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Old Oct 11, 2012, 12:59 PM
FPV Noob KD0VMK
United States, MO, Platte City
Joined Jun 2012
432 Posts
Help!
Wiggle Waggle Woes

I'm at my wits end, so I've come to you, almightly heli gurus, for help. I currently have an HK450V2, that I have never been able to keep from tail wagging.

I'm using an assan GA250 gyro, and an older 72mhz JR X388S radio. I currently have the radio set to use the Aux2/Rudder dual rate switch to control the gyro.

I have set the rudder dual rates (supposed to be the gain), from 0 to 100%, and everywhere in the middle. It seems to have no effect at all on the tail. I've also tried the rudder travel adjustment, no effect. I've heard that the gear channel travel adjustment will sometimes control gain, so I've set that from 0 to 100 and everywhere in the middle. No effect.

on the gyro side, I've tried various end points, and every delay setting available. The delay setting changes the waggle a bit, but it still does it.

It will also wag it's tail even while in rate mode, which is really strange. I'm beginning to suspect a faulty gyro/damaged gyro. I had a "hard landing" a couple weeks ago, and the impact somehow reset all the gyro settings. It still seemed to work fine, but the wag got 10x worse afterwords (though it has always been there). Does anyone have any ideas? I've tried about everything I can think of, and I'm about to start replacing parts.
Thanks all.
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Old Oct 11, 2012, 02:44 PM
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Philippines, Calabarzon, San Pedro
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Maybe your tail servos too slow?
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Old Oct 11, 2012, 03:19 PM
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Australia, VIC
Joined Dec 2011
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Yeah , too slow a servo could be a problem ...
Or the gyro simply does not like the tail servo [ compatibility ]

PS / what tail servo are you using ?
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Old Oct 11, 2012, 03:31 PM
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Joined May 2010
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I have the assan ga250. I wasn't lucky enough to get it to work right. I'd suggest trying out the gy48v. Its in the same like 10 dollar price range and imho, its a bit easier to work with.
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Old Oct 11, 2012, 03:33 PM
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Wiggle Waggle Woes

You said you had a hard hit a while back. I had a similar problem a while back and it turned out that the set screw for the tail shaft was loose
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Old Oct 11, 2012, 03:49 PM
AMA# 548800
jombo's Avatar
United States, CT, Trumbull
Joined Dec 2007
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Quote:
Originally Posted by Chubbs View Post
I'm at my wits end, so I've come to you, almightly heli gurus, for help. I currently have an HK450V2, that I have never been able to keep from tail wagging.

I'm using an assan GA250 gyro, and an older 72mhz JR X388S radio. I currently have the radio set to use the Aux2/Rudder dual rate switch to control the gyro.

I have set the rudder dual rates (supposed to be the gain), from 0 to 100%, and everywhere in the middle. It seems to have no effect at all on the tail. I've also tried the rudder travel adjustment, no effect. I've heard that the gear channel travel adjustment will sometimes control gain, so I've set that from 0 to 100 and everywhere in the middle. No effect.

on the gyro side, I've tried various end points, and every delay setting available. The delay setting changes the waggle a bit, but it still does it.

It will also wag it's tail even while in rate mode, which is really strange. I'm beginning to suspect a faulty gyro/damaged gyro. I had a "hard landing" a couple weeks ago, and the impact somehow reset all the gyro settings. It still seemed to work fine, but the wag got 10x worse afterwords (though it has always been there). Does anyone have any ideas? I've tried about everything I can think of, and I'm about to start replacing parts.
Thanks all.

Try moving the ball on the servo arm in . if its too far out it acts as too much gain too . try setting it about 5 to 6 mm from center of the screw horn
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Old Oct 11, 2012, 04:24 PM
FPV Noob KD0VMK
United States, MO, Platte City
Joined Jun 2012
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Originally Posted by jombo View Post
Try moving the ball on the servo arm in . if its too far out it acts as too much gain too . try setting it about 5 to 6 mm from center of the screw horn
I will give that a shot. I have already done it once (moved 1 hole in), but I am still more than 5 or 6mm from the servo pivot point. Just moving the one hole did seem to make a slight difference. I'll move another one or 2 and let you know how it goes.

It sucks that the gain adjustment on the radio is basically useless. Messing with servo mounting points is a rather crude adjustment compared to radio programming.

The tail servo is the cheapest of the cheap, an HKSCM9-6. Although it's cheap, the speed is pretty good and it hasn't burned up yet, so I really don't believe that's the problem. Even if it's a problem, I don't believe it would cause a tail wag as severe as mine. For compatibility, I have the gyro set to 1520/250, which is the correct setting for the servo from what I've read.

I'll move the servo ball again and let you all know how it goes.
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Old Oct 11, 2012, 10:21 PM
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Australia, VIC
Joined Dec 2011
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Yeah

Quote:
Originally Posted by Chubbs View Post
I will give that a shot. I have already done it once (moved 1 hole in), but I am still more than 5 or 6mm from the servo pivot point. Just moving the one hole did seem to make a slight difference. I'll move another one or 2 and let you know how it goes.

It sucks that the gain adjustment on the radio is basically useless. Messing with servo mounting points is a rather crude adjustment compared to radio programming.

The tail servo is the cheapest of the cheap, an HKSCM9-6. Although it's cheap, the speed is pretty good and it hasn't burned up yet, so I really don't believe that's the problem. Even if it's a problem, I don't believe it would cause a tail wag as severe as mine. For compatibility, I have the gyro set to 1520/250, which is the correct setting for the servo from what I've read.

I'll move the servo ball again and let you all know how it goes.
I think I tried two of those , and not much chop with any gyro I have ..
Go to HK and look at - http://www.hobbyking.com/hobbyking/s...g_0_08sec.html for analog
and http://www.hobbyking.com/hobbyking/s...8kg_0_07s.html for digital .. [ havent tried mine as yet ] 1520us

as well as http://www.hobbyking.com/hobbyking/s...g_0_07sec.html
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Old Oct 12, 2012, 09:01 AM
FPV Noob KD0VMK
United States, MO, Platte City
Joined Jun 2012
432 Posts
I believe I made some progress last night, and I think i've identified the issue: Vibration.

Moving the servo ball link to the innermost slot produced no change of behavior. Adding additional supports to the tail rotor push rod (to try and eliminate some flex) did nothing. Then I remembered that prior to the crash, my gyro was stuck on the heli with a thick piece of foam tape. AFTER the crash, I "upgraded" it, and had a thick piece of foam tape, a heavy metal plate, and another piece of foam tape, THEN the gyro. The idea was that this would isloate the gyro better.

So I returned the gyro to it's previous config....one piece of foam tape. The tail wagging seems greatly reduced. So perhaps I had too much vibration damping and it was getting into a weird resonance? I don't know, but removing the metal plate and one piece of foam tape seems to have reduced the problem.

For what it's worth, the heli doesn't seem to have any excessive vibrations. Even while holding it and running up the rotors (scary!) it feels smooth to me. Not sure if I'll get a test flight today or not, as the winds are 10-15 mph and gusty. I'll report back after a good test.
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Old Oct 12, 2012, 09:19 AM
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Philippines, Calabarzon, San Pedro
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I thought the dampener (metal plate) was a recommended setup. Maybe your foam tapes were too thick and the gyro was waving around like it was sitting on gello?
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Old Oct 12, 2012, 09:22 AM
FPV Noob KD0VMK
United States, MO, Platte City
Joined Jun 2012
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Quote:
Originally Posted by Hajile View Post
I thought the dampener (metal plate) was a recommended setup. Maybe your foam tapes were too thick and the gyro was waving around like it was sitting on gello?
That seems possible. I have 2 types of tape that came with my gyro...a thick black foam tape, and thinner white foam tape. My setup was thick black foam, then plate, then thin white foam, then gyro.

There were no instructions on how it should be done, so I just guessed. Perhaps I should put the thinner foam between the metal plate and the heli? How are others set up?
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Old Oct 12, 2012, 01:51 PM
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United States, CA, San Diego
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chubbs (great name btw, Happy Gilmore?) how is your gyro and servo mounted? Just interested because maybe they need to be more perpendicular or more parallel with each other. I had weird problems with my tail when I had my servo mounted at an offset angle upside down on the tail.

Have you tried a different servo?

I think the more obvious thing I read, if I read right, is that you can't seem to adjust your gyros gain sensitivity, correct?
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Old Oct 12, 2012, 02:04 PM
FPV Noob KD0VMK
United States, MO, Platte City
Joined Jun 2012
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Originally Posted by finguz View Post
chubbs (great name btw, Happy Gilmore?) how is your gyro and servo mounted? Just interested because maybe they need to be more perpendicular or more parallel with each other. I had weird problems with my tail when I had my servo mounted at an offset angle upside down on the tail.

Have you tried a different servo?

I think the more obvious thing I read, if I read right, is that you can't seem to adjust your gyros gain sensitivity, correct?
Gyro is mounted just above the tail boom holder. I don't have a picture, but it looks like this one
http://www.e-voo.com/forum/files/hk450_664.jpg
Mine is mounted in the opposite direction though (servo wires come out towards the rotor head).

The servo is mounted on the tail, again like the picture. It's slightly canted to one side to allow the pushrod a straighter path.

I have not tried another servo or gyro yet, but plan to order one of each with my next HK order (unfortunately, it will be several weeks before it gets here, even if I ordered today). I'll probably end up trying their other cheap gyro, the HK401B. Although it's not a super gyro, it has a longer service history and is more well known than the GA250 I think.

The gain adjustment thing is frustrating. With the gyro vibrating, I won't place any blame on the Tx before I fix the vibration issue. Clearly the gyro isn't going to function correctly if it's not mounted right. But the fact that the extreme swings in gain seemed to produce NO results, is frustrating. Shouldn't it have produced noticable differences in behavior, even if it didn't fix the issue? Is anyone familiar enough with the X-388s radio to tell me if I'm doing it correctly? The manual seems pretty clear that the gain is adjusted by setting the rudder dual rates, but it doesn't seem to work.
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Old Oct 12, 2012, 05:21 PM
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United States, CA, San Diego
Joined Mar 2012
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Quote:
Originally Posted by Chubbs View Post
Gyro is mounted just above the tail boom holder. I don't have a picture, but it looks like this one
http://www.e-voo.com/forum/files/hk450_664.jpg
Mine is mounted in the opposite direction though (servo wires come out towards the rotor head).

The servo is mounted on the tail, again like the picture. It's slightly canted to one side to allow the pushrod a straighter path.

I have not tried another servo or gyro yet, but plan to order one of each with my next HK order (unfortunately, it will be several weeks before it gets here, even if I ordered today). I'll probably end up trying their other cheap gyro, the HK401B. Although it's not a super gyro, it has a longer service history and is more well known than the GA250 I think.

The gain adjustment thing is frustrating. With the gyro vibrating, I won't place any blame on the Tx before I fix the vibration issue. Clearly the gyro isn't going to function correctly if it's not mounted right. But the fact that the extreme swings in gain seemed to produce NO results, is frustrating. Shouldn't it have produced noticable differences in behavior, even if it didn't fix the issue? Is anyone familiar enough with the X-388s radio to tell me if I'm doing it correctly? The manual seems pretty clear that the gain is adjusted by setting the rudder dual rates, but it doesn't seem to work.
dual rates is something different all together, that's weird. Where is the gain, from your gyro, plugged into on your rx?
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Old Oct 13, 2012, 06:52 AM
FPV Noob KD0VMK
United States, MO, Platte City
Joined Jun 2012
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Originally Posted by finguz View Post
dual rates is something different all together, that's weird. Where is the gain, from your gyro, plugged into on your rx?
Gyro gain is plugged into channel 7, or the Aux 2 channel, as recommended by the JR manual.

I had a very brief test flight yesterday, as winds were 10-15mph and gusting. But my problems appear to be fixed! (or at least 90% fixed...good enough). The tail rotor really lacks authority now (since the travel has been cut down so far), but at least the wiggles are gone.

WIth the vibration issue fixed, I'm making other adjustments to see if I can get some responsiveness back. I've moved the ball link 2 holes out on the control arm to get some travel back. I've also plugged the gyro gain plug into channel 5, the gear channel, so see if I can get the TX gain to do anything with that channel. Clearly "Aux 2" didn't do anything like the instructions said they would.


Edit: By the way, I finally found a thread here http://helifreak.com/showthread.php?t=290655 that seems to back up my theory that the metal plate was causing my problems. It seems like some setups just don't work well with the metal plate.
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