How to attach "node attachment" engine radially?

[Sharpy]

Nope, not through a Cubic Octagonal Strut.

PandoraKitten's X-COM Skyranger replica involves cargo bays where VTOL engines are stowed.

I've tried to reverse-engineer them and I'm baffled. This is the subassembly composed of such a bay.

I've peeked into the engines looking for cubic octagonal struts. I've checked the subassembly file. Nothing, just the bay and the three engines. And both end nodes of the bay are free, so it's not even like they were attached and then rotated or the nodes would still be occupied. Plus there are only two nodes and three engines, plus two "adapters" that cap the bay from both ends.

How does one make something like this?

Edited August 15, 2015 by Sharpy

[Rhomphaia]

Editor Extensions mod.

[Red Iron Crown]

^^ Yep. You can permit radial attachment for any part with it, but the craft files still work in stock.