Bayou Bert

Bayou Bert

Well Known Member
Cowling stuff, man oh man.
I am no fiberglass guru, don't even like cutting it, like most.
I am not sure exactly how to fix the mis-alignment of my cowling.
I have made the first cut on the bottom across the intakes to see
where and what. I dressed up the over lap at spinner to make it
fit best. I put clecos on side of spinner and two temps in front,
just to get it to fit as you see it.
I have no clue how to get rid of the offset. I cut some 2x4's the height
of my firewall and have them on the inside for spacing so everything
is square.
I can not get the bottom of cowling to overlap the top, just won't go.

This shot is to show the overall cowling clecoed together at the front with
the boards inside.


This shot is a little closer showing the mis-alignment both sides


This is a close up showing the left side alignment


Once again, any and all recommendations appreciated
 
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Looks fine to me.
The rear of the cowl is currenly lined up because you have both halves sitting on the floor. In real life they need not or may not be equal length.
Instead line up the front so that it is is flush or even.
Since your mis-alignment is about 3/8" on the left side (from pilot seat) stick a 3/8" shim on the floor to raise the bottom portion of the cowl. This will allow the front to line up. When on the plane the side hinges will hold this alignment for you once you have everything fit.
 
Far from perfect parts

The cowl parts aren't perfect and don't fit quite right. I had to buildup and remove material in this area. It takes some time but the results will look good. You also might find that the spinner ring area isn't going to be parallel to the spinner backplate. Once again filling and sanding will fix it as well.

There are many posts on the forum on the cowl miss-fits.

Hope this helps.
 
MarkW said:
Looks fine to me.
The rear of the cowl is currenly lined up because you have both halves sitting on the floor. In real life they need not or may not be equal length.
Instead line up the front so that it is is flush or even.
Click to expand...

Absolutely. Do whatever you must to work around the front contours when they're lined up. i ended up with about 1/8" of misalignment at the L side of the spinner opening. Initially I thought it would be WAY worse than that. Keep in mind, you can cover a lot of "sins" with micro once you get all the cutting done.
 
A slightly different approach from what Mark suggested: remove the clecos from the spinner area and line up the sides. Here's how this worked on my -6A. I fitted the bottom cowl to the firewall, lining it up with the spinner and making sure it fit around the engine properly. This was all done with the FAB off but the exhaust system on. Once I was happy with the fit of the bottom cowl, I fit the upper, adjusting it so the sides mated. I found that one side of the spinner was perfect and the other about 1/8" too far forward. Since I was putting in camlocks, I drilled for clecos at those locations and removed the cowling from the airframe. I then built up the inside of the upper cowl with layups of glass - I wasn't particularly careful about biasing to the misaligned side because there is plenty of clearance behind the spinner area and we are not talking a huge weight gain here. Once the glass cured and was trimmed so I could cleco the halves together, I set the unit pretty much like you have in the photo and used an orbital sander to bring the front surface of the upper cowl down to match the bottom. Actually, before I did the sanding, I put the cowl on the airframe and used the spinner and a spacer to mark a reference line around the front opening; I found that the top was slightly closer than the bottom. Since my spacer was exactly the gap I wanted (also matched the gap set on the bottom cowl, sanding to the reference line resulted in an even gap all around. I wish I had taken a couple of pictures during the process but it was so quick to accomplish, I had it done before I remembered the camera.
 
Appreciate the Help

Filler and stuff, I have West 105 and 205.
Filler I have 407, is that what I need for filler or
is there something better from West.
They have a store in Baton Rouge, not too far.
 
After reading most of DanH's fiberglass tutorials I found that during the fiberglass portions of the build I needed a few things. All listed on this website.
http://www.jamestowndistributors.com/userportal/search.do?refineType=1&sub_attr_name=Type&refineValue=Fillers&refine=1&page=GRID&history=3tf45jq8%7Cother%7Crefine%7E1%5Epage%7EGRID%5Ecategory%7E210%5EprodPage%7E15%5EsubCategoryName%7EThickeners%2B%252F%2BFillers%2B%252F%2B%2BAdditives%5EcategoryName%7Ecat_203%5Euser_att_name0%7EUserType%5Euser_att_value0%7ENewUser
I use the West 105, 205,206 and 410 micro.
The 410 is good for fairing to a feather edge and easily sanded. Other times you want strength but hard to sand and you will want Milled Glass Filler. Other times you will want straight epoxy but want it thicker so it does not run. For that you will want Cab-o-Sil.
 
Fitting of Cowling

Mark,
If I read your post correctly you are expecting the cowl side joints to overlap. The guys on the forum will correct me if I'm wrong but the side are a but joint. Refer to the "Fitting the Lower Cowl " on drawing 45.

"I can not get the bottom of cowling to overlap the top, just won't go."

Hope this heads you in the right direction.
Mark
(Grezdlitn)
 
I think we are calling two different things the bottom.
I would not suggest that the sides of the cowl overlap. (only while fitting the cowl)
I think when Bert is refering to the bottom he is talking about the front bottom that is not matching the front top as in the picture.
If he slides the bottom of the cowl forward it will remove the overlap he is talking about. (forward as if on the plane)
 
Note in your first photo how the aft edge of the bottom cowl is not touching the floor (because they are not exactly the same length in raw form)? That means some of the weight of the bottom half is hanging from the top half where it is clecoed. Even though they are quite stiff, they can still be distorted out of shape somewhat.
I think that is the cause of what you are seeing.
 
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