Klaw and Juno in a fairing!

[Hotel26]

Here's a question that is vexing me!  Expert advice required! 

Please think of a torpedo-like craft.  The body is made up predominantly of Mk1 fuel tanks.  The for'ard end is a Klaw.  The aft end is a Juno.  I want to stow it in a fairing and deploy it to jettison it in mid-air.

I can't get a separator to attach to the Juno!  There's no convenient end of the "torp" to get a dock onto for attaching it into the fairing staging nodes.

I tried re-rooting to the Juno but it didn't expose a node for connection.

(I've done this in hokey way with a radial coupler and a dock and then gizmo'ing into position but did not make myself happy.  Is there no better way?)

Good ideas??

[KerbolExplorer]

I think the Juno only has an attachment point at the front area

Edit:You might be confusing the juno with the bigger goliath engine that can be attached at both sites

Edited August 23, 2018 by KerbolExplorer

[mystifeid]

It's probably not ideal due to the diameter but you could attach the Juno to an EP-18 engine plate (short variant) which will give you a coupling point beneath the Juno. Don't forget to rearrange the staging when you have finished attaching things.

[swjr-swis]

2 hours ago, Hotel26 said:

The body is made up predominantly of Mk1 fuel tanks.

Those will allow radial attachment. Attach a small hardpoint to one of them, offset it inside the tank, then use that as the root/decoupler of the torp subassembly. Attach to the side of the fairing body, adjust the release force to zero if you don't want any push off the fairing centerline - for the purpose of release it won't matter.

 

2 hours ago, Hotel26 said:

I want to stow it in a fairing and deploy it to jettison it in mid-air.

Second method, if you make a 1.25m fairing part of the torpedo body: place it as far aft as possible, rotated backwards, and use one of the interstage nodes for the decoupler on the fairing that houses the torp craft.

This one is probably the most 'seamless' method, as the fairing interstage nodes can invisibly extend a good bit beyond the end of the Juno, so no need for offset or clipping.

Edited August 23, 2018 by swjr-swis
rewording for clarity

[swjr-swis]

Another method: Add a 1.25m service bay and use either of the internal nodes of the bay for a decoupler.

One more: radially attach a Jr docking port to the last part before the Juno that allows surface attachment, then rotate and offset so the free docking node is at the end of the Juno.

Edited August 23, 2018 by swjr-swis
There's always a way. Or four.

[bewing]

Any method that creates and exposes an extra stack node is going to add a lot of extra drag to your missile.

The only way that will release a relatively streamlined dart is going to require a radial decoupler on the side of one of the MK0 fuel tanks.

 

 

[Vanamonde]

As the Juno is an air-breathing engine, are you intending to try to get the Claw to grab things in atmospheric flight? Because that is going to be quite a challenge. It's a finicky part even when moving at minimal speeds in free fall. If so, then I think you're going to have bigger problems than the design of the craft, and the whole idea might just be unworkable. Consider that before you put more time and effort into trying to make the thing. 

Just my advise.  

[swjr-swis]

21 minutes ago, bewing said:

Any method that creates and exposes an extra stack node is going to add a lot of extra drag to your missile.

Using either the internal nodes of a (closed!) service bay, or an interstage node of a fairing, will add no drag to the craft.

 

 

Edited August 23, 2018 by swjr-swis
lag <> drag

[Hotel26]

I had a ship get low on fuel, so the "torpedo" was actually for an emergency airborne fuel drop.  It worked pretty well after some messing around in the water to find a connection point (an air intake, finally).

I'm in 1.3.1 and couldn't get the hardpoint method to work but the thing I've learned is that the fairing interstage nodes are bi-directional, not omni-directional.  So you have to approach to attach from a particular direction.

@bewing As for the drag, I was hoping that everything inside the fairing was shielded from drag.  Not so?

In any case, what worked relatively nicely was to attach a Quad Octa strut to a tank and then two Junior docks to it.  One dock to release the strut and one to release from the fairing simply for the aesthetic reason of not leaving it hanging in mid-air after release as the cargo plane was flown back to base.  Both docks staged together, releasing the "torpedo" and the dock jetsam.  Naturally, I used the gizmo to move the QO strut deep into the torp after placement so as to be not visible at all once the torp had gone into autonomous mode... 

Thanks for all the expert advice!

Edited August 25, 2018 by Hotel26

[bewing]

31 minutes ago, Hotel26 said:

I was hoping that everything inside the fairing was shielded from drag.

While it's inside the fairing, yes. I was talking about after it goes into autonomous mode.

 

[Hotel26]

1 hour ago, bewing said:

I was talking about after it goes into autonomous mode.

Good deal, thank you.

So after release the only part still attached is the QO strut.  Even gizmo'd internally to be invisible, maybe it still has some drag but it seems like the best you can do to use a fairing, doesn't it?

 

Edited August 25, 2018 by Hotel26

[bewing]

Yes, it still has drag even if it's clipped. And no, it really really should have worked to just use a radial decoupler without any CO strut, and I don't understand why it didn't for you.

[swjr-swis]

14 hours ago, Hotel26 said:

I'm in 1.3.1 and couldn't get the hardpoint method to work

1. The decoupling side of the hardpoint would need to attach to the base of the fairing - not the shell, or the interstage nodes... that will indeed not work.
2. Keep in mind the root order required by KSP for part attachment, and the attachment rules for hardpoints (surface attachment on both 'ends'). For the hardpoint to work as the decoupler of the torp-like craft (the payload), it would need to be the root of that payload. If you already have the main craft and payload craft separately built, you would need to follow a few steps to make it attach by the hardpoint:
   • Attach the small hardpoint to the base of the fairing.
   • With the re-root tool, make one of the Mk1 tanks the root of the craft - you need to use a part that can be surface-attached to place it on the hardpoint.
   • Load the main craft.
   • Load the payload craft with 'Merge'.
   • Now you can attach the payload to the hardpoint.

The hardpoint adds a tiny bit of drag to the payload craft, even if clipped - but much less than the CO construct you use now. So it's worth doing.

 

14 hours ago, Hotel26 said:

As for the drag, I was hoping that everything inside the fairing was shielded from drag.  Not so?

Yes it is. As long as the fairing is closed it's shielded. But don't take mine or anyone's word for it: Alt-F12, Physics, Aero - enable the first option to see drag numbers in the rightclick menus and confirm for yourself.

 

[Hotel26]

21 hours ago, swjr-swis said:

base of the fairing

"I am not worthy, Master!" 

I got this to work only when I connected the term "base of the fairing" with "surface attachment", which means the outer rim of the fairing part.

But your instructions were consistent and complete and saved the day.  Thank you very much!  This is brilliant!

After conversion, I have this:

You can see the "internal" hard point highlighted in the screenshot above...

Thank you all!

[bewing]

Hmmmm. That radial air intake is going to cause a lot of drag.

A stack air intake such as a nacelle would probably work a lot better. Also note that activating the klaw (so that the shell opens up) will reduce the drag a lot too.