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Staging issues with air launch...


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I'm trying to air drop a small rocket from a plane. I have all the structural parts figured out...

It's just that the staging for the rocket goes bat guano crazy as soon as I drop it.

Does anyone know what causes this, or if there's a way to fix it (other than spending 20 seconds reorganizing the staging sequence while in flight)?

Edited by MaverickSawyer
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Would help to have a more specific description of:

- what exactly is wrong

- what exactly you're doing

i.e. what do you mean by "crazy," such as "I expected it to do X, but it does Y instead"

and how you have the staging set up

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Would help to have a more specific description of:

- what exactly is wrong

- what exactly you're doing

i.e. what do you mean by "crazy," such as "I expected it to do X, but it does Y instead"

and how you have the staging set up

Okay... the rocket is tucked inside of a Mk II cargo bay, attached to the launching aircraft by a TT-38K decoupler (flipped 180 degrees so it's internal, not external). The first stage is a solid rocket motor, second stage is a liquid fueled engine and tank. Payload mounts atop the second stage beneath a fairing.

Upon detaching the rocket from the carrier aircraft, I immediately switch to the rocket (I do have FMRS, so I can recover the other vehicle). THe rocket's staging is no longer Solid - decoupler/liquid - fairing/payload jettison. It's now something else, like fairing jettison - solid/decoupler - payload jettison - liquid. It's always the same scrambling of the sequence for a particular rocket... but different between rockets.

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change the root node to the top of the air-launched rocket. when you separate the plane will carry on doing it's thing, with it's staging messed up - but there shouldn't be any staging on the plane.

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change the root node to the top of the air-launched rocket. when you separate the plane will carry on doing it's thing, with it's staging messed up - but there shouldn't be any staging on the plane.

o.O

Oh, I am SUCH an idiot. Thank you, guys. Marking this one as SOLVED.

EDIT: Yep, that's the ticket. Now it's time to optimize the rocket design.

Edited by MaverickSawyer
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You could possibly also.. before you separate, select the pod/probe core on the rocket and do a "control from here" on it.. should be the same effect - you''re effecting decoupling the plane from your rocket, that way.

Another thing I though of earlier though (I do the same thing with my lifters).. when you build your craft like that, the decoupler remains mounted to your payload. Not necessarily a big drama, but for something like a little satellite that can actually be a significant amount of weight.. and with it mounted to the side it'll throw your CoM off, too. However, if you set your root part to the rocket, you can detach the plane and remove the decoupler, then build the decoupler onto the rocket, and then re-attach the plane to the decoupler.. in effect, turning the decoupler around the other way so that the main part of it stays on the plane when you separate, insted of the payload.

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You could possibly also.. before you separate, select the pod/probe core on the rocket and do a "control from here" on it.. should be the same effect - you''re effecting decoupling the plane from your rocket, that way.

Another thing I though of earlier though (I do the same thing with my lifters).. when you build your craft like that, the decoupler remains mounted to your payload. Not necessarily a big drama, but for something like a little satellite that can actually be a significant amount of weight.. and with it mounted to the side it'll throw your CoM off, too. However, if you set your root part to the rocket, you can detach the plane and remove the decoupler, then build the decoupler onto the rocket, and then re-attach the plane to the decoupler.. in effect, turning the decoupler around the other way so that the main part of it stays on the plane when you separate, insted of the payload.

Hmm... The benefit of the decoupler remaining there is that the offset CoG helps pitch the nose up during the climb... Since I only have fixed fins at that size, every bit of nose-up moment helps!

Also... I've discovered that I do need the added kick of the decoupler firing to get it clear of the cargo bay when flying at ~900 m/s. ANd I have NO clue how well it'd work backwards...

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If you're staging apart like that in atmosphere still, then.. yeah, maybe it has its benefits. As far as decoupler force.. Netwon's 3rd law.. that decoupler applies its force equally both ways. flipping it wouldn't have any impact. In fact, since the 'mass part' of the decoupler would be staying with the plane, then that equal force would equate to a greater dV for your payload!

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As far as decoupler force.. Netwon's 3rd law.. that decoupler applies its force equally both ways.

The Newton's 3rd law forbids the existence of the K-Drive, and it definitely exists in KSP. Don't take things like these for granted.

Give the rocket a reaction wheel for your nose-up movement.

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If you're staging apart like that in atmosphere still, then.. yeah, maybe it has its benefits. As far as decoupler force.. Netwon's 3rd law.. that decoupler applies its force equally both ways. flipping it wouldn't have any impact. In fact, since the 'mass part' of the decoupler would be staying with the plane, then that equal force would equate to a greater dV for your payload!

I dunno... I'll give it a try at low speed first to see if it has the desire result. if it does, then we'll go with it. If not... back to the drawing board. Again. ;)

The Newton's 3rd law forbids the existence of the K-Drive, and it definitely exists in KSP. Don't take things like these for granted.

Give the rocket a reaction wheel for your nose-up movement.

Already has one. And it gets maxed out pretty quick. My only fins are pretty far back on the rocket, so I'm having to fight some pretty significant aero forces to make it go nose up.

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