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        Discussion Dummy radial instalation in 1/4 scale round cowl

#1 greggk Jun 10, 2012 12:15 PM

Dummy radial instalation in 1/4 scale round cowl
 
Hi all,
Looking for some building-technique advice. Have a round 1/4 scale cowl and a plastic dummy radial that I'm planing on gluing the area of the cylinder heads to the inside of the cowl. I was going to make a plywood backing to add structure and support. What I don't know how to do is to get it perfectly centered around the prop nut and how far out to bring the radial. Any suggestions, advice and/or pictures would be great.

Thanks

#2 w1nd6urfa Jun 11, 2012 05:29 AM

Hi
You should first install the engine on the mount, then dry fit the cowl on its mounts.

Position the cowl so it looks straight with the fuse and the prop nut is at the centre of the cowl, the prop backplate should protrude about 1/4". Mark the cowl position and drill the mount screws

Assuming your engine has right-thrust, the next step is to look at the cowl from the top: you should be able to judge if the dummy engine will be "true" parallel to the cowl or it needs some right thrust too to align with the engine. You can dry fit the dummy engine in the cowl (cowl is attached to fuse) and experiment with various positions until you find the right place. Mark the position and then remove cowl and dummy engine and glue in place.

Measure twice - cut once applies here a lot more than in other stages of the build!

#3 greggk Jun 13, 2012 11:24 AM

Thanks all, any advice on what to use to "fill" in the back of the hallow plastic (fragile) radial? I didn't want to use epoxy because of weight. I want a silicone like (flexible) material but light. Any ideas?

#4 RCFVR Jun 16, 2012 09:47 PM

Quote:

Originally Posted by greggk (Post 21886510)
Thanks all, any advice on what to use to "fill" in the back of the hallow plastic (fragile) radial? I didn't want to use epoxy because of weight. I want a silicone like (flexible) material but light. Any ideas?

You might consider epoxy with micro balloons mixed in. It will give you sufficient rigidity with little weight. The more micro balloons, the less weight, compared to straight epoxy. I use it for shaping, where strength is not a requirement.

#5 greggk Jun 17, 2012 07:19 AM

Hi all,
I was trying to detail the dummy 1/4 scale Pratt & Whitney 985 Wasp radial. I'm want to find something to make up the spark plugs and wires, also I want to use small hex bolts around the hub (I think around 2/56-4/40 in size) Any suggestions on where to find this stuff and what to use? Any other input would welcomed, I have never done this before! The installation is going well.
Thanks

#6 w1nd6urfa Jun 18, 2012 04:06 AM

This is a great article I have referenced many times:

http://bestpilots.typepad.com/my_web...-insignia.html


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