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nasty tail wag

Old 01-21-2007, 01:40 AM
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Default nasty tail wag

Ok, I've got a gy401 with a HS55 servo.....I've also got a Multiplex radio, so I'm not looking for any real help with that... allthough, I should mention that I've got my throws at 100% and am limiting the servo travel with the gyro itself.
The problem is that in a hover the tail doesn't move at all, it's rock solid. Same for when I punch it full pitch and shoot it skyward and then slam it the other way full negitive. Rock solid. Fast forward flight is another story all together, wags something nasty. It's the absolute worst while doing a hammer head or some other stall type manuver. I've tried turning the gain down...and then up...so far I've tried it from 20% to 80% and everywhere inbetween and it acts about the same. My hover stablitly is perfect right at 40% I should probably mention that I have the ball mounted on the servo horn in the second to last hole....Might be it???
I've tryed messing with the delay a little. I used to have a little hover wag and played with the delay.... turned out it was a temp problem there. Let it sit outside for a 15 or 20 minutes befor the flight and...well, like I said.....Rocksolid...
Anybody got any ideals? Mechanical? Servo??? Mounting???? Oh yeah, mounting. I've got it mounted on top with two layers of 3M double sided tape. It's cheap stuff they sell at the supermarket. It's not nearly as soft and foamy as the stuff that comes with it. I've read somewhere that that can effect it... but I thinking that was a vibration problem.... I've got no vibration problems, it's super smooth. Blade tracking is spot on and ALL the shafts are strait and true.
Many thanks
Old 01-21-2007, 02:30 AM
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Default RE: nasty tail wag

Move the ball in on the servo horn and redo the limit setting, if that doesn't do it then you're going to need a better servo.

I presume you've made sure the linkage is completely free of binding and you're running decently stiff tail blades. Upgrading to the latest tail linkage is worth while too.
Old 01-21-2007, 07:35 AM
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Default RE: nasty tail wag

It was explained to me that the tail rotor needs to mechanically set. If you set it with the radio (endpoints) It will reek havoc on the gyro.

Hope it helps.
Old 01-21-2007, 01:52 PM
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Default RE: nasty tail wag


ORIGINAL: Andrew McGregor

you're going to need a better servo.

Old 01-21-2007, 02:03 PM
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Default RE: nasty tail wag

The HS 55 is is a terrible servo for the precision that the tail rotor needs. Get a 9650 or if you are on a budget a HS81. If you use the 9650 don't forget to switch to DS mode. The servo limits on the radio have nothing to do with the throw of the servo on the heli when using the 401. The throw is set by the pot on the gyro and the piro rate is set by the limits. The aux channel sets the gain and switches between hh and rate mode. If you haven't read the gyro directions take a look at them. I bet it is just the crappy HS-55 servo that doesn't work. Good luck.
Old 01-21-2007, 07:37 PM
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Default RE: nasty tail wag

Hey thanks guys,
I was somewhat suspecting the servo.... they are really cheap servos.... What about the HS65? Still to cheesy? What about this HS81? I'm not familier with that one. Metal gears? Digital?
The thing that puzzles me is that it wasn't allways like this... maybe the pot is worn. Anyways, I'll try it. If I can get a good deal on it, it will be the 9650 but I'm going to be looking for the HS81. Anybody tried the Multiplex mini digitals? Allthough multiplex products are really hard to program "right"... Well, I just love my old nasty cockpit MM. I was thinking about junking all the HS55's in my bird for the multiplex's but I haven't heard much of anything about them other than from people trying to sell them... Which is the same crap I heard from the guy I bought the HS55's from.... Anybody running full digital servos on the swash? I can program my radio and receiver for digitals on everything. Any big pros or cons from digi's on the swash? The thing that I'm most motivated by is that I've fried one of the HS55 allready, not on the tail, but the guy at the LHS just gave me a new one for free. I would perfur not to have another one go out. It's really fun to land with a roasted servo
Anyways, thanks for the help.
Old 01-21-2007, 10:31 PM
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Default RE: nasty tail wag

lose the hs55 all the the way around. One slight bump and the gear train is toast in a heli. If you go with digi's all the way around you may need an seperate BEC. The HS65 is a great servo just not for the tail it is too slow. Use them on the cyclic. The HS81 is fast and centers well for the money. Don't know anything about the multiplex stuff.
Old 01-21-2007, 10:43 PM
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Default RE: nasty tail wag

Personally, I'd say, if you want cheap, get Blue Bird 306BBs. They're good on cyclic, OK on the tail, and very cheap. They're also tough as old boots because they use the same gears as the much stronger 371. I ran a 371 on the tail for ages, and was very happy with it. I've got an HDS877 on there now, which is better but not amazingly so.
Old 01-22-2007, 12:53 AM
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Default RE: nasty tail wag

the hds577 is the better one i have been told. Mine is sweet!
Old 01-22-2007, 03:50 PM
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Default RE: nasty tail wag

I've got HS65HB on the cyclic servos and so far they've been great. I think I paid $70 for three of them.
Old 01-22-2007, 05:47 PM
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Default RE: nasty tail wag

As far as the HDS servos are concerned apparently they both work great for awhile but the smaller one (577?) has been known to burn out quickly when used in the DS mode of the 401 gyro. You can get the digital control board from the HDS servos for about $10 and convert most small servos over to digital including the HS-65 and the HS-81.
Old 01-22-2007, 10:55 PM
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Default RE: nasty tail wag

What what???? really? What about the pot? How is the servo speed effected on the HS65 and HS81's? Now you've done it! You mean I can justify some mirco surgery! MAHAHAHAHA "evil laugh" Has any body actuelly done this? Who sells just the board? Got any pics???? What about radio setting? Multiplex digi setting aren't all that compatable with Futaba.... but it really shouldn't matter...should it? Just a regular servo input 4.8VDC-6VDC pulse .6ms-2.4ms at 40 Hz right??? Oh buddy, you got to share on this one.
Old 01-23-2007, 09:28 PM
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Default RE: nasty tail wag

ashtekelectronics.com The speed won't change that is set by the motor and the gear ratio but the holding torque should go up. There is a web page that shows the mod but I can't find it. Only some servos will work with it. Some servos the boards are hard soldered directly to the motor and pot and can't really be modified as far as I know. Check out runryder.com and rcgroups.com to find a link.
Old 01-23-2007, 09:31 PM
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Default RE: nasty tail wag

http://ashtekelectronics.com/tutorials/digi/index.html thats the link
Old 01-27-2007, 01:39 PM
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Default RE: nasty tail wag

Hey guys,
Thank you! Replaced the tail servo with a 9650. Wow, what a difference. Rock solid no matter what. No twiching while stalling or even hauling ass backwards and upside down.
I also replaced the others with those HS65mg's.... I might tinker with those and turn them into digis but I don't think they need it. Those things are stought, really fast and center great. Thanks for everyones input.

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