GBx1 ~ 11T 22AWG Wye

Alan Hahn · 04-13-2008, 03:43 PM

Motor Configuration

General Info			Motor Constants
Kit Type	Stator Size	Weight (g)	Io	Rm	kV	kT
GBx1	(1) GB 22.7mm 9-pole	36.5	0.68	0	2250	0

Rotor Configuration					Winding Configuration
Type	Magnet Size	Shape	Total Magnets	Total Poles	Turns	Strands	Gauge	Termination
N50	5 x 4 x 2 mm	Flat	12	12	11	1	22 AWG	Wye

Test Results & User's Setup

#	Manufacturer & Type	Prop Dia	Prop Pitch	Voltage	Current	RPM	Remarks
1	APC Thin	6	5.5	7.0	10.8	11700	These data [1-4] taken 2/19/08
2	APC Thin	6	4.0	7.3	8.8	12940	pm measured with TNC Tach and EagleTree Data Recorder
3	APC Thin	5.5	4.5	7.2	8.9	12730	Battery used for tests =EvoLite 2s1p 2500 @50%
4	Not Listed	0	0	8.05	0.68	18940	No Load Measurement--gives kV =2250 and Io=0.68A above
5	Not Listed	0	0	7.56	0.60	17750	No Load taken 4/14/08 after using motor--kV=2350. Io=0.60A
6	Not Listed	0	0	7.56	0.70	16530	Same but with StrongRC curved magnets, kV=2190,Io=0.70A
7	Not Listed	0	0	0	0	0	See following comments on last two measurements
8
9
10

User's Setup
Aircraft:	Brodak Baby Clown CL
Prop:	APC 6-5.5
ESC:	Thunderbird 9
Receiver:	None--use timer
Battery:	ThunderpowerProLite 730

Note to forum users: The motor characteristics and performance indicators above have not been verified by GoBrushless.com or any 3rd party entity. As a result, we cannot guarantee the accuracy or validity of the configuration or test results listed. Please feel free to post a reply to this thread should you have any questions regarding this motor and/or its test data.

Alan Hahn · 04-13-2008, 04:00 PM

This is the same motor that I erroneously entered last Febriary 2008 with wrong label of GBv. Since can't seem to fix the original entry, I have re-entered the original data, and two new points that I took today.

I was curious as to how well a stronger field would work, so I bought a new bell, ring, curved N50 magnets, and motor shaft from StrongRC (cost about the same or more than original GBx1 kit!). Actually I wanted to upgrade the housing of a GBv1.1, but couldn't easily do it since the motor tube has an offset on that model, so the magnets in the GBx Bell don't overlap. I could push the tube back (and may still do that), but I was too lazy up to now to do that. But I thought it would be fun to switch bells and magnets between my GBx1 motor to see how the curved magnets behave. Also I think the curved set actually have a higher coverage than the original GBx1 magnets do.

Up to now I only reran the no-load measurement. I did it both for the original bell, and the new StrongRC . These are the last two entries in the table above. Comparing those two entries, the kV has decreased by ~7%, showing that the new magnets are producing a stronger field in the armature. To regain the rpm, I probably should rewind to 10 turns of wire.

I am not sure that the curved magnets are really worth the cost if you did a benefit analysis. I enjoyed the test, so I it was worth it to me since I learned something.

Another interesting point is that my kV for the recent measurement of the original setup also is higher 2350 vs 2250 originally, and Io is lower. I checked the original measurements and this seems to actually be real. I am not sure exactly what it does mean---either the bearings could be wearing in better (giving a lower Io and a higher apparent kV since calculate kV ignoring Io), OR the magnet field strength of the original magnets is decreasing. Both are speculative but interesting!

Alan Hahn · 04-13-2008, 04:13 PM

Here is a post that was included in the original miss-posted thread. The only reason I repost this is the comment at the end. As you can see, at the lower voltage, the Io was also lower, so my comment in the previous post about Io being lower in today's measurement must be bogus, and due most likely to the lower battery voltage in today's measurement .

A couple more comments. Battery used for these measurements was a EvoLight 2s2500mAHr battery. Measurement was made with Astroflight Whattmeter (for V and I), and a combination EagleTree sensorless rpm sensor and TNC Tach (both rpm measurement values were consistent). The Eagletree voltages measured were also consistent with the Whattmeter, but the propeller current measurements were typically 0.7 to 1.0 A higher with the Eagletree than the Whattmeter (Whattmeter values are the ones given in the table). No-load current values were pretty close between the too.

Also mention that the Io given above was measured at the start of the run (this comes from the no-load row above). All propellers were run within a total time period of ~1/4 hour or so. The motor was completely cool after each run (less than a minute per run). At the end of the test, I ran another no-load run (for fun!), but this time I measured
V=7.7V, Io=0.58A, rpm=18150, so you can see Io isn't completely constant. Just thought I'd mention that!

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04-13-2008, 04:00 PM	#2
Alan Hahn New Member Join Date: May 2007 Posts: 17	This is the same motor that I erroneously entered last Febriary 2008 with wrong label of GBv. Since can't seem to fix the original entry, I have re-entered the original data, and two new points that I took today. I was curious as to how well a stronger field would work, so I bought a new bell, ring, curved N50 magnets, and motor shaft from StrongRC (cost about the same or more than original GBx1 kit!). Actually I wanted to upgrade the housing of a GBv1.1, but couldn't easily do it since the motor tube has an offset on that model, so the magnets in the GBx Bell don't overlap. I could push the tube back (and may still do that), but I was too lazy up to now to do that. But I thought it would be fun to switch bells and magnets between my GBx1 motor to see how the curved magnets behave. Also I think the curved set actually have a higher coverage than the original GBx1 magnets do. Up to now I only reran the no-load measurement. I did it both for the original bell, and the new StrongRC . These are the last two entries in the table above. Comparing those two entries, the kV has decreased by ~7%, showing that the new magnets are producing a stronger field in the armature. To regain the rpm, I probably should rewind to 10 turns of wire. I am not sure that the curved magnets are really worth the cost if you did a benefit analysis. I enjoyed the test, so I it was worth it to me since I learned something. Another interesting point is that my kV for the recent measurement of the original setup also is higher 2350 vs 2250 originally, and Io is lower. I checked the original measurements and this seems to actually be real. I am not sure exactly what it does mean---either the bearings could be wearing in better (giving a lower Io and a higher apparent kV since calculate kV ignoring Io), OR the magnet field strength of the original magnets is decreasing. Both are speculative but interesting!

04-13-2008, 04:13 PM	#3
Alan Hahn New Member Join Date: May 2007 Posts: 17	Here is a post that was included in the original miss-posted thread. The only reason I repost this is the comment at the end. As you can see, at the lower voltage, the Io was also lower, so my comment in the previous post about Io being lower in today's measurement must be bogus, and due most likely to the lower battery voltage in today's measurement . A couple more comments. Battery used for these measurements was a EvoLight 2s2500mAHr battery. Measurement was made with Astroflight Whattmeter (for V and I), and a combination EagleTree sensorless rpm sensor and TNC Tach (both rpm measurement values were consistent). The Eagletree voltages measured were also consistent with the Whattmeter, but the propeller current measurements were typically 0.7 to 1.0 A higher with the Eagletree than the Whattmeter (Whattmeter values are the ones given in the table). No-load current values were pretty close between the too. Also mention that the Io given above was measured at the start of the run (this comes from the no-load row above). All propellers were run within a total time period of ~1/4 hour or so. The motor was completely cool after each run (less than a minute per run). At the end of the test, I ran another no-load run (for fun!), but this time I measured V=7.7V, Io=0.58A, rpm=18150, so you can see Io isn't completely constant. Just thought I'd mention that!