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# Asymmetrical and delayed action groups for symetrically placed parts?

## Question

So I built a fighter plane that has two missiles mounted under its wings, one left, one right. I built one missile and then placed two using symmetry, but apparently, I can only fire (aka activate engine and decouple) both of them at the same time, because due to the symmetrical placement, they count as one part. Has anybody got an idea how to control one part of two symmetrically placed?

Issue number two: when I put "activate engine" and "decouple" into the same stage, the missiles are decoupled without the engines activating. I assume this is because activating an engine takes half a second or so, whereas they're decoupled immediately, making the missiles lose connection before the engines are on. Can I somehow delay the decoupling by a handful of seconds? I've tried using different stages for decoupling and firing, but the delay between activating stages takes too long (plane gets out of control because having an engine running on only one side loves with the centre of mass). Any ideas?

HashtagMC

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1 hour ago, HashtagMC said:

So I built a fighter plane that has two missiles mounted under its wings, one left, one right. I built one missile and then placed two using symmetry, but apparently, I can only fire (aka activate engine and decouple) both of them at the same time, because due to the symmetrical placement, they count as one part. Has anybody got an idea how to control one part of two symmetrically placed?

Option 1:  Don't use action groups.  Manually activate via the right-click menu.

Option 2:  Don't make them symmetric.  Place one of them, without symmetry.  Then copy it by alt-clicking and place it in the same corresponding location on the other side.  (You can use the snapping of the translate widget to get the placement exactly right).  Then you could put each one of them in a different action group.

1 hour ago, HashtagMC said:

Issue number two: when I put "activate engine" and "decouple" into the same stage, the missiles are decoupled without the engines activating. I assume this is because activating an engine takes half a second or so, whereas they're decoupled immediately, making the missiles lose connection before the engines are on.

No idea what's going on.  It ought to "just work"-- activating is instantaneous, yes?  For example, for fun I once built a stock "missile launcher" plane that has SRB "missiles" slung under the  wings on radial decouplers.  I put the SRB activation and the decoupler activation into the same action group, and it worked perfectly:  hit the button and they go tearing off.

Are you using liquid-fueled or solid-fueld engines?  And are they basically just using the same engine module that other stock KSP parts use, or is it some special mod thing? Might be something to do with the mod you're using?

1 hour ago, HashtagMC said:

Can I somehow delay the decoupling by a handful of seconds?

Not in stock.  There are mods that let you do this, though.  For example, there's one called "Smart Parts" that has some neat little timers that are stageable.  When they're activated via the staging sequence, they wait a set time period (you set it up in the vehicle editor while building), then activate the next stage.  You can even have two-stage missiles if you want (there's another part in the mod that can automatically activate the next stage when the fuel in the last stage runs out).

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1 minute ago, Snark said:

Are you using liquid-fueled or solid-fueld engines?  And are they basically just using the same engine module that other stock KSP parts use, or is it some special mod thing? Might be something to do with the mod you're using?

Completely vanilla except for this mod that lets you see speed and delta-v and apoapsis altitude and such (something with engineer in the name). The missiles are 0.65m fuel tanks plus engines (liquid fuel + oxidizer) and a control unit + reaction wheels. Works perfectly fine when I activate the engines first, decoupling second (via staging), but that takes long enough to destabilise the plane.

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12 minutes ago, HashtagMC said:

Completely vanilla except for this mod that lets you see speed and delta-v and apoapsis altitude and such (something with engineer in the name). The missiles are 0.65m fuel tanks plus engines (liquid fuel + oxidizer) and a control unit + reaction wheels. Works perfectly fine when I activate the engines first, decoupling second (via staging), but that takes long enough to destabilise the plane.

I'm not much of a fighter jock , so I've never tried this.  But, what happens to the throttle setting?  When you launch them, your control stays with the plane, yes?  So perhaps what's happening is that when they separate, they become a separate ship of their own, and maybe KSP is just setting the throttle to zero.

Is the intention to make these guided missiles?  i.e. you want to switch control to them and actually steer them in flight after launching?  If not... what happens if you remove the probe cores and the reaction wheels?  Reason I ask:  I think that if you stage away a fuel tank with a running engine, the engine will continue to run at whatever the previous throttle setting was.

Or try replacing the liquid fuel with an SRB.  I know those work, I've tried it.

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Just now, Snark said:

I'm not much of a fighter jock , so I've never tried this.  But, what happens to the throttle setting?  When you launch them, your control stays with the plane, yes?  So perhaps what's happening is that when they separate, they become a separate ship of their own, and maybe KSP is just setting the throttle to zero.

Is the intention to make these guided missiles?  i.e. you want to switch control to them and actually steer them in flight after launching?  If not... what happens if you remove the probe cores and the reaction wheels?  Reason I ask:  I think that if you stage away a fuel tank with a running engine, the engine will continue to run at whatever the previous throttle setting was.

Or try replacing the liquid fuel with an SRB.  I know those work, I've tried it.

Mixed up some stuff in my memory - the rockets described above don't have reaction wheels or control units. The one I built afterwards has guided missiles, but the ones that don't work when decoupled and activated at the same time are nothing but tanks and engines.

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3 minutes ago, HashtagMC said:

Mixed up some stuff in my memory - the rockets described above don't have reaction wheels or control units. The one I built afterwards has guided missiles, but the ones that don't work when decoupled and activated at the same time are nothing but tanks and engines.

Yeah, I suspect that the problem there may be that they're not active already at the time they launch due to the fact that they need throttle to be on.  (I'm speculating there, I'm not sure.)  So it may be that you're just out of luck in stock, unless you can design them so that you activate the engine and then the decoupler afterwards.

But SRBs absolutely work.

Incidentally, if you'd like a wider selection of SRBs to work with, SpaceY is a great parts mod.  Mostly what it's about is big stuff (they have SRBs up to 3.75m, and liquid-fuel tanks and engines up to 5m), but it also has a really nice selection of small SRBs with a 0.625m form factor.  Those would make dandy missiles, I betcha.

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Nah, if it doesn't work in stock, I'll just stick with guided ones. I built an Mk2 plane that drops a 0.675m guided missile out of a cargo bay. Doesn't do much damage, but works like a charm, so I'll try to scale that thing up to an Mk3 plane. I'm crap at flying planes in KSP, too, so unguided missiles always miss when I'm the pilot.

Right now, I'm trying to build a working ICBM. I've put a warhead onto my LKO base rocket that I also used to bring my space station into orbit, but it's always the last mile that loves it up. Atmosphere friction and gravity make me miss the target by about two hundred metres. I'm trying to hit the old airfield next to KSC, by the way. Quite a waste to shoot a multi-stage rocket into orbit just to hit something that's next door, but it's fun.

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