Motor Differences

[Chuppster]

Hello! I'm motor shopping, and I'm between 2 motors:

PROPDRIVE v2 2826 1200KV (https://hobbyking.com/en_us/propdrive-v2-2826-1200kv-brushless-outrunner-motor.html)

and

Turnigy D3530/14 1100KV (https://hobbyking.com/en_us/turnigy-d3530-14-1100kv-brushless-outrunner-motor.html)

Why does the Turnigy say it draws 22A with an 8x4 prop, while the PropDrive draws 15A with the same prop, even though the PropDrive has a higher KV? Is there any advantage to the lower-kv, heavier Turnigy?

 

[rockyboy]

I'd take those HK posted numbers with a grain of salt - there are a couple vendors like http://www.headsuphobby.com/ that actually test the equipment they sell with various props to confirm the real world performance, but I've found the data on the HK motors to be rather theoretical - in some cases undersold, and in other cases oversold. The higher max amp rating of the Turnigy means you'll be able to hold full throttle with a larger prop for longer without burning up the motor for sure though.

One of the important numbers they mention on both of these specs is max wattage. This is a good measure of final energy produced out of the prop as reflected by energy consumed by the motor. The heavier turnigy has a max rating of 315 watts, where the smaller prop drive tops at 286 watts.

Using the 100 watts per pound for an aerobatic sport plane rules of thumb (good explanation of this over here http://www.hooked-on-rc-airplanes.com/rc-electric-motors.html ) the turnigy will haul a plane around the sky that's almost 1/2 pound heavier with the same kind of performance expectation.

All that being said, I have used both of these motors on DTFB planes and they have performed just fine. I don't remember weights off the top of my head, but the quality of both were good and I wouldn't shy away from buying either of them again for a project - depending on final weight of the model of course.

Does that help?

 

[Chuppster]

Thank you for the input! It's great to hear from someone who has actually used the motors.

I have heard that the wattage is an important factor in motors, and I see that the Turnigy has a much higher rating. I can also understand that the Turnigy should be able to hold full throttle for longer.

I have a Propdrive and I can confirm that it pulls 15 amps with a 8x4 on a 4s. So the Turnigy may be able to drive a bigger prop on the 4s (say, an 8x6)? Or it likely doesn't pull 22 amps on an 8x4? It would be really neat to have specs for the motor with different prop/cell configurations.

 

[quorneng]

Chuppster
To be fair to HK the spec does not say what current it draws with an 8x4 on a 4S but only that the maximum current the D3530 can sustain is 22A.
As rockyboy says all such figures are a guide, not gospel.

 

[rockyboy]

A watt meter like this one can be a great testing tool to see how a motor really performs with different props:

https://www.amazon.com/dp/B017YCTRK...t=&hvlocphy=9007543&hvtargid=pla-318070468062

Just be safe!

 

[Chuppster]

rockyboy,

I do have a wattmeter! So, I just should keep the wattage below the specified wattage from the manufacturer?

 

[rockyboy]

When I test with a watt meter, I'm looking to keep the amp level at or below the motor's stated "Max Amps" - and below the ESC's max amps too - don't want to let the magic smoke out of anything! Then I just try out different props / battery voltage combinations looking for what gets the highest (or target) wattage without putting the hardware in danger of smoking out.

 

[Tim Stinger]

It does depend on the power supply and prop type. Props have different performances on different motors so most company's recommend certain props for motors.

 

[Rasterize]

rockyboy = well written and concise input. Thanks rockyboy

 

[rockyboy]

rockyboy = well written and concise input. Thanks rockyboy

Happy to help!

 

[nhk750]

Also check out Ecalc, just google it, and play around with different settings there. I have had really good results with that, then double check with watt meter.