[DonFromTX]

I am needing to add some air inlets to my cowling, and would like to make one on each side, identical to each other.
I am up against the problem of how to make them both the same shape, I am not THAT artistic, and don't want them to look like they were made by different people. How do I make a mold that allows them to be identical? The scoops will be located on either side of the large mouth shown in the cowling, and be shaped something like the second photo.

 

[David Paule]

If you were able to give them a horizontal plane of symmetry, then you could use the pattern or mold on either side.

Dave

 

[Jerry Cochran]

Would something like these work? Relatively cheap and save hours of fabbing...

https://www.pegasusautoracing.com/group.asp?GroupID=DUCTNACA

What are you using them for and how large do they need to be?

Dan Horton on this forum is expert, might ask him.

 

[DanH]

You can make an opening with a jigsaw. Fabrication of a practical air inlet requires more information. To what does the inlet lead? Have you sized them based on any particular requirement or operating theory? Do they need to seal to anything?

 

[DonFromTX]

Sorry, not enough information given. The right side will intake to the oil cooler and combustion air, thru a 3 inch hose that splits. The left (pilot side) one will cool the plugs and injectors, not much flow needed on that side. The right side will probably need all the air I can cram in there, the more the merrier..
See my kitlog link below, look at 8/13 for a photo of where the air goes on the right side.

 

[DanH]

Sounds like you are talking about openings which lead to scat hoses, much like Jerry linked, but perhaps not NACA inlet shapes. Building them is easy; pink foam forms to make the duct transitions:

http://www.vansairforce.com/community/showthread.php?t=44856

The transitions would be bonded to the inside of the cowl. You only need one template to define the shape of the duct transition base, which would be their footprint on the inside of the cowl. Just flip the template for the opposite side. The footprint template is also the shape of the cut opening. The opening and the duct are faired together with a radius. Done.

 

[DonFromTX]

Lots of good ideas there, thanks for the link. I can handle the layup and stuff, my big question is how to make them look like each other. I started out thinking that if I make one, it will work for both sides, but due to the compound curve that don't work at all.
My hope was someone had an idea of how to make both of them the same shape, an artist I am not.

 

[curtis]

The image below is how I made my intersection fairings (copied idea out of a Van's rvator newsletter). The grid gives you visual reference from side to side when shaping the clay or foam.