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Old Nov 24, 2007, 10:28 AM
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AEOTech's Avatar
China
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contra-rotating motor from AEO Technology

Let me introduce our newly designed masterpiece AEM CR28M- cotra-rotating motor, it is perfect for electric F3A.
Advantages for the motor:
(1) High power with high efficiency.
(2) Lighter and smaller than similar motors with the same thrust and performance.
(3) Contra-rotating design eliminates adverse torque. Two propellers of the same diameter and pitch rotating in opposite directions completely eliminate torque. This also provides a very smooth operation with greatly reduced vibration.

Specification:
Dimension:Φ28mm x 51mm
Weight:79g / 2.83oz (not including connectors)
Diameter of shaft:Φ3.0mm
Length of front shaft:10.25mm
11V 10.5A*2 Thrust:1320g/46.56oz

we welcome business inquiries from companies who are interested in the product.
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Old Nov 24, 2007, 05:30 PM
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Basingstoke Roy's Avatar
United Kingdom, England, Basingstoke
Joined Oct 2005
448 Posts
Hi

That's an interesting looking contra power unit

Love to have some more details like what props, max power output, cost?

I assume that both motors are running the same KV or has the aft unit a higher KV to stop the prop unloading?
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Old Nov 24, 2007, 07:17 PM
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ni'ihau
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Beautiful motor. I am concerned about efficiency only though. Good luck with the project.
jimbo
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Old Nov 25, 2007, 03:50 AM
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Quote:
Originally Posted by Basingstoke Roy
Hi

That's an interesting looking contra power unit

Love to have some more details like what props, max power output, cost?

I assume that both motors are running the same KV or has the aft unit a higher KV to stop the prop unloading?

Its prop is two 10*5 wood propellers, max power output is 500W(250W for each), retail price can be 98USD or above. yes, both motor are same KV, but I can't understand your sentence"has the aft unit a higher KV to stop the prop unloading"

Thank you!

AEO Tech
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Old Nov 25, 2007, 04:48 AM
http://roys-rc-tv.webs.com/
Basingstoke Roy's Avatar
United Kingdom, England, Basingstoke
Joined Oct 2005
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Quote:
Originally Posted by AEOTech
I can't understand your sentence"has the aft unit a higher KV to stop the prop unloading"

AEO Tech
Hi Thanks for the reply.

Re comment about the aft motor. The front prop accelerates the air flow to the aft prop, which will unload the aft motor. So to balance the loads on the two motors, you have two choices. 1: increase the pitch of the aft blades. 2: increase the rpm of the aft unit.

With my power units I use a higher pitch on the aft prop, to try and Max out the efficiency as best I can.
Its not such a big problem with small models as chances are you got more power than you need anyway. But with larger scale models I found I need all the thrust I can get.

98USD a good price for a 500W motor, it's a nice mid range size to. bigger than the PJS 550R but smaller than the AXi units on sale here in the UK.
Do you have a UK retailer yet?
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Old Nov 25, 2007, 12:14 PM
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ni'ihau
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AEO Tech,
In the picture you show one set of wires (3 wires). Do the front and back motors run on one speed controller? I have heard that it is impossible to do that, and that it is also inefficient.
thanks,
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Old Nov 25, 2007, 12:44 PM
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Hastings, Hawkes Bay, New Zealand (Aotearoa)
Joined Feb 2000
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Quote:
max power output is 500W(250W for each)
500W for a 79gram motor I suspect that would be for a very short time!

Maybe in a ducted fan or high speed model where the motor has direct airflow , but not really what contra rotating props are about.



Heather
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Old Nov 25, 2007, 01:17 PM
http://roys-rc-tv.webs.com/
Basingstoke Roy's Avatar
United Kingdom, England, Basingstoke
Joined Oct 2005
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well spotted Jimbo

I've had a look at the unit on there web site, and its two separate motors. So two ESC thens.

http://www.aeorc.com/english/index.p...wt&goodsid=118
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Old Nov 25, 2007, 02:18 PM
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ni'ihau
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Hi Roy,
I hope your plane is still tearing up the sky.. I am playing the "clown" devil's advocate here. I guess I miss being constantly beat up about the 1 esc, efficiency, and prop pitch thing..


best regards,
Jimbo
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Old Nov 26, 2007, 02:20 AM
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Quote:
Originally Posted by Basingstoke Roy
Hi Thanks for the reply.

Re comment about the aft motor. The front prop accelerates the air flow to the aft prop, which will unload the aft motor. So to balance the loads on the two motors, you have two choices. 1: increase the pitch of the aft blades. 2: increase the rpm of the aft unit.

With my power units I use a higher pitch on the aft prop, to try and Max out the efficiency as best I can.
Its not such a big problem with small models as chances are you got more power than you need anyway. But with larger scale models I found I need all the thrust I can get.

98USD a good price for a 500W motor, it's a nice mid range size to. bigger than the PJS 550R but smaller than the AXi units on sale here in the UK.
Do you have a UK retailer yet?
The air flow to the after prop is not in a straight way, but in a swirl way, so the air- flow can't unload the aft motor, on the contrary, the swirl wind can be a balance force for the aft propeller on different rotating way, so it is no problem when we use same rmp motor and same picth for the aft propeller as the front one, it is a aerodynamic principle, I'm not sure I can make everybody here understand me, but guys here can see the following picture for rear part of a ducted fan system, you can see the part I circled is in a tilt way, not in a straight way, it is the same principal.

The working current for the contra-rotating motor is 34A, voltage is 11V, so its power is 380W or so, if output power can reach 500W, it can't be lasted a long time, or the motor will be damaged.I'm sorry for the mistake I made yesterday. its KV is 1050.

We have no dealer in UK for the motor, but some dealers in UK are contacting us up to now.

Thank you and best regards!

AEO Tech
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Last edited by AEOTech; Nov 26, 2007 at 07:39 AM.
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Old Nov 26, 2007, 02:24 AM
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Quote:
Originally Posted by Heather
500W for a 79gram motor I suspect that would be for a very short time!

Maybe in a ducted fan or high speed model where the motor has direct airflow , but not really what contra rotating props are about.



Heather
yes, you are right, thanks for reminding us.
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Old Nov 26, 2007, 03:00 AM
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ni'ihau
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.....so it is no problem when we use the same rmp motor and same pitch for the aft propeller as the front one,


AEOTech,
In my book you are OK!
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Old Nov 26, 2007, 08:02 AM
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United States, NJ, Frenchtown
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Good motor for a set of variable pitch props.

They wouuld allow for a fast tuning of the best pitch of the second prop.

Dual props on sterndrives of boats use 2 different pitched props.
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Old Nov 26, 2007, 11:07 AM
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Kingston, Canada
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Keith Shaw, on his Italian raceplane, said there wasn't enough difference in amp draw to warrent two different prop sizes.

Gord.
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Old Nov 26, 2007, 11:51 AM
homo ludens modellisticus
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near Nijmegen, Netherlands
Joined Feb 2001
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But the props on his Bugatti are further apart, front and rear, maybe that makes it different.
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