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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 10-15-2013, 01:32 PM   #261 (permalink)
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Default tail wag == VIBES

I finished balancing 3 HK250GTs. None now has any tail wag. All three have Chinese weights and double bearings in the tail girps.

One has an HK $10 gyro, Inolab 202HB digital servo, lots of slop in the tail hub and a Z-bend in a metal tail rod. NO WAG.

Another has the same cheap gyro and servo with a straight steel linkage to the tail. This one has no slop in the tail mechanism. NO WAG

The third is FBL Beastx, Turnigy DS480 servo, staight skinny steel linkage rod and NO WAG.

I had put them all away for over a year while I have been learning to fly using modified mcpx and ncpx Blades. I didn't want to spend $100 each for fancy servos or spendy tail parts for the 250s. I recently learned to use Audacity to balance the Blades. I applied that technique to the 250s and I now have 3 stable HK250GTs.
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Old 10-15-2013, 03:05 PM   #262 (permalink)
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Quote:
Originally Posted by daveapplemotors View Post
I recently learned to use Audacity to balance the Blades. I applied that technique to the 250s and I now have 3 stable HK250GTs.
Never heard of it. Care to share?
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Old 10-15-2013, 03:33 PM   #263 (permalink)
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Default tail wags == vibes

my post #245 of Sept. 21 in this thread has a link and some explaination. Here is the link to a thread at rcgroups where theres is more detail.
http://www.rcgroups.com/forums/showt...3#post26168424
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Old 10-15-2013, 04:38 PM   #264 (permalink)
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Quote:
Originally Posted by daveapplemotors View Post
my post #245 of Sept. 21 in this thread has a link and some explaination. Here is the link to a thread at rcgroups where theres is more detail.
http://www.rcgroups.com/forums/showt...3#post26168424
Thanks. Looks like I missed a few posts...
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Old 10-28-2013, 06:03 PM   #265 (permalink)
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Zero slop tail! Microheli Dual pitch slider modded to work on the new belt tail,and the Preload spacer kit is installed! The tail assembly is totally solid now ! Now I'm gonna follow the weight loss trend and get some of the DS servo's since I don't have any issues to mask/cover up that dreaded wag!! I'm sooooooooo Happy now

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Old 10-30-2013, 09:49 AM   #266 (permalink)
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In the end the biggest difference for me was the DS951 upgrade. It was flyable at low rpm but still had the wag. Finally went to a Kbar (vbar clone) and the thing is perfect. Tons of gain solid tail 100% throttle and no wag unless I go silly high on the gain. Like 65% real +

The 250 has a place for me for traveling as its easy to take on a plane and the lipos are small enough to get through security easy. Other than that it has been the hardest heli I have set up and taken the most time to get right. My Trex 500 and Goblin are a piece of cake in comparison. I see people post saying they are looking at a 250 for there first real heli and it makes me cringe.
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Old 11-24-2013, 12:43 PM   #267 (permalink)
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It took me a while and several different threads to realize that people meant the ds95i when the typed ds951. LOL I'm really dumb. Anyway, I discovered after a couple of years of frustration that my 250's wag was from its stupid gyro. I had a bad gp750 and however I tried, the way would not go away. Sometimes, its just they gyro that is not cooperating. My 3gx and turnigy 306 are holding terrifically at 5.5v as of now. No wag, no blowouts, nothing.
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Old 11-24-2013, 02:46 PM   #268 (permalink)
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I'm swapping equipment around and stuck my CopterX CX-3X1000 cheapy flybarless controller on my 250. It has no less than seventeen different tail settings, and most importantly, it gives you access to the PID gain settings (the fundamental control loop settings). It took me a while to get it set up, but I have been able to remove the big, heavy, expensive MKS ds95i and replace it with the old DS420 and all is well (for the moment, anyway... ) Anyway, just though I'd pass that along...
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Old 02-04-2014, 12:03 AM   #269 (permalink)
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Good day all
So I had some wags on my 250 dfc 3gx and my tail kicked out about 20 degrees doing something stupid like a slow gentle flip not even talking about funnels and fast sideway loops. Changed any setting imaginable on the 3gx.
Went back to default with all 3gx settings and installed a cf tail push-rod, Helped a bit on wag, but my tail still kicked out.
Busy installing another tx/rx on my skookum sk540 Trex 600N DFC, so I thought to 1st try the SK540 on my 250. Clicked on small heli in the tail tab, test fly, increased tail gain and no wags or kick out`s - 100% locked in with the DS425M/Skookum. Replaced the sk540 on my 600N and replaced the 3gx on the 250 for the meantime while my sk540 order arrive.
Replaced the ds425m with a savox sh-0257mg which are a bit slower, but more torque. Kick out`s a bit better, but still wagging. Had a tgy-306 (low voltage version) laying around. Installed it and the 250 tail are rock solid in any move with default settings on 3gx.
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Old 02-05-2014, 08:27 PM   #270 (permalink)
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Default Tail Wag Cures

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Good day all
So I had some wags on my 250 dfc 3gx and my tail kicked out about 20 degrees doing something stupid like a slow gentle flip not even talking about funnels and fast sideway loops. Changed any setting imaginable on the 3gx.
Went back to default with all 3gx settings and installed a cf tail push-rod, Helped a bit on wag, but my tail still kicked out.
Busy installing another tx/rx on my skookum sk540 Trex 600N DFC, so I thought to 1st try the SK540 on my 250. Clicked on small heli in the tail tab, test fly, increased tail gain and no wags or kick out`s - 100% locked in with the DS425M/Skookum. Replaced the sk540 on my 600N and replaced the 3gx on the 250 for the meantime while my sk540 order arrive.
Replaced the ds425m with a savox sh-0257mg which are a bit slower, but more torque. Kick out`s a bit better, but still wagging. Had a tgy-306 (low voltage version) laying around. Installed it and the 250 tail are rock solid in any move with default settings on 3gx.

How did you mount the SK540? I have a SK720 in my Goblin 500 and that will not fit In between the frame of my 250. Don't think I would be comfortable mounting it under the bottom plate.
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Old 02-06-2014, 12:37 AM   #271 (permalink)
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For the 3 test flights I did, I mounted it underneath on the bottom plate. Have seen somewhere that you can add spacers to the bottom frame to make the sk540 fit, I will maybe do that when my 3rd sk540 arrives. Must say, it fly`s great with stock settings. Just needed some tail gain tuning.
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Old 02-09-2014, 06:32 PM   #272 (permalink)
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Default Tail Wag Cures

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For the 3 test flights I did, I mounted it underneath on the bottom plate. Have seen somewhere that you can add spacers to the bottom frame to make the sk540 fit, I will maybe do that when my 3rd sk540 arrives. Must say, it fly`s great with stock settings. Just needed some tail gain tuning.

Don't think you can widen the bottom frame of the pro with the servo tray. That is unless you can get a wider servo tray.
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Old 03-01-2014, 09:58 AM   #273 (permalink)
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I mounted my SK540 inside the frame, on the gyro mount. Initially the rudder servo blocked the USB port, so I boom mounted my servo - I think it cost $16 to do that. While the 540 does touch the side frames, and is basically rigidly mounted, Skookum says that it is "immune" to vibrations. So far it performs fantastically!

Here are a couple of pics from before I boom mounted the tail servo.


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Old 03-01-2014, 01:07 PM   #274 (permalink)
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Nice shots of the 250 in the grass.
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Old 05-19-2014, 12:59 AM   #275 (permalink)
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For the record, I fixed my tail wag on my HK250 by fitting a Turnigy 306G-HV tail servo instead of an HKSCM9.

Initially the wag was not too bad, then quickly got worse - nearly crashed the last time.

Of course I had already made sure that there was no friction on the tail slide. I am using the following:
a) Ikon FBL controller
b) a carbon push rod
c) Tarot 250 FBL head (I had to modify it to get it to balance properly, the blade grips were not evenly spaced from the main shaft)
d) Tarot TL25095-02 tail rotor grips with built in Chinese weights
e) Turnigy XGD-11MB Digital Mini Servos for the swash

I also used the Audacity stuff for balancing the heli - see post #245 (do this, it's magic! By far the best way to balance)

Nothing helped until I changed the tail servo.

Lothar
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Old 05-20-2014, 01:28 PM   #276 (permalink)
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Another typical case, cured my tail wag with the DS95i. Took a few years, but I gave in. Was flying it with a new DS290, but that developed issues after a few flights too. I'm using a DFC head with an AR7200 BX on an old 250 with a belt tail - boom mounted servo with a carbon rod. Old style tail. Plenty of slop in the tail as well. It has Chinese grip weights, but I wonder how much they matter. The 290 had plenty of torque, but I think the speed of the 95i did it. The slop of the tail just needs incredible speed and for some reason you also need to compensate with a servo that has lots of torque. With Nanotech 800 batts, the thing is even pretty balanced.
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Old 06-01-2014, 06:49 PM   #277 (permalink)
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Something that was causing pretty severe (but intermittent) tail wag for me was one of the 681ZZ bearings inside a tail blade grip. It was separating; little metal rings were coming off of it. I only found it during a fishing expedition to see if anything in the tail was binding.
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Old 10-31-2014, 07:47 PM   #278 (permalink)
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Well, the 250 has taught me more about tail setup than any other heli. For anyone reading this thread, here are my recommendations for getting a solid tail, in this order:


1) Make sure there is no binding AT ALL in the tail. Including links on the pushrod (size them by pinching them with pliers slightly), the control arm, pitch slider, grip links, etc. And try to eliminate any slop you can find.

2) Buy a couple 681X bearings, and replace the tail grip washers with these bearings. This will give you a solid dual bearing mod for under $4.

3) Learn about adjusting Integral and Derivative gains in addition to the P gain, and tune that tail. This will save you a lot of time and money.

4) Install a DS76t servo. For many 250s, the DS76t is sufficient, but the torque on it isn't great. To decrease the torque needed to move the tail grips, install the chinese weights. Alternatively, get a DS95i servo, but keep in mind that's it will add undesired weight to your heli.

5) Check for binding and slop (yes, again!), and adjust P.I. and D. gains.

Good luck!

P.S. People say the governor can mess with the tail if not setup correctly, so turn it off before attempting to fix the tail.
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Old 11-01-2014, 02:31 AM   #279 (permalink)
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Agreed 100%, but I'd add a couple of extra detail:

4a) With the DS76t and Chinese Weights, you should use the small white plastic blades. The carbon blades or larger plastic ones aren't the ones the Chinese weights are designed for, and also give the tail too much mechanical gain.

6) Take an hour to make a carbon fibre tail pushrod. Its not essential but saves weight and reduces friction in the tail assembly.
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Old 11-04-2014, 05:18 AM   #280 (permalink)
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I hear about this all the time with the 250 mine flys awesome no ways at all even with a 3gx I also put 3 Tt bearings in the boom
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