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Old Oct 14, 2011, 11:16 PM
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Too Much Prop!

I've been flying my Twinstar using the powerpack from Multiplex. The Himax 2812-1080 Brushless Motors are swinging 9 x 6 APC Props. I have way too much thrust even at 50% power! Anyone have the same problem and arrived at happy medium? Or, anyone out there with a prop size/pitch suggestion?

Thanks
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Old Oct 15, 2011, 01:13 PM
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yeah. don't go full throttle.
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Old Oct 15, 2011, 07:58 PM
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Switch to an 8X6
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Old Oct 16, 2011, 10:22 AM
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Switch to an 8X6
Thank you
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Old Oct 16, 2011, 01:51 PM
So many UMs, so little money.
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I had the same issue with different motors and switched to 8x6. Made a bit difference all the way around, including much cooler running motors/ESCs/batteries. All of my electronics stay cool to the touch now, even after running for 20 minutes.

Brandon
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Old Oct 16, 2011, 03:33 PM
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Originally Posted by NeveSSL View Post
I had the same issue with different motors and switched to 8x6. Made a bit difference all the way around, including much cooler running motors/ESCs/batteries. All of my electronics stay cool to the touch now, even after running for 20 minutes.

Brandon
That's an intriguing point. I expect that I will be running the motors at a higher power setting with the smaller prop thus increasing heat. Instead of 33% I might be running at 45%.
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Old Oct 16, 2011, 04:03 PM
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Originally Posted by flyingflipper View Post
That's an intriguing point. I expect that I will be running the motors at a higher power setting with the smaller prop thus increasing heat. Instead of 33% I might be running at 45%.
It sounds odd, but most esc's run hotter at lower speeds, because they have to dissipate the extra power somewhere and it goes away as heat...Tony
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Old Oct 16, 2011, 09:02 PM
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It sounds odd, but most esc's run hotter at lower speeds, because they have to dissipate the extra power somewhere and it goes away as heat...Tony

Well, with the esc's positioned right behind the props, it couldn't work out any better.
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Old Oct 17, 2011, 09:26 AM
So many UMs, so little money.
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Originally Posted by flyingflipper View Post
That's an intriguing point. I expect that I will be running the motors at a higher power setting with the smaller prop thus increasing heat. Instead of 33% I might be running at 45%.
You have to consider the amount of torque. With an 8x6 prop, you have the same pitch and an inch less of prop than a 9x6. It takes less torque since there's an inch less of prop and this means less stress on the motors and ESCs. Also, with less energy going to heat, its more efficient. For my motors, an 8x6 on 3S was a really good match between power and efficiency. I can fly comfortably at half-throttle and generally take off by hand-launch at 3/4 throttle.

Brandon
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Old Oct 17, 2011, 10:31 AM
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Originally Posted by flyingflipper View Post
That's an intriguing point. I expect that I will be running the motors at a higher power setting with the smaller prop thus increasing heat. Instead of 33% I might be running at 45%.
By going from 9x6" to "8x6", you will run your motors at around the same power, i.e. the same average current, but with lower current peaks, so nothing to worry about.

Jürgen
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Old Oct 17, 2011, 10:34 AM
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It sounds odd, but most esc's run hotter at lower speeds, because they have to dissipate the extra power somewhere and it goes away as heat...Tony
That's not how ESCs work. They don't dissipate the extra power, but switch the power on and off several thousand times per second. When you reduce power, the phases of "power-off" are getting longer.

Jürgen
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Old Oct 17, 2011, 10:42 AM
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Originally Posted by Jurgen Heilig View Post
That's not how ESCs work. They don't dissipate the extra power, but switch the power on and off several thousand times per second. When you reduce power, the phases of "power-off" are getting longer.

Jürgen
Thanks Jürgen. I stand corrected. As I get older, I realize I will never stop learning...Tony
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Old Oct 23, 2011, 07:52 PM
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Replacement Motor Recommendation

A hard landing caused damage to one of my motors. The prop didn't break but was enough that the motor needs to be replaced. Prop Savers might have saved it. It wasn't apparent when I ran them up before flight but enough to cause the plane to yaw to one side one at 50% power.

I had Himax 2812-1080 brushless motors installed but if I can get by with a decent "almost as good as" motor, so much the better.

Any recommendations are appreciated. Just general all around flying and an occasional camera (6 oz) on board. The 2812's, by the way, gave me more power than I ever needed!
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Old Oct 23, 2011, 09:07 PM
So many UMs, so little money.
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I'm not familiar with the Himax 2812-1080, but I'm using these Turnigy 2830-1100s and I couldn't be happier. Take off is easy at 3/4 throttle. They are very efficient with the Turnigy ESCs I'm using. I can fly at half- to three quarter-throttle for 12 minutes or so and they'll only use around 1000 mAh. Love it! Plus they haul my GoPro no problem at all.

http://www.hobbyking.com/hobbyking/s...dproduct=12921

At $9, I even bought a spare and it turned out handy to have after some less than stellar motor mounts by yours truly failed.

Brandon
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Old Oct 23, 2011, 09:45 PM
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Originally Posted by NeveSSL View Post
I'm not familiar with the Himax 2812-1080, but I'm using these Turnigy 2830-1100s and I couldn't be happier. Take off is easy at 3/4 throttle. They are very efficient with the Turnigy ESCs I'm using. I can fly at half- to three quarter-throttle for 12 minutes or so and they'll only use around 1000 mAh. Love it! Plus they haul my GoPro no problem at all.

http://www.hobbyking.com/hobbyking/s...dproduct=12921

At $9, I even bought a spare and it turned out handy to have after some less than stellar motor mounts by yours truly failed.

Brandon

Thanks, Brandon - I would like to buy from them but all I hear is negative stuff about HK in vendor talk. If another company sells their stuff, please direct me!
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