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HelicopterScale Model RC Helicopters › Vario EC-135/GY401 Tail problem HELP!
12-21-2003 12:23 AM  13 years agoPost 1
Madman

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Roswell, GA

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Well I test flew the Vario giant EC-135 today. Not very successfully though...

I had major issues with the fenestron and tail control. I am using a GY-401 gyro and 9253 servo. Here is my setup...

Vario EC-135 (large)
Xtreme Mechs
Rossi 65 shimmed for 10% nitro
Cool Power 10%
GY-401 and 9253 combo
Joe Howards new scale 800+mm blades
9Z-WC2

I have flown and setup a lot of helicopters and I have never had as little control or as uncomfortable a feeling as I did on this tail. Tried head speeds from 1200-1450, gains from 70-100%, limits from 50-100% and both Normal and Heading Hold mode on the gyro.

It was windy and the tail response felt like I was flying in syrup. Any given input took a long time to react and when it did, it had that nasty 'pendulum' feeling. It wouldn't stop or start when commanded. In Normal mode, even with 100% gain, a good gust would blow the tail around about 1/8-1/4 turn and correction was like flying on Qualudes.

In heading hold, the tail was certainly more stable in a stationary hover, but a good gust once caused the fenestron to 'stall' it seems altogether and it went almost nose-in and no amount of input put it back - even holding full over rudder. Had to set her down in a weird side angle cross to the wind.

The tail control linkage is smooth as silk so it is not the servo overworking. The gyro was flying in my Airwolf with the same servo and worked fine.

I know these gyros and my 9Z very well - so I don't get it. It's anti-intuitive that a 'cheap' gyro would make it fly better - the 401 in Normal mode is, in effect, a cheap piezo.

Maybe something is 'slipping' in the fenestron. That's ALMOST what it feels like - that or the gyro isn't working at all. The servo pushrod is not it as it is solid at both ends.

What am I missing? Has anyone flown (I mean FLOWN with the capability of doing controlled stationary piros - not using forward flight to 'weather-vane' the machine) this large scale EC fenestron yet? If anyone has - what headspeed and gyro are you using?

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12-21-2003 02:46 AM  13 years agoPost 2
optikaman

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EnglishTown N.J.

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Madman are you running the speedup gears in the tail gear box?
i built and flew the smaller EC135 with skyfox mechanics and had a week tail until i went to the speedup tail gears.

i have been told that you should not use the heading hold function with the fenneston tail.

Alan...

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12-21-2003 03:18 AM  13 years agoPost 3
heliVoY

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NJ

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I don't buy the fact that you can't use heading hold ... I understand not using a super fast servo, but heading hold does not stres the tail any more than manually correcting for drift on the tail in no HH mode ... heading hold basically brings the tail back to the original position, instead of just stoping an unwanted motion ... so if you use a strong, standard speed servo on the fenstron, it should be fine .. as for lack of response on the fenstron, 1. check if the fenstron unit is pointing in the right direction ( flat side of the blades pointing either right or left , depending weather you are tunning CW or CCW rotation on the main blades, 2. what Optikaman said ...

Wojtek

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12-21-2003 03:50 AM  13 years agoPost 4
Madman

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Roswell, GA

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I am running a high-speed digital (9253). What would be the reason not to with the fenestron and to run an analog?

Also, I believe that heading hold will work too. But only if the fenestron itself is efficient enough to control the torque of the heli and external forces (e.g. side winds). I watched today what happens in HH when the fenestron wasn't efficient enough - it stalled, locked over and the gyro reset in a place that required full-over stick to maintain stationary hover. Very interesting to handle.

I am not sure if I have the speed-ups. Can you please help me and send me some info on part # and tooth count?

Thanks!

Mike

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12-21-2003 04:54 AM  13 years agoPost 5
optikaman

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EnglishTown N.J.

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madman i looked up the gears in the new catalog. Depending on the input shaft size this is what i found.

p/n - 95 16 tooth
p/n - 95/1 19 tooth
p/n - 42/19 19 tooth 6mm shaft

Here is my old EC135

Alan...

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12-21-2003 06:23 AM  13 years agoPost 6
DStJohn

Senior Heliman

Ft. Collins, CO

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Hi Mike,
I suspect the 9253 is too weak for the fenestron. My Dauphin manual recommends a 60 n/m servo. If I converted it correctly that is about 80 oz/in. I am using a GY240 and a 8101 servo on the Dauphin and it felt great. Try a stronger servo, the speed is not as important as the strength. Remember you have 8 blades to move, not 2.

Dan St.John
East Coast Scale Helicopters Vario Field Rep

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12-21-2003 06:28 AM  13 years agoPost 7
Madman

Veteran

Roswell, GA

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I'm going to try the simple fix of using a high-speed/high torque analog like some 9204's or 9205's I have hanging around first.

Then if that doesn't work, I'll open the box up and figure out the gear situation.

Sounds like I've got two alternatives to make this work (or both). Thanks guys.

Mike

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12-21-2003 06:34 AM  13 years agoPost 8
Moore

Senior Heliman

California 93094-0940

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READ THIS POST

http://www.runryder.com/helicopter/...fenestron+servo


Mike @
Moore Scale Model Helicopters

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