Looking for Cowling Tips

[kmacht]

I'm at one of those points in the build that I have been putting off for far too long and really dreading doing. I need to fit the cowling. I'm looking for any tip / tricks / how to's from those who have already done it. Websites or pictures would be awesome. My fear is ending up with a big gap somewhere that needs to be filled. Fiberglass and I do not get along well. Let me know what did or didn't work for you.

Keith

[N111YX]

Keith, I had no prior fiberglass experience prior to installing my cowl but it went well. Guys with serial numbers right next to mine (and Jabiru 3300's as well) had trouble with theirs and had gaps and I don't know why. I just followed the instructions per the engine install manual and mine turned out pretty good.

Basically, you make the hub adapter and work back from there. The front is a known point in space and all of the trimming is aft of that point. Keep in mind that taking a few extra thousandths off here and there with a few more tedious "on and off" cycles pays for itself with years of admiring a nice fit.

Jump on in...you may find that while it's a big job it is not exceedingly difficult.

[MichaelFarley56]

Hi Keith,

Kip is right on with his pointers...work slowly as its much easier to sand a few thousands off verses taking off too much and needing to add material back.

My guidelines were using the Sonex posting... http://www.sonexaircraft.com/documents/ ... lation.pdf

It's really not that bad...have fun!

[ldmill]

I'm at one of those points in the build that I have been putting off for far too long and really dreading doing. I need to fit the cowling. I'm looking for any tip / tricks / how to's from those who have already done it. Websites or pictures would be awesome. My fear is ending up with a big gap somewhere that needs to be filled. Fiberglass and I do not get along well. Let me know what did or didn't work for you.

Keith

Hey Keith - I'm one of those guys that Kip referenced. No question about it, my cowling was one of - if not the most - difficult part of my build. I had over 150 hours into it alone. Part of the issues were of my own doing - but some of them were due to original cowling layup as well. The biggest issue was my own doing - I cut too much off on the pilot side and had to glass the pieces back on. Hint - when you cut off the pieces shortening it up - KEEP THEM JUST IN CASE... I did, and am very glad I did.

One of the more significant issues that I had (and so have others) is that my cowling didn't fit around the upper longerons(where the engine mounts bolt on to). They humped up and were over 1/4" above the windshield and also stuck out from the side of the plane by almost 1/2". I had to cut out pieces and reform using heat.

End product looks really good and I'm glad I spent the time on cleaning everything up and doing it right. They are actually at the paint shop right now with all my other glass parts.

Lorin Miller
N81YX - getting ready for first engine start...

[ldmill]

Just to add a little - in retrospect I should have probably contacted Sonex and discussed a replacement and driven up and showed them since I don't live too far away. I had one cowling half that was in pretty good shape with few fitment issues - but the other I a lot of additional clean up that I had to do. I had portions of the fiberglass that were 1/8" thick - but then had other portions that were way over 3/8" thick with big humps of fiberglass resin goobered on it that I had to grind off. The sides were wavy in places. That cowling half also had a top that had a droop of over 1/4" molded into right behind where the spinner fits at.
In the end - it's all just fiberglass and turns out to be pretty easy to fix, just time consuming. I had absolutely no experience with glass before this - but feel pretty comfortable working with it now. I kept telling myself that the intention of building is to learn new skills.
Just think though - even though I had issues - it was still much faster than if I would have been scratch building a cowling with carved foam. For that - I am eternally thankfull to Sonex...
Lorin