Wing Failed on my 3D KATANA flight 4.......WHY???

[3D Trev]

Hey guys
Check this vid and give me your comments.

After looking at many suitable models I decided to fly this 27% Katana
for our 2007 Free - style season. It just looked like a perfect plane.
Basicaly a 27 % Katana with an all up weight of 11.3 LBS. 3D Extreem right.
Well the plane flew awsome once we moved the cg back. And then on flight 4 of day 2 out of nowere I got a big snap sound followed by hectic flutter.
I was flying just more than harrier speed ( I never fly fast ). Both aileron servo's stripped from the flutter and I had to land her with rudd and elev only.

There was no slop at all in the aileron setup and my hinge gapps are sealed with ultracote on both sides. Can anyone help me understand why this happened.

http://www.flyinggiants.com/gallery/...0&ppuser=14399


Cheers
Trev

[50%plane]

did you go over the glue joints? The Funtana 90's had this problem when they first came out due insufficient glue and wood.


50%

[airborneSGT]

Man that was a good save. Lots of reasons why that could have happened. I would just get another wing half as the rest of the plane seems fine.

[bodywerks]

The good thing is that it appears obvious that the foam core wing was simply not assembled properly and you shouldn't have any problem getting a new one, if the company is still around. Good save - way to stay calm!

[as722]

I hate to say this but it is becoming a common thing to see arfs fail in one way or another. The only thing you can do is to go over it but you can only do so much.

Albert

[TheTank]

What servos are you using? Could one of them possibly have stripped out, causing the severe flutter and stripping the other out as well? I beat on my arfs like they are red-headed step children sometimes, and have yet to have a failure, and I never go over any glue joints. The quality has been 100% A-OK.

[Wojcigitty]

Agreeing with Tank here, I have beat the piss out of my ARF's with never a problem. You didn't build the airplane, so you can never be completely sure, but for the most part ARF's today are great, and agree that stripped servos can cause that kind of thing.

Either that, or I'll bet you got a "bad one." Stuff happens at the factory, where a bunch of tolerances line up to make something very weak. This happened with the Goldberg Obsession - one person was flying it with an RCS 1.4 gas engine, at about half throttle straight and level, and the tail ripped off with no warning. Other people have put DA-50's in them and had no problems. My dad's got one with a Moki 1.80 and it looks great (except for the canopy and hatch coming off in Woodstock. Let me know if you find that, guys).

Great save, too, by pulling the throttle back so quickly. Look at the failed wing and see if it's lacking for glue in some places?

[JimC-MD]

From what I saw on the flight, I cannot understand why the left aileron servo would be stripped. The right one I can understand. What power rating where the servos and where they metal gear? Was there a buzz of flutter before the popping noise? The wing tube support looks like it just broke out of the wing.

[bodywerks]

There was no flutter. He pulled a whopping 2 G's and the wing tube support busted through the bottom of the wing, likely due to a lack of CF or other fabric reinforcement in that area, happens all the time - happened to my buddy's WH 41% Extra. Luckily, with the same result as this guy. If it was flutter, the aileron would have continued to oscillate all the way to the ground. The guy was flying as slow and graceful as I have ever seen; not a time when you should expect flutter.

[Dangerous Dan]

Mabie its a Katana/Funtana Thing, Watched a H9 Funtana 40 flutter to death this weekend?

[PLANKBONE]

Fludder was the case.....

[Dangerous Dan]

i had a 1/34 scale CMP katana 140, Its wing snapped off in flight, I was not able to Hemple it. The wing tube was too short and the shear webbing was going the wrong direction.