Brian - so the design calls for a shaft drive, it seems. Any specific ideas/recommendations?

@nsg - Here's what I've been using:

5mm Coupling bush (Graupner USA #3373)
5mm drill rod (McMaser-Carr #8116K34)
5mm X 16mm x 5mm Bearings (VXB # 625ZZ20-1)

I've also use Lothar's design for the rear bearing cup shown below (the top part).

I had some of these machined locallly but I don't have any more right now. I will be ordering more soon. They've generally ended up costing about $15 each.

I hope this helps!

Brian

Thanks, Brian, it does help. I think I can reuse a few heli parts to set up a shaft drive.

Is the shaft drive because of the space, or CoG? A smaller Hyperion glider motor will probably fit in the tail, but I don't know if I'd be able to balance it.

@nsg - I believe the Graupner part is intended for for use on boats. If you heli parts that'll work then by all means go for it.

On most of the Horten's I'd say it mostly about the CoG. Most of the Horten's already have enough lead in the nose. Moving the motor to the tail would no doubt result in more lead in the nose. On the 2m Horten XII I'd say it's about both space and CoG. It you can fit a small and light motor in the it might work.

Brian

An image of a scale model of the XII by Erik van den Hoogen. Has some landing gear details. I wish I find the sources for things like this. It must be easier to do in Europe.
Ken

It looks like HobbyKing's KH-450 uses a 5mm main main shaft, about 110mm long. Not sure whether the shaft itself is long enough, but the bearings, bearing holders, etc. can definitely be reused.

This is my solution, it is very easy, needs no consuming tools and is in Funktion since nearly 2 years, drive power is over 700 W.

I use a aluminum tube with 5/6 mm in diameter. At the spinner side i have glued a short piece of 5 mm shaft in the tube. The glue is thread locking fluid Loctide blue 242. I can solve the bonding with heat if it is necessary.

There is only one bearing in a plywood seat, but two bearings would be possible, too.
The bearing is held outside by a plywood disc. The larger diameter of the aluminium tube fixes the bearing on the inside.

The aluminum pipe to the motor shaft is also only glued with loctide.
To disassemble the drive, the motor screws need only be solved and then it is possible to pull the shaft and the motor forward out.

I think the drawing and the pictures show the most important details.

@Ken: in europe it is not easier to find Photos and details of the Ho XII, we use the same sources than you: the books of Selinger / Horten, David Myhra, google and patience

The books of David Myhra have the problem that a lot of information in it are confused. Name of aircraft at the pictures and text are often reported incorrectly.

I have only one more photo of the XII which was not yet shown here, I still hang on there.

Regards,

Uwe.

Geez! 700 Watts on this poor little plane. I'm surprised you haven't ripped it to pieces. I guess that's a testiment to how strong it's been designed and build.

I like what you are doing with the prop shaft and bearings. I will definitely have to try this!

Brian

Originally Posted by cpdude

Geez! 700 Watts on this poor little plane. I'm surprised you haven't ripped it to pieces. I guess that's a testiment to how strong it's been designed and build.

700 W is possible with my reinforced middle section, but this is the border.
Currently I have a 10 x 6 prop mounted, but if I fly a 10 x 7 it flutters in rough weather and in rapid down passages.

Here ist a log with the 10 x 6.
Fastest horizontal speed is ~ 135 km/h, fastes speed after nosedive is ~ 165 km/h.

Uwe,

I was looking at your drawings in your post above. How did you attach the 5/6mm tube to the motor shaft?

Brian

Originally Posted by cpdude

How did you attach the 5/16" tube to the motor shaft?

I cut the tube in the correct length, put the shaft from the front through the rear bearing. Then I pushed the engine shaft with the mount from forward in the tube and have everything aligned. When the shaft is turned by hand, it must rotate clean.
Then i glued the bulkhead in the cockpit and the shaft in the tube, all with fast epoxy. It is possible to glue the shaft in the tube with thread locking fluid Loctide blue 242.

For disassemble the tube from the motor shaft, I use the heat of a lighter. The glue will soften and I can disconnect the parts very easy.

Now I remember why I didn't use a thin wall aluminum tube for the propellor shaft. It's basically unavailable in the US.

Anyway, that's why I ended up using the 5mm drill rod. If anyone knows of a source for small diameter thin wall metric tubing I'm listening.

Thanks!
Brian

There's CF..several places sell 5mm OD tubes. BP Hobbies is one.

It's been pointed out (thanks Fly Wheel) that the shear webs have the wrong grain orientation. While I'm not going to fix this on my plane the drawings have been revised.

Brian

I have found a nice old picture with 6 of the Ho XII. The aircraft can be parked very space-saving