Ultimate 46% - Any known problems?

[ayrobotech]

I'm looking to find out if there are any known structural problems or things to look out for with the Hangar 9 Ultimate 46%. I bought a used one and went through it very well and fixed a few problems that the original ARF builder had not done correctly.

For example, I know that with the 1/3 scale GP Pitts, there are known issues where the firewall will tear off since it needs better bracing and there is another issue where the upper wing will tear off in flight (I saw it happen!) because the aluminum bracers fatigue and snap while flying. I didn't know if there were any notes anyone had about the Hangar 9 Ultimate?

Thanks
David

[Hinckley Bill]

David,

Here's a thread I started when I found problems with the preinstalled hard points on the elevator halves............this one could lead to the loss of your Ultimate if failure occurs in flight.......Bill

Check those preinstalled hardpoints!

[ayrobotech]

THANK YOU THANK YOU. I found that one of my hard points was slightly off like in your picture, and on top of that had TWO holes drilled in the balsa. I filled in the second hole (outside of the hard point) with balsa filler and then sealed up the seams and the filler with thin CA. Then glued on some thin ply supports. All in all it looks nice and I bet is many times stronger. I just wish I knew of any other weak points...

Check out my pics and my modifications.

David

[ifshnee]

Ayro:
I am not sure how many folks have this issue but a real H9 Ultimate guru round where I am showed me about the top wing. Seems it can vibrate out & back in against the center CF rib. You know when you run the engine. It actually can make a banging noise that corresponds to the RPM. This has ripped the wing apart in flight I am told. Mine did this. Fortunately the fix is easy. As I keep the top wing full assembled (gotta have space for 96") I leave it this way. You just put the wing halfs tightly together and wrap clear tape around the entire junction. I you don't keep the wing assembled you should do it each time you assemble. Some never have this problem. You hear it when running the engine if you got it.