Split cowling help

[EricS]

Here’s a German builder who recently completed his metal cowl with homemade fibreglass nose, He has the RevMaster engine hanging from his Sonex.

Now that is some serious handy work! He's got several hours in that project alone. That makes the horizontal split mod seem minor.

Thanks for sharing.

[structurespilot]

Love the metal cowl, I personal think it makes the Sonex look way better. I vote for Dana Thurston's cowl. The German cowl looks great, but the RV 3 style cheeks are not my thing. I'm planning on ordering a nose bowl from Dan Wiesman (panthersportaviation). Thanks for the pictures!

[kmacht]

I took pictures of the cowling issue I was having but can't figure out how to post them on here. If someone can clue me in I will post them up.

I ended up drilling a hole and tapping the engine mount. It fits ok but not great. The original problem back by the motor mount now sits nice and flush but once I got the screws down the side it wants to bow out a bit between screws. Not sure how I am going to fix that one yet. I was thinking of maybe putting some metal fingers coming down from the top half and going over the flange on the bottom half. It doesn't take much pressure to get it to sit flush.

I'm pretty sure I wouldn't do this mod again. I'm too far into it to turn back now so I'll have to just keep chugging along.

Keith

[EricS]

The original problem back by the motor mount now sits nice and flush but once I got the screws down the side it wants to bow out a bit between screws. Not sure how I am going to fix that one yet. I was thinking of maybe putting some metal fingers coming down from the top half and going over the flange on the bottom half. It doesn't take much pressure to get it to sit flush.

If it's not much of a bow between each screw, can you simply oversize each hole slighly all the way across the edge? Slightly larger holes (that can still be covered up by the screw heads) all the way across the edge might give you just enough room to take out some of the bow without compromising the strength of the attach seam.

I've done this before on other fiberglass parts that didn't fit quite right due to the mold being slightly off. Just an idea. Good luck!

[Bryan Cotton]

I see in this month's Kitplanes an RV7 guy modified his cowl to a vertical split, like the Sonex!

[floridasonex]

By far the worst part of the Sonex build is the cowl.

This was my experience, too. I had a LOT of hours wrapped up in this and the
cooling baffles. Longer than any other part of the plane.

RT

[kmacht]

Seeing my original thread resurrected I figured I would give a little update. Slightly oversizing the holes on the horizontal split flange fixed bowing issue between screws. With that said I don't recommend doing the horizontal split mod. I like the look but almost all of the work I have had to do in the first few hours of flying my airplane has been related to tuning the carb. With the horizontal split I not only have to undo all the screws that hold the top cowl on but I also have to pull the pins and remove the lower section so I can access the carb. If I had stuck with the vertical split I could have just pulled the pins separating one side from the other and pulled off half the cowl to get to the carb instead of having to pull everything off. The horizontal split also made it very hard to get the baffles fit correctly as you can't see where to trim them once you put the top on. With the vertical split you can work on one side of the engine at a time when installing the baffles. Like I said, I like the way it looks but that is the only thing I like about the horizontal split after living with it for a while. I would not do it again if I were building another Sonex.

Keith
#554

[mike.smith]

I also did the horizontal split, and for the most part I echo what Keith says. I actually do like the horizontal split to some degree, but it has all the down sides noted by Keith, and took me a LOT (let me say that again... LOT) of time to do it. And doing the baffles was atrociously difficult. Like Keith, if I had it to do over again I would not do the horizontal split.

[DCASonex]

Once you get the carb issues resolved, you will appreciate the horizontal split. Can remove or install my top in less than one minute, and the two lower sides are easier for one person to handle than the full sides. Remove and install both of those in under two minutes, including center pin, Go to a Sonex fly-in and see who opens their cowl. If it is not split horizontally, about the only time you see one off is for trouble.

David A.

[Sonerai13]

Can remove or install my top in less than one minute, and the two lower sides are easier for one person to handle than the full sides. Remove and install both of those in under two minutes, including center pin, Go to a Sonex fly-in and see who opens their cowl. If it is not split horizontally, about the only time you see one off is for trouble.

I take issue with that. I can remove half a cowl on one of our airplanes in about 30 seconds. Definitely less than one minute. And I never have to ask for help in removing or installing our cowl. If the cowl is properly fitted, there's no problem removing or installing it by yourself.