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Old Jul 12, 2003, 03:43 PM
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Joined Jul 2002
527 Posts
Corona tail Servo Died in flight?????

Ive been using an HS-81 servo and an Ikarus micro gyro on my tail for corona for over about a year and then i switched to futaba
GY240 and used it for about 3 months and this evening my servo died on me in flight. The heli was piroretting and go thing i can fly nose in.

I checked for stripped gears and there were none; the servo just died.I use it on HH and and just below 50% sensitivity. Is that to much for the servo?

I also notice that the servo is constantly moving rapidly in a 1-2mm range during flight. There are no noticable vibrations on my corona.

What should I do?

Thanks
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Old Jul 12, 2003, 04:29 PM
A man with too many toys
United States
Joined Feb 2001
17,778 Posts
HS-81 servos are not very durable. Controlling the tail rotor on a helicopter is very hard work. These servos work well you just have to replace them often. A more expensive Futaba or JR servo would be more durable. I think that most (including me) just replace keep replacing HS-81 servos. It seams like the newer ones donít last as long as the old ones did Ė or maybe itís just because I fly a lot more. Some think the GY240 in the HH mode is easier on servos. This may be true because I notice very little activity on calm days.


Decreasing gyro gain should help; the tail control will just be a little sloppier. For the fixed pitch Corona itís not really necessary to get a hard lock on the tail. . I fly my GY240 at 70% gain in the HH mode so you are way more conservative than I am.

Just replace and go back to flying.
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Last edited by RC Man; Jul 12, 2003 at 04:33 PM.
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Old Jul 12, 2003, 05:38 PM
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Honolulu Intl, Hawaii, United States
Joined Feb 2003
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I agree, it was probably just coincidence that your servo was about to go and nothing to do with the Futaba gyro, that is an awesome gyro. Over a year on that servo is pretty stinkin good, well depending on how much flying you did...

50% is a really good setting if you're happy with the tail, I used to run my gy 240/hs-81 on my corona, gyro gains were at about 65-70% and I haven't had any probs at all for the 60 flights or so I had it
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Last edited by Astro30; Jul 12, 2003 at 05:41 PM.
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Old Jul 12, 2003, 08:07 PM
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Thanks guys,

But when you are flying you don't notice much tail servo activity?
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Old Jul 13, 2003, 08:55 AM
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lenrev's Avatar
Grayslake, Illinois, United States
Joined Mar 2001
352 Posts
I had the TR jitters at one time and found my gyro mount had loosened. The gyro (JR) was on a platform behind the MR near the top of the crutch.

Eventually moving the battery to the skidsd allowed me to put the gyro on the battery shelf and eliminated the movement.
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Old Jul 13, 2003, 10:43 AM
A man with too many toys
United States
Joined Feb 2001
17,778 Posts
I hope everyone is aware that Kyosho Vibration Mounting Gel is the best for mounting any gyro. This is much better than the rubber stuff that comes with gyros. This is also much stickier and absorbs a lot more vibration. I have used it on all my gyros for many years and would never install a gyro with anything else.

http://www2.towerhobbies.com/cgi-bin...FVSEARCH=z8006
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Old Jul 13, 2003, 10:44 AM
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yup, thats what im using too.
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Old Jul 13, 2003, 12:45 PM
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United States, NY, Mechanicville
Joined Mar 2003
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EP -
I have seen the excessive TR servo movement. I like to call it "pumping". The servo is moving +/- 20 percent, extremely fast, so fast that you don't even see it as wagging or hunting..

Couple of things-
#1- I turned the gain down until it stopped pumping. Settled in at about 50-60%.

#2- Vibration. By getting rid of my vibrations, and using good foam for the mount, I was able to get back up to about 80% gain before it started pumping the servo.

#3- Replaced the Gyro. It was a JR GY460T, and it had been beaten by the last owner. After replacing it, I can go to 100% with the pumping (but it does hunt at 100%)

Good Luck..
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Old Jul 14, 2003, 03:34 AM
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San Carlos, California, United States
Joined May 2002
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Same thing happened to me today.

There was some wind, and I was flying up and down the field and as it was flying back towards me I noticed I couldn't turn. Wag the rudder back and forth...no response. The wind was holding the tail steady, so I landed her and checked the tail servo - sure enough, it was dead.

Toshi
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