Pusher cowling ideas

[Appowner]

Eugene's engine is liquid cooled, so there's not much need to guide a lot of air through the heads and cylinders (as we'd have to do with a Lycoming, VW, etc). The vast majority of the heat will get into the cooling air via the radiators (for oil and coolant) at the front of his nacelle.

Well of course it is! Duh! I knew that but for some reason it simply didn't register with me. I don't know what I was thinking...

 

[dog]

Here is visual difference between 10 inch spinner and 14 inch spinner

View attachment 113201View attachment 113202

Put blisters over the cylinder heads and make the whole cowl 6 " narrower ,and then a narrower spinner to match.
Maybe pictures centered on the prop center from directly aft and the same from the front
could be good references.

 

[Eugene]

Made some progress towards building new spinner. And of course have some questions:

- I am assuming high density foam should be used and not stuff from Home Depot. What kind of foam should I use and where to get it?

- what kind of glue should I use between foam layers and between the wood and foam. This plug would be spinning at 1200 RPM and I don’t want it to fly apart.

 

[wsimpso1]

Eugene,

If you have access to a CNC router with a vertical axis, just glue up your foam to the MDF backing plate and machine it there.

I do not know if glue and foam will hold up to wood turning speeds and tools. I have never done that. Somebody has to know if it will run on a wood lathe...

Bill

 

[poormansairforce]

Eugene,

If you have access to a CNC router with a vertical axis, just glue up your foam to the MDF backing plate and machine it there.

I do not know if glue and foam will hold up to wood turning speeds and tools. I have never done that. Somebody has to know if it will run on a wood lathe...

Bill

It will if attached properly. Use your CNC router to cut round pieces of 2-in Dow foam in progressively smaller circles with a center hole and just stack them on with 3M contact adhesive. That will save a lot of dust and time getting it turned down to your plug. When I did something similar I used a thick hot wire to rough it down just turning it by hand. Then slow rpms to do the finish sanding.

 

[Eugene]

If you have access to a CNC router with a vertical axis,

No vertical CNC. I will have to do it old-fashioned way. Same way they build spinners thousand years ago (using turntable)

 

[poormansairforce]

It will if attached properly. Use your CNC router to cut round pieces of 2-in Dow foam in progressively smaller circles with a center hole and just stack them on with 3M contact adhesive. That will save a lot of dust and time getting it turned down to your plug. When I did something similar I used a thick hot wire to rough it down just turning it by hand. Then slow rpms to do the finish sanding.

Billski said that so I'm not sure why the quote turned out that way. But the principles are the same. Use your CNC to cut out foam circles and stack them together just like you show.

Edit: I'm not sure what's going on but now I'm quoting myself even though I replied to Eugene. LOL

 

[Eugene]

Use your CNC to cut out foam circles and stack them together just like you show.

For some reason I am more comfortable with turntable concept. Makes me feel safer. This way I know that my turning piece is 100% balanced

 

[poormansairforce]

For some reason I am more comfortable with turntable concept. Makes me feel safer. This way I know that my turning piece is 100% balanced

It's not going to matter with foam. But your the one doing it so do it how ever it seems appropriate. Good luck.

P.S. Now that we know you have a CNC router and can use it you can never again claim to be just a "dumb Russian". It's not going to work with us anymore!
FWIW, I've never believed it anyway.

 

[Eugene]

Now that we know you have a CNC router and can use it you can never again claim to be just a "dumb Russian". It's not going to work with us anymore!
FWIW, I've never believed it anyway.

Oh yes, please believe me, I know nothing about CNC or how to program it. I am just lucky to rent a hanger space from a friend who is 10 times smarter than I am and offered to help. He build this CNC table by himself from scratch.

This dumb Russian doesn't do very good with computers or programming. You see all my pictures and drawings made by hand, old-fashioned way. Old dogs and new tricks don't mixed well.

 

[Pops]

Dumb like a fox.

 

[Eugene]

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwiFnv7Oy_TxAhVXHc0KHZNdAHkQwqsBegQIDBAB&url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DLfM2RuK4zNk&usg=AOvVaw24D6y6IPLVYM4muyWg2Gs7

 

[poormansairforce]

Old dogs and new tricks don't mixed well.

Yeah, well, most of the old dogs have the best tricks wrapped up anyway.

 

[Eugene]

just stack them on with 3M contact adhesive.

So, regular contact cement will not destroy my foam pancakes if used it in a spray bottle form?

 

[Vigilant1]

So, regular contact cement will not destroy my foam pancakes if used it in a spray bottle form?

View attachment 113328View attachment 113329View attachment 113330

You could try whatever glue you have handy on some scraps and see if the foam gets gummy, etc.
If you have any of the 3M "Super 77" spray adhesive around, it would be worth testing on some scrap foam. If it is compatible, you'll find it is easy to spray a light coating on your surfaces and they'll stick together very well.

 

[Vigilant1]

So, regular contact cement will not destroy my foam pancakes if used it in a spray bottle form?

In this post from a few hours ago, MadRocketScientist used spray adhesive to glue up a polystyrene mold blank. CriCri MC-15 in NZ

 

[Pops]

There is water based contact cement. Used it for hundreds of foam and balsa wings for RC model airplanes.

 

[Eugene]

It works. I used my handheld CNC.

 

[Eugene]

What I am learning, that if you only spent $200, you will only get $200 machine. That little motor is getting pretty hot pretty quick. But from far away this piece already almost look like a spinner!!! I think it's going to work and it's going to be beautiful!

 

[Eugene]

Made some progress and found some more questions:

- oil cooler area 36 in.², water cooler area is 69 in.². Oil cooler positioned right behind water cooler. Combine area for two radiators is 105 in.² I am planning to have inlet opening of approximately 30 in.² with clearance from BRS about 1.5 inches. Is that correct?

- I am going to avoid acute angles and engine cowling vertically against the wing will have 90° walls. Yes or no?

- should I have between engine cowling and the wings some sort of fillet? If so what would be approximate radius?

- Engine installed crooked with 1.5° angle, but new engine cowling should be installed and made square to the world. Or I should say square to the wing?