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May 27, 2018, 01:30 PM
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Brushless upgrading a Blade mCPS

After having so much fun with my brushless-upgraded Blade Nano CPS, I decided to pick up a Blade mCPS. It seemed that the mCPS is a bit better supported by Horizon Hobby, or at least most of the parts listed on their site aren't discontinued like with the Nano CPS. Being just a bit bigger than the Blade Nano CPS, the mCPS seems better built and more refined than the Blade Nano CPS. Upon flying the mCPS, however, I soon discovered the stock brushed motor in the mCPS is pathetically weak, maybe even weaker than the Nano CPS! I could actually hear the brushed motor losing power throughout each pack I flew, and the mCPS had nearly zero climb-out towards the end of the pack. There have been many discussions in the forums about potential causes of the mCPS's anemic power output, but I immediately knew that the mCPS desperately needs a brushless motor upgrade!

Unlike in the case of the Nano CPS, Horizon Hobby still offers a plug-n-play brushless upgrade for the mCPS. There is a wide variety of different approaches to installing a brushless motor into the mCPS, and many pilots have posted builds using various powerful brushless motors and ESCs. The easiest way, however, is to just go with Horizon Hobby's brushless motor, BLH5104, and brushless ESC, BLH5105, as shown in Fig. 2. Unfortunately, this brushless motor and ESC add about $50 plus shipping to the cost of the mCPS, pushing the total for the BNF version close to $190! Since I really wanted this compact helicopter for front yard practice, I decided that I would just have to eat the cost of the upgrade.

Removing the stock brushed motor turned out to be simpler than I had envisioned. I just pulled off the skids and rotated the main gear to reveal a pair of motor mounting screws, as shown in Fig. 3. Upon unscrewing the motor mounting screws, the brushed motor was easily lifted upwards and out of the air frame. After unplugging a single plug that connects the brushed motor to the receiver board, I removed the brushed motor from the mCPS.

Figure 4 shows the stock brushed motor placed side-by-side with the brushless BLH5104 motor. It is just stunning that after about a year and many customer complaints, the BLH5104 motor is still being sold with the pinion gear incorrectly mounted onto the motor shaft! Although it isn't too difficult to press the pinion gear fully onto the motor shaft, some care does need to be taken to avoid bending the motor shaft. I chose to use a vise and a leftover piece of an old 450 pitch gauge that I had laying the garage to carefully push the pinion gear all the way onto the shaft, as shown in Fig. 5.

Unfortunately, pushing the pinion gear onto the motor shaft is a required step to install the BLH5104 motor into the mCPS. With the pinion gear at the end of the motor shaft, as shown in Fig. 4, only part of the pinion will mesh with the main gear. The trick is to press the pinion until it just barely contacts a step in the motor shaft's diameter--pushing any harder threatens to bend the shaft, destroying the motor! Once the pinion contacts the step in the motor shaft, the pinion gear aligns very well with the main gear, as shown in Fig. 6.

After using the motor mounting screws to fasten the motor into the mCPS, it's time to connect the wires. As shown in Fig. 7, the brushless motor plugs into the ESC, and the ESC plugs into the socket for the brushed motor on the receiver board. I decided to verify that everything works correctly before proceeding any further with the installation. With the wires still dangling, I plugged in a battery to make sure that the mCPS correctly initializes and that the motor can be spooled. Seeing the blue LED instead of magic smoke is a great sign!

Once I was confident in my wiring, I used a small piece of double-sided foam pad to mount the brushless ESC onto the receiver board, as shown in Fig. 8. I like to use Align's receiver pads, HEP15002, for the Trex 150X--they are super sticky and I've never had one fail. After mounting the brushless ESC, all that remained was to find a suitable routing for the wires that allows the canopy to be easily installed. I recommend going to some effort to ensure that the wires are not pinched between the receiver board and the inside of the canopy. Restricting the receiver board has been known to cause drifting of the mCPS and unwanted tail behavior. Keeping the receiver board freely supported by its rubber mounts will ensure that mCPS flies as stably as possible.

With the mCPS flying decently, all that remained was to set up a convenient travel kit. I chose a PFC Stock Case, PFC 135-100-044-5SF, made by the Plastic Forming Company. I like the PFC Stock Cases because they include a type of foam that is super easy to cut with a razor blade, resulting in professional looking helicopter cases. I chose 6 Turnigy nano-tech 300mah 45C packs, based on overwhelmingly positive advice of many other mCPX/S pilots. And to complete the kit, I included an mCPX/S parallel charging cable, by Buddy RC, that can charge all 6 packs at once. As shown in Fig. 9, everything fits neatly in the case. In practice, I can charge all 6 packs and then be out flying in about 30 minutes!

Having a brushless motor in the mCPS makes all the difference in the world! Although many pilots feel Horizon Hobby's BLH5104 motor is under powered, I tend to disagree. Perhaps, my goals are different, though. I just wanted a motor that doesn't noticeably lose power throughout every pack and has a reasonable amount of punch toward the end of the pack. To this end, the BLH5104 motor has been great! I found no need to change the stock throttle curves recommended for the mCPS. The BLH5104 motor provides plenty of pop even at 80% throttle. In fact, I opted to decrease the servo travel to 80% to avoid tail blow-outs due to the increased torque of the brushless motor!

I honestly believe that the BLH5104 is the motor that Horizon Hobby should have included with the mCPS in the first place. Perhaps, they knew that the brushless motor would necessitate a brushless tail motor, too, which would lead them to a platform resembling the mCPX BL. As far I can tell, they don't seem very interested in updating the mCPX BL, at least not yet. If this is indeed the case, I really do hope they'll reconsider.
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May 27, 2018, 07:34 PM
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blitzen's Avatar
Nice upgrade. Kinda expensive but nice. Also, it was a good read. The best line..." Seeing the blue LED instead of magic smoke is a great sign!"

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