Install Cowling

posted Jun 6, 2013, 9:49 AM by Bill Thomasson
Wow with the engine on, and then shortly after the cowl on it is really starting to look ready to fly..... probably 9
months from now.
First Align the Cowl with the spinner.  I used about 3/16 spacers (4 craft sticks)
Also aligned the center of the cowl with the center of the aircraft.  I did this with a lot of measuring,  but then found I could just count how many rivits down each side was along the sides.
Aligned it and measured front corners with plumb bobs and measuring tapes.
I ignored the directions for setting a 3" line, then measuring 3:"  I just used the same hole/edge finder I had made for the doors to mark the edge.
A picture of the edge finder.  I made it earlier out of a 2 strips of aluminum and 4 rivets.
Cut right at the line (leaving the lline)  99% the first time.
Just had to sand it down in a couple places with a belt sander after to get a slightly better fit.
Now time for the bottom cowl.  Holding it up with bottle jacks.
 Used same 4 craft stick spacers on bottom
got it alligned and used edge finder again to find the rear edge to cut. Had to trim some interference with the top cowl in the front to get it to align correctly.
Before cutting the sides I wanted to make sure it was very repeatable positioning the cowl, so I installed the camlocks. (Skybolt).  I had already installed the recepticals in the firewall, but then read the directions, and should have waited until I could match drill the 2 holes together... arg.  I put a bright light under the cowl and was able to see the center holes of the cams.  I drilled a 1/8 hole with it on, then enlarged to 1/4.  Then put the cowl back on  to check that it was centered.  Then expanded the hole to 1/2, adjusting as needed.  I only did a couple cams at a time, so this involved a ton of on and off of the cowl.  Don't do it this way.
Same with the bottom cowl, except it is a major pain to take it on and off, so it took forever.
Then trim bottom and top so that there is a 1/16 gap between cowls.
Add lower hing.  Hinge line is offset with the hinge exposed by plans above the cut.
not sure why, but followed plans.
Top hing match drilled.
Riveted hinges on. Then cutout for Aerosport hing pin covers.
Glassed a backing for it. (4 layers)
Exterior of cover area.
Main cowling work done!.