Y Tail Forward Doubler Bar

[jrs]

I installing the Forward attachment for the Y tail and the plans show the doubler bars to be sloped on each end. I understand the outside ends as they matche the ends of the lower attach angles. Don't understand why we would grind off the inside ends. They just set in the lower attach angle. What am I missing ? Generally if there is something that I don't understand it bites me down the road.

[Rynoth]

Hello JRS, I assume you are referring to the "Y tail forward doubler bar" as referenced in the top-left of the following service bulletin link, and presumably included in all Waiex plans since this SB was issued:

https://www.sonexaircraft.com/files/pdf ... rawing.pdf

One guess to the trapezoidal design for that part is that the strength of the component is adequate with or without the angled cuts, and removing that material is a weight-saving measure. It would also make the plans easier since you can make 2 parts the same way to satisfy the requirements, without having to specify which one goes on the right or left side (this might be the main reason it's shown this way.). I don't really see the harm in leaving the inside edge at 90 degrees, but I built it per the plans.

Also, I'd try not to grind on that part TOO much to get those angles, rather cut them and then clean up the cut, for fear of overheating (and weakening) the aluminum. If you do grind, just take it slow.

[jrs]

That is the part sir. I had thought about the weight reduction but that is so small seems to not count but I had not thought about right / left aspect. I bet that was it. Found the thread from about 5 years ago about the accident and assumed that was the reason for the bar. Never thought to look for service bulletin. It is all a learning process for me.

[LarryEWaiex121]

As a long time, builder/flyer of the Waiex, I can assure you that weight savings in the tail is the object of the design.
The Waiex is definitely favoring an aft cg compared to the standard tail aircraft. Between the weight of the mixer and additional hardware from the split in the fuselage aft, it all adds up. I'd follow the plans.

Larry

[Bryan Cotton]

Weight is the enemy.

[jrs]

I was looking for good advice and appreciate it. Took that advice and worked the interior ends. I calculated the weight of the material removed and it should have been .2986 ounces for the two combined. 1/3 of an ounce seems like not much weight but following the plans is no doubt a good habit to get into.
Thank you.