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[XV Pilot]

Hello again!

I am running two 380-size motors with contra-rotating props, and I find that one motor runs faster than the other. I know nothing of the history or origin of the motors as they were in the hull when I got it, but I have a feeling that it is because the motors have advanced timing.

Could anyone point me in the direction of a pair of zero-timed 380-size motors that will run at the same speed regardless of the direction of rotation, and perhaps give me some insight into how many turns to go for (if there is a choice)?

Thanks!

[derekwarner]

 ....VX Pilot

I suggest that if these are true 380 motors.........they are all built uniformly & designed to rotate in one direction only  

The rotor windings are just that  
The EMF when a current is applied creates an off balance force that throws the rotor in one direction either ->>>> or -<<<<
This when considered   in your case [with reverse polarity] will result in one motor drawing a higher current than the other.....and also less RPM for the same input parallel voltage
Some simple electric motors.....eg., automotive wiper motors or automotive ventilation fan motors have a thrust bearing/ball to compensate for the EMF thrust created  
This is why wiper/vent fan motors run at differing speeds & current draw when reversed

So after saying this ...I like STEAM.........   Derek

[HS93 (RIP)]

Hello again!

I am running two 380-size motors with contra-rotating props, and I find that one motor runs faster than the other. I know nothing of the history or origin of the motors as they were in the hull when I got it, but I have a feeling that it is because the motors have advanced timing.

Could anyone point me in the direction of a pair of zero-timed 380-size motors that will run at the same speed regardless of the direction of rotation, and perhaps give me some insight into how many turns to go for (if there is a choice)?

Thanks!

sounds like they are buggy motors and yes they will have an amount of timing to make them even  better in one direction about 5 deg is all they have there is a way you can knock back the timing some cans have three tabs on each side and a notch you can lift a tab and turn the bell a few dg  to back of the timing but I thing graupner sell 380 size motors that are neutral timed you have to pick the correct ones so go on there site to look for the right number, they also do timed 380 so watch out.

Peter

[dodgy geezer]

Are you running them in parallel or series?

[XV Pilot]

Thanks - I shall have a look at the Graupner motors. Are Speed 400 motors the same diameter as Mabuchi 380s?

I am running them in parallel, with identical length wires of identical gauge connecting them to the ESC. The speed differential is noticeable even when the motors are out of the hull, so I know it isn't a prop/shaft/bushing issue.

Cheers!

[HS93 (RIP)]

   speed 400 are there 27.7mm dia and 37.8 long according to the chart I have. I can send you the pdf if you pm me with an email address.

peter

[XV Pilot]

Thanks - those dimensions are the same as a Mabuchi 380, give or take a fraction of a mm. A pair of zero-timed Speed 400s should fit my hull with no modifications to the motor mounts. Now to pick which ones to order...