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Old Jan 23, 2011, 06:26 PM
What package dear?
Hellysmack's Avatar
USA ILLINOIS
Joined Nov 2002
2,185 Posts
Question; For those with the Phoenix RC simulator, how close is the Trex 250 in the simulator like flying a real 250 helicopter.
And what are some of your throttle and pitch curves for the simulator?
What are the settings you use for your real 250?
Do you use the same throttle and pitch curves for both?

Cool spOOfman I am eagerly wanting to see how your set up works out keep us posted, and I too need to know the same things you are asking.

I ordered a set of these to try because the one metal gear I was told will replace the one gear that always breaks in the HXT900, this would still keep weight down.
http://www.hobbycity.com/hobbycity/s...idproduct=6760
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Last edited by Hellysmack; Jan 23, 2011 at 06:32 PM.
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Old Jan 23, 2011, 06:33 PM
Low rates are for wimps
bwoollia's Avatar
United States, CO, Colorado Springs
Joined May 2008
3,403 Posts
Sp00fman,

Couple of points. Get the CF blades, stiffer is better.
https://www.hobbyking.com/hobbycity/...dProduct=10473

I think your tail servo might be a bit marginal. I've had good luck with the MKS DS480.
https://www.hobbyking.com/hobbycity/...idProduct=8511
Other guys have used mini servos like the Futaba 9257, MKS DS8910, etc.

I'd up your pinion. I'm using the 4200kv motor with the 12t pinion. Headspeed is important with this heli.

For the cyclics, I have recently installed some digital Blue Birds with good luck, they aren't metal but they're not that expensive and very light:
https://www.hobbyking.com/hobbycity/...idProduct=9446

Don't sweat the weight that much. As long as you're not making it ridiculously heavy you'll be more than fine. Check out some of the weights at Helifreak: http://www.helifreak.com/showthread.php?t=135057
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Old Jan 24, 2011, 02:19 AM
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Son, Norway
Joined Sep 2004
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Quote:
Originally Posted by bwoollia View Post
Yes, you sort of have to plan your headspeed and work backwards with pinion, kv and battery voltage. 3S is more efficient than 2S - less current does more work.
I had the fist lift off yesterday. My 10A CC ESC quit after a short time.
The 2627 Motor with 4200kv seems to be too hot on 3S with the 15T pinion. 40-50% throttle seemed to give decent headspeed. I tried 2S just for fun, but that was just enough to leave ground. Anybody know a source for smaller pinions that fits these motors? Another alternative would be 3S A123 1100, but that would be 120g of battery.

Fred
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Old Jan 24, 2011, 02:55 AM
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DerClown's Avatar
Lithuania
Joined Mar 2009
220 Posts
Hey guys!
Could you recommend me decent motor instead of Turnigy 2627 ? Its on backorder and holds all my order forever, im tired of waiting for it. Maybe something same or more powered as scorpion, etc. ? And please advice pinion with it.
Thank you
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Old Jan 24, 2011, 03:40 AM
Looptastic!
sp00fman's Avatar
Enschede, Netherlands
Joined Nov 2009
2,292 Posts
Try to at least fly at 80% throttle. This will be much easier on the esc. You will need a smaller pinion to keep headspeed in a normal range.
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Old Jan 24, 2011, 03:44 AM
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Son, Norway
Joined Sep 2004
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Quote:
Originally Posted by DerClown View Post
Hey guys!
Could you recommend me decent motor instead of Turnigy 2627 ? Its on backorder and holds all my order forever, im tired of waiting for it. Maybe something same or more powered as scorpion, etc. ? And please advice pinion with it.
Thank you
The 3800 version is in stock. I'm currently ordering these pinions in the range 11-14T, hoping it will solve my issues: http://www.hobbycity.com/hobbycity/s...idProduct=9252

Fred
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Old Jan 24, 2011, 08:29 AM
Low rates are for wimps
bwoollia's Avatar
United States, CO, Colorado Springs
Joined May 2008
3,403 Posts
Quote:
Originally Posted by flarssen View Post
I had the fist lift off yesterday. My 10A CC ESC quit after a short time.
The 2627 Motor with 4200kv seems to be too hot on 3S with the 15T pinion. 40-50% throttle seemed to give decent headspeed. I tried 2S just for fun, but that was just enough to leave ground. Anybody know a source for smaller pinions that fits these motors? Another alternative would be 3S A123 1100, but that would be 120g of battery.

Fred
You will want lots of headspeed for this heli, but 4200kv and 15t pinion is a bit much. Like Sp00fman said, keep the throttle curve as high as you can - your ESC will run cooler and the system will be more efficient. You were likely well over 10A with a 100% throttle setting with your setup.

The 2627 motors require the smaller 2.3mm pinions which are press fit to the shaft, use red loctite to lock them in place. Also, the shaft for the 2627 needs to be cut short.
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Old Jan 24, 2011, 09:32 AM
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DerClown's Avatar
Lithuania
Joined Mar 2009
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bwoollia so what are you saying ? I should go with the Turnigy 2627 but 3800 kv version ? Is it the same power as 4200 kv version ?
I need to act fast, the Chinese new year is coming...
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Old Jan 24, 2011, 09:58 AM
Low rates are for wimps
bwoollia's Avatar
United States, CO, Colorado Springs
Joined May 2008
3,403 Posts
Quote:
Originally Posted by DerClown View Post
bwoollia so what are you saying ? I should go with the Turnigy 2627 but 3800 kv version ? Is it the same power as 4200 kv version ?
I need to act fast, the Chinese new year is coming...
Go ahead and get the 3800kv version, just get a bigger pinion than I did. The Align stock motor is 3400kv and uses a 15t pinion (I believe). If you use a 13t or even 14t pinion you should be fine!

3400kv x 11.1v x 15t / 120t (main gear) = 4717RPM (not including efficiency losses, etc)
3800kv, 13t = 4569RPM
3800kv, 14t = 4921RPM
4200kv, 12t = 4662RPM
4200kv, 13t = 5051RPM
4200kv, 14t = 5439RPM
4200kv, 15t = 5827RPM

Please note that these numbers aren't the headspeed you are going to see, there are efficiency losses, etc that will reduce those numbers: they are only useful for comparison. You could multiply by 85-90% or so for a reasonable guesstimate.

Having a higher kv motor with a smaller pinion can be helpful in that you have the higher rotational momentum to help maintain headspeed, but that's a small point.
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Old Jan 24, 2011, 10:04 AM
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Lithuania
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Thank you very much !
I try somehow to change my order from HK.
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Old Jan 24, 2011, 10:25 AM
Low rates are for wimps
bwoollia's Avatar
United States, CO, Colorado Springs
Joined May 2008
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Quote:
Originally Posted by DerClown View Post
Thank you very much !
I try somehow to change my order from HK.
I've done that before using their online chat, hopefully you'll still be able to get them before they take off for CNY.
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Old Jan 24, 2011, 09:17 PM
Low rates are for wimps
bwoollia's Avatar
United States, CO, Colorado Springs
Joined May 2008
3,403 Posts
Hey guys,

I just did a quick "cold weather" flight in my 250gt. It was -15C out - a bit too cold for the poor 6g cyclics. Check it out:

Winter Flying the HK-250GT (5 min 45 sec)
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Old Jan 25, 2011, 06:31 AM
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frebou's Avatar
St-Hilaire,Québec,Canada
Joined Sep 2001
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Lol, I live in Quebec, Canada and looking at your video gave me an idea : stay inside until spring

thanks for sharing
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Old Jan 25, 2011, 11:27 AM
AMA# 548800
jombo's Avatar
United States, CT, Trumbull
Joined Dec 2007
5,151 Posts
Quote:
Originally Posted by sp00fman View Post
I ordered a copterX 250SES. Now need some electronics and i could use some help. Aiming for 5 or 6 mins flight time. sports and some mild 3d. I want to build it cheaply.

After searching i think this combo will get me close:
Blades: Fiberglass 200mm http://hobbyking.com/hobbyking/store...dproduct=10824
ESC: Plush 18A http://hobbyking.com/hobbyking/store...idproduct=4312
Motor: Turnigy 2627 Brushless Outrunner 3800kv http://hobbyking.com/hobbyking/store...idproduct=8143
Pinion:12T and 13 T to test out, from firefox200 http://hobbyking.com/hobbyking/store...idproduct=9252
Lipo: Turnigy nano-tech 850mah 3S 25~40C Lipo Pack http://hobbyking.com/hobbyking/store...dproduct=11899
Rx: (i have a spare one) Hobby King 2.4Ghz Receiver 6Ch V1 http://hobbyking.com/hobbyking/store...idproduct=8440
It does run without the satellite, and i will heat-shrink it instead of using the case.

gyro GA-250 MINI-MEMS Gyro http://hobbyking.com/hobbyking/store...dproduct=15318
Tail servo: D05010MG 5.7g / .61kg / .07sec Digital Metal Gear Micro Servo http://hobbyking.com/hobbyking/store...dproduct=10965


I hear its important to keep weight low. This gives me a dilemma, as it's a fast bird flying low to the ground i might want metal geared servo's... but they are about 13 grams a piece. I do have some fast Henge 922 digital metal servo's om my 450. I could put these on the 250 and upgrade my 450 with something with a little more torque.
Running digitals will add another 5 grams for a sbec

Thus getting 9g plastic geared servo's saves me about 17g.
Will that make a noticeable difference in the handling of the heli?

For cheap servo's the HXT900 seems used a lot, but i have one to just test out and it overshoots severely, is in-precise and draws a lot of current.

Anyone know a light weight servo with good centering and resolution, and has spare gears available?


I could get this firefox 200 canopy http://hobbyking.com/hobbyking/store...idproduct=9222 to save some weight.
I will shorten as much wire as i can.
What is a nice lipo connector? the little red one is only rated at 10A, and a set of XT60's are half the weight of a lipo
that all looks good , if you want longer flight times go with the flightmaxx 1000 3cell . i would go with the cf blades since there isint much of a price difference between fg and cf . the corona 919 are pretty good on the cyclic but i feel the d922 are better all around including for the gyro .
oh wait you got that new gyro , i would definitly get the d922 then , i noticed a big difference using a hk401 and a g106 gyro and switching between the corona 919 and the d922 , the 922 felt smoother
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Old Jan 25, 2011, 04:18 PM
What package dear?
Hellysmack's Avatar
USA ILLINOIS
Joined Nov 2002
2,185 Posts
Please
Is the CopterX 250 parts compatible with the Trex 250?
I am close to hitting the buy button.
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