Ultimate Fun Fly flutter and CG
10-29-2003 | 01:43 AM
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From: Clinton, MS
Ultimate Fun Fly flutter and CG
Anyone had any rudder/elevator flutter issues on this plane? I moved the servos to the tail for balance (Saito 80 out front) and to cut down on flutter but i still get some...usually in a harrier or hover where there is little forward airspeed. I sealed the hingeline on the elevator and it helped some but it still happens occasionally. Also how far back has anyone gotten with the CG...I'm a bit nose heavy at the CG indicated on the plans but with more time on the sticks I'll want to bring it back. Thanks for any help...all input is appreciated.
Rocky
I don't do tail touches...I do NOSE touches!
Rocky
I don't do tail touches...I do NOSE touches!
10-29-2003 | 01:01 PM
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From: Clinton, MS
RE: Ultimate Fun Fly flutter and CG
Standard Futaba servos with heavy duty horns, 2-56 pushrods with keepers on the servo end and locking clevises (clevi?) on the control surface. There is no slop in the linkages, but I'm wondering if maybe I have the pushrod too far out on the servo arm and too far in on the control surface horn, putting the servo at a mechanical disadvantage and it's having trouble holding center. I'll tinker with that a bit this afternoon and see what happens.
10-29-2003 | 01:14 PM
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From: Bartlett,
TN
RE: Ultimate Fun Fly flutter and CG
Are you saying that you're having low speed flutter? I've never experienced that before....
Now if you're talking about the tail surfaces moving around a little in response to the prop wash from the engine... Then yeah... No big deal.... Just make sure your linkages are slop free and then torque it on the deck!!!
You mentioned you were using 2x56 linkages.... You might want to make sure you have the jam nut up against the clevis to lock it in place... Otherwise it'll work around on the threads some and make things a little sloppy. You can also try ball swivels as an alternate... Gives a very crisp control response....
Now if you're talking about the tail surfaces moving around a little in response to the prop wash from the engine... Then yeah... No big deal.... Just make sure your linkages are slop free and then torque it on the deck!!!
You mentioned you were using 2x56 linkages.... You might want to make sure you have the jam nut up against the clevis to lock it in place... Otherwise it'll work around on the threads some and make things a little sloppy. You can also try ball swivels as an alternate... Gives a very crisp control response....
10-30-2003 | 10:12 AM
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From: Menasha, WI
RE: Ultimate Fun Fly flutter and CG
Maybe 50+ ounce inch servos (67 ounce HS-225MGs for my last one) and 4-40 pushrods will help. I generally flew the plane way too fast, and never had flutter. My first one flew on a Rossi 53 with an 11x5 APC and (in level flight) flew full power with no flutter. Also, heavy duty servo arms will help.
Put the CG at least a 1/2 inch (3/4 for me) back from the indicated spot.
Good luck,
Put the CG at least a 1/2 inch (3/4 for me) back from the indicated spot.
Good luck,
