Here's how to make a Cub cowl with dummy engine

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09-17-2013, 06:57 AM

jester_s1

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Here's how to make a Cub cowl with dummy engine

Note: I'll come back and fix the images later so they display properly.

I wasn't happy with the look of the Hangar 9 Cub cowl after I had recovered the plane in Solartex and detailed the interior. So I spent at least as much time on the cowl as I had on the covering job getting it to look right. I'll estimate I have 12 hours total in the job, but could probably do it again in 5 now that I've learned how to do it and not have to fix mistakes. I'm very indebted to the www.thecubden.com for plans and scale ideas for the plane. There are some amazing models there along with ideas gleaned from RCU and details pulled from Google images.

Here is what I started with. I had painted the exhaust pipes and made the black parts flat to simulate some depth, but it wasn't fooling anybody. The upside is that it was lightweight and really durable, two concerns that seem to not matter at all to the scale modeling crowd.

http://i851.photobucket.com/albums/a...psb2f92b8e.jpg

It starts with cutting off the dummy engine that is there and filling in the huge gaping hole with glass. I forgot to take pictures of that, but essentially I CA'ed balsa wood on the outside and glass up to it from the inside with 3 layers of 2 oz cloth. If I were doing it again, I would just go buy a thicker grade and save some time, but the 2 oz is what I had. I then built boxes inside the cowl to glue the dummy engine on that were wide enough to accommodate the engine. You can see on one that i had to knock off a corner on one side for the Saito exhaust. It isn't noticeable from the outside and allowed me to fully hide the exhaust inside the cowling.

http://i851.photobucket.com/albums/a...ps74e6dc5c.jpg

Making the dummy engine isn't as hard as i thought it was going to me. I used the plans on www.thecubden.com scaled down to 5.27 scale (which is what my 80 inch Cub turns out to be) to get the dimensions right. Here are the parts of the pattern you will need.

http://i851.photobucket.com/albums/a...psa97df6ce.jpg

His plans are for a plywood built up engine that is 1/4 scale. I wound up making mine out of a solid balsa block and cutting the cooling fins with a hacksaw blade. It's not quite as accurate but the difference will never be noticed by 99% of the people who look at this plane.

http://i851.photobucket.com/albums/a...ps8b42b274.jpg

http://i851.photobucket.com/albums/a...ps8352ebf9.jpg

http://i851.photobucket.com/albums/a...ps3943018b.jpg

http://i851.photobucket.com/albums/a...ps942ed787.jpg

I found that going back with some 400 grit and cleaning up the slots will thin the cooling fins a bit and give the whole project a much better finished look. I did that both before and after priming.

http://i851.photobucket.com/albums/a...ps888cf6af.jpg

The valve covers are the main focal point of the engine, so it's worth your time to get these right. I made them in two pieces so that the flange would look right. The pattern will show how thick they need to be and how they are supposed to taper from top to bottom. I used a piece of thick sheeting for the main part and a thin piece for the flange. I carved the contours with a hobby knife and finished it with 150 grit sandpaper before priming, glazing, and painting.

http://i851.photobucket.com/albums/a...ps2c76bae1.jpg

http://i851.photobucket.com/albums/a...ps6506b631.jpg

The exhaust assembly is simple per the plans, and I made the eyelashes out of a piece of Diet Pepsi can. If you don't drink Diet Pepsi I imagine a Coke can will probably work fine. Then it's a simple matter of gluing it all up and painting it. I used Rustoleum silver for the engine block and testor's aluminum for the exhaust. The two metals should have a different sheen, so I think it worked well. The weld lines are pieces of kite string CA'ed on after priming and filling but before the final paint. All of the black parts are Rustoleum camo flat black. I still have some cleaning up to do on the cowl, but I'm pleased with the results overall. The plane will look much more scale with this dummy engine and cowling. I wish I had thinned the cooling fins a bit more and maybe made them out of basswood instead of balsa so they would be strong enough to be that thin. the paint adds substantial thickness so it's tough to get them as thin as the actual Continental cooling fins. I also have thought about printing out a photo of the engine internals and just gluing it to the black backing to make it look more realistic, but there does come a point where it has become an obsession and you really just need to finish the plane and fly it.