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450 Class Electric Helicopters 450 Class Electric Helicopters manufactured by Align, Tarot, SYMA, Airhog, Chaos, HK and similar.


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Old 08-09-2014, 04:52 PM   #1
blorph
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Default Tail spins up to 360 degrees

Hi all. Have a persistent problem with my #2 machine. From my profile: Originally was a lowly TREX 450 SA but after a couple hundred crashes now has an all metal flybar head, carbon frames, HK swash, Sonix carbon main blades, Spektrum AR 6200 receiver, Spartan Quark gyro, Gorilla Gear and a Rotor Drive 1700K 6s motor.

Recently it won't hold heading. I've set it up in rate mode to hover pretty much hands off and then binded the radio to the receiver again. I recently replaced the old tail gyro with a TGY-S306G. It has no vibes that I'm aware of. I can shimmy the tail back and forth by hand as fast as possible and it responds incredibly quickly, in the correct direction. The tail belt is tight. It has a new Tarot tail.

I lift off in Normal mode, about 60% rpms and all is well. Then I switch to Idle 1 (80%) and after a few seconds the tail gets very lazy and will slowly turn right (the hard direction). After a few more seconds it will let go and spin right at a fast rate, too fast to keep up with and a crash results.

The TGY tail servo is new but seems to get rather warm. The Spartan Quark is prolly 2 years old. I'm thinking it's one of those.

Any thoughts?
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Old 08-09-2014, 10:27 PM   #2
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Sounds like binding in the tail someplace

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Old 08-10-2014, 09:54 AM   #3
salrica
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Quote:
Originally Posted by blorph View Post
Hi all. Have a persistent problem with my #2 machine. From my profile: Originally was a lowly TREX 450 SA but after a couple hundred crashes now has an all metal flybar head, carbon frames, HK swash, Sonix carbon main blades, Spektrum AR 6200 receiver, Spartan Quark gyro, Gorilla Gear and a Rotor Drive 1700K 6s motor.

Recently it won't hold heading. I've set it up in rate mode to hover pretty much hands off and then binded the radio to the receiver again. I recently replaced the old tail gyro with a TGY-S306G. It has no vibes that I'm aware of. I can shimmy the tail back and forth by hand as fast as possible and it responds incredibly quickly, in the correct direction. The tail belt is tight. It has a new Tarot tail.

I lift off in Normal mode, about 60% rpms and all is well. Then I switch to Idle 1 (80%) and after a few seconds the tail gets very lazy and will slowly turn right (the hard direction). After a few more seconds it will let go and spin right at a fast rate, too fast to keep up with and a crash results.

The TGY tail servo is new but seems to get rather warm. The Spartan Quark is prolly 2 years old. I'm thinking it's one of those.

Any thoughts?
Not sure about what servo you used before for tail.
But, have you check or change servo type in the spartan?
Also what head speed and throttle curve are you using?
Governed speed?
And binding as stated before, that's why servo gets hot or compatibility
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Old 08-10-2014, 01:52 PM   #4
blorph
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Thanks for the replies.

"But, have you check or change servo type in the spartan?"

No, unsure how to do that.

"Also what head speed and throttle curve are you using?"

14 tooth pinion. 75% Idle 1 and 90% idle 2, both straight line with no curve. No governor. Same for years.

Hmm. Will recheck for binding in the tail.

Again, the tail servo is a TGY-S306G and not the HV or 'high voltage' version if that makes a difference.
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Old 08-10-2014, 04:03 PM   #5
salrica
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Servo type selection, page 9-11 on gyro installation guide book.
First step to do when setting up your gyro.
Unplug servo first then select servo modulation.
http://www.alofthobbies.com/kst-ds115-servo.html
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Old 08-10-2014, 04:05 PM   #6
blorph
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Checked the tail for binding and found very little. However....after a very close exam I noticed one tail blade grip had about a 1mm space between it and the tail hub. Also noticed the tail blade tracking was off, just spinning it by hand. That's not normal. Completely disassembled the tail hub and on the side where the space was I found one bearing (the tiny MR52ZZ) was coming apart. I keep every conceivable spare so replaced that bearing and lubed the other 3 and reassembled it. Tail tracking is perfect and no binding. Don't know if that will necessarily solve my heading hold problem, though.
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Old 08-10-2014, 04:11 PM   #7
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Salrica, yeah remember doing that a couple years ago when I first got the Quark. Haven't checked since. Will do, thanks.
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Old 08-11-2014, 06:46 PM   #8
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Ding, ding, ding. I do believe we have a winner. Salrica. Today I ran the Quark setup program. Didn't have to make many changes, just the endpoints a little bit, but...during today's flying I saved the very last battery to test in the problem machine. It performed admirably. Granted, I did replace that one tail bearing also. First successful flight in about a month and after a bodacious number of crashes. Thanks, Salrica, and all of you.
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Old 08-11-2014, 06:46 PM   #9
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Default Success!

duplicate

Last edited by blorph; 08-11-2014 at 06:49 PM.. Reason: duplicate
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Old 08-12-2014, 12:33 AM   #10
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Old 08-24-2014, 04:17 PM   #11
blorph
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Default It's baaaaaack

My issue with the tail not holding has returned after ~2 weeks. In that 2 weeks this heli (my #2) has flown 55 flights with no crashes and no mechanical issues.

Yesterday on flight 2 the tail started getting 'lazy' again and drifting a bit both directions. After a couple more batteries it was up to it's old tricks again: It would slowly turn RIGHT (weird, against the torque) about 90 degrees. Opposite rudder was totally ineffective for about 5 seconds then it would slowly respond to rudder input. Switched to heli 1 for the rest of the day.

Last night I set up the tail again on heli 2: set up in rate mode to hover hands off. Then set up the Quark gyro again. It wasn't impressed. Today it would be fine for about a minute (no extreme maneuvers, just pitch pumps) then boom! the heading would drift right again and rudder inputs would be ineffective for about 5 seconds then normal. I would quickly land, check everything, takeoff and...same thing. Several times. Tail servo temp was definitely elevated, almost hot, especially when compared to tail servo on heli 1.

Tomorrow will try replacing the tail servo (TGY S306G) with another of the same from stock. Both servos have had the tape mod performed on the inside bottom.
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Old 08-27-2014, 06:03 PM   #12
blorph
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Here's the latest on my tail issue with heli #2.

Couple days ago replaced the tail servo with a totally different servo from stock. Made absolutely no difference.

So it's gotta be the gyro. Replaced the gyro. Still exact same symptoms. Tail is still lazy and turns uncommanded left and right at random, mostly right. Up to about 90 degrees.

For years I've run my gain at about 60%. After the initial issues I upped the gain to about 85% after setting up the Quark gyro again. That worked for 55 flights. Over the last couple days I gradually upped the gain to 110%. Didn't help. Today on a whim I took the gain all the way to 150% and moved to the outermost hole on the tail servo horn. Not even a hint of wag and still a very lazy tail.

Is it possible for the gain to stop working?
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Old 08-27-2014, 06:32 PM   #13
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hi, do you know if it is the servo pushing or pulling the pushrod to make the tail move, if not there may be play in your tail gear shaft or in that area. I had it after not checking the grub screw on my tail blades so they moved freely up and down the tail pitch shaft turning left and right as it saw fit (embarrassing mistake I know , but one I shall not make again)
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Old 08-28-2014, 12:25 AM   #14
salrica
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I would check cold solder joints and wires.
Maybe anything rubbing the frame and loosing power.
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Old 08-28-2014, 02:39 PM   #15
blorph
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Default Success!

Finally, success again. And the reason seems embarrassingly simple in retrospect. Today checked for binding in the tail and there was little/none. Set up the tail gyro ~again~, test flew it and...bogus, still. Landed and rechecked the gyro endpoints: the tail servo stalled before reaching the right/outboard limit. Huh? Removed the tail pushrod from the tail servo and I could barely move the tail slider back and forth by hand. So I knew there was an issue in the tail somewhere. Then noticed one tail blade grip had juuuuust a smidge more space between it and the hub (just like a couple weeks ago). Disassembled it: sure enough, bad outer tail grip bearing, the MR52ZZ again.

So, reassembled it with a new MR52ZZ and prepared for the test flight. I knew that, with the gain still at 150% and the tail push rod still on the outermost hole on the horn since yesterday that the tail had better start wagging immeeeejitly or something was still wrong. Sure enough, before spooling past about 50% blade rpm's the tail wagged violently. Success! So eased the gain back down to 60% and moved back to the inner hole on the servo horn. And all was well.

Now have to gradually go back to the original tail servo and Quark gyro (Quark, how could I doubt thee?) and put the new parts back in the bin.

So, Salrica and Chargh were on the money with their "binding" and "hot servo" remarks. Also, Grimlok with his "check the tail pushrod": I had doubled up the strength of the tail pushrod a few days ago as I felt it might be bending during 'pushing' movements. Not normally required if the tail isn't binding. If I just could have put it all together sooner......
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Old Yesterday, 04:55 AM   #16
338federal
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Do you have the tarot tail? Change it to another maybe align. Thread lock there were it not to be. Small part and liquid thread lock bad combo. I use blue thread lock in tube. Not liquid. Works great.
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450 Class Electric Helicopters 450 Class Electric Helicopters manufactured by Align, Tarot, SYMA, Airhog, Chaos, HK and similar.

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