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HelicopterRadio - Servo - Gyro - Gov - Batt › Periodical tail swinging with a GY-401/9254
06-02-2004 08:47 AM  13 years agoPost 1
Zerofreak

rrNovice

Tórshavn, Faroe Islands, Europe

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Hi!

Sorry, my english is not so good, but I will try my best.

I've got a new GY-401/5294 on my new Evo, and I'm very pleased with it. But now is the tail beginning to swing periodically both in hover and in fast forward flying. And the symtom is both in HH and in Normal mode.
I've never chrashed with the Evo yet, and have not done any canges otherwise than adjusting Pitch/Throttle Curves.
Have replaced the Rudder Servo and cheked almost everything, but can't find anything wrong.
Can the problem be the Gyro

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06-02-2004 09:58 AM  13 years agoPost 2
cjw

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UK - Cheshire

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Hi,

If the tail is hunting back and forward, you could have the gain too high. If the tail is swinging as you increase collective, such as in a full power climb, then the gain is probably too low. Try increasing / decreasing the gyro gain.

Other possibility is that your engine is running rich and 4 stroking, giving the whole heli a kick every now and then. This could also cause the tail to twitch a little, but probably not swing.

Clive

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06-02-2004 11:19 AM  13 years agoPost 3
pistole

rrVeteran

Heli Land ....

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Hi.

Do make sure that your linkage is smooth and no binding occurs.

.

Rap70. TT70.Rap50. TT50.RD8000.

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06-07-2004 09:22 AM  13 years agoPost 4
Zerofreak

rrNovice

Tórshavn, Faroe Islands, Europe

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Hi

I have now confirm, that my problem with tail swinging can't be a Gyro issue, because the sympthom is worse if the left side of heli points against the vind, than with the right side.

Thanks!

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06-07-2004 10:18 AM  13 years agoPost 5
Parsifal

rrVeteran

Singapore

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Funny you should mention this issue, i started having the problem with my 3 year old 401/9253 a couple of weeks ago, i would lose authority in the turns, more so when i was applying right tail inputs (with the tail turning into wind).

I would have to use lots of stick movement to get it half way round then the wind would join in and kick the tail around... basically, it started to feel generally soft all around in terms of tail authority, just worse in one direction.

Figured the gyro was three years old and had been crashed numerous times before so i got a new 401 / 9254 set.

Everything is fine now, tail is pretty much rock solid and i have tons of authority.

Its strange that you are facing a similar problem with a brand new set... Perhaps its just faulty, perhaps you could try another gyro in place of the 401 (borrow a friends or something) and see if it is indeed the gyro..

Pars.

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06-07-2004 09:53 PM  13 years agoPost 6
Zerofreak

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Tórshavn, Faroe Islands, Europe

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Hi Parsifal

Very interesting.
I just thought that it have to be a mecanical problem, when I found out that different vind direction on the Heli changes the output of the symphom.
So perhaps I should try another Gyro anyway.

Thanks

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06-07-2004 10:29 PM  13 years agoPost 7
mrNoodles

rrProfessor

Borlänge, Sweden

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How much gain do you use in normal and HH mode?
What radio and how long servoarm?

/Fredrik
'Hm now I just have to find out where to connect the GV1 sensor to the Jazz80 ESC.

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06-08-2004 03:49 AM  13 years agoPost 8
Parsifal

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Singapore

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I thought it was a merchanical problem at first too... i changed to a carbon tail rod, (but that i wanted to do for ages anyway coz it looks cool ) but the problem still cropped up. At first, half way through my flight and then earlier and earlier...

I figured, no sense in tempting fate so i bought the new gyro/servo set. And now everything is rock solid again.

In your case, i am just surprised that the gyro is new...

It could also be the fact that your tail blades are not sufficiently long. I felt my tail was a little weak with the original blades and got myself a set of 95mm NHPs.

I don't know what level or flying you are at at this stage but perhaps you are finding it more of a problem now because your flight envelope has increased and you are throwing it around more maybe?

Pars.

Ps: My gain is 54% in AVCS i think.. i'll have to check... to be sure though..

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06-08-2004 12:10 PM  13 years agoPost 9
Zerofreak

rrNovice

Tórshavn, Faroe Islands, Europe

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Hi

mrNoodles - In HH I use 40% gain and in Normal 50%, and I have tryed both more and less gain but with same result.
I'm using a JR-3810/PCM Radio and my TailServoArm is 17mm long as in the Evo-manual.

Parsifal - With Freya Tailblades witch are 92mm long, the symphon is much more visible vs. Evo Tailblades witch only are 87mm long.
Well - my flying skills is progressing to basic aerobatics, such as Loops/Stall Turns/Rolls, and yes I am throwing the heli more around now than before.

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06-29-2004 03:49 PM  13 years agoPost 10
gnichola

rrApprentice

Santa Rosa, CA. USA

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I have a new (2 months) old 401/9254 combo and I am noticing that the tail lets go occasionally. But only on my 2nd or 3rd flights. I flew a lot of backwards yesterday on my first flight. I landed fueled up and went back up. Mid flight I was making a medium speed backwards inverted pass and the heli spun completely around. I landed right after that and checked the 9254. I did notice that it was hot, almost to the point of burning my finger.

I don't know if the heat is a problem or not, but I bought a small heat sink and mounted it to the bottom of the servo. I will fly today and see if the heat sink even gets warm and if it helps.

Regards, Guy

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06-29-2004 09:17 PM  13 years agoPost 11
TMoore

rrMaster

Cookeville, TN

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Are ya'll running 4 cell packs?

Terry

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06-29-2004 09:24 PM  13 years agoPost 12
sbalder

rrApprentice

Brighton, Michigan

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For what it's worth, I had to increase the gain on my GY401 to a point that was rediculously high to keep it from drifting. Much has been written about the slop in the EVO tail blade grips (that it has no effect in flight.) I disagreed that it wasn't harmful and fixed the problem by fitting a set of Miniature Aircraft grips. Others have gone to a Freya hub and grips. Anyway, when I eliminated the slop I was able to greatly reduce the gain and had good tail authority.

-Steven Balder

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06-29-2004 10:48 PM  13 years agoPost 13
G.Man

rrProfessor

Bristol

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Your engine is running smooth and not barking isnt it?

Are you PPM or PCM?

If its PPM it may be a glitch?

Don't Email me as I wont reply - PM Only (spam countermeasures)

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06-30-2004 04:39 AM  13 years agoPost 14
gnichola

rrApprentice

Santa Rosa, CA. USA

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Well, I flew today and the results were much better. I flew quite a bit of backwards without any incidents. My heat sink did get slightly warm, so it was doing something. I think it would be better if I mounted a pair of them to the sides of the servo, but still, I will have to investigate further to see if I have something wrong that is causing the over heating issue.

I am running a 5 cell rx pack through a 5.0v regulator.

Later, Guy

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10-31-2004 06:22 PM  13 years agoPost 15
Zerofreak

rrNovice

Tórshavn, Faroe Islands, Europe

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Hi

Well, at least my Tailproblem is resolved.
First I tryed another Gyro, but the problem was still there.
Then I shorten the Tail Rotor Servo Arm from 17mm to 14mm and reset End Travel Adj on top of the Gyro, and BINGO.
Have tryed the newer configuration for about 1 month now, and have not recognize any tailswinging.

Thanks

Jógvan Hansen

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HelicopterRadio - Servo - Gyro - Gov - Batt › Periodical tail swinging with a GY-401/9254
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