First Mods for the New Heli

[HPIguy]

I've been busy butchering and modding the mCPX the last week or so. After a few weeks of flying, it's short comings started becoming apparent, starting with tail blow out, followed by a lack of power IMHO. I could have saved a few crashes, had it had more power on tap. So, I decided to fix it the RC way, with some mods.

To start, I ordered up a tiny Heli Max 11,000kv brushless inrunner and ESC combo.

Look how tiny, ain't it cute?

Then, a brushed to brushless signal converter. I used The Steve converter as it's super small and has a good rep.

The wires on the steve

Soldered up to the ESC

Hardest part was the throttle signal wire. Had to solder to only one side of a tiny resistor like the one circled on the PCB. Thanks to you guys, I even pulled this one off without much drama.

I picked up some nice stuff from Dylan at Astroid Designs. One of his frame braces, and an SR 120 tail motor holder. He CNC's all his parts, and they're top notch

All mounted up

Done, brushless main motor, extended tail boom, SR 120 tail motor, and cut down SR 120 tail prop.

I also ordered a few packs for it

I also had to file down the feathering spindle .4mm, and still needed a super thin washer for a shim to remove all play from the head, as with the head speed on the brushless setup (around 6,000 RPM) any play in the head (and there's quite a bit stock), and it wanted to shake itself apart. But it's smooth as glass now.

It's also nuts power wise; I have IU limited to 90% flat throttle curve, but I was able to turn my pitch travel up to 77%, vs 67% stock, and zero tail blow out issues even on hard pitch pumps. This is how it should have been out of the box honestly, it's so much easier to recover from things that would have otherwise caused a crash. Best of all, it's cheap to do if you do it yourself.

Downsides? I guess it's likely more stuff will break in a crash now as all that energy has to go somewhere. Main shafts seem to be most common, but considering you can make your own mains out of 3mm carbon rod for cheap, who cares. Also, flight times went from 3:30 to 2:30, and I may pick up a 9T pinion to get some of that back soon.

I'll get some video of it later for you guys, even if it's in the house, it sounds like it's never going to stop gaining RPM on spool up.

 

[hamz9561]

Cool build thread! I've been thinking of doing a brushless conversion of my mCX or mSR.

 

[HPI-Killer]

Wow nice little start for THE CHOPPA! Lookin good HPI

 

[grgbulldog]

Very nice. I know where I'm throwing some money when I get paid thurs.

 

[HPIguy]

Thanks everybody, it was well worth it. Hmmm, a brushless MSR you say? That could be interesting.

Very nice. I know where I'm throwing some money when I get paid thurs.

Yep, it's a lot of work, but a big payoff in the end. You can do it for about $75 or so for all of it I think. There's a great how to over at helifreak, and if you have any questions, feel free to ask.