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Hirobo SDX Electric Conversion

 
I have flown this helicopter for more than 200 flights. I have been going to use it for a few different scale projects, but it never made the cut. Why is that you ask. Because it was a nitro burning mess maker. No matter how well this heli flew I just could not get past the mess it was to clean up after a day of flying. No way would I put it into a scale body and give myself all that work to do after flying even one flight. So as I bought more electric helicopters for my scale builds this one was flown less and less. As of this writing it has been sitting for around two years, with this last year having it's engine removed and just sitting there waiting. I the mean time I have bought myself a mill/lathe combo with some bonus money from work. I have never done machining and did not go to school for it, but it was something I wanted to try so I could make my own parts. How cool would that be I thought.
 
So my very first real part was the coupler to connect an electric motor to the existing clutch assembly. I like using a clutch with electric helis as it gives it a more scale like start up. Anyway, I was close to completing the couple when I made a rookie mistake and used a normal drill bit instead of a center drill to start the hole for the motor. The drill bit walked over sideways and the part was junk. Just like that my work was for nothing, other than learning what not to do. So after spending the last year working on three other scale projects, and some other things, I finally got back to converting my SDX to electric.
 
So what's needed; 1) a coupler to connect the electric motor to the nitro clutch, 2) a motor mount that also doubles as a heatsink for the motor, 3) and side frames to connect the motor mount to the helicopter frames. Well that doesn't seem like much at all does it? Well it's not except that I was learning while making parts that I wanted to keep, not throw away. Oh yeah, I also had to measure and design these three parts. I am not a mechanical engineer either, but that isn't going to stop me. o with a caliper, ruler, pencil and paper, I go started. Drawing the coupler idea from my head to the paper first, then figuring out the dimensions. I also used the original nitro engine to clutch couple as a reference tool. he side frames and motor mount were easier and less critical because they would be slotted to allow motor pinion gear alignment. So if they were not exactly perfect it should not matter.
 
 

Here you can see the original nitro engine, muffler, motor mount, clutch, and fuel tank.
You can also see the ESC I plan to use as it's a spare from the original Trex600 used in my MD500TD. 
 
Here is the ESC and motor from the Trex600 used in my MD500TD.
 
And the Hirobo SDX without engine and fuel tank. Looks pretty open now.
 
Here I am getting ready to make the electric motor to nitro clutch adaptor.
 
Just making lots a metal chips right here.
 
 Now it's starting to look like something.
 
Here I have all the sizes stepped down to what I want.
 
Here I just finished cutting the recess to align the clutch perfectly in the center
of the adaptor. If not centered it will shake and vibrate and not be usable. 
 
 Next I drilled and tapped the holes to mount the clutch,
and to secure the adaptor to the motor shaft.
 
The parts are getting introduced to each other.
 
Adaptor and clutch are test fir onto the motor. It fits perfect.
What a relief this was for me as I was worried it would not. 
 
Now all the parts are in place as they will be in the heli.
 
Here is the raw material the will turn into the motor mount/heatshink,
and the side frames to secure the motor mount to the heli frames.
 
Motor mount is rough cut to approx size.
 
Center hole and all four mounting holes are also drilled.
 
Here I cut ribs into the mount to help disapate heat.
 
Side motor mount frames have been cut and drilled. The two holes at the top
will be slotted to allow proper pinion gear meshing when installed.
 
Here is a test fit of all the motor mounting parts.
 
Here's a short video of the bench test after everything was installed.
 
Here it is ready for the maiden test flight.
 
Here is the maiden test flight from today, Dec. 21, 2012.
 
I have went over my settings and everything looks good. The one thing I did forget was that
I moved the tail boom back slightly to tighten the drive belt. This would have changed the center
for the tail rotor blades. I have fixed that and now must wait for daylight to come back. 
 
Im very pleased at how smooth everything is running. Maybe I should quit my day job and become a machinist, ha-ha.. 
 
Well I made it out to my flying field (needed four wheel drive at times) today, 12/22/2012 to get two real test
flights in. I am super pleased as this thing is smooth as glass. It's always been a good flying heli, but now it is so much
quieter without the screaming nitro engine, and running a slower scale head speed sounds great. It still had an issue
with the tail holding solid, but it was only 18 - 19 degrees F while flying. Might just be too cold for the gyro. I was not
able to find any temp specs for it. Anyway, here's a couple photos, but no flying video as I was alone today. After a few
more flights I will be installing the NAZA-H system on this heli and will start a new entry for that project. Thank you for
checking out my site. Happy flying to ya!!!
 
Date 12/25/2013:
Thought I would add an update to this project. Frigging awesome!!!!  This conversion has a good 50 or more flights on it and it works great. The heli is super smooth running and in flight. I am very
glad I did this. This Hirobo helicopter in general has been a great helicopter. It has bee my test bed for everything, scale 5 blade head, flybarless setup, electric conversion, NAZA H flight controller.
It has served me very well.
 
I fly 6S1P 5000mA Lipos an after a 6 minute flight I have only used 50% battery capacity. Not bad I'd say. I do run low head speeds, 1725 is max. Not sure what the next lower speed is, but I guess
around 1625 - 1650.