SonexBuilders.net

Looks pretty similar to how mine was before I kept trimming. I did much of the fitting without the wooden spacer attached to avoid being misled by the pressure it can apply to the cowl, making the fit seem different than reality. Without the spacer, you can see how an angled cut will move the propeller opening up or down, left or right. I expect you'll be able to remove at least an inch off the bottom before you finish.

Also, I think adding baffles and the seals tends to apply pressure that moves the propeller opening forward. I thought I had a good gap, but ended up having very little gap once finished. I wouldn't worry too much about erring on the side of a little too much gap for this reason.

Just did this recently. Follow the instructions! They work!

As frustrating as it was, I found the instructions to be accurate.


Robbie Culver
Sonex 1517
Chicagoland
Tails and Wings complete - finishing fuselage.
N1517S reserved

The main problem I have with the instructions (or rather, the instructions as they work with my provided cowling) is that the bow strap becomes worse the farther up the cowling is positioned once past a certain point. The instructions reference the bottom of the cowling as the dictating factor for vertical position (i.e. a clean flow line from cowling to fuselage), and as you can see from my pictures I achieved this flow line. The higher (vertically) the cowling went, the worse the top-strap issue became, and if I went any higher, the "edge" built into the cowling would be well above the "edge" bent into the side panel for the windshield, referenced by these pictures:





Look closely at how the curve built into the fiberglass matches the curve in the fuselage side panel. If following the Sonex instructions, the bottom side of the cowling isn't trimmed until the very end of fitment (even after the center-lines are trimmed), so I can only imagine what you're telling me is to continue to trim the side (mainly the lower part of the side) and raise the cowling vertically.

I don't mean to be snarky, but following the Sonex instructions to a T will not solve this problem (in my case.)

Full disclosure, I've already solved the problem and will post about it soon, but I believe this dialog to be important and I am very interested in others' experiences.

Yep. The instructions sure won't cover every eventuality and I agree with you on that. They worked for me. But, as an example, the wing rigging instructions did not work for me and I had to use the advice I got at ASA 2014. That worked.

All I know is that when ai cut my cowling I used the instruction sheet, read dozens of posts and emails, and it worked for me.

Very interested to read what worked for you!


Robbie Culver
Sonex 1517
Chicagoland
Tails and Wings complete - finishing fuselage.
N1517S reserved

Here's how I solved my cowling fitment issue (link to blog post:) http://www.rynoth.com/wordpress/waiex/2 ... e-cowling/











All told it only took about 10 hours of work (not counting curing time and time spent studying) and $60 worth of materials, but it was a steep learning curve as I had never worked with fiberglass before. The final fit is excellent.

Nice work Ryan!

Cowling fitment is complete! Blog post: http://www.rynoth.com/wordpress/waiex/2 ... d-cutouts/

Looks great. I think you got a much better fit on the top corners and strap than I did without modifying the cowl.

I didn't remove the knuckles on the piano hinge across the lower firewall despite having the same cooling hole. Leaving them full length seems to allow both hinges to prevent the other side's pin from backing out. I insert the bottom pin from the back and have a system of interlocking it with the other two pins to hopefully prevent it from backing out. You might come up with a better system.

I also don't have the bottom oil cooler hole. I built the fiberglass tab but never used it. The tab was always getting caught on things and preventing me from being able to lay the cowl down. I ended up removing it after it got damaged. I'd consider using an even longer bottom hinge on my next Sonex and just use a shorter pin if the curve is too much.

Your top pin handle is clever. If you look closely at the fuel filler box, there is a small hole at the front. I thread the pin through that hole to prevent it from sliding forward. I think this is even shown in the plans.

All good points Chris. I took the top pin shape from Jeff Shultz' cowling video on youtube. I am however still trying to figure out how to secure the 3 bottom pins and you make some good points for leaving the piano lugs on the bottom of the firewall in place. Jeff also had a good solution for the bottom cowling-to-firewall pins, but I am currently at a loss as to how to secure the bottom center hinge pin. As for the fiberglass tabs at the front, after making them I can see how easily they can become damaged when removing the cowling, will need to be careful for that. The cowling does seem very secure even without those tabs.

Yesterday I took the monumental step of moving my build from my basement to its new home in a hangar at KRKW.

To commemorate this occasion, I made the following time-lapse video. This video includes nearly the entire build of my airplane to date (900 hours condensed into 2.5 minutes), followed by time-lapse video of the move to the airport.

Enjoy!

https://youtu.be/Q8QTd2HoyAM