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  #1  
Old 08-14-2018, 05:41 PM
IowaRV9Dreamer's Avatar
IowaRV9Dreamer IowaRV9Dreamer is offline
 
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Default about to make first cowling cut - seems extreme?

I'm finally going to start work on this cowl from 2010. The first step is apparently to get the front and back to mate and form a 13" circle. The manual provides some high level guidance - basically trim it till it works.

This is how it looks to start (left side):


The right side is similar, but the outboard edges are reversed:


I put a straightedge across the lower cowl molded lip (on the inboard sections, where the upper cowl is supposed to sit) and you can see that there is a lot of extra material above line where top and bottom cowl should meet.


So I have to cut this much off the bottom cowl, on both the outboard fronts and sides? It seems like a lot, but I think that is why the cowl won't nest together in the front.


Am I even close to the right path?
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There is no sport equal to that which aviators enjoy while being carried through the air on great white wings." Wilbur Wright, 1905
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  #2  
Old 08-14-2018, 06:44 PM
Kyle Boatright Kyle Boatright is offline
 
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Quote:
Originally Posted by IowaRV9Dreamer View Post
Am I even close to the right path?
Yep. For the cowl halves to fit, you've gotta trim that bottom cowl down to approximately the widest point on the outside edge of the inlet so it'll join with the upper cowl cleanly. For you, that looks like a big cut.
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  #3  
Old 08-15-2018, 12:30 AM
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Wunderon Wunderon is offline
 
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also aiming for same inlet shape and size on each side, for a sanity check. step back and try to visualize where it needs to go, then the steps needed to get there. For example, your molded lip reference might be wrong. have a good centerline.

http://www.vansairforce.com/communit...60&postcount=2

dave
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Last edited by Wunderon : 08-15-2018 at 12:36 AM.
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Old 08-15-2018, 11:23 AM
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BSwayze BSwayze is offline
 
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That's about how much I had to trim, Dave. But follow Dan Horton's advice. He's the man. Trim the top cowl first, and then the bottom cowl to match. I trimmed mine about that much, but went just a bit too far. I had to fill the gap later. If I were doing it again, do it a bit at a time. Cut half that amount, then check. Then half the amount again, and so on. You'll get it.
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Old 08-15-2018, 11:31 AM
Timberwolf Timberwolf is offline
 
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Quote:
Originally Posted by BSwayze View Post
That's about how much I had to trim, Dave. But follow Dan Horton's advice. He's the man. Trim the top cowl first, and then the bottom cowl to match. I trimmed mine about that much, but went just a bit too far. I had to fill the gap later. If I were doing it again, do it a bit at a time. Cut half that amount, then check. Then half the amount again, and so on. You'll get it.
Great advice. I’m currently fixing my cowl that a P.O. trimmed too far. Much easier to sand a little at a time than having to build up an edge.
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Last edited by Timberwolf : 08-16-2018 at 06:00 AM.
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  #6  
Old 08-15-2018, 08:58 PM
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Jaypratt Jaypratt is offline
 
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Default Look on 3rd page

Look on the third page of this fiberglass area. Near the bottom, look for my post Cowl tool. I fit the bottom first, and trim a little off again and again till the top lays down to fit
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  #7  
Old 08-16-2018, 07:32 AM
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sahrens sahrens is offline
 
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My cowling was very similar to your cowling when I started. It took a lot of small cuts and sanding to slowly bring it together. Many times I used a rasp to cut material away. The rasp was long enough that I could take material off on a fairly straight line.

Here is my cowling install.

http://www.mykitlog.com/users/catego...category=11167

Good luck.
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  #8  
Old 08-16-2018, 08:02 AM
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Boy, this takes me back.

https://youtu.be/-84oX4tkVvw
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  #9  
Old 08-16-2018, 03:10 PM
Wolfpack3 Wolfpack3 is offline
 
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The very best thing I can offer anyone trying to work with their cowling is to rent Flyboy Accessories cowling tool http://www.flyboyaccessories.com/product-p/1502.htm to align the top with the bottom and account for the engine sag at the same time. Alleviates a lot of guess work. My .02 cents
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  #10  
Old 08-20-2018, 09:47 PM
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IowaRV9Dreamer IowaRV9Dreamer is offline
 
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Thanks to all of you for your help. It is funny how I get stuck so badly on simple things.

After a small amount of trimming of the bottom cowl at the outboard corners, and about 3 hours of sanding / filing / dremeling, I have a top and bottom cowl that actually mate together:


It is a better fit than it looks in the picture; when I clamp it together and drill it I'm sure it will be OK for now. I think it will get bettter when the sides are trimmed to allow them to touch rather than nest. At least the spinner base is round.

I was surprised to see that the right inlet is about an inch "deeper" than the left one, especially since the right cylinder is closer to the front of the engine. I'm sure it will all work out.
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Building RV-9A N149DG (slider, IO-320, IFR)
Restored and Flying Beech Super III N3698Q
Marion IA

Restarting the project after too many years off

There is no sport equal to that which aviators enjoy while being carried through the air on great white wings." Wilbur Wright, 1905
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