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Old Jan 28, 2010, 07:25 PM
Gone Flying.
ChrisWNY's Avatar
Western NY
Joined Nov 2006
2,401 Posts
Completed HK-250GT

Here are some photos of my completed HK-250GT. Power setup and parts used are as follows:

Motor: Scorpion HK-2206-3900Kv
ESC: Castle Creations Phoenix 35-Amp
Servos: 2 x HXT900 Cyclic, GWS Park HPX-f for tail
Gyro: HK 401B

Upgraded parts:
Align Belt, Align main gear and 1-way bearing, Align 205D carbon fiber blades, Microheli CNC precision tail, Fusuno Canopy - quite a bit more room than the stock canopy, servo arms are completely clear and my 1000mAh 3S LiPo pack actually fits within the canopy.

The Micorheli precision tail made a huge difference in terms of tail response. There is virtually 0 slop in the tail and very smooth tail blade movement on the pitch slider. Definitely recommend this upgrade though it's costly at ~$50.
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Old Jan 30, 2010, 09:50 AM
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St-Hilaire,Québec,Canada
Joined Sep 2001
269 Posts
Real nice! I've been looking at that tail upgrade since a couple of days since mine is getting very bad and rought

Are you using the stock tail shaft with it?

Quote:
Originally Posted by rcnewb View Post
Here are some photos of my completed HK-250GT. Power setup and parts used are as follows:

Motor: Scorpion HK-2206-3900Kv
ESC: Castle Creations Phoenix 35-Amp
Servos: 2 x HXT900 Cyclic, GWS Park HPX-f for tail
Gyro: HK 401B

Upgraded parts:
Align Belt, Align main gear and 1-way bearing, Align 205D carbon fiber blades, Microheli CNC precision tail, Fusuno Canopy - quite a bit more room than the stock canopy, servo arms are completely clear and my 1000mAh 3S LiPo pack actually fits within the canopy.

The Micorheli precision tail made a huge difference in terms of tail response. There is virtually 0 slop in the tail and very smooth tail blade movement on the pitch slider. Definitely recommend this upgrade though it's costly at ~$50.
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Old Jan 30, 2010, 10:05 AM
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UK
Joined May 2007
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I've just returned from a session - flying my HK250 GT... 4 batteries through it and... the more I fly it more I like it!

I even managed nice side tic tocs (still original tail + align tail slider - gy401 with InoLab 201 tail servo) with it... 2627 motor does bog a bit (when tried to do normal tic/tocs) - but I am still running it with 15T... and HXT900...

Now - I have couple of questions:

1. Where's the best place to get nice 13T and 14T pinions for 2627? (nice = pinions with a grub screw!) Mind you - I'll be ordering it to UK

2. Is it worth replacing it with scorpion's motor?

3. Is there anything else someone would go for feathering servos instead of HXT900? Is it worth getting faster/stronger servos of appropriate size for 250 heli? What's the optimal/are there metal gear strong servos for it?

I'll try to organise a small video tomorrow (wind permits)
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Old Jan 30, 2010, 10:25 AM
Gone Flying.
ChrisWNY's Avatar
Western NY
Joined Nov 2006
2,401 Posts
Quote:
Originally Posted by frebou View Post
Real nice! I've been looking at that tail upgrade since a couple of days since mine is getting very bad and rought

Are you using the stock tail shaft with it?
Yes, I'm using the stock tail shaft and gear. Considering the HK250GT actually uses a metal gear on that shaft, I think it's a better setup than the Align. Make sure you retain the tiny little spacers that are on the stock shaft, otherwise the tail gear will have way too much "wiggle room" back there when you install it into the Microheli tail. The spacers are tiny and fall out easily when you disassemble the stock tail. Otherwise, the stock tail shaft/gear work perfectly with the microheli tail assembly.
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Old Feb 01, 2010, 02:27 AM
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UK
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3,192 Posts
HK250 GT (3 min 8 sec)


I'm sorry for the bad camera and even worse flying. If you're stare enough you'll see little black dot doing incredible climbouts and really fast rolls (a bit of side tic/tocs to).
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Old Feb 01, 2010, 10:05 AM
Shut up and talk to me!!
Manila
Joined Aug 2006
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My dumb question for those who are using G401B gyro, do you set the delay to zero or something higher when using a digital servo?
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Old Feb 01, 2010, 10:08 AM
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Slovenia
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Quote:
Originally Posted by deanc338 View Post
My dumb question for those who are using G401B gyro, do you set the delay to zero or something higher when using a digital servo?
Yep, zero. I'm using the G401B + MKS480. Had to shorten the tail blades a bit to get it to hold though.
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Old Feb 01, 2010, 11:26 AM
Gone Flying.
ChrisWNY's Avatar
Western NY
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Mongo - I was gonna ask that question. How many of you could not get the tail to hold on the stock blades? I find that lateral movement on the pitch slider is rough on the stock blades and am thinking of going with smaller Align 250 tail blades as a result. The tail blades just seem to over power the torque generated by the head to the point where the Gyro simply can't find the center/neutral point.
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Old Feb 01, 2010, 12:21 PM
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Slovenia
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406 Posts
Don't waste money on new blades. Just take a long screw, put it through both blades and slice them down a few mm.
Also drill a new hole on the servo arm as close to the output shaft as you can, not too close though (control rod binding).
Before I did that I could only go as far as ~75 on the gyro servo limit pot without binding the tail pitch slider (90 now).
Or you could get a longer tail control arm, you get less throw either way.
The tail semi-holds even without this mods but it definitely doesn't feel locked in and you get the occasional blow out on pitch pumps.
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Old Feb 01, 2010, 06:25 PM
Shut up and talk to me!!
Manila
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Thanks mongo. I was thinking what would happen if I put the delay a bit higher say around 25% and increasing the gain a bit. Anyways at zero delay my tail holds just fine, but piros have some bounce.

BTW, I have replaced my tail blades with Align flat tipped ones and the tail holds better than stock.
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Old Feb 02, 2010, 02:35 AM
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UK
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Quote:
Originally Posted by mongo56 View Post
Or you could get a longer tail control arm, you get less throw either way.
Any particular part to get or particular place to get it from?
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Old Feb 02, 2010, 02:52 AM
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Slovenia
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Quote:
Originally Posted by clicky View Post
Any particular part to get or particular place to get it from?
Here you go.
http://www.helidirect.com/align-tail...50-p-11022.hdx
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Old Feb 02, 2010, 03:35 AM
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Cool. Thanks! I wasn't aware that it's longer than HK one... I was even thinking extending that one for another 2-3 mm...
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Old Feb 04, 2010, 03:32 PM
Gone Flying.
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Western NY
Joined Nov 2006
2,401 Posts
HK-250GT Tail issues - need some expertise here

I've installed the Microheli CNC Precision tail, 37mm Align tail blades, and swapped the oversized GWS HPX-f servo with an INO-LAB HGD-201HB Digital Servo. The stock tail was terrible as it was erratic, binded easily, and had way too much slop, which is why I decided to upgrade to the Microheli all-metal CNC precision tail. The Microheli tail is great but something else is restricting tail movement at full head speed.

Gyro is a HK401B, delay set to 0, travel set to 100%. The tail moves great when the heli is in park, I get equal tail blade pitch on both sides, and the servo has been installed so that the tail blades are essentially at neutral pitch when the servo is centered. I'm using the innermost hole on the servo horn (disc). Tail holds ok in flight but I get very little tail pitch slider movement as the head comes up to full RPM. I'm guessing I'm somewhere in the 3000 RPM range based on the Kv of the motor (Scorption HK-2206-3900Kv), but I haven't tach'ed the head yet to confirm this. The battery was relatively flat during the test I recorded in HD (shown below).

I've posted photos of the Servo horn and the tail pitch slider when everything is neutral. I also uploaded a video of the problem to YouTube so that others can observe for themselves what is happening. Either there is too much flex in the control rod, not enough travel (I need to use the outer hole instead of the innermost), or some sort of tennis racket effect is causing the problem which of course could be improved by the Chinese weight mod. Would appreciate anyone who can lend their expertise here. Thanks.

http://www.youtube.com/watch?v=Td-T1dhRJ8Y

Sorry about the focus of the video, the camera wanted to focus further up the heli rather than on the tail, but the tail movement is clearly visible. Facing the tail, once the head speed is up at full RPM, I have essentially no LEFT tail pitch movement, but enough right movement to kick the tail to the left.
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Last edited by ChrisWNY; Feb 04, 2010 at 03:50 PM.
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Old Feb 04, 2010, 05:51 PM
Excellence is Expected
MakMov's Avatar
Aurora, Colorado
Joined Nov 2005
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looks like it's all jacked up.
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