Opinion of Contra-Rotating motors

[ELEMODEL]

Hi guys,

Do you have or use a contra-rotating motor?
What's your opinion of it,please?
And what's the predominance to all the BL outrunners?


Thers is a nice Contra-Rotating motor which I have--ELE-CR28M

Dimension：Φ28mm x 51mm
Weight：79g / 2.83oz (not including connectors)
Diameter of shaft：Φ3.0mm
Length of front shaft：10.25mm
Max power: 17A*2=34A
Max power: 375W
KV: 1050rpm/v
Prop:10*4 or 10*5
11V 10.5A*2 Thrust:1320g/46.56oz

[BuzzardBait]

my opinion...

I love the idea.... it plays to the geek in me... and i can think of quite a few scale modles where this would be perfect for..

However....

the realist says.. the benifit you get from torque cancellation and thus no need for right thrust correction to the motor mount.... is outweighed by the cost and complexity of the motors.....

[Gohmer]

The only one I have seen was a double cd rom custom at the Metrodome fun fly in Oct 07. Extremely noisey, but lots of power. I'm going to wait and buy a scorpion one. That's my favorite brand!

[wilky]

Ok i'm interested more details please.

[ron_van_sommeren]

Thread with several diy successes:
http://www.rcgroups.com/forums/showt...contrarotating

[ELEMODEL]

Originally Posted by wilky

Ok i'm interested more details please.

Dimension：Φ28mm x 51mm
Weight：79g / 2.83oz (not including connectors)
Diameter of shaft：Φ3.0mm
Length of front shaft：10.25mm
Max power: 17A*2=34A
Max power: 375W
KV: 1050rpm/v
Prop:10*4 or 10*5
11V 10.5A*2 Thrust:1320g/46.56oz

[FlyWheel]

If I ever think to build a scale model of the Northrop YB-35, I know at least I can get the props right!

[Alpea42]

Hi Max has at least one .I saw it at the AMA show

[FlyWheel]

Originally Posted by Alpea42

Hi Max has at least one I saw it at the AMA show

Is this in response to my post? If so post some pics please!

[Dr Kiwi]

Originally Posted by FlyWheel

Is this in response to my post? If so post some pics please!

Here you are:

[ELEMODEL]

Originally Posted by Dr Kiwi

Here you are:

What do you mean?

[frostman]

Hello: Frostman here I am trying to find out if anyone has done any testing on the CR28M counter rotating setup? I want to use it with 9x6 3 blade props but I am worried about overloading them. Can anyone help?
Please PM me with any information you have, Thank You...

[frostman]

Hello all: Frostman here I just thought you might want the link to the Hobby City site.
http://www.hobbycity.com=45683
Happy flying Frostman...

[mkarim]

Hi Guys
I am impressed by the ElE CR28M contra-motor. Is the thrust really 1320 gm?
The Himax motor CR2805 has a thrust of 681 gm. Although the motors are not identical, yet the thrust difference is huge.
Can anyone help with a comparison?
Thanks

[vtol16]

Originally Posted by mkarim

Hi Guys
I am impressed by the ElE CR28M contra-motor. Is the thrust really 1320 gm?
The Himax motor CR2805 has a thrust of 681 gm. Although the motors are not identical, yet the thrust difference is huge.
Can anyone help with a comparison?
Thanks

mkarim,

Did you conduct a thrust test on the CR2805 or did u get that thrust number from somewhere else? Is that with the standard 7x5 APC props at 10 amps? Thanks!

[mkarim]

Originally Posted by vtol16

mkarim,

Did you conduct a thrust test on the CR2805 or did u get that thrust number from somewhere else? Is that with the standard 7x5 APC props at 10 amps? Thanks!

I am quoting figures provided by the manufacturer (HIMAX). I believe the figure is with the standard 7x5 APC props, don't know the current rating. I am assuming the thrust is with the maximum allowed current.

[vtol16]

Could you provide me with the link to where you found that data? I have been looking for a while, but I have not been able to find it.

[mkarim]

A copy of a reply from "Dean" at Maxx Products (http://www.maxxprod.com/mpi/mpi-266.html):
There is no test data for the thrust. Theroeticaly it should be about 24 oz".
"That is 24 oz for the CR2805 and 40 oz for the CR2816".
These are theoretical values - not measured values.
Hope this helps.

[CESARNOGUEIRA]

I´m in the meddle step of a XB-42 Mixmaster bomber full depron construction.

It will be motorised, as the rela one, with 2 contra rotating motors.

My calculations shows thata it will have a AUW of 2,5 Kilos.

My questions, if somebody could kindly help me :

1)A contra rotating motor set wit 1.320 grams will make it take off from a grass
runway?

2)The Xb-42 is a PUSHER bomber, how should the contra rotating electric motors AND PROPELLERS BE POSITIONED AND ADJUSTED?

YHANKS A LOT FOR THE HELP, WATTFLYER IS A PLACE FULL OF VERY KIND FLYING PEOPLE !