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250 Class Electric Helicopters 250 Class Electric Helicopters manufactured by Align, Tarot, SYMA, Airhog, Chaos, HK and similar.


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Old 06-17-2011, 11:56 PM   #101 (permalink)
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no puedo arreglar esto, el gyro es Spartan Quark, Servo 290G, Engrase toda la mecanica, cambie el rotor de cola entero, e probado distintos tamaños de palas, kevlar belt.

Que mas puedo hacer? Porfavor ayudenme amigos se los ruego!
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Old 06-24-2011, 02:48 AM   #102 (permalink)
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Hi all , cured my 250s tail wag last night with the new Align tail grips (same as my 450pro but smaller ) , very low gain setting 58 on my Dx7 on the GP780 gyro but it works nice holds great , very pleased to have her back in the air .
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Old 06-24-2011, 03:41 PM   #103 (permalink)
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Quote:
Originally Posted by goldie100 View Post
Hi all , cured my 250s tail wag last night with the new Align tail grips (same as my 450pro but smaller ) , very low gain setting 58 on my Dx7 on the GP780 gyro but it works nice holds great , very pleased to have her back in the air .
Likely the new bearings that came in the new blade grips had more to do with curing your wag than the new tail blade grips themselves did. New bearings are a cheaper fix and an easy job.
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Old 06-29-2011, 01:54 PM   #104 (permalink)
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Quote:
Originally Posted by leich View Post
no puedo arreglar esto, el gyro es Spartan Quark, Servo 290G, Engrase toda la mecanica, cambie el rotor de cola entero, e probado distintos tamaños de palas, kevlar belt.

Que mas puedo hacer? Porfavor ayudenme amigos se los ruego!
Tal vez la velocidad más alta de la cabeza del rotor principal? Yo tenía una cola sacudir uno de mis helicóptero y un aumento de la curva de aceleración para una velocidad superior de la cabeza y que funcionó bien para mí.
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Old 07-14-2011, 01:23 AM   #105 (permalink)
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Originally Posted by thefrog View Post
I switched my ESC to Gov mode yesterday with throttle at 75% for normal and 85% for idle up. Now I've got a serious wag in normal, seems like increasing head speed helps a lot.
The headspeed itself isn't much different from before I enabled the Gov. Is the Gov setup related to the wag?
I have seen the crappy governor on the stock 450 ESC interact with the stock 450 gyro. My engineer flying buddy who's big on control theory loved it -- said the two control loops were interacting. Reducing gyro gain (a lot) helped. Turning off the governor mode fixed it.
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Old 07-14-2011, 02:10 AM   #106 (permalink)
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Exclamation Alphabetical list of the first 100+ tail wag cures

Below and attached are an alphabetical list of the first 100+ tail wag cure posts. (It's imperfect; it's late.)
Post number(s) follow each cure.



Here's what the list suggests to me to try. What does it suggest to you (besides the fact thay I'm desperate enough to compile this list. )?
  • Get rid of slop
  • Get rid of all mechanical resistance (including in bearings)
  • Replace the stock gyro with a really good one (11 posts).
  • Replace the stock tail servo with really good one (8 posts).
  • Replace the stock tail mechanism with a MicroHeli one (3 posts)
Tail wag cure and post number:

A whole bunch of stuff: Do it,61
Ball joints: Size them,99
Bearings: Collar on upper main shaft bearing too tight,57
Bearings: Double up tail grip bearings with no spacer,52
Bearings: Notchy tiny bearings in rear blade grips,"92, 102"
Bell crank: Get a metal one,?
Bell crank: Must take zero force to move back and forth,97
Bell crank: Sand and polish, make smooth,"?, 100"
Belt: Get Kevlar,1
Blades: Don't use CF tail blades,42
Blades: Tighten main blade grip screws,29
Blades: Tighten tail blade screws,"32, 34"
Blades: Try different tail blades,"1, 52"
Components: Use Al pitch slider, boom mount, servo mount,33
Control rod: Carbon fiber 1,33
Control rod: No bends,22
Endpoints: Rudder <= 100%,22
Gears: Don't mesh too tight,60
Gears: Pinion setscrew must not touch main gear,23
Gyro: Get a BeastX,18
Gyro: Get a G190,86
Gyro: Get a GY520,"13, 65, 98"
Gyro: Get a HG-D201HB,91
Gyro: Get a mini Vbar,63
Gyro: Get a Quark,"54, 67, 75"
Gyro: Mount plate on lower slots,49
Gyro: Mount solidly,26
Gyro: Reduce gain (overall or with increased headspeed),"21, 33, 102"
Gyro: Reduce stop gains,3
"Gyro: Set to ""AS"" (analog, not digital)","1, 65"
Gyro: Set to delay 100%,1
Gyro: Use 2 layers tape ,1
Gyro: Wires must not touch it,26
Headspeed: Set RPM to be non-resonant ,2
Heim joint chinese weights,99
Hub: File each end so no play,31
Mechanical: Binding,1
Mechanical: Vibration,2
Metal rotor unit: Slop between 2 bearing units,30
Servo: Ball position,"1, 2, 3"
Servo: Correct servo and horn position,56
Servo: Get a DS290G,"65, 69"
Servo: Get a DS3500G,"63, 67"
Servo: Get a DS 520,"53, 72"
Servo: Get a MKS DS95i ,99
Servo: Get a MKS 8910,75
Servo: Needs 5 volts,"1, 4"
Slop: Get rid of it,"99, 100"
Tail mechanism: Get a MicroHeli,"41, 44, 54"
Tail shaft: Polish it,99
Travel adjust: Set to 125% with 100% throttle curve,13
Attached Files
File Type: xls AlignWagCures.xls (23.0 KB, 146 views)

Last edited by crashmore; 07-18-2011 at 10:55 PM.. Reason: Update
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Old 07-18-2011, 08:27 AM   #107 (permalink)
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Well I put new KBDD tail blades on and set my TX gain setting very low, and it stable in hover with high head speed. I haven't tried fast forward flight yet, didn't make it to the field yesterday, did a bunch of hovering and tweaking in my back yard.

On that note, I have a DX8, my gain is down to 15! That seems VERY low to me, any thoughts?
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Old 07-18-2011, 03:08 PM   #108 (permalink)
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Quote:
On that note, I have a DX8, my gain is down to 15! That seems VERY low to me, any thoughts?
Assuming your tail servo has the link set somewhere around 5mm, that is VERY low gain, and your tail won't be crisp enough or even hold. If the reason it is that low is to avoid tail wag, then you have at least one mechanical issue to sort out. Unhook the tail pushrod from at the servo end and move it back and forth to the extremes. If there is ANY sticky spots, find and eliminate them. If the whole tail assembly moves freely, you probably need new bearings in the tail blade grips (ideally Heim Joint's bearing mod).
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Last edited by Helioop; 07-18-2011 at 11:23 PM..
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Old 07-18-2011, 11:04 PM   #109 (permalink)
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Default The HEIM JOINT dual tail bearing + spacer upgrade exorcised my bird's wag!

The HEIM JOINT dual tail bearing + spacer upgrade exorcised my bird's wag!

T250 Tail Binding Analysis Part 1:
T250 TAIL BINDING ANALYSIS PART 1.wmv (7 min 11 sec)

T250 Tail Binding Analysis Part 2:
T250 TAIL BINDING ANALYSIS PART 2.wmv (6 min 6 sec)

T250 Preload Spacer Assembly:
T250 Preload spacer assembly (10 min 0 sec)


That's the best $13 I ever spent on a heli!
PM HEIM JOINT for ordering info.

Last edited by crashmore; 07-19-2011 at 01:16 AM.. Reason: Correction
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Old 07-19-2011, 12:57 PM   #110 (permalink)
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Default Tail Wag puzzle

A little puzzle on HK250 tail wag:

I don't know two things:

Why did a heli that was locked on start to wander after a few weeks?
What fixed it?

The tails on my two 250s with flybars were locked after I did the tail mods in April and then I started having trouble with the one a couple of weeks ago.

The one with the black 205mm Tunigy blades / Turnigy 2627 4200kv motor,14T pinion & Kevlar belt. The tail either wouldn't hold or would wag a lot if I set the HH higher. My other 250 with 200mm CF blades / Align BL250 with 16 tooth pinion was still solidly locked on. Both flew well in rate mode so the mechanical setups were pretty close. And both have 37mm Align tail feathers, Chinese weights and dual bearings with spacers.

I tried all kinds of things to get this weak tail strong again. I checked everything: belt,
replaced main bearings (they were notchy), re adjusted tail blade grips at both places,
checked blade balance, etc.

I crashed both within minutes and both needed minor repairs like feathering shafts, one gear, skid pipes, but nothing to repair in the tails. I accidentally swapped the heads when I had them off to check mainshafts. I put the long blades onto the heli with the Align motor and the shorter white CF blades onto the heli with the Turnigy motor. I had to do a little radio retrimming and swash leveling but when I got them both back into the air both of the tails were LOCKED ON. Hard pitch pumps and no tail movement. Solid.

My third HK250 with Beastx is really good on the tail but not as good as those two flybar babies. They are solid.

What did this?
What fixed my wandering tail on my hi powered Turnigy heli ?
Slightly more RPMs from shorter blades?
Why didn't the good one start to wander after the swap?

My DX6i throttle and pitch curves are nearly identical on both copters so I believe some
small change had profound results.

What was it?

BTW
I am running the cheapest gyros known to man. G104 Etec or E104 Gtec? (probably same as the HK mini MEMs gyro $8-10). One heli has an Inolab HGD202 and the other a 7 gram $3 digital servo from HK on the tail. Stock linkage to the tail and the toothed belts, both the Kevlar AND the HK cheapie, each have way over a hundred flights. Go figure!

Before I met Heim Joint and Finless Bob I replaced a lot of belts.

I think the cheap stuff works because of Chinese weights and Finless Bob / Heim Joint
spacer mods. And I learned a lot from some really fine videos. Thanks to God, Finless
Bob and Heim Joint.

Happy Flying Good People
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Old 07-19-2011, 11:00 PM   #111 (permalink)
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I have been struggling with the wagging tail on my copterX 250 (now with mostly hobbyking parts
except for the frame and head) since day one. If I get the tail to be tolerable (never no wag),
it wouldn't stay that way for more than a few flights and I had to constantly adjust the bearing
tightness in the tail grip to make sure there is minimum slop but not binding.

My theory is that the 250 is much more sensitive to slop than other helis because the tail
rpm is too high. I noticed that for the tail to stay put in rate mode, there is very little static
pitch compared to other helis. This means that any little slop that can affect the pitch
will be much more noticeable than in a tail that runs on a lot more static pitch. This evening
I roughly measured the gear ratio of the 250, the tail turned about 4.25 turns per main revolution.
In comparision, my 450 trex turned about 3.75, my 4g6 also turned about 3.75. I didn't have
the spec to do actual gear ratio calculation, so I simply turned the mainshaft and counted the
number of turns in the tailshaft.

I can't think of an easy way to change the gear ratio. A bigger tail shaft gear would make the tail belt
rub in the tailcase, a smaller gear in the drive end would make the belt bend too sharply and shorten
its life, ..etc. So it seems like the only thing to do is to use smaller tail blades so that the same
amount of slop produces less change in tail thrust.

I am not capable of backward flight so I don't know if reducing the tail blade size will affect the ability
to do very fast backward flight.

It should be quite easy to trim down the tail blades and see if that makes it less sensitive to mechanical
slop. I suspect people may have already tried it, but I haven't heard if it works.
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Old 07-20-2011, 01:24 AM   #112 (permalink)
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Do you think a stretched 250 will have less wag?
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Old 07-20-2011, 10:52 AM   #113 (permalink)
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A stretched tail requires less tail thrust to hold its position, so any slop will have more effect,
but it also slows down the angular velocity of the wag, making the servo effectively faster. So
it is hard to say if it helps or hurts since there are two countering forces, but my guess is
that it'll make it worse.

A stretched tail with corresponding longer mainblades will help because now it effectively makes
the tail ratio smaller.

BTW: I cut down my tail blades last night, and tried a hover in the backyard this morning. I
was able to up my gyro gain from 35 points in my transmitter to 42 points, and the tail
still doesn't get the high frequency wag. It still does the random couple inches of slow
wag whenever I move the tail and stop I need to fly it in the park to know for sure, but it
seems like an improvement.
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Old 07-28-2011, 11:11 AM   #114 (permalink)
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I feel your pain on tail wag. It sucks and ive dealt with it on many small helis. Heres something to try that has fixed some intermitting tail wag. Put a few drops of gear oil on the belt. Sometimes static builds up and the oil seems to help.
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Old 08-30-2011, 06:30 AM   #115 (permalink)
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Default Tail wag cure.

I solved the problem by backing off the tail rotor belts tension.
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Old 09-03-2011, 01:50 AM   #116 (permalink)
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Mine is great in a hover and FF but sometimes it flips out and wags hard and fast for a few seconds traveling sideways or backwards. It doesnt always happen and when it does happen it doesnt happen long.
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Old 09-03-2011, 09:23 AM   #117 (permalink)
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Quote:
Originally Posted by TeeJayShelton View Post
Mine is great in a hover and FF but sometimes it flips out and wags hard and fast for a few seconds traveling sideways or backwards. It doesnt always happen and when it does happen it doesnt happen long.
That sounds like a classic case of just a little too much gain.
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Old 09-30-2011, 01:24 AM   #118 (permalink)
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I stopped tail wag on my 250 by changing rotation of the tail rotor. What this did was make the ball on the blade grip trail in rotatation rather than lead, giving more leverage against the biggest part of the blade that over extends the centerline of the blade. I also rolled the tail rotor assembly to
the opposite side of the tail boom because you loose travel in the tail pitch slider in the normal position in the direction that needs the most movement. So now my rod and servo ride on top of the tail boom and no more tail wag. Works for me!
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Old 10-28-2011, 12:10 PM   #119 (permalink)
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Quote:
Originally Posted by newtothesport View Post
...Installed the heim joint tail grip bearing and spacer kit. The grips went from very sloppy to perfect in under $20.
...sized the ball joints. They were quite stiff.
...Installed the heim joint chinese weight kit. I like the theory behind it and several people said that it worked for them.
... I purchased and installed an MKS DS95i tail servo - the fastest and most expensive tail servo can you put on a micro heli. It's an awsome piece of technology.
I did all of the above plus adding a CF control rod, and it did all definitely help. I hate to solve a technical problem by throwing money at it when fixing slop and stuff that's out of adjustment will do, but after all of the fussing and tightening and tweaking, the tail still wasn't 100% locked in.

Last night I replaced the stock DS420 tail sevo with an MKS DS95i, and during this morning's one-battery test flight before work the tail was just LOCKED.

I had experimented with a bigger, heavier, less-quick ("slower" seems like the wrong word) JR DS3500g (which is a pretty hot tail servo) off another heli, but it didn't work anywhere near as well as the 95i.

I didn't have time this morning to do any more than run one battery down to LVC getting the bird stable in Rate mode, but this weekend I'm going to see how it does with more tail gain. Anyway, I just thought I'd report that I'm very happy with the DS95i. (At $100 a pop, it had damned well better be the miracle servo. It sure is a pretty little thing sitting back there.)
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Old 11-01-2011, 01:01 PM   #120 (permalink)
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hi harbormaster,

any luck this weekend??
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