tail wag

[shaggybirdman]

now i'm getting annoyed. my trex was flying great till i broke the tail housing for the second time. i won a aluminum tail off of evil bay, and installed it. what a pain in the bumm. i had it set nice, but somehow managed to tighten things up too much. oh well i can straighten that out.

i now have tail wag. i have a digital servo, and have the 401 set for a digital servo. the sensitivity set to zero. i wind her up, and before i even lift off i get tail wag. i remove the main blades, and no tail wag. in the last crash o broke the sea saw (part the fly bar goes threw), and replaced it. the main, and feathering shafts are straight. i put the blades back on, and i again get tail wag although sometimes i have been able to lift off, and practice hovering, but then the wag comes back.

i'm going to check the gyro setup again. maybe i missed something, or the servo connection is loose. i just don't know.

if the gyro is setup ok what should i look for? i have another set of blades that i'll balance, and install. hopefully that's the problem. i'm flying a set of fiberglass blades that came with the kit. going to woodies.

trex 450x cde
spektrum
401 gyro

hope that's all the info to try, and figure out my problem, and i was hovering much better too.

[outhouse]

im going with main shaft bearings are probably notchy

wagging is 90% vibration related, the rest can be slop in the linkage, worn pinion gear, out of balance anything, worn bearings, gain to high, servo gears worn, ect.

atleast youve done a good job of tracking it down

[Skarn]

What do you mean by "and have the 401 set for a digital servo. the sensitivity set to zero". What are you referring to by sensitivity? The 401 has a pot for delay and another for limit.

What gain are you running on the gyro? Tail wagging is also caused by too high of a gyro gain.

Skarn

[shaggybirdman]

well the 401 directions say "servo selection""for digital servo, switch to on position." also it says "with a high speed servo such as a S9253 ( i have a S9650), set the delay trimmer to "0"

it was set that way, and the tail was rock solid. the first tail case crash it waged a very little. the second tail case crash it started to wag bad. that's where i am now. i thought i bought spare fly bars, but don't see them anywhere.

i don't think the bearings are bad because it's almost brand new. only like 20 packs threw her. in the last crash there was a tiny piece of fiberglass broke off one blade. i'll rebalanced them, and the 325's i have. i'll report back with my findings.

i checked the main shaft by removing the head, and wound her up. straight as a arrow. i rolled the feathering shaft on my drafting table. no wobble there as well. i'll fiddle with her later. thanks for the input so far. anything else i should check?