as they have more mass and drag.

[ColourOfFire]

Sepatrons. I'm a sucker for Korolev crosses