# Motor Mount for RC Helicopter (CNC work)



## [X]Outlaw (Nov 25, 2014)

Hi Guys,

I've been registered with this forum about a year now. I'm fairly new to machining, only been doing it as a hobby for the last three years or so. I would like to share some of the more interesting projects I've worked on for the last couple years.

This mount will convert the Miniature Aricraft USA Stratus/Spectra airframes from Nitro/Gasoline respectively over to electric power. It essentially replaces the clutch stack and the electric motor occupies the area once filled by the internal combustion motor.
It incorporates bolt patterns for all motors currently available for 90 size electric machines making it very flexible. The elegant shape raises the motor close to the main gear so that the motor shaft is kept very short. The diamond profile and sloped edges help to keep the weight down without having to drill unsightly holes all over the part.

The below was the first one of this part sent out to a customer. It was made on my Taig CNC Mill 









These are pictures of a prototype being test fitted. This did not have the mounting holes drilled in the flanges, since it was just to debug the program.






The most challenging thing in this part was getting everything aligned when I flip the part over to machine the reverse side.
For that I made up an indexing jig that allows me to locate the part very precisely via dowel pins.





Chevy


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## stupoty (Nov 25, 2014)

Nice stuff,  I made a nitro to electric convertor bracket for a revo truck recently, not quite as pretty as the one you made 

Stuart


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## [X]Outlaw (Nov 25, 2014)

Yea Stuart,

Electric is where the power is these days!

My two main helis are both 12s 700 size machines (Vibe E12 Ito Edition and Forza 700) running the Scorpion 4525 Ultimate motor...10HP output!
I still have a 50 size nitro (Vibe 50) but haven't flown her in a couple years as electric power has me spolt. Maybe next year I'll put a OS 55 DRS in her and have some fun. As you can see my other passion is RC Helis 

Post up a pic of your motor mout I'd love to see it.

Chevy


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## stupoty (Nov 26, 2014)

I will try and find a pic of it.  The electric is amazingly torque'y , he had the issue that if the esc wasn't dial'd back a bit the thing kinda just did a back flip from stationary , wow.

12s battery thats quite a lot of voltage. Are the motors running through gear boxes for the hellies? Excuse the ignorance, I don't have any experience with them(apart from the tiny ones you can fly indoors)

ive been having some fun helping a friend i do some work with setting up his new Y coptor (dual motor thingy).

the most chalengeing thing so far has been trying to find battery conectors that deal with 200 - 300 amps :-0

Stuart


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## [X]Outlaw (Nov 26, 2014)

Yes stupoty the torque is amazing. Imagine that little motor turning a rotor with the span of about 60 inches 2000rpms while hitting max pitch at 12.5*!

Many helis that enter speed competitions go up to 16s setups and hit 400 amps, for their connections motor --> ESC they either solder or crimp directly.
I'm not sure what they use on the battery -->ESC but on my 12s setups I have been using EC5s with no issues for the past 4yrs, my setup can hit 220amps. I've also used EC5s on 14s setups. On my ESC--> Motor I use 6.5mm bullet connectors. Hop that helps you out a bit.

Helis have multiple gear boxes. This the the various transmission assembles from the JR Forza 700. I'm currently building this model.

* 1. Main rotor power*





* 2. Complete main transmission (Main tail rotor drive included)*




* 3. Tail rotor fore gear box*



* 4. Tail rotor aft gear box*




*The fore tail rotor gearbox transmits power to the rear via a drive shaft (What in the heli world we call a torque tube).

There are many variations to this, some designes use a belt to transmit power to the tail rotor. On Helis built for speed competitions the main rotor transmission is multi staged and the gears narrow in diameter so that the body of the model is more aerodynamic.*

Chevy


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