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Counter, no Contra rotating electric motor system challenge. (I hope I spelled it right ;)

Ryan O.

Well-known member
#1
I foumd these odd motors when trying to find a power system for my now dead XF8B-1. It turns out very few companies make these systems for rc. Many aircraft have used contra rotating prop systems like: the Boeing XF8B-1, the Bristol Brabazon, some air race upgraded Spits and Mustangs, and several civillian planes. I challenge scratch builders to either modify one of their existing planes (like and Eflite Corsair) or scratch build a new plane to accompany the Contr Rotating propeller system. https://www.amazon.com/dp/B07D7SYPMK/?tag=lstir-20

https://www.amazon.com/s?k=contra+r...ting+brushle&ref=nb_sb_ss_i_1_23&tag=lstir-20
 

LitterBug

Troll Spammer
#4
Hmmmm. I've actually been looking for something like that.....
SingleCopter.jpg


Need a bigger printer for those specs though. Looks like 8-9 inch props for the smallest one. Guess I could run smaller props on 6S though.. :-D
Cheers!
LitterBug
 

quorneng

Well-known member
#5
"The shaft of motor 1 goes through motor 2....."
Modifying the front brushless motor to have a larger diameter & hollow shaft is a major modification.
A concentric shaft arrangement is a requirement of any contra prop system even if the whole thing is actually driven by one motor.
 

willsonman

Builder Extraordinare
Mentor
#8
Yeah, Mine was a very custom setup and it works very well... scary well. While they are a neat novelty, I'm not entirely convinced that the efficiencies of them scale down very well on our model levels. Still, they are neat and the sound is certainly something that gets the attention of spectators.
 

DutchRoll

Well-known member
#9
I foumd these odd motors when trying to find a power system for my now dead XF8B-1. It turns out very few companies make these systems for rc. Many aircraft have used contra rotating prop systems like: the Boeing XF8B-1, the Bristol Brabazon, some air race upgraded Spits and Mustangs, and several civillian planes. I challenge scratch builders to either modify one of their existing planes (like and Eflite Corsair) or scratch build a new plane to accompany the Contr Rotating propeller system. https://www.amazon.com/dp/B07D7SYPMK/?tag=lstir-20

https://www.amazon.com/s?k=contra+r...ting+brushle&ref=nb_sb_ss_i_1_23&tag=lstir-20
Yeah, those! I found them too, while looking for 4 blade props the other day. I thought the might might make an interesting warbird build, like the Westland Wyvern, Fairey Gannet, or Douglas Skyshark. Or if you really wanted to bite off more than you can chew, a Tupolev T-95 Bear with four of them. I'd pick the Westland Wyrvern for my build, and I found some plans for a rubberband version over on freeflightarchive.com that should match the 8" prop 20A esc version of the motors.

Edit: Add the Douglas Skypirate to that mix too.
 
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DutchRoll

Well-known member
#10
Actually, there seems to be a bunch of WWII/Post WWII contra-rotating designs: The Curtiss XF14C, Curtiss XP-62, Fisher XP-75 / P-75 Eagle, Hughes XR-11, Martin Model 201. And those are just some US designs.
 

Piotrsko

Well-known member
#11
How about running the shaft of an inrunner through the drilled out shaft of an outrunner? May have to make a new shaft on the inrunner that's long enough but that should be easy and it's only a couple of mm diameter.

For $60 the web thing looks interesting if it works.
 

DutchRoll

Well-known member
#12
From what I see of the design, the inner prop bolts directly to the body of the outer motor via a clamshell collar, while the outer prop attaches to the shaft of the inner motor.
 

quorneng

Well-known member
#14
The simplest possible contra rotating prop system is to use one motor.
Any motor produces an equal and opposite torque on the fixed part, the stator. Mount the stator on its own bearings and fix an opposite rotating prop to it and you have a contra rotating motor assembly.
The down side is you have to provide slip rings for the current to reach the windings.
Apart from requiring 3 sets of slip rings a brushless motor stator is almost perfectly balanced. The case of brushed motor is likely less well balanced but of course only requires 2 slip rings. ;)
 

DutchRoll

Well-known member
#17
Some bad news, I'm afraid. Dancing Wings Hobbies, the seller of these motors, is located in Xiaogan City. They've been quarantined due to the virus outbreak. I have no idea how this would affect shipping something from them.
 
#18
I'm interested in this as i have always wanted an Martin-Baker MB5. I have seen one back in the UK but no counter rotating prop, my interest runs kinda deep for the MB5 as I used to work at Martin-Baker Aircraft back in the UK and always had pictures of it everywhere, it out performed Spitfires and Mustangs, had no vises on take offs or landings, i know one pilot tested it at Farnborough with multiple low passes. wish I was old enough to see this in real life, but would be more than happy with a true scale RC with CR props
 

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leaded50

Well-known member
#19
my setup on the Payen 400 , CRM 2413 system. It will take some machining of new parts to make it for 3blade props. If just cut out in the spinner and rear-spinner part, it will get out of balance.
But i like the setup... well functioning, and looks great!! :)

DSC_0300.JPG
 

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