full throttle

Can you believe what happened to me, while flying on Sunday, my Lanier Edge 540T 1/4 scale elevator aluminum tube snapped on both sides of the fuse at the same time. Flying level flight, 1/2 throttle, using 440 linkage, 65 oz servs per surface and with out flutter noise the aluminum tube snapped. Both elevators were less than 10 feet apart on the ground. The remaining aluminum tube in the fuse is still inside. The tube is flush on both side of the fuse, unbelievable, or not? The Edge was on its 15th flight, flawless in all other perspectives.

Has anyone else had this happen to aluminum elevator tubes? I suppose I should have inserted a dowl inside the tube to strengthen the tube itself....

I guess I will start on my H9 Alitalia 80" cap. BTW, what 3.2 gas for power? Brison, BME, DA, ZDZ.......?

Thanks,
Chris

Flyfalcons

Don't discount the possibility of flutter even if you didn't hear it. Flutter can destroy your surfaces very quickly, and the fact that both came off simultaneously sounds like possible flutter due to a number of things such as harmonic vibration, airspeed/elevator position combo, etc.

I'm working on an 80" MW Extra and have a Brison 3.2 in it. Not the most modern but a very good quality engine.

CGAV8R

My Feedback: (2)

Full throttle, sorry bro. What engine were you running? I am assembling my Lanier 540t now, I guess I should add a dowel? Did you have them epoxied on in addition to the tube? I hope that doesn't happen to me :-(

full throttle

CGAV8R: Running a Moki 1.8, The elevators are removable, each elevator half attaches to the aluminum tube with alan bolts. No epoxy needed, just a dowl if you can find one to fit....

Flyfalcons: My elevator halfs are exactly the way they were new. I used robart hinges w/ epoxy, nothing came apart on the elevator surface to horz. stab, just the aluminum tube snapped on each side of the fuse at the same time. Can each entire elevator stab and control surface create flutter together to cause the aluminum tube to snap? I did not lose any control surfaces from either elevator stab. I hope it wasnt a bad batch of aluminum tubes or tube.

Chris

Jaco

I'm working on the Lanier Edge now and have heard of the wing tube bending but not the elevator tube breaking! I glued my elevator halves on so hopefully it will last.

Flyfalcons

Yes, flutter can attack the entire surface and make a very clean rip when it does fail. I had a profile plane lose one of its elevator/stabilizers in level flight and the piece did not show any sign of hard bending; only the root ripped off cleanly. Generally, if you over stress a surface, the aluminum should bend some but both sides breaking clean at the same time points in the direction of flutter. Using the larger Moki engine will increase the metal fatigue a little bit. That, in addition to the colder winter temps and a tube that could have already been weak for some reason, would allow flutter to develop quickly.

full throttle

Thanks Flyfalcons, makes sense!

Jaco

Were the elevator servos in the tail or inside the fuse?

0tter

My Feedback: (39)

WOW, I ended up gluing my horizontal stab. in place. I just wasn't satisfied with the small amount of movement that was apparent. I think this resulted from not getting each stab. in tight to the fuse (I guess) when drilling the tube for the mount?

Perhaps a condition where the fit is a bit loose could have exaggerated the conditions fly falcons described. Too bad....

full throttle

Jaco,

Servs were mounted on the side of the fuse in the tail.