1/2A stunt trainer design

I just noticed the radius cuts at the rear of the ply nose-doublers. That's a nice touch to add a more dimensional look to a profile fuse too.

My 2nd self-designed flying model was a little 1/2A bipe. I've still got it.. but it's "war ravaged". Shown below with flaps which I added later.. but never flight tested. Probably a good thing.. because those two 1/16" wire pushrods certainly added a lot of weight to the tail. It was part of a mod for a Fox .15 that never happened. Plus.. I don't know whether flaps on a bipe would be better on the top wing or the bottom one.


circa 1992 (pre-flaps) with a Babe Bee fitted. The wings and tail-feathers are direct tracings of a Sterling E2 DR1 kit's top and bottom wing and tailplane. The wing-struts are craft (popsicle) sticks CA'd into slots in the sheet wings. I used a vertical 1/4" balsa center support-block between the upper-wing and fuse.



opted soon after for a product-engine style with an external wedge-tank.




I had a lot of fun with this model, and often did "balloon-busts" and towed happy birthday banners with it.




Installing flaps on only one wing, positions them far from the datum line.. and installing upper and lower flaps requires a degree in mechanical engineering for the linkage!   This would be an interesting topic for discussion. I'm thinking that the airflow over a bipe's tailplane having "elevator-only" control, would be disrupted when the model pitches toward extremes. The Bi-Slob is an example of both wings having flaps. Check out the engine-offset!

Geez Rog.. that's super cool! I really like the looks! It looks very capable of stunt to me.

I had very good luck running external wedge-tanks with the Cox .049 horseshoe backplate for the reed-valve engines. It also moves the fuel-weight closer to the c of g. You probably have a bee already, that could be converted. I bought the back-plates and needles direct from Cox.. back in the days that you could, but you can still get them from Cox International.

Below are examples of the horseshoe backplate. The firewall mount pattern is smaller.. but the holes can be drilled along with the tank-mount's pattern.. just inside of it. I use "Perfect" brand wedge tanks on my 1/2A profile models, which worked well with this style backplate.



Have you thought about stitch-hinging the flaps on later builds? I'm gonna try stitching sooner or later.. The more I see it done.. the more I like the way it looks.

Have you thought about any names? It's a handsome design.

rogermharris wrote:Great News!

Got my wood order today from Sig!!! It was still not showing shipped on the website and never got notification till I got a "delivered" email today.

Ill bee doing some lunch time lawyer'sin for a few days!!

That's a nice surprise to come home to. All micro-sanded.. ready to cut. I have a lot of wood.. but most of the sheets are rough-cut and narrow (1.75") so.. making a plank-wing requires edge-gluing at least two pieces together. I made fixtures to sand the sheets to three different common thicknesses.. but.. I need to obtain a 24"L. aluminum extrusion (I-beam) that I can face with coarse/fine abrasive for a block. If it works well... I'll probably sand a lot of stock. The fixture sizes are 1/4", 1/8" and 1/16" and are made from pairs of 36"L. gaged steel strips. One serves as a back-fence and the other is held by hand against the sheet's front edge while block-sanding.



I hope all goes well with the laser-cutting. I'm really enjoying this thread Rog. Oh btw.. I'd say that the pit-box you designed/built, is of heirloom quality!