krproton

Sorry guys. Haven't been over here in a long time. Looks like the thread is dead, but I'll answer anyway...

Yes, the 4040 has a higher kV than the recommended 3180, but the 3180 is already being pushed to its limit (over the limit?) on 3S with a 4.75 x 4.75. Even with that motor you can't fly full-throttle the whole flight or you will cook the motor eventually. If you jump to a 4040 and use the same prop and battery, you're DEFINITELY going to smoke the motor. What you need to do is run it for a second or two with a Watt meter and read the current its drawing and compare that to what's the limit for the motor. I've found that for most motor and prop combinations one woud run in a plane like this you can shave about 30% from the static current to predict what you will get in flight. In the case of the 3180 it draws about 28A staitc which, less 30% (to find out what it's actually going to draw in-flight) = about 20A (in flight). But the 3180 is rated for 17A constant current/20A bursts, so as you can see she's right at the edge already.

Now, if you step up to a higher kV (4040 as suggested) it's going to draw even MORE current with the same prop and battery because the motor is going to TRY to spin the prop faster, thus working harder (and drawing more current).

Actually though, this motor makes a WONDERFUL 2S setup. But you need to step up to a 5.0 x 5.0 prop. With this prop and a 2S, 1800mAh 25C I get 30A static @ 19,700rpm off the initial battery charge. History tells me current drops about 30% in flight putting it at about 21A in the air (in-flight Eagle Tree data proves I am at about 21A or less in-flight). The motor is rated for 18A constant current, 28A surge.

You'll need to add about 1/4 oz. of led in the nose to get it to balance though.

Tim