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Old Feb 07, 2010, 10:04 AM
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othmanskn's Avatar
Petagas, Kota Kinabalu, Sabah, Malaysia
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Double Horse 9074 3.5CH Gyroscope

http://www.youtube.com/watch?v=fJq9yZQQymI

I can vouch the authenticity of this video because I bought the same model and brand.

It is labelled as having a gyroscope but it is so cheap that it cannot be an electronic gyro. I suspect the fly bar with a large weight at their ends act as a gyro device that limits its rotating movement.

Coaxial helicopters pioneered by Llama helis, reduces spinning torgue but not enough to stop very small helis from spinning widely because of wide variations in throttle. The adjustment/trim is only valid for a small range of throttle setting.

By introducing a fly bar with a high angular momentum, it stabilises the whole heli horizontally. Much easier to align and the setting is valid for larger variations of throttle setting.

I chose the 9074 model because it is the smallest with a removeable liPo battery. It turned out that it is a single cell LiPo with more than 700mAH rating. I charged a nearly flat battery with Mystere B6 compatible charger.

Although it is labelled as being suitable for children above 14 years old, my 11 year old son managed to control the heli nicely.

When I bought it, I actually tested it. My brother who bought it at a supermarket, claimed that it didn't fly properly because it kept on spinning. In my case, I tested my purchase and be shown by the boy selling it, how to align it. He told me that a demo model, that had survived for more than one month. The only weakness was in the flybar attachment because fliers didn't release the throttle when their heli crashed to the ground.

The 9074 model is not big enough to be easily damaged but not too small to be blown by the wind. In fact my son played outdoor at the entrance to our house. It wasn't windy this afternoon.

This technology should be extended into full size electric helicopters equipped with 3 electric engines. It should be cheaper and simpler than the current helicopters with tail rotors. It should also be safer because it does not need complex electronics and mechanical parts to stabilise and control it.
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Old Feb 07, 2010, 11:13 AM
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Boston, MA.
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The LED lights in the fly bar is certainly interesting. And aren't a lot of even less expensive helis coming with electronic gyros now?
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Old Feb 07, 2010, 02:02 PM
Fly Runaway Fans
United States, TX, Fort Worth
Joined Jan 2009
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I'm pretty sure it can be and is an electronic gyro. They're showing up in $25 (US) submicros, which would be around $12 HK.
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Old Feb 07, 2010, 11:35 PM
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Mesa, AZ
Joined Dec 2002
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It sure looks like it has a gyro. Nice Heli for $50.

MIke DPP
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Old Feb 07, 2010, 11:43 PM
Fly Runaway Fans
United States, TX, Fort Worth
Joined Jan 2009
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I've got one very similar, $60, very snappy gyro, Huangxing T Series. LEDs in nose and tail strut. THR doesn't affect yaw at all.
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Old Feb 07, 2010, 11:50 PM
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Mesa, AZ
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Yeah, but T series seems to be sold out at XHeli, with no where else to buy right now. Isn't that correct?
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Old Feb 08, 2010, 12:18 AM
Fly Runaway Fans
United States, TX, Fort Worth
Joined Jan 2009
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It may be available from Hong Kong but I haven't looked closely. Huangxing sells them in minimum lots of 360 so Xheli must have sold that many. They also make a 4ch at $51US, min order 100.

If I had $5100 to loan myself for a couple months, I'd be inclined to resell them in the US for $80. Well below other 4chs at same scale, and these are sturdier and better looking. The company is only 2yo and their stuff beats Eflite/Esky/Walkera except no mention of parts.

Xheli was supposed to be stocking parts too. I haven't looked closely at that either. The blades have whacked solid furniture and scarcely dented. The flybar straightens. The rest is so sturdy I can't imagine busting it short of flying it fullspeed into a tree.
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Last edited by arbilab; Feb 08, 2010 at 12:54 AM. Reason: mfr data
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Old Mar 22, 2010, 01:45 PM
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Mandurah, Western Australia
Joined Mar 2007
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I have this chopper and it's great. Sure it's no T-Rex 450 (which I also have) but it's a bit of fun. It definitely has a gyro, but it's not heading-hold (and wouldn't expect it to be for this price!).

Anyone do a brushless conversion yet? I'm confident I could convert the main motors, but the rear motor needs to spin in both directions for elevator control, and I don't know how to do this. Ideas????
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Old Mar 22, 2010, 03:08 PM
Fly Runaway Fans
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Little to be gained for the complication of making that tailmotor brushless bidirectional. Not that it's hard to make BL run backwards, just reverse two wires, but that no BL ESC is equipped to run bidirectionally on command.
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Old Mar 30, 2010, 09:39 PM
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Mandurah, Western Australia
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Quote:
Originally Posted by arbilab View Post
no BL ESC is equipped to run bidirectionally on command.
Damn. That's what I figured. I've got plenty of experience with BL motor systems, but until I saw this heli's tail rotor, I'd never seen an "on command" reversing motor. Pity it can't be done brushless - the stock tail motor lacks push!
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Old Mar 30, 2010, 10:22 PM
Fly Runaway Fans
United States, TX, Fort Worth
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I know. I've had the T outoors in wind and it does fine except the weak tailmotor makes the difference between flying and slowly drifting away.

But a tailmotor big enough to be strong--BL or not--would be a problem for CG and adding fore weight to balance it would make it a different craft.
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Old Apr 30, 2010, 12:58 PM
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I bought the GYRO Huge Metal Sky King 3.5CH Electric RTF RC Helicopter. When I charged the battery and tried it out, the tail rotor and the top main rotor does not respond. Anybody else have any of these issues?
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Old Jul 11, 2010, 11:41 PM
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Hi Guys,

I recently bought a 9074 while I was in Thailand. I brought it back, and after purchasing the right adaptor, plugged it and charged it up. First flight, it work fine. Flew it around until it went flat.

Charged it up again and went to use it again. But now the remote control just flashes when I turn it on. So it doesn't seem to recognise the helicopter.

The blue and red LEDs inside the nose are working when I turn the copter on. But then switch the remote on, and it just flashes.

Any suggestions?
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Old Jul 11, 2010, 11:51 PM
Fly Runaway Fans
United States, TX, Fort Worth
Joined Jan 2009
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When the TX flashes it means the batteries are below standard. That can be anywhere from 1.3 to 1.17V. Put new ones.

Also, don't fly it until it won't fly anymore. That can kill a lipo. Stop the moment you can tell performance is declining.
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Old Jul 12, 2010, 12:11 AM
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New to RC helicopters and seeing problems...

We just bought this model and it flies backwards direction! Need your great advice! Thanks!
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