Mini-Review Hacker A20-26M v Torque 26T/1135

[Dr Kiwi]

I have come under fire for suggesting that the Extreme-Flight Torque series seems to be similar to the Hacker A20's.

How similar, you ask, quizzically!

I'll let the data tell the story.

On the same day, under exactly the same conditions (24C ambient), I ran the Hacker A20-26M and a Torque 26T/1135 with a 7x5 APC E, 8x4 GWS HD, 8x4 APC E and 9x5 GWS HD. (I also ran each motor with a 9x4.7 APC SF on exactly 9v, because that was the only data point on the Hacker spec sheet which I was able to match). Edit: I sure hope these Hackers don't break down on me because, having read the fine print, it would appear that all implied warranties are negated if one uses a Power Supply [very specifically, "may only be supplied with electricity from batteries" - The connection to a power supply is not permitted].

The attached images are:

(1) Hacker A20-26M and 22L; Torque 26T and 22T [my Hacker 34S is still "on backorder"]
(2) Hacker A20-26M on test stand
(3) Data sheet for Hacker A20-26M [amp draws exceeding the recommended running current (12A, as given on the Hacker spec sheet) are shown in red].
(4) Data sheet for Torque 26T [as above]
(5) Graphs of performance at 7v, 8v, 9v, 10v, 11v on the power supply, for three of the props tested [7x5 APC E, 8x4 GWS HD, 9x5 GWS HD].

I'll get to the A20-22L and Torque 22T tomorrow.

Cheers, Phil

[cadconversions]

Wow, interesting results. Great Job again!

[dick hanson]

If I don't seem surprised ---------------------

[adamg]

My conclusion from that data:
The Hacker A20 26M and Torque 26T are extremely similar motors. Same kv, same heat, same efficiency, same weight. The only noticeable exception is a slightly hotter wind on the Torque, but no one would notice this in practice.

Edit: Disregard that last sentence. They are slightly different in every way, but noticeably different in none.

[Dr Kiwi]

Originally Posted by adamg

They are slightly different in every way, but noticeably different in none.

Exactly right - perhaps their Kv's are slightly different (quoted as 1130 for the Hacker and 1135 for the Torque) but even if those numbers are correct, it's surely not enough to make a significant difference.

I've just completed running 5 different props on the 22L v the 22T - give me an hour or two and I'll have those numbers for you.

Cheers, Phil

[KillerAir]

You...you...your good. Quick question ol good dr. Are you going strictly off the spec sheets for maximum currents, because I do believe they are somewhat conservative. Adam where do you see heat, am i missing something?

Killer

Great work Phil.

[Dr Kiwi]

Originally Posted by KillerAir

You...you...your good. Quick question ol good dr. Are you going strictly off the spec sheets for maximum currents, because I do believe they are somewhat conservative. Adam where do you see heat, am i missing something?

Killer

Great work Phil.

As a bench mark I did use the spec sheet running currents as a maximum, and I believe that they are not far away for static running. Remember that for each prop the motor is running for only 15-20 seconds at a time at WOT at the 5 different voltages. The maximum temperature recommended for the Hackers is 65C (149F) and where I have run the motors to near that maximum amp draw on 11v, the temperatures have been getting up there. It is noticeable that in all cases where temperatures exceeded 50C, there was a drop off in performance and the motors could not maintain their peak amp draw. I am told that electrical resistance of wire increases by 0.4% for each degree C rise in temperature - so that's ~10% in going from 25C ambient to 50C running.

Yes, in the air they might run cooler, but I like to be conservative.

Also, as will be revealed in my next epistle - the Hacker spec sheet estimates of current draw for the 22L with a 10x4.7 APC SF are dangerously low!

Cheers, Phil

[adamg]

Killer, in the leftmost column of Dr's spreadsheets he shows a temperature at a capacity elapsed for the near-the-limit runs.

A few guys were mentioning part-throttle efficiency as a possible performance standard that can be useful along with full-throttle efficiency and power. The great thing about the Dr's data is that it shows part throttle efficiency! When you go part-throttle, the ESC simply drops the voltage the motor sees, imitating the situation where Dr runs the motors at full throttle on reduced voltages. So, if you always fly 3cell Lipos, don't just pay attention to the 10v performance; take a look at the 7v performance (read: efficiency) as well.

Edit: Evidently I am wrong about the workings of brushless ESCs at part throttle. Discuss.

[KillerAir]

Oh I see it now Duh. Thanks
Phil I am pulling 22A (3s tp2100 genII) on the 10x4.7sf with the 22L. Specs say 19, haven't hit that yet, but AF meters are subject to +-% off.
Killer

[DavidB.]

Ok, both motors seem identical in performance, weight, and price. So which one is built better and seems to have better cooling?? Cooling holes are very important and I'd want the motor with the bigger holes

[Dr Kiwi]

Originally Posted by DavidB.

Ok, both motors seem identical in performance, weight, and price. So which one is built better and seems to have better cooling?? Cooling holes are very important and I'd want the motor with the bigger holes

I think that the cooling holes are identical! I don't think there is much in it as far as heating goes - both Hacker and Torque run cool when compared with a lot of other motors out there. I can't say much about the quality except that the bearings and shafts look identical and the quality of the machining on the cases is awesome for both.

Killer - I just recorded 17.70A on 10.0v with 10x4.7 APC SF on both the 22L and the 22T - unlike you guys I didn't dare go any higher just to see if I could fry something.

Cheers, Phil

[Tom Frank]

Originally Posted by adamg

... A few guys were mentioning part-throttle efficiency as a possible performance standard that can be useful along with full-throttle efficiency and power. The great thing about the Dr's data is that it shows part throttle efficiency! When you go part-throttle, the ESC simply drops the voltage the motor sees, imitating the situation where Dr runs the motors at full throttle on reduced voltages. ....

Are you sure about this? It was my (perhaps erroneous) understanding that when run at reduced throttle, a brushless ESC still delivers the same voltage and amps, but for a shorter duration during each power cycle on each phase. Hence the motor slows down and the (time-weighted) AVERAGE amps delivered to the motor (as measured on one of the power supply or battery wires) also goes down. I'd still like to see Dr. Kiwi do a couple of data points for the 22L by throttling down to 6 amps and 8 amps, and take readings on the other variables so we can compare with the data points on the comparable AXI 2212/26 in post #171 in the otehr Hacker thread (A20-22L WOW). This would confirm what is really going on.

<edit>: I just re-read the post #171 I referenced and see that it was done with a lipo pack and the voltage was not recorded, hence a test by the good Dr. can not be used for comparison with his regulated power supply

[KillerAir]

I remember talking to Patrick at Castle about this and he said the controller always sees the same current draw and voltage, just for shorter durations, sort of pulsing. Partial throttle Efficiency may also be a product of the controller.
Killer

[KillerAir]

Just going by the recomended prop for that motor as posted on the Hacker spec sheet

[Tom Frank]

Originally Posted by KillerAir

I remember talking to Patrick at Castle about this and he said the controller always sees the same current draw and voltage, just for shorter durations, sort of pulsing. Partial throttle Efficiency may also be a product of the controller.
Killer

Thank you. So my understanding was correct, and we can't just look at lower voltage data to see what the system will actually do at part throttle, as I expected.

I think this is a big missing hole in static performance data (i.e. partial throttle data at a couple of fixed amp loads). Since most of us don't fly at WOT except for brief periods, the partial throttle data may be more revealing, e.g. post #171 (although the Hacker compared there should really be the 22L, not the 20L to be fair).