2 speed pre-rotor

[WHY]

Hi Brent

I GOT THE PICTURE !!!! and I like the idea !! You working on something like that ???

Would make for full engagement all the way thru takeoff !!

NOW YOUR TALKING !!!

Tony

[Brent_Brown]

I have it all worked out in my head but I am away from home until Nov. so I will be looking for someone here to get it done. I was thinking at home I could put a big batt pack at the end of my runway and have a cable that can plug into the keel next to the tail wheel and power the e-motor to 300 RRPM go full power and as I roll forward the power is unpluged and off I go.

[WHY]

Brent

You will have to turn off the power a few seconds before you move foward. If you pull loose with e-motor under load there WILL BE A HUGE ELECTRICAL ARC AND A MAJOR "FLYBACK VOLTAGE SPIKE"

Tony

[James]

Instead of a current robbing resister set up, I use a square wave gererator with a reostat to drive an electric clutch. It pulses the voltage from 0 pulse (a full 12 vote ) to a 1000 (a lot of slip). I have a one amp fuse in the circuit.

James Lee - TN

[WHY]

Just got the PWM controller in (straight from China) will post pics later ITS SMALL .

Tony

[WHY]

Well it was Christmas time today first the controller and later the motor.

The motor as you see it is 6.5 lbs.

This came from a company in Florida, but I got a Fiver says it's made in China

Now all that has to be done is make the end housing to hold the gear and incorporate a mounting for a 2 x 2 mast. The big job is going to be finding someone to cut a internal spline to match that pinion gear, -----then mate it to a "u" joint and sliding shaft.

Tony

Pictures in next post

[cburg]

"made in China" is redundant ;-)

[RotoPlane]

Some motor controllers don't come with a heat-sink but must have one above their stand alone amp rating. Some also require standoffs to clear the circuit board. The instructions should say what the heat-sink surface area size must be for use at its full amp rating.

[WHY]

Don't know what the end housing and the sliding shaft will weigh but all looks promising. this motor is not a Permanent magnet field .

Tony

[WHY]

Good point Ed, will watch that item

Tony

[WHY]

BTW this motor is originally used with a "spur gear" reduction output.

Tony

[WHY]

This could be mildly funny. The controller is from China for sure, and if the motor is from China also, and if this output housing and shaft arrangement work out, then they can copy it in a hearbeat and have a great pre-rotor made right there in China.

Tony

[Alan_Cheatham]

One thing you might want to consider is wiring so the PWM controller does the soft-start but use a contactor to carry the full current load, this will reduce the thermal stress on the controller and increase it's duty cycle. Duty cycle is going to determine how many prerotations you can do in a specific time period, something that will be important if you prerotate then abort a take off. You don't want to be sitting on the ramp for too long waiting for the controller to cool off before you can go again.

.

[WHY]

Right Alan

The instructions specify a contactor, would mount it near the contorller. since we don't need a "solenoid contactor" on the motor to engage a bendix, we can use the replacement motor as is with out a solenoid. May still need some gear reduction, wont know until it is tried

Tony

[WHY]

I think I see maybe what you were talking about was different than what I posted. If you use a complete 3 hp starter motor on the head with the solenoid and bendix as presently used, then you will indeed need to add an additional contactor near the controller to carry the main load.

Tony