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Himax HC 6320-250

Old 10-12-2013, 08:48 AM
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OhD
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Default Himax HC 6320-250

I'm trying to help a friend get a 110 size Mythos flying. It has a Himax HC 6320-250 motor that he is running on an 8S LiPo. The prop is a 19x12 which should turn 6200 rpm on 1700 Watts which is the maximum power rating of the motor. With a Kv of 250 the motor should easily turn 6200 on 8S. It doesn't. It looks like it has a Kv closer to 200 which is too low for an 8s pack. Another thing that bothers me is they recommend a 9S-12S pack which I infer means the Kv is lower than specified.

Has anyone else had any experience with this motor? Is there a better motor suited to an 8S pack in this power and weight class?

Thanks in advance, Jim O
Old 10-12-2013, 05:55 PM
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RCBruski65
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I'm running a Hacker A60-5s on 8S. With a 20x10 Xoar. Right at 70 amps and 2000 watts.
Old 10-13-2013, 08:25 AM
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Originally Posted by RCBruski65 View Post
I'm running a Hacker A60-5s on 8S. With a 20x10 Xoar. Right at 70 amps and 2000 watts.
That sounds like a good match for an 8S pack. A little heavy though.

Jim O
Old 10-13-2013, 09:18 AM
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I'm also running the Hacker A60-5S on my mythos with 8S - PT20x12 2700W so not short of power!! - Agree though motor is too heavy, batteries are all the way back, rudder servo in the back too.

The Motrofly DM5320-300 sold in the US by Subsonic planes might be a good alternative, 568g total weight with the light X-mount option. Which is over 100g lighter than the Hacker & is good for 2800W on 8S. A friend of mine has one on an AJ Slick 71" & it works very well.

Steve
Old 10-14-2013, 11:14 AM
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Look at the Hacker A60-7xs, it's for 8s and one of the lightweights.
Old 10-14-2013, 12:01 PM
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If you factor in 80% efficiency, 250x0.8=200.

I had the Scorpion 250kV motor. Many of us were running that motor on 10S with something like an 18x10 prop for pattern. 4000mah 10S is about the same weight or lighter than 8S 5000mah packs (based on the Zippy packs I was using at the time).

8S and big prop is fine if you have the clearance.
Old 10-14-2013, 12:11 PM
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Originally Posted by RCBruski65 View Post
Look at the Hacker A60-7xs, it's for 8s and one of the lightweights.
That looks like the winner to me. Kv seems high though for 8s. What prop and what rpm is to be expected?

Jim O
Old 10-14-2013, 12:21 PM
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Jim:

Some test data about this motor:
APC 18X12E ~ 6100rpm at 50A
APC 19X12E ~ 6100rpm at 55.18A 1720W
APC 19X12WE ~ 5800rpm at 60.87A 1858W
TURNIGY (wood prop) 19X12 ~ 5800rpm at 59.7A 1826W

My understanding, to determine the Kv, Himax manufacturer was using a known RPM drill to drive the motor then direct measure the voltage generated. Typical tolerance 250+-5.
When estimate the possible RPM, I will use 3.7V as loaded cell voltage (full charged at full throttle), and 80% efficiency. That comes out 250x3.7x8x0.8=5920, about the same ball park as the test data.
The Mythos 110 is so big, very close to a full size patternship. My friends in Taiwan are using Himax 6330-200 running at 10S. Take off weight is about 4.8kg. It flies just like a 2 meter plane. They told me the 6320-250 is somewhat too small for it.
Hope this will help.

Luke

Last edited by lsjpeng; 10-14-2013 at 12:25 PM.
Old 10-14-2013, 01:58 PM
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Originally Posted by lsjpeng View Post
Jim:

Some test data about this motor:
APC 18X12E ~ 6100rpm at 50A
APC 19X12E ~ 6100rpm at 55.18A 1720W
APC 19X12WE ~ 5800rpm at 60.87A 1858W
TURNIGY (wood prop) 19X12 ~ 5800rpm at 59.7A 1826W

My understanding, to determine the Kv, Himax manufacturer was using a known RPM drill to drive the motor then direct measure the voltage generated. Typical tolerance 250+-5.
When estimate the possible RPM, I will use 3.7V as loaded cell voltage (full charged at full throttle), and 80% efficiency. That comes out 250x3.7x8x0.8=5920, about the same ball park as the test data.
The Mythos 110 is so big, very close to a full size patternship. My friends in Taiwan are using Himax 6330-200 running at 10S. Take off weight is about 4.8kg. It flies just like a 2 meter plane. They told me the 6320-250 is somewhat too small for it.
Hope this will help.

Luke
Hi Luke,

Thanks for the data. We actually did see similar numbers on the 19x12. The problem is, you get the 6100 rpm and 1700 watts only with a fresh battery. By the end of the flight you are in trouble. I think we are all in agreement the 6320-250 is too small for that plane. Interestingly, my friend started with a 6330 and 10s but it was very nose heavy and just plain heavy. I can't see how your friend got it under 5 kg and got it to balance.

The .8 in your equation to estimate rpm may be right but I don't believe it is related to motor efficiency as such. Motor efficiency is the power out divided by the power in. Power varies with the cube of rpm. For example it would only take 210 watts to turn that prop 3100 rpm. So you can see rpm does not vary linearly with power or efficiency.

I'm recommending the Hacker A60-7xs.

Jim O
Old 10-14-2013, 02:39 PM
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Jim:

If you're interested in how he did, check here: http://www.rctw.net/thread-272939-1-1.html .....no need to register if you only look the picture.
Don't like the term "efficiency"? No problem, let's call it an empirical scale factor, how about that? There are too many factors may affect the rpm; for example, swap a CC 80HV with an OS ESC may boost up another 100 rpm, different brands of battery packs also make difference. And of cause, fresh charged or new battery pack has higher rpm..... As long as it is in the same ballpark, I'm fine.
Old 10-14-2013, 09:42 PM
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I really enjoyed the photos of the build. Those guys do beautiful work. Wish I could read the language.

Yes, I will accept that there needs to be scale factor and I suspect it is different for different size packs, that is 8s vs. 10s etc.

Thanks everyone, for your inputs.

Jim O
Old 10-15-2013, 06:08 AM
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I had the same 0.8 scale factor in my Scorpion 250kv setup, and very similar 'scale factor' for my Hacker (I think 310kV and 8S). Also, if you look at published motor/prop data on the web it seems to be a pretty accurate scaling factor, at least from what I have seen. It certainly gets you close to what you could expect.

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