HobbyKing.com New Products Flash Sale
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Old Nov 11, 2010, 07:39 AM
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Red seems to be the standard color for EMP versions... HXT are purple, Aeronuts are light-blue, Turnigy are gold or silver and there is a dark blue Alpha variant too.......I think they are exactly the same motor, from the same factory... only the anodizing is different!

What about this from Puffin in the UK: Ray-Pelikan????

And the Alpha from Nitroplanes.

And Aeronuts!

Turnigy!

HXT!
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Old Nov 11, 2010, 08:04 AM
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I wonder which one has the best quality control ?

All I want is 4 within say 5% of each other, but 50% has got to be unacceptable.

Does it follow the more you pay the better matched they will be?
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Old Nov 11, 2010, 08:18 AM
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Does it follow the more you pay the better matched they will be?

I doubt it... since they all come from the same place! Now if you switch to AXI, Hacker, Plettenberg, MicroDAN....then you will probably get 4 close to the same.
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Old Nov 11, 2010, 09:36 AM
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Ok Thanks

I do like my AXI's
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Old Nov 19, 2010, 11:04 AM
just Some Useless Geek
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HelioSS, you need to invade the power system subforum and cast about for motor recommendations. You are bound to find guys who have already gone through what you are doing and can give you a hand. I wish I had known how good a source the folk here are a couple of years ago before I spent an unnecessary couple of grand at Grayson, Hobby King, etc. trying to find the right motors, servos, speed controls, yada yada. A little bit of searching can reduce or outright eliminate a whole buncha spending. Eh?
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Old Nov 20, 2010, 11:40 AM
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I can't say Hi Usless Geek....Oh I just have
You're nearly on the money here....I am actually pretty good at selecting what I want it is finding something representative of the origional spec that eludes me. Quality control is non existent so it's a complete lottery what you end up with, kinda frustrating.
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Old Nov 20, 2010, 01:13 PM
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Quote:
Originally Posted by Dr Kiwi View Post
I think they are exactly the same motor, from the same factory... only the anodizing is different!
!
I do too, as well as the Monster motors from HobbyPartz and Lighning motors from Skyshark RC and many others. If you compare the motor stats with the EMP motors and the bells, not end bells and the shaft diameters, weights and the like, it certainly appears they all come from here.

http://www.xingyaohua.com/web/en/index.asp
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Old Nov 20, 2010, 02:17 PM
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Quote:
Originally Posted by Heliosupersix View Post

. So I built a rig with a digital spring balance which could be raised and lowered by turning a screw perpendicular to but 1cm to the side of the motor shaft. I put a small ruler with a hole drilled at 1cm on where the prop would be and connected it to the digital balance.
Comment invited.
Jon
Jon

Please post a diagram or photo of your test set-up.
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Old Nov 20, 2010, 02:23 PM
just Some Useless Geek
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Quote:
Originally Posted by Heliosupersix View Post
Quality control is non existent so it's a complete lottery what you end up with, kinda frustrating.
I disagree that it's a complete crapshoot. Once you've tried certain things from the various vendors (I use HK almost exclusively now) you find out what's good, reliable, repeatable, and available. There are a few motors, ESCs, batteries, and servos that I get from HK that are the same good stuff every single time I get them. Armed with that info I can reliably build planes that will perform to a predictable standard every time as well.

As I said before, the trick is finding the good stuff without spending your kids' college tuition to do it. Sure, E-flite is great stuff, but the motors cost anywhere from 2 to 5 times what an equivalent unit from HK costs. I can't afford the luxury of that dependable level of quality, so I wasted a few bucks (!) finding out what I could rely on. If you use this board the right way you can find out for nada.
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Old Nov 20, 2010, 03:16 PM
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Jon

Further to my post #308.

The description of your test rig leaves much to the imagination.

Are you measuring stall torque ? [ie; with the motor prevented from turning]

If so, that's the quickest way to ruin a motor. And the readings will be meaningless.
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Old Nov 21, 2010, 05:15 AM
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Hi all

As requested
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Old Nov 21, 2010, 06:47 AM
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Jon

I take it that you are measuring "cogging" torque, with no power supplied to the motor.

The test results do not indicate any fault with the motors. They do not indicate poor quality control.

I see in post #298 that you did a test run with motor 1. The prop looks suitable since it slowed the motor to 75% of its no-load speed.

You should repeat this test run with the other 3 motors. Hopefully, they will all show similar performance.
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Old Nov 21, 2010, 07:28 AM
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Hi Peter

We agree on one thing the motor prop match is spot on. It will operate bang in the middle of the published best efficiency.

If the electro motive force of a motor results from the reaction of an electro magnet acting against that of a permanent magnet, please explain to me how one with 50% less strength in its permanent magnets can operate to the same specification.

Jon
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Old Nov 21, 2010, 05:17 PM
just Some Useless Geek
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Jon, you aren't measuring the flux of the magnets with a test that measures cogging. You are only measuring cogging, a measurement that reveals very little about the actual performance of the motor. For instance, I used several 2204-1400 motors from both Grayson (Grayson/Welgard) and Hobby King (Turnigy). These motors were nearly identical in appearance, mass, KV, max current, yada yada yada. Their magnet clearances were different, so they cogged differently. On aircraft, however, they were nearly indistinguishable.

You need to do side-by-side comparisons of motors under load to determine if the cogging has any relation to real world performance. Look around here and you'll find all kinds of test jigs that have been created by insightful RCers with a bent towards collecting useful info that they can then share with the rest of us.
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Old Nov 22, 2010, 02:32 AM
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Hi AUG
I am still struggling to understand why six examples of the same motor and manufactured to a fairly comprehensive specification can have any measurable parameter that is so variable. Taking a scientific approach one would expect them to be identical in all respects.
OK you call it cogging but say that it says nothing about how the motor will perform. That's the bit I don't get.
Ultimately I have an open mind I just need to understand why. Thanks for your patience.
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