Electric contra-rotating motor
 

I recently found this motor, seems light for a contra-rotating unit at only 640g. I don't think we need the motor mount but the spinner is quite heavy (can be replaced though).

Here's the link to the manufacturer page:
[link]http://www.gsmodels.com/en/products010.html?proTypeID=100097247&proID=1013129 67&fid=100080417[/link]

I'd like to give it a try but unfortunately i couldn't find where we can actually purchase this motor. I sent an e-mail to the manufacturer asking for more details but didn't receive an answer yet.

RE: Electric contra-rotating motor
 

I think you need the motor mount, it looks like these are two separate motors, front one with a hollow axis, rear one with a solid axis running trough the hollow one.

So both motors turn opposite directions. No gearbox.

RE: Electric contra-rotating motor
 

Hi Alex,
Those motors are way too small for F3A - maybe a 60 size.
A few motor manufacturers are doing this for medium size models - axi, turnigy etc.
You also need 2 x Esc.
Very heavy set up.

Brian

RE: Electric contra-rotating motor
 

Of course, no gearbox, the unit works as you described.

I think the X mount is attached to the motors and is part of the unit, but it's possible to attach the X mount directly to a firewall and get rid of the stand offs and circular mount (53g according to the manufacturer specifications).

RE: Electric contra-rotating motor
 

Hi Brian,

According to the specifications, each motor is capable of pulling max 80A and 1500W at 15-25V (5S LiPo), so it's 3000W in total.
Motor without spinner and mount is 640g, my Himax weighs almost the same.
You're right, you need 2 ESCs, but since each motor runs on 5S you don't have to use HV ESCs. These are usually much heavier than the Lite version.
Sure, it won't be as light as a single prop setup, but some small weight penalty is to be expected when using a contra-rotating setup.

RE: Electric contra-rotating motor
 

Hi Alex,
Wow, the lay out of this unit IS THE WAY TO GO !
I do believe that two separate motors, driven with two separate ESC`s ( from 5s each ) will be the final Standard in F3A !
That this chinese company is doing it as a first - surprise, surprise !
Following this development with great intrest !

see you
Hans

RE: Electric contra-rotating motor
 

Hi All,
Very interesting.
Two 500 KV motors on 5S ... that's maybe 8000 to 8500 RPM, and the props are not that far apart, so I am eager to hear this one.
We still have one isue that the differential gearbox contras solve innately: that is the desired effect of torque or power sharing that cancels the spiral airflow at a variety of speeds, RPMs, and maneuvering loads. A new control circuit that slaves one ESC to the other will be necessary.

Regards,
Dean Pappas

'y' lead would work if the motors are not geared together .

What revs do the blades achieve?

I don't have the motor yet, but i managed to get in touch with the manufacturer. They have been very helpful and will manufacture a custom motor with 270KV for me. The motor will be shipped after 15 August, so i have to wait for a while to test it.

I plan to run both motors on 5S and use the APC propeller set for Brenner's contra drive, we'll see how this works out. Maybe it's a good idea to wire the two 5S batteries in parallel, so both motors run on exactly the same voltage.

Spinner is quite heavy, so i will probably manufacture my own spinners and if the length of the shaft allows, will increase the distance between props.

Of course the configuration of this motor doesn't allow power sharing between the 2 props, so i plan to use 2 separate throttle curves to balance the power of the front and rear motors.