Hi.

 Lately I've been making propellers for the MB engine. After lots of testing, the right size for the engine seems to be about 14,2x6. (Lots of power in an engine that weights under 10oz and uses about 4oz of fuel.. ) I tried several commercial props but found none of them satisfying.
 So, I decided to make my own ones. I just came from testing the first 5 examples and I must say that I'm extremely happy with the results. Very quiet, no vibrations.
 The blades are CNC-cut by Y. Yatsenko. They are very accurately milled from Maple and only minimum finishing is needed for a nice looking and well balanced prop.
 Here is a few notes that I find important:

 -For safety and longevity reasons, the glue joint must be absolutely perfect. As Glue I use Loctite Hysol E-120HP. Hysol an ultra strong high-viscosity epoxy with 3 hours working time. Also, I use a mixing nozzle, it makes work easy, clean and precise.
 -For best results, the glue application and curing should be made in raised temperature (about 50..60C). It's good for epoxy strenght and it also helps the glue to penetrate deep into wood. The blades must be pre-heated before glue application.
It is allways surprising how much end-grain wood, even hard one, sucks glue into it and this must be taken into account before joining the pieces together. So basically I applied more and more glue until there was no more absorption, and then joined the parts. That took about 40 minutes. I estimate that Epoxy penetrates up to 5mm into the wood.
 -After curing, the prop was removed from jig, extra glue removed and grooves cut for 2 dural rings. The ring's cross area is 2x3mm and they have circular grooves turned in the end that goes inside the prop to help glue adhesion.
 -After that, some sanding, finishing of tips, balancing and 2 coats of 2-component acrylic clear.

 Lauri

  

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I have been a modeler for most of my life yet, I never ceased to be amazed at the talent and skill of control line stunt flyers. Fabulous!!

 Yes, Randy. I've seen the Chinese using the method you described.
 But I must say, I feel that the propeller would be strong enough without any metal reinforcement, just relying on the glue joint strenght. But I'm NOT going to test that.
 I think that the ideal would be like Alan Resinger's method but with 2 aluminium washers located so that they are abour 2mm under the top and bottom surface. That way there would be no strenght discontinuation in the very surface.
 But it's so much simpler to prepare tools for cutting a circular groove than a narrow slot. Maybe in the next props I will not use the dural rings but just fill the groove with carbon/Kevlar tows. L

 Impressive stuff! Took me an hour to BALANCE a prop last night!