# For who try/have tried direct drive with outrunner

**URL:** https://foil.zone/t/for-who-try-have-tried-direct-drive-with-outrunner/362
**Category:** Propulsion System (Motor, Gears)
**Created:** [October 22, 2017, 4:17pm UTC](https://foil.zone/t/for-who-try-have-tried-direct-drive-with-outrunner/362 "2017-10-22T16:17:15Z")
**Posts on this page:** 1
**Showing post:** 211

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### Author: ![Jsonnett](https://foil.zone/user_avatar/foil.zone/jsonnett/32/240_2.png) [@Jsonnett](https://foil.zone/u/Jsonnett)
#### Post date: [April 20, 2018, 8:50pm UTC](https://foil.zone/t/for-who-try-have-tried-direct-drive-with-outrunner/362/211 "2018-04-20T20:50:37Z")

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So I started to test my Alien powerglider outrunner motor inside a soon to be oil flooded aluminum housing. I discovered something interesting and really annoying. The spinning magnets used in the outrunner design are causing induction heating of the aluminum housing. With no oil inside the housing and only the housing (aluminum tube) over the motor, the outside will quickly get too hot to touch. I have verified that the outer bell of the motor is not rubbing on the inside of the housing tube so it must be induction heating. The aluminum housing can be super hot and then if you slide it off quickly and feel the motor housing it is cool to the touch. At wide open throttle and no housing over the motor, the motor pulls about 70W no load. Doing this same test again but with only sliding the housing over the motor it draws about 180W no load. So I have a 110W heater!

Has anyone else run into this issue before? Any ideas how to fix it? I borrowed an induction heating book from another engineer at work and am trying to figure it out. So far all I have figured out is that It appears to be due to “joule heating” where the susceptor does not need to be ferrous.

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