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Hello, I am ready to fit my cowl. Question
1. I will need to cut out some in the bottom corners to clear the landing gears. Is there a template somewhere or should I just free hand it? Mine is a tail dragger -7.
2. Do I need to cut out any material to clear the exhaust pipes?
3. Should I fit the top or bottom cowl first or does it matter
Charles,
I have done two James cowlings.
Bottom cut outs are free handed, remember they are covered by the gear leg fairings so you don't need to tight a fit. Remember that the brake lines go out that same area as well so you will be enlarging the front of the hole for that as well.
I did not cut any material off or out for the exhaust pipes. I even let the extra couple inches that James put on there to extend the cowling. You will have to trim rear edge FW cuts to transition to that area.
Top and bottom cowls? I could write a book on the subject...:-(
Read the instructions over and over until you understand what you are trying to accomplish. There are many ways to do it. The plans are an excellent guide. I am a woodworker so cutting scribing and fitting come natural to me. Think about the big picture and what you are trying to accomplish in the end. There is an order of things.
First the front nose area.
Then the rear...top or bottom first.
Then the horizontal fits.
First you have to match the top and bottom together correctly to fit the size of the intake rings and the correct round center for the spinner. All this while letting the horizontal edges overlap each other so you have to find the cut line at the front outer corners and cut an inch or two of the horizontal joint to allow the halves to overlap.
Now comes the big question, top or bottom. My first was top first. My second was bottom first. I proved either way will work. I changed to bottom first because the bottom is 3 sided, Bottom, left and right. You can center the bottom and pull up on both sides. Remember you eventually have to get the nose area to fit back like you trimmed it and fit to the spinner, so you pin the bottom sides temporally until you fit the top to it.
The top only slides left or right a little and this pivoting will help you get the proper fit at the nose. This is why I switched to bottom first because trying to get the three sides of the bottom to align to meet the top was not fun.
Note: 99% of the attachments of the cowl to airplane are made at the firewall. It has to fit properly without pushing the front around. Do not depend on the 2 screws at the front to fix alignment issues!!
Once you are happy with the front fitting, trim the rear to the firewall.
Lastly the side cuts. You have to pick a spot in the overlap area at the firewall, same on each side. Think of your paint scheme, for example I lined mine up with the center of the naca vent and broke my 2 tone paint line there so it looks correct. Cut one half first, then mate the adjoining half to it.
There are many ways to do this, I just explained the way I did it...twice.
Again, understand what the end goal is....the cowl is a three dimensional item and pushing here pulls there and vise verse, go slow, check often.
Tip...sneak up on final cuts, meaning cut long and adjust/sand to fit.
Example of this is the gap between the cowl and spinner. Fit the cowl tight to the spinner on initial cuts...then you can sand the cowl/fuselage joint to fit better while creating the proper space behind the spinner.
Also, this is not a one man job. Get help!
Good luck!
