Hybrid 3D printed / DFTB Intruder


Elite member
I was looking for a new project to continue my 3D printed / DTFB hybrid designs and stumbled across @SP0NZ 's intruder thread. Reached out and got the ok to leverage the work of SP0NZ and started the design.

Took the top/side layouts and some images graciously shared and drafted a quick outline in Fusion 360 which I converted to SVG to do a quick chuck glider to figure out CG. Chuck glider is actually full size what I expect the final model to be at 34" wingspan. A couple of glide tests and CG is right at rear of the KFM step in the chuck glider - I completely lucked out on that one.

Multiple stumbles in Fusion360 but made enough progress on this one to start to share some pictures. The plan is to print this in vase mode using LW-PLA with two F pack motors up front. I'm hopeful a 1300 3s in the nose is enough to balance and version 1 will have DTFB Hstab and fin.

F360 so far is below. Wing have no spars yet nor have I figured out the nacelle but making progress.
Screenshot 2022-09-06 200004.jpg

When I'm ready, I'd like to ask 2-3 volunteers on this forum to test print and give me feedback. I'll be printing at the same time so warning as there may be some re-do's. Ultimately I'd like to offer the STL's discounted to the FT community as a small thank you for all the benefits I've received over the years using this forum. I certainly would not mind if anyone wishes to make a small donation as there is quite a bit of time invested, and a lot of LW-PLA samples :)

I'll keep posting as progress is made but I'm a few weeks away from the first STLs being ready.

Also check out my prior DTFB designs through the link in my signature. Thx!
Last edited:


Elite member
Goal is for a single servo to be hooked to two pushrods, one for each elevator half. In the picture below, the servo will attach to the bump out in the fuse and you can see the bowden tube cutouts in the rear fuse for the pushrods to pass.


If there is interest I can start a thread or add to this one about vase mode design in F360 which itself is a complex animal to wrap your head around.


Elite member
Just dry fit but going together nicely. Filament as the hinge line for the aileron. You can see the notch in the fuse for the top fin and hstab which will be DTFB to keep weight down.

Hole in wing top will be for the esc wires to pass through the nacelle. Hoping to get that printed tomorrow to confirm everything fits.


Elite member
V1 done. 525g without battery. Going to start with a 1300 3s so heavier than I wanted but has a nice big wingspan.

Had to add tail weight for cg so assuming this flys, v2 will definitely get a 3d printed hstab and fin.

That looks amazing!


Elite member
Too far back. Kinda shaking my head as the chuck glider flew fine. But I then compared it to the EZ intruder on the forum and after scaling up I was 1- 1.25” too far back which explains a lot.
Maybe a difference between having propellers blowing air over the wing and just gliding. Or could be different aerodynamics at different scales or that the chuck glider was just barely stable in the first place. My money would be on the first one though.

Edit: the direction your props are spinning would enhance lift on the wing but maybe hurt elevator effectiveness


Elite member
Probably over did it but I wanted to use a single servo to drive the elevator and based on where the fuse cuts were I needed the pieces to be able to be inserted from outside the fuse. Wanted to also make sure the elevator halves were level.

The rod is round where it goes through the fuse but square at each end. Pics hopefully show my thought process. Getting things tight but not too tight was “fun” but I think it will work well.