Multi-port radial decouplers: Is this possible?

[ibanix]

For particularly huge tanks (3.75m ones), I sometimes find myself wanting to attach to the base object via more than one of the Hydraulic Detachment Manifolds. Is this actually possible? If so, how? Thanks.

[FullMetalMachinist]

Unfortunately, the answer is no, it's not possible to attach a radial tank using more than one radial decoupler. Not for a single tank, nor for a stack of radial tanks. They may look like they're both attached, but only the one that you click on to place the tank will actually attach. 

If you're having stability issues, the answer is to put one radial decoupler towards the top, attach the side tank, then put one or two struts at the bottom. They will disappear when you stage the decoupler. 

Be sure to place the struts from the side tanks to the center. This is because after the struts let go when you stage, their mass and drag are still applied to their parent part (which is the one you place first when doing the strut). 

[Loren Pechtel]

Expanding upon FullMetalMachinist's answer:  Except for struts and fuel lines Kerbal rockets are pure trees.  Branches can never cross no matter what the rocket looks like.   You get only one decoupler to knock off that stage.  If that's not enough to get it clear you need separatrons (note: you have to rotate them, the supplied rocket points down) or there are some mod parts that include separation motors.

When staging in space I have never had problems with a single decoupler that is placed close enough to the center of inertia (not the center of mass!  You need to consider how far away from the decoupler the mass is, although I have always done this by testing rather than with a pencil & paper) of the stage.  In atmosphere things don't behave so well, bigger stages need separation motors.  If you're playing with separation motors you probably want to download SmartStage.  Separatrons are a royal pain to properly configure on an asparagus-staged rocket, SmartStage generally can figure it all out for you, but doublecheck as I've seen it confused at times.

[ibanix]

I use separatrons, but they feel like a hack. It's too  bad that that multi-connect decopulers don't work when multi-port docking ports do (well, at least some of the time...). 

[Chakat Firepaw]

4 hours ago, ibanix said:

I use separatrons, but they feel like a hack. It's too  bad that that multi-connect decopulers don't work when multi-port docking ports do (well, at least some of the time...). 

If they're a hack, they're a hack that real world space agencies use.

[AlamoVampire]

@Chakat Firepaw has an excellent point about irl space agencies. ever watch videos of the shuttles SRBs? Notice that they tend to fall end over end a bit? thats because of the separation motors kicking the SRBs away from the shuttle stack after SRB shut down. If you watch some launch videos where launches take place on clear days and the lighting is right, you can see separation motors firing to increase distance from the expended stages and the rocket as it climbs away. They are your friend not a hack  

[kBob]

Interesting.  Maybe the thought that they are a hack partly comes from the name.  I never really thought about this, more saw them as an evil necessity, but nice to know they are used in Real Life.  What do NASA et. el. call theirs?  If it's just Separation Motors, oh well still sounds more "professional" than separatron ;).

[Superfluous J]

I like to put 2 of the smallest fins on, right in the dry COM of the thing I'm dropping and tilted slightly (5 degrees, the smallest snap tilt you can give something with the rotation gizmo) outward. No sepratrons and (if you're low enough) the dropped tanks just split away from your craft. Though TBH I almost never use anything and let them fall straight down. I only add the fins if I'm having problems with stuff colliding.

[bewing]

I agree completely with 5thHorseman -- on those occasions when I want to radially decouple during launch, the stuff that's getting decoupled can always use a fin or two on the outside to improve stability during the thrust phase. On burnout, that little fin provides drag on exactly the correct side, which peels the part away from the stack just perfectly every time. I don't tilt my fins, though.

[Nathair]

7 hours ago, Chakat Firepaw said:

If they're a hack, they're a hack that real world space agencies use.

Is that gorgeous R-7 Korolev Cross achieved with separation motors, or is it all pure aerodynamics?

It looks like separatrons;

Edited June 6, 2016 by Nathair