Vibrations

[cambs flyer]

OK back to what matters, shortly before my short leave I'd had the worst accident with the 450 to date, since then everything bent or broken has been replaced, new Gyro, tail servo, all main servos, main/feathering shafts, blades etc.

Now when she starts up the tail turns almost 90 degrees to the right, once a good head speed has gained strength I can turn the tail back to tail in, but the main rota head has really bad vibrations like a bent main shaft or after an accident without fixing any bent parts, however once airborne shes as smooth as silk, I've adjusted the blades and the tracking is perfect, she holds good regardless what direction, but she does sound a little different and TBH I'm fresh out of ideas, I've checked all the parts, making sure the Paddles are the same length apart etc.

There's no binding anywhere, the main gear and pinion bush move very freely as by the book.

Throttle curve L- 1.0%, 2- 31%, 3- 51%, 4- 70%, H- 96%.

Pitch curve L- 30%, 2- 37%, 3- 52%, 4- 75% H- 90%

Gyro, Rate 0- 80%, Rate1- 20%

Swash Mix, Aile- +80, Elev- -76%, Pitch- +58%

Sub Trim, Thro 0, Elev +71, Gyro (down) 8, Aile +45, Rudd 0, Pitc +20

I know it's a mess, and I didn't really have time before to do any better, however if anyone can offer a few recommendations I'd be really grateful

Thanks.

[Sieze2]

Sub trim of 71 sounds alot bud? Might be an idea to move/change the servo horn.

Regarding the problem in hand, if you have fitted new shafts all round, the blades are ballanced, and the paddles are the same weight/distance, the only other possiblities off the top of my head:

Motor is vibrating (spin it up while holding it to check) or main gear is on wonky. I am sure others will come up with more, but that the best I can do for now.

Did you check the tail shaft, that can create some wicked vibrations.

[cambs flyer]

OK, I've just tried a different set of main Rotas and it made the vibrations worse to the point where she nearly toppled over?

[machasm]

Hi Wayne,
Sometimes the tail will turn on initial startup especially if the blades spin up quickly (no soft start) as the torque produced twists the heli but the tail has not picked up enough speed to counter-act it.
Also if the head is wobbling a lot are the blades too tight in the grips?
If they are when you spool up unless they are dead straight then this can cause a wobble as one side would be unbalanced from the other.
Once headspeed is high enough the centripetal force pushes the slighly cocked blade straight and the wobble disappears.

[cambs flyer]

Sub trim of 71 sounds alot bud? Might be an idea to move/change the servo horn.

Regarding the problem in hand, if you have fitted new shafts all round, the blades are ballanced, and the paddles are the same weight/distance, the only other possiblities off the top of my head:

Motor is vibrating (spin it up while holding it to check) or main gear is on wonky. I am sure others will come up with more, but that the best I can do for now.

Did you check the tail shaft, that can create some wicked vibrations.

Cheers bud, I'm a little unable to anything else right now, but clearly I have a lot to check, when I held her and spooled up before changing the blades she seemed quite steady, however on the ground is another thing.

[GizmoB73]

Hi Wayne, long time no speak. It sounds like it could well be blade balancing to me.

[Twister3D]

Hey Wayne

Welcome back fella, hope all ok

1: the 90 deg business is probably your soft start is (off) on your esc set-up
2: After my 450 crash it seemed nowhere near as smooth on start up, also sounded slightly different sort of nosier, but as you said flys as smooth as silk.
so dont worry too much
3: Why do you need sub-trim on GYRO, I cant see what thats for? then again I do not have a DX7.

[cambs flyer]

Adrian thank you mate.

The new red blades are very tight in the grips, to the point where I need to force them in, however an older set of black 325's are a bit looser and create dangerous levels of vibrations.

I've checked all the dampeners and spacers and everythings where it should be, bit of a puzzler this one.

[Made2Fade]

Wayne id find better servo arms for both aileron and elevator mate as both subtrims are unsatisfactory for me anyways. Did you replace the tail shaft like i told you last time we spoke? You'd be surprised how much vibes you can get off an even slightly bent one. Only other things i can think of is the main shaft bearings or blades too tight in the grips. Maybe even a bent shaft on the motor (pretty unlikely but you never know). When you crash a model the vibes/impact from the crash transfer right through the heli and it is possible they reach the motor shaft. A video would be a good way to get help here if you can sort something out mate.
Cheers
Lee

[cambs flyer]

Gary hi mate long time no see, or fly, yea the balance was first on my list, but the older 325's worked fine before (back in the days I was a tart and the slightest blenish made me change everything, lol) but they never made this much hassle?

Thank you too Dave, indeed it's a little better thank you mate.

I'll be honest I don't know about the soft start on the ESC, that side of things is a little over my head right now.

[jimheli]

hi wayne i had same thing one time it was a cracked blade gripe on the arm , allso have you checked all links for play or cracks, if you loosen the blades a little not to loose mind & spine here up slowly then stop & re pinch them that works for me allso check all screws in leavers & balls are tight , cant think of any thine ells jim

[Made2Fade]

check all screws in leavers & balls are tight , cant think of any thine ells jim

Yip they can be missed alot of the time and i have done it in the past myself. Physically try and move each ball by hand. Sometimes the screws that hold them in can come slightly loose and you cant even tell. It puts little movements on the balls which travels up through the links etc.

Lee

[cambs flyer]

Thanks guys for your suggestions, I've just ran a complete batt through her and to say she's gutless compared to before is an understatement, plus just before I landed she started to go nose in like before, luckily I was only about 7" off the ground and landed quickly.

There seems to be a kind of screeching noise coming from the tail end I think, I upgraded the gearbox to alloy, but not the blade holder or movement arm, the main head is all alloy, and when I looked closely while she was in flight the head still had vibrations going through it as I could see the blur on the Swash and other parts.

I'm grounding her for the time being as I can't afford another £60 repair bill, as what evers up with her is beyond my knowledge level even if told what to do.

All I know is all these problems started when I changed over the ESC & Motor, prior that she was fine, but as for extras parts now it'll have to wait a bit.

[Rob O]

Could it possibly be a loose and slipping tail belt , or even a tight belt Wayne , just from what you say it sounds like it's certainly a problem at the tail end , Rob

[robgt]

Check your motor pinion to main gear mesh - if thats too tight it will squeal, and certainly not deliver the proper amount of power.

Cheers,
Rob