Cowling problem

[rizzz]

No idea whether it is true or not but I've heard several times that the stock valve covers, painted black, will give better cooling than the aftermarket chrome bolt on ones.

That's what some of the people on the VW racing forums claim as well. They also say the stock covers are less prone to leaking, it seems many bolt-on covers will start leaking through the bolt holes, even the more expensive ones witch have the o-rings in place.

From what I gather, the bolt-on covers only really make sense when you install high lift rockers as they allow more clearance to the rockers. High lift rockers are of no use in low rpm applications though so we don't install them on Aero conversions.

Your cowling work looks great. Just remember that it only has to be "perfect enough" for you. When you do a 200 mph (OK 197) sheep clearing pass, hardly no one will see the small imperfections anyway ...

:lol:

Yep, that's what I have to keep reminding myself off.

[rizzz]

Ah ok.. was just about to send you the cowling pages
Cheers
T

Thanks anyway.
Cheers,
Michael

[Timwaiex0146]

Hi Everyone ! Im in the middle of my cowling installation and would like to add a few comments > It is by far the hardest project in building our waiex so far. I started with the right side and was amazed , we fitted it in about two hours with hardly any cutting and fitting, just popped right on there. The left side was a different story entirely ! It was too short by about half an inch along the top where it fits up against the windshield. So, after thinking about it a bit we started cutting the side back and moving it back . eventually we got it on and back almost to the windshield line. Took quite a bit longer than the right side , but still , not too bad. We thought we were pretty much done and were wondering what everyone was so excited about. Then we tried to put them on TOGETHER !!! SURPRISE !!!! the bottom curves of the halves were totally different ! Cutting back the left to make it fit on the top caused the bottoms to be about an inch and a half off front to back. Needless to say we started adding fiberglass where we removed it and ended up almost back where we started cutting it off. We also had to add the half inch to the top that was missing in the first place. After getting them to roughly line up front to back along the bottom they would still not come together all the way. we ended up using metal straps along the joint to hold it together and fiberglassing the bottom halves together. they were about 5/8 of an inch short. we found that we could force them together but they would have been so tight that you would never have gotten the pins in the hinges without two guys pushing on the sides and another one hammering the pin in . Once it was together it was easy to slide the whole cowl on and off to trim the sides and drill the holes for the hinges. I firmly believe the two halves I received from the factory were different lengths. the left was shorter front to back and both were tooo narrow to come together on the bottom. The most important lesson I can pass on is make sure the bottom lines up Before you start trimming the sides ! You can't tell if you just follow the plans directions and do one side and then the other. Its like sculpting a bowl of jello, theres no place to start because you have to get each measurement right and each one affects the next. You have to keep going back and forth between the sides top and front and nibble away at it. The factory could sure help by putting out a video on doing this. Not some four minute blurb either. Something that shows the common mistakes and how to avoid and fix them. That would have saved us a solid weeks work glassing and trimming and re glassing. Tim K Waiex 0146

[rizzz]

Hi Everyone ! Im in the middle of my cowling installation and would like to add a few comments > It is by far the hardest project in building our waiex so far. I started with the right side and was amazed , we fitted it in about two hours with hardly any cutting and fitting, just popped right on there. The left side was a different story entirely ! It was too short by about half an inch along the top where it fits up against the windshield. So, after thinking about it a bit we started cutting the side back and moving it back . eventually we got it on and back almost to the windshield line. Took quite a bit longer than the right side , but still , not too bad. We thought we were pretty much done and were wondering what everyone was so excited about. Then we tried to put them on TOGETHER !!! SURPRISE !!!! the bottom curves of the halves were totally different ! Cutting back the left to make it fit on the top caused the bottoms to be about an inch and a half off front to back. Needless to say we started adding fiberglass where we removed it and ended up almost back where we started cutting it off. We also had to add the half inch to the top that was missing in the first place. After getting them to roughly line up front to back along the bottom they would still not come together all the way. we ended up using metal straps along the joint to hold it together and fiberglassing the bottom halves together. they were about 5/8 of an inch short. we found that we could force them together but they would have been so tight that you would never have gotten the pins in the hinges without two guys pushing on the sides and another one hammering the pin in . Once it was together it was easy to slide the whole cowl on and off to trim the sides and drill the holes for the hinges. I firmly believe the two halves I received from the factory were different lengths. the left was shorter front to back and both were tooo narrow to come together on the bottom. The most important lesson I can pass on is make sure the bottom lines up Before you start trimming the sides ! You can't tell if you just follow the plans directions and do one side and then the other. Its like sculpting a bowl of jello, theres no place to start because you have to get each measurement right and each one affects the next. You have to keep going back and forth between the sides top and front and nibble away at it. The factory could sure help by putting out a video on doing this. Not some four minute blurb either. Something that shows the common mistakes and how to avoid and fix them. That would have saved us a solid weeks work glassing and trimming and re glassing. Tim K Waiex 0146

Wow, and I thought I had issues with my cowling.
Mine was slightly short on the top end but at least both halves matched and I had no problem on the bottom.

You’ve got to wonder how it is possible so many people have such different experiences with the cowling installation,
Some seem to have hardly any difficulties whilst others have to go as far as cutting the thing in half, taking out material and glassing it back together (I believe forum member Mike Smith was one who had to do this).
Surely they make all these cowlings using the same mould so you would not expect too many differences? But clearly there are, even between cowl halves as you say.
Differences in our individual engine/mount/firewall installation could account for some variations but not to the extent that we’re seeing I would believe. We’re all building according to the same plans.

I agree a comprehensive video like they have on other subjects would be of tremendous help, perhaps it’s just a matter of technique.

[rizzz]

Made the exhaust tunnels this weekend and got one installed, fits nicely:

[rizzz]

Some pictures to show how little space there really is under a Sonex cowling with a VW installed.

[rizzz]

Well, I’m considering my cowling done “for now”.
I’ve spent the last weeks filling, sanding, filling, sanding, filling, sanding, filling, sanding, filling, sanding, … You can really just keep going with this.
I believe I have it to a point where the surface is smooth enough for a thick primer filler but that will be a job for later. I’m going to do some more investigating on the products to use etc. first.

During all this I have been searching other builders logs to see to what detail they’ve finished their cowling but really couldn’t find many pictures that had a lot of detail so I’ll share a few of mine.
The surface looks kinda rough in some pictures but that’s just the gel coat having been sanded away, in reality it feels quite smooth.

[Darick]

Help!
I started the pilot side cowl and after cutting clearance for the gear leg and screwing to the wood hub spacer, am ready to start trimming. The instructions say trim so the side fits and the bottom corner (at the gear leg) transitions smoothly to the fuselage bottom. Are you supposed to trim the the top also, where the windshield is or just the side? Is the cut parallel to the existing cowl line or does it end up being tapered?

[wlarson861]

you will end up cutting all the edges. The cowling is like nailing Jello to a tree! Make sure you have the smooth transition at the bottom corner or the bottom center will not meet. You trim as needed which may or my not be a taper, the top will need to be trimmed to fit back to fit the wind shield. See Bob Meyers wed site for the fix. I have seen several builders add fiberglass to fix the problem and when you look at the bottom corner you can see an up swoop in the fiberglass. That indicates it was not trimmed far enough. The cowling was the worst part of the build as far as I'm concerned. I spent several days fitting the cowl and wanted to throw a hammer through it several times. I have heard that the new cowl with the horizontal split is much easier to fit. If it wasn't so much money I would get one and get rid of the vertical split.

[LarryEWaiex121]

Bill,

I fiddled with my cowling for over a week when I built my Waiex over 5 yrs ago. I have the referenced upswoop at the bottom where it meets up with the fuselage as you mentioned. That particular reason is why I fly 90% of the time without gear leg fairings. I'm one of the few folks that have foregone the fairings for the majority of my over 500 hrs of flying.
My reason is exactly that upswoop causing interference with the tops of my gear leg fairings. I simply don't have the patience to take the fairing off every time I want to pop the cowling,(which I normally do about each 5 hrs of operation). Call me a skeptic but I've always been one to keep a close eye under the hood for surprises building up. None do for the most part but my non-trusting self is still diligent about checking under the hood.
For me the cowling was far and away the most frustrating, daunting exercise in building my plane.
As the plane gets more hours (520 roughly), I have more cowling maintenance. Rivets are beginning to loosen. I did the dimpled flush rivets and don't recommend it. The material is too thin for the purpose and I would do the full head rivet if I choose to build a new cowl some day as a matter of keeping things up.
My airframe is doing extremely well except for the cowling. Some is wear and tear and some is mis-handling by the owner. Ooops!

Larry
Waiex121YX, Camit 3300, Skyview