Now children, we need to fit our flight-deck to the perimeter, don't we?
There's a bit of a gap here and there and so I've centred it broadly and pinned it to the floor with a bit of ballast whilst I mark where the external bolt-holes need locating.
Note the sign "U/side" and the stanchions (or legs to you) all point upwards here, with the airframe inverted.
