What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Cowling Install

D

drone_pilot

Well Known Member
Hello All,

I'm finally fitting the pepto-pink cowling on the business end of my 7A. Im using Skybolts for the entire cowling. With the bottom and top cowlings laid on the fuselage and leveled, it looks like I have about a 1/8th inch gap on the horizontal split at the firewall on each side. Once the cowls are trimmed at the firewall, I'm hoping this gap will close.

Has anyone out there experienced this? How do you go about resolving this gap? I wish I had a little more material to work with here.
 
Yes, I had the exact same situation and after trimming to the firewall, the side seam only required a little sanding to match perfectly.
 
Pictures, please? I'm confused by what you're saying.

I'm doing my cowl right now, and the top and bottom halves overlap all across the horizontal joint, by at least 1/2". In fact, I drilled some temporary holes to cleco the halves together before final marking and trimming.
 
I can't upload pics from work, so I will try to verbalize.

At the very first stage of installing the cowl, the top and bottom halves are overlapped on the fuselage by about 2 inches.
This causes the top and bottom to be about 3/16 taller and wider.

On my cowl and apparently the OP, the factory sides were cut so close to the finish dimension, that I had a 1/8" side gap before trimming to the fuselage.

When trimmed flush to the firewall, the pieces are flush with the fuselage skins and my sides had about a 1/16" overlap that I sanded off with a long 2x4 with sandpaper on it.

I admit I was quite surprised that I did not have an initial overlap and thought I was going to have to do a lot of build up work, but it came out just right after trimming the ends.

Hope that helps.
 
I left a good credit card gap. It looks a little wide but after painting, you will need the separation. I saw several planes at Oshkosh where they didnt leave enough gap and the vibration between the two caused the paint to crack along the edge of the cowl. 1/8" does seem like too much though. If you need to add some, do a search on "scarf" joint.
 
Ben, I too had a very poor cowling shipped to me. In fact there was no over lap on the sides an the only saving grace was after I trimmed the back along the firewall and allowed it to sit on the skybolt retainer pieces one next to another riveted in place. then the sides touched.

the front was off my over 1/4 inch. I was lucky to have a friend who had a constant speed hub which we bolted on the engine and with the prop spinner back plate also fastened it was easier to make the whole mess go together.

I unlike others who had huge overlaps on the side was not so lucky.
Like Bruce S.

I marked a line 2 inches back on the aluminum aft of the firewall. all the way around the fuselage.
I then put the cowling in place even though it only came over the firewall by about a 1/2 inch. Squeezed it tight with the straps. and made clearance measurements on the back or the prop spinner back plate.
I then measured forward from the line I drew on the aluminum and transferred a hundred or so points to the fiberglass. Now I was able to connect the dots using a piece of flexible aluminum on top of the fiberglass. This gave me a cut line on the fiberglass and it was really tight against the firewall when I cut it. . I cut it with a dremel tool. and the little 1 1/4 inch disk.

The cowling then rested on the skybolt retainers and I could shape it as needed. Just having the cowling drop down on the retainers the sides finally touched.

It was a lot of boy this is not good.... but it turned out really good.

Jack
 
Okay. It looks like if I'm careful that they just may touch after trimming. Problem is that the horizontal cut lines aren't that straight. I may need to build them up just to get a straight split line cut.

I guess with the extreme high price of fiberglass that Vans couldn't afford to have their vendor keep an inch or so extra material on the sides. :p
 
Smilin' Jack said:
Ben, I too had a very poor cowling shipped to me. In fact there was no over lap on the sides an the only saving grace was after I trimmed the back along the firewall and allowed it to sit on the skybolt retainer pieces one next to another riveted in place. then the sides touched.

the front was off my over 1/4 inch. I was lucky to have a friend who had a constant speed hub which we bolted on the engine and with the prop spinner back plate also fastened it was easier to make the whole mess go together.

I unlike others who had huge overlaps on the side was not so lucky.
Like Bruce S.

I marked a line 2 inches back on the aluminum aft of the firewall. all the way around the fuselage.
I then put the cowling in place even though it only came over the firewall by about a 1/2 inch. Squeezed it tight with the straps. and made clearance measurements on the back or the prop spinner back plate.
I then measured forward from the line I drew on the aluminum and transferred a hundred or so points to the fiberglass. Now I was able to connect the dots using a piece of flexible aluminum on top of the fiberglass. This gave me a cut line on the fiberglass and it was really tight against the firewall when I cut it. . I cut it with a dremel tool. and the little 1 1/4 inch disk.

The cowling then rested on the skybolt retainers and I could shape it as needed. Just having the cowling drop down on the retainers the sides finally touched.

It was a lot of boy this is not good.... but it turned out really good.

Jack
Click to expand...
Glad to hear there is hope. I finally got both halves together on the plane tonight and all I see when I look at it is a lot of fiberglass filling, sanding, filling, sanding, etc.
 
i hadnsuch a miss match in the front cowl openings that i had to fiberglass the inside of the cowl openings inorder to have material to sand away.
The flat flange behind the back plate had to be built up to 4 layers of Glass to make it symmetrical on the back of the spinner plate
inwill add some pictures next
Jack
 
Pictures

After the cut on the firewall the sides finally touched in some places. I set the fuselage up level and used a laser level to scribe points on the side. Then using a large 2X4 carefully sanded the sides down until they were even the entire length. IT is a large picture but wanted to be able to show the line drawn on the fuselage. the initial cut on the top. and how the sides barely touched and where they did there was not a lot of material to make matters worse. I was given the excuse that Vans had now gone to a different manufacture of the cowling after I purchased mine
14uddo0.jpg
 
Front of the cowling same on both sides. Almost a mis match by 3/16 inch
http://
r73jom.jpg

The front after adding fiberglass to it.
http://
24yd7k4.jpg


It just takes time.... one thing at a time.
Get the back secured. then work on the sides and get them sanded even you do need a little gap 3/32 is about max.. to allow for paint After you paint it that will close up to less than a 16th. but it will keep you from chipping it when you put the cowling on and off
Jack
 
You must log in or register to reply here.
Back
Top