Oh my goodness..... I'm in shock. Cool project indeed. I was wondering if it was something like this when you mentioned the swivel engine.

OK, let's get started.

Right off the bat you will need to move the engine pivot forward. That wing NEEDS to balance in the normal place. No way around it. So the center section of the wing has to go if you want to use the engine pod as is. Nothing you can do short of tripling the size of the stabilizer AND doubling the moment arm all at the same time will move the neutral point back behind the pivot of the engine pod so that you can balance the model on that spot. So some serious mods are going to be needed.

I'm going to suggest that you've got a good learning experience there but at this point I don't think this arrangement will work and I think you are also coming to realize that "you can't get there from here".

I've got an idea for the next one. The wing should be in three parts and twin booms are used just as you have there. BUT the engine sits at the leading edge of the center panel and the whole center panel rotates on a pivot tube of carbon fiber that also acts as the carry through spar for the two outer fixed panels. In normal flight the balance point sits in the conventional spot and the pivot is located about 20 to 30% chord behind the balance point. To transition the whole center panel rotates on the pivot and the CG starts to move back. The center panel has it's own vertical stabs, rudders and elevons built into the rear of the center panel. The wing fins and rudders being located such that the hinge for the rudders is even with the trailing edge of the elvons so that no clearance angle cutaways are required and the wing verticals are rearward enough that they aid the conventional verticals rather than fight them.


I know this isn't what you wanted to hear but frankly I don't see how you can possibly get the balance point back that far and still fly it in any conventional sense. But all is not lost. Why not finish it off and use it as a hover trainer to test the concept? I would go ahead with the swivelling engine so you can try for semi transitions but I wouldn't let it build up much speed or it'll become very pitch unstable as it tries to begin "normal" flying.

Or if you don't mind hacking this one to bits then do so but here is what you'll need to do for this to work. First off there is just not enough spar stucture for any load carry through in that bit of leading edge. The first normal flight dive recovery is going to snap this thing like a dry twig as it sits. And that is only if the engine vibration doesn't do it first. Look into the idea of that carbon or aluminium tubing as a carry through spar and pivot axle all in one. If aluminium it will need to be something like PROPER aircraft stuff that is heat treated for some springy'ness without bending and it'll need to be about 1 inch in diameter. Alloys like 6061-T6 come to mind. Put this pivot/spar in about at the 50 % mark on the root chord and make it long enough to run about 6 inches out into eacy wing outer panel. Then add spars over the tubing and from there out close to the tips. Same goes for carbon. Stick with the twin booms but then make your engine pod a little more wing like to fill in the area between the booms and wide as the wings. Make the engine mount so that you can telescope it back and forth a lot. Trim the model in the vertical mode using weights so that you can set up the balance to be right on the thrust line with the pod vertical. Then to set the normal balance ONLY move the engine, prop and spinner along the mounts to set the normal arrangement trim. If the mounts are sticking out past the engine trim them away as required. Done this way the model will be close to balanced for the two extremes and hopefully in between as well. Any trimming you need to do for the normal mode should be added to the engine pod ends only so that the vertical mode balance is not affected. Also the stab as it sits is far too small for decent normal flight. Make sure the elevator is wide enough that you gain another 50% in area over what you have there.

And a hearty good luck to you.