Hey guys, apologies if this has been asked and/or covered before.

As we all know, most times, the best way to find out how much thrust made and/or current drawn from a given motor-batt voltage-prop combo is to either refer to the manufacturer's test results, or when available, miniquadtestbench.

More often than not, the manufacturers themselves and/or MQTB just simply can't test all the motor-batt-prop combo in the world, and we'd have to resort to either 1) guesswork or 2) just run with it and hope nothing explodes mid-air.

My question is -- given a set of test results, how do we derive/scale such numbers for an unlisted/untested motor-batt-prop combo?

Consider the iFlight Xing-E 2207 1700KV motor. According to the published test results, with 24V and 6045 props, at 100% throttle, it'll draw 32.42A. But 6045 is as high as it goes on the list. What if, for example, I wanna run 7042s? Do I look at the 5043 and 5045 current draws (27.62A and 25.22A respectively), subtract each one of them with the number for the 6045, assume that for each increment of prop inches the motor will draw an additional ~5-7A, and use that figure if I were to run 7042s? Or is there more science to it? 

A lot of time the manufacturer do not list a larger prop because they don't recommend that you use the larger prop.

As for scaling, I don't think the curve is linear. You probably will need multiple samples data before you predict the numbers for a new motor.

Try ECALC....The pay version has a good list of motors by manufacturer and a good selection of props as well (the free version is highly limited).  The data gleaned is pretty comprehensive, so it may have what  you need.  Also, the creator says the system is +/- 15%.  I have found in most cases it is closer to +/- 5%

(17-Mar-2020, 04:17 PM)voodoo614 Wrote: A lot of time the manufacturer do not list a larger prop because they don't recommend that you use the larger prop.

As for scaling, I don't think the curve is linear. You probably will need multiple samples data before you predict the numbers for a new motor.

So just as I thought, it's not as simple as linearly deriving the numbers from existing test results. Thanks for the enlightenment!

(17-Mar-2020, 04:58 PM)Krohsis Wrote: Try ECALC....The pay version has a good list of motors by manufacturer and a good selection of props as well (the free version is highly limited).  The data gleaned is pretty comprehensive, so it may have what  you need.  Also, the creator says the system is +/- 15%.  I have found in most cases it is closer to +/- 5%

I'll take a look into it -- thanks!