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the out runner motor blues

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Old 03-22-2019, 04:24 PM
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Captainbob
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How would one go about controlling a 3 phase DC out runner motor without going thru the throttle channel or some other channel?
I have been experimenting with developing a working hydraulic system for my model airplanes. the systems so far have used a turbine model fuel pump. these pumps are very expensive, around 400. dollars. I have found a pump made in China that is intended for construction equipment modelers for around $125 but the speed control provided with the motor requires the use of one r/c radio channel. This is not necessary on my system as the pump is simply "on'' or "off" and this function is controlled automatically by a pressure switch. Call for the gear "up" and the pump comes on and runs until the gear cycle is finished then shuts off when the pressure reaches 100 psi.
How can I do the same thing using an outrunner motor?
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Old 03-24-2019, 04:36 AM
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Why not use a simple brushed motor?
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Old 03-31-2019, 03:17 PM
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I'm trying to get away from brushed motors, that's the whole point, the brushes don't last long at the 15 amp load it takes to generate 100psi pressure.
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Old 03-31-2019, 10:22 PM
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Originally Posted by Captainbob View Post
How would one go about controlling a 3 phase DC out runner motor without going thru the throttle channel or some other channel?
I have been experimenting with developing a working hydraulic system for my model airplanes. the systems so far have used a turbine model fuel pump. these pumps are very expensive, around 400. dollars. I have found a pump made in China that is intended for construction equipment modelers for around $125 but the speed control provided with the motor requires the use of one r/c radio channel. This is not necessary on my system as the pump is simply "on'' or "off" and this function is controlled automatically by a pressure switch. Call for the gear "up" and the pump comes on and runs until the gear cycle is finished then shuts off when the pressure reaches 100 psi.
How can I do the same thing using an outrunner motor?

This is easy to do and much cheaper than you have been doing it. Go to www.magomrc.com. They do both brushed and brushless pumps with integrated tanks for 98 euro if brushless or 91.99 euro for brushless. You need to look up the recent post on hydraulic systems for retracts where I showed the brushless system working using a pressure switch.

Best way to get more oomph in pneumatic retracts

We all have plenty of channels these days so using one channel to arm a brushless system is not really an issue.

John
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Old 03-31-2019, 10:56 PM
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Originally Posted by Captainbob View Post
How would one go about controlling a 3 phase DC out runner motor without going thru the throttle channel or some other channel?
I have been experimenting with developing a working hydraulic system for my model airplanes. the systems so far have used a turbine model fuel pump. these pumps are very expensive, around 400. dollars. I have found a pump made in China that is intended for construction equipment modelers for around $125 but the speed control provided with the motor requires the use of one r/c radio channel. This is not necessary on my system as the pump is simply "on'' or "off" and this function is controlled automatically by a pressure switch. Call for the gear "up" and the pump comes on and runs until the gear cycle is finished then shuts off when the pressure reaches 100 psi.
How can I do the same thing using an outrunner motor?
Program up a microcontroller to output 2 different pulse widths based on the state of a digital input.
Something like the adafruit trinket would be perfect.
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Old 04-01-2019, 07:04 AM
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You can use a 555 timer to generate a pulse train to the motor controller that turns it on at a fixed speed determined by the characteristics of the pulse train.

About half way down in this page https://www.jameco.com/jameco/worksh...-tutorial.html you will see a setup for an "Astable circuit" using a 555 that is controlled, on and off, by a single input. That should do what you need.

Bob

ps. RC pulses are 1.0 to 2.0 ms long and have a period of 20ms, so to run the pump at 1/2 speed, you'd need Th to be 1.5ms and Tl to be 18.5ms...
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Old 04-01-2019, 12:13 PM
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https://www.droking.com/motor-controller/15w-brushless-motor-driver-dc-5-12v-1.5a-three-phase-brushless-sensored-controller-bldc-speed-control-switch-for-motor-hard-etc

You might have to remove the potentiometer and rig up an equivalent circuit through the pressure switch, don't know

EDIT : sorry I did not see the 15 amp load of the OP, not sure what voltage. Anyway I dont think this will work but it gives you what to search for.
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Old 04-01-2019, 11:50 PM
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If you really want to run without using a separate channel, you could operate the ESC using a manual servo controller. This could be left in the max running position with the pressure switched on and off via the pressure switch. This would leave you unable to switch off the ESC from the transmitter if anything went wrong, but would work. You would have to start and stop the servo controller at the beginning and end of each flight. The servo controllers are very cheap and only cost a few dollars and you need no other parts. I used them in testing on the bench with my system.

John
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Old 04-08-2019, 04:42 PM
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Fellas,
thanks for all the helpful replys. I just got back from Toledo and will be trying some of these ideas. thanks for the help.







f
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