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ahahn · 01-25-2014, 05:17 PM

I decided to install my new HH nano BL upgrade on my 2 week old nano. I haven't flown it much, so as far as I am concerned the original brushed motor is basically new.

I charged up two relatively new 45C Eflite 150mAHr cells and first measured the rpm of the brushed system at WOT.

1a) Main blades off, tail motor unplugged--Spool up on fresh cell, rpm= 5500
1b) Put Main blades back on, same cell (didn't recharge), rpm=3100--full positive pitch

2a) Installed BL upgrade, but same conditions as 1a) except continue with same cell (again, didn't recharge), rpm = 5820.
2b) Put on main blades, using same cell (no recharge) rpm=3110--full positive pitch.
2c) Replaced cell with fresh cell and redid 2b measurement, rpm=3240.

So the brushless is putting out a bit more than the brushed motor. Whether this equates to 20% more power isn't clear to me. What I am hoping is that unlike the stock motor which loses "oompf" as it ages, this BL should at least stay the same. The only loss hopefully will be the batteries aging. I guess we will see.

Other observations:

Mine was a bit harder to install that what others seem to have experienced. I had to unplug my tail motor since it was woven into the original brushed motor leads. Also my elevator servo leads were really short--couldn't really push them out of the way to remove the original motor. After the BL motor was installed, the extra height made it difficult to reinstall the elevator servo leads. Had to remove the servo since the brown wire looked like it was captured by the servo pc board and was causing the tightness in the servo leads.

Had same problem that others have had with attaching the ESC to the main board--ESC is "too lumpy" for that layer of tape, so added another layer of 3M tape. Finally the power cabling is messy, so probably will redo that to clean the installation up.

I agree with Dylan that the ESC has a brake on it---motor makes a little whine when TH is engaged, not what a BL sounds like normally when you hit TH. Would be nice to have a way via the stick to reprogram that out.

ahahn · 01-25-2014, 05:27 PM

As an aside---typically these motors are most efficient when running at an rpm ~80% or so of the unloaded rpm value. In my case, considering the unloaded value to be something higher than the ~5800rpm (since with the gearing it isn't really an unloaded measurement even wthout the main blades), that would imply that at WOT, you would like the rpm to be ~4800 (I just let 6000 rpm be the unloaded value).

Now the full pitch 3100 rpm is pretty heavy loading. Roughly 1/2 of the unloaded rpm. It is a characteristic of these motors that you make the most power output at 1/2 the unloaded rpm value, but the power input is twice that output value. In other words, half of your cell energy is going into heat.

When flying I'd expect the unloaded rpm at WOT to be higher than these static values, so it isn't quite as bad as it looks, but maybe it isn't such a bad idea to back off the collective range a bit to keep the rpm up there. I didn't measure my pitch--it is what the stock heli came with, but I think I might consider lowering maximum pitch.

MoFreak · 01-26-2014, 08:50 AM

Good job on the analysis! I wonder how factory tail mixing is effected by running the BL at lower throttle since it is expecting the brushed motor torque. Mine seems to hold best at higher throttle setting.

The braking sucks on spindown but I can live with that knowing it is best for practicing 3d and using TH before crashing.

I made a battery meter wire harness that measures 1S volts and amps using two voltmeters. It goes in series inbetween the battery and nano. I use it to compare older suspect batteries and check for excessive drag. With this and a scale one could plot a power curve and find best efficiency points for throttle and pitch settings.

splatt860 · 05-03-2014, 09:17 PM

Hopefully someone will check this thread and answer this question...
I have the hh bl kit... I don't like it so I wanted to pick up a different brushless motor, the question is can I run different bl motors and keep the hh esc? I tried to find some info on this but no luck

Sent From My Dx7 Flying My Brushless MCPX

01-25-2014, 05:17 PM	#1 (permalink)
ahahn Registered Users Join Date: Aug 2010	Some simple HH BL nano upgrade measurements I decided to install my new HH nano BL upgrade on my 2 week old nano. I haven't flown it much, so as far as I am concerned the original brushed motor is basically new. I charged up two relatively new 45C Eflite 150mAHr cells and first measured the rpm of the brushed system at WOT. 1a) Main blades off, tail motor unplugged--Spool up on fresh cell, rpm= 5500 1b) Put Main blades back on, same cell (didn't recharge), rpm=3100--full positive pitch 2a) Installed BL upgrade, but same conditions as 1a) except continue with same cell (again, didn't recharge), rpm = 5820. 2b) Put on main blades, using same cell (no recharge) rpm=3110--full positive pitch. 2c) Replaced cell with fresh cell and redid 2b measurement, rpm=3240. So the brushless is putting out a bit more than the brushed motor. Whether this equates to 20% more power isn't clear to me. What I am hoping is that unlike the stock motor which loses "oompf" as it ages, this BL should at least stay the same. The only loss hopefully will be the batteries aging. I guess we will see. Other observations: Mine was a bit harder to install that what others seem to have experienced. I had to unplug my tail motor since it was woven into the original brushed motor leads. Also my elevator servo leads were really short--couldn't really push them out of the way to remove the original motor. After the BL motor was installed, the extra height made it difficult to reinstall the elevator servo leads. Had to remove the servo since the brown wire looked like it was captured by the servo pc board and was causing the tightness in the servo leads. Had same problem that others have had with attaching the ESC to the main board--ESC is "too lumpy" for that layer of tape, so added another layer of 3M tape. Finally the power cabling is messy, so probably will redo that to clean the installation up. I agree with Dylan that the ESC has a brake on it---motor makes a little whine when TH is engaged, not what a BL sounds like normally when you hit TH. Would be nice to have a way via the stick to reprogram that out.

01-26-2014, 08:50 AM	#3 (permalink)
MoFreak Registered Users My HF Map location Join Date: Mar 2013	Good job on the analysis! I wonder how factory tail mixing is effected by running the BL at lower throttle since it is expecting the brushed motor torque. Mine seems to hold best at higher throttle setting. The braking sucks on spindown but I can live with that knowing it is best for practicing 3d and using TH before crashing. I made a battery meter wire harness that measures 1S volts and amps using two voltmeters. It goes in series inbetween the battery and nano. I use it to compare older suspect batteries and check for excessive drag. With this and a scale one could plot a power curve and find best efficiency points for throttle and pitch settings. __________________ 450 3DX + fbl beastx, tgy306g servos; mCPX BL (2) + airtime skids, mh head, xp7a tail wag free; Nano CPX (2) xp3a & HH BL motor, airtime skids, mh head Retired nitros - Schlüter Mini-Boy ('84, mechanical mixing tail), Kyosho Concept 30**

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01-25-2014, 05:27 PM	#2 (permalink)
ahahn Registered Users Thread Starter Join Date: Aug 2010	As an aside---typically these motors are most efficient when running at an rpm ~80% or so of the unloaded rpm value. In my case, considering the unloaded value to be something higher than the ~5800rpm (since with the gearing it isn't really an unloaded measurement even wthout the main blades), that would imply that at WOT, you would like the rpm to be ~4800 (I just let 6000 rpm be the unloaded value). Now the full pitch 3100 rpm is pretty heavy loading. Roughly 1/2 of the unloaded rpm. It is a characteristic of these motors that you make the most power output at 1/2 the unloaded rpm value, but the power input is twice that output value. In other words, half of your cell energy is going into heat. When flying I'd expect the unloaded rpm at WOT to be higher than these static values, so it isn't quite as bad as it looks, but maybe it isn't such a bad idea to back off the collective range a bit to keep the rpm up there. I didn't measure my pitch--it is what the stock heli came with, but I think I might consider lowering maximum pitch.

05-03-2014, 09:17 PM	#4 (permalink)
splatt860 Registered Users Join Date: Mar 2014	Hopefully someone will check this thread and answer this question... I have the hh bl kit... I don't like it so I wanted to pick up a different brushless motor, the question is can I run different bl motors and keep the hh esc? I tried to find some info on this but no luck Sent From My Dx7 Flying My Brushless MCPX

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