Shaking Heli

[Cralis]

Hi guys.

On about the 5th flight of my EP550 (Carbon pro), the heli started to shake like made while in a hover. Landed (hard) and all is OK. Some guys have told me my tail blades were too slack. Also, we found one of my main blades a bit loser than the other. These have since been tightened, but I have not had a chance to fly. Could these cause a shake??

[Fredrick]

i don't think loose blades are the reason.....
more likely that you have got somthing out of alignment.....
ore maybe your blades are unbalanced.
but keep the main blades tight, and tail blades on the loose side and your safe.

[Cralis]

I haven't check the blade balancing. :( Maybe that? Also, I'm (ever so slightly) out on the tracking...

[Phoinix]

One blade tighter thatn the other may cause the problem. I have all my blades loose to that point wher i can hold the heli at 90° and the blade still doesn's swing around. Blades have to have lead lag motion enabled!


I got the shaking problem when i configured my flybar links to the outer position on the flybar. The heli was shaking around the longitinal axis pretty violent. The problem went away as i reconfigured the ball link back to the center position.


If you haven't checked the blades for balance, thatn that is one big failure in the preflight check and you can be happy you got away with no damage. I'm surprised, you have 3 helis and you missed that basic error.

[Fredrick]

Could not agree more Phoinix.
if your gonna fly heli's then you have to go thr xtra mile and do it properly... imo. do all the preflight check needed to keep people around you as safe as possible including you self ;)

[Cralis]

Aye, fair enought... I was under the impression that carbons didn't need balancing. I guess I was wrong... Will balance them... just... need to work out how...

[oppie]

I have a real bad shake on one of my T450s. It happens near the end of a flight when I flip back to normal to land. I was thinking I need to up my throtle in normal to get more head speed. It is set at 0-25-50-75-100. Might up it a little and see. I also think my TP 2100 is getting week, nearing 75 to 100 flights on them.

[CompuFoil]

oppie, check for a bent flybar. A bent flybar will causethe heli to shake at low speeds, but smooth out nicely at higher speeds.
Eric

[oppie]

Eric, good thought I just checked my flybar and it is straight. I havent had any crshes in a long time:oops: Oh I'm going to be sorry I said that! I'll try and change my throtle curves and see if that is it. It is turning very cold here I flew yesterday it got up to 50 but no good weather for tne near future.

[Pinecone]

That is WAY low on head speed with that throttle curve.

I run 0 - 60 - 80 - 90 - 100. You are trying to hover at about 50 - 60% throttle.

[ke6d]

That is WAY low on head speed with that throttle curve.

I run 0 - 60 - 80 - 90 - 100. You are trying to hover at about 50 - 60% throttle.

50%-60% is way too low, the heli is unstable but I don't think it will shake (vibrate). I would first change the throttle curve to what Pinecone is suggesting, remove the main and tail blades, then spool the heli up on the ground to see if the vibration is gone. Balance the main blades, put the main and tail blades back, then spool the heli up on the ground with 0 degree pitch. You should be able to find out where the vibration comes from.

Dan, KE6D

[Pinecone]

I also found my tail baldes were 0.1 grams difference in weight and giving me some shake. I balanced them in weight ( should have pulled out the balancer), and a lot less vibration.

[dennis22g]

A little about Vibration....
I have just read what was said about balance and vibration. I agree about the balance and the flybar shape. I have just checked all that on my 550 but I have found a unique situation (I think)

My balance problem is as the heli is on the ground and the throttle is cut. I just drop the stick to the bottom and as the head speed decreases the cha-cha starts. It is on brick pavers, so there is not much grip, similar to concrete, but the bird just moves all over the place. Probably the total distance is 6 inches from side to side, but it also jumps about 1/4 inch in hops and has some rotational movement. This happens for a few seconds till the blades slow right down.
Quite frightening really...
I have put some other info on my other post but I would really appreciate some help here!
I am so keen to see the big bird fly! :)

[Wazzer]

A little about Vibration....
I have just read what was said about balance and vibration. I agree about the balance and the flybar shape. I have just checked all that on my 550 but I have found a unique situation (I think)

My balance problem is as the heli is on the ground and the throttle is cut. I just drop the stick to the bottom and as the head speed decreases the cha-cha starts. It is on brick pavers, so there is not much grip, similar to concrete, but the bird just moves all over the place. Probably the total distance is 6 inches from side to side, but it also jumps about 1/4 inch in hops and has some rotational movement. This happens for a few seconds till the blades slow right down.
Quite frightening really...
I have put some other info on my other post but I would really appreciate some help here!
I am so keen to see the big bird fly! :)

I get the same thing but on the spool up not the spool down with my Shogun 400 would be very interested in finding out what type of thing may cause this.

Cheers

Ben

[mjdee14]

try tightening the blade grips a little more....sometimes on spool down one blades gets a little behind the other and puts the head out of balance. I had the same thing with my ECO8 and after tightenign them, the vibs went away.

[Cralis]

I saw this on a mates EP550, and tightening the main and tail blades fixed it... this might be your issue. Hope it is. Good luck!

[mjdee14]

My balance problem is as the heli is on the ground and the throttle is cut. I just drop the stick to the bottom and as the head speed decreases the cha-cha starts. :)

What are you running for neg pitch in normal mode...?

If you dump the stick and you have lots of neg pitch it puts a load on the blades...then one gets behind the other and you get the "chicken dance"

That is where the blade tightening comes in...the blades stay in position till they stop.

When I fixed my ECO8 an experieinced heli pilot had me tighten the main grips "much" more than just the normal "blade does not fall under own weight"

tighten a little at a time and see where/if the vibs stop.... they still have to be able to move...but at 1500 - 2000 rpm they should fling themselves into position. If that doen's work.....go looser..maybe you have one too tight and it's not allowed to follow the other blade....they both should feel the same

[woz]

Dennis , IMHO go with the pitch issue and the blade grip tension and the tracking of your blades - seen the renowned ' Chicken Dance' solved with addressing these 3 issues.
One other thing that may contribute is ground resonance and have put the rubber stoppers on my skids. very little of the chicken action if any !

good flying
Warren

[dennis22g]

To my very learned friends: I think you have all hit the nail on the head.
That is one thing I noticed at the end of one of my 'dance' sessions. One blade was bent!

I have set the normal pitch at neg2 for windy conditions as my trex450 has a bad habit of floating away when landing (although I usually land on idleup now.) and as I have not flown above a hover with the 550 I wanted to be safe.
I do agree that on fast deceleration the neg pitch could contribute to blade movement so I will tighten my blades some more. I didnt do that in the first place because I got a big wobble on startup, so I thought my blades were too tight. I have found that my tail blades were a reasonable bit out so I fixed that. Fingers crossed.. I hope I havent bent my main shaft in getting the Chicken Dance!

Boy I can hardly wait for this tropical wind to stop over here in Brisbane so I can get this bird in the air.This Hurricane is sure different from the Aligh trex450.

WAZZER - I would be interested to know if this fixes your problem also......

Thanks guys,
I really appreciate your help and consideration.

Dennis

[Jungle Bob]

This may help. Just flew my Hurri this morning having painted one blade tip for orientation purposes. Heli all over the place with heavy vibration, balanced the blades by adding a bit of tape to the unpainted blade, balanced, no vibration....job done! Very surprised how much three thin coats of paint could effect the performance!

[Wazzer]

WAZZER - I would be interested to know if this fixes your problem also......

Thanks guys,
I really appreciate your help and consideration.

Dennis

Hey Dennis

I didnt have a very good flying day today so didnt have chance to try out your theories.

as soon as i get back from my short new years break i will give it a go.

Cheers

ben