chaupt

I'm a nitro guy trying to turn electric. I just purchased a Mini Pulse XT. I've installed and E-flite outrunner 450 890kv with a E-flite 7310 speed controller 22 amp. I'm using a 2100mah 3 cell Li-po it calls for 10x8 prop but the hobby shop was out so I purchased a 10x7 instead.
I also purchased an inline meter. I don't want to burn anything out or ruin my batteries. These are my readings:

voltage 12.54
Amps 20.1
Watts 203

These readings are with the 10x7 prop and full throttle with the plane stationary.

My question are these readings OK and how does the changing of a prop vary your readings. I don't quite understand pitch versus diameter and does increasing the size increase or decrease your readings. Should a buy a big variety of props.

Thanks

Rugar

Bigger diameter will give you more power/thrust and increase the amp draw.
More pitch will give you more speed and also increase the amp draw, but not as much as bigger diameter will.

E-Flite shows that motor rated at a max. Burst of 18amps for 15 secs. At the 20amps your showing you should be fine as the prop will slightly unload in the air and pull less amps, and as long as you limit your WOT to short bursts. Just make sure that the motor is not hot after a flight. Most of these motors are underrated anyway.

Recheck your readings because the voltage reading cant be right on a 3 cell pack under load.

BobbyDog

The pitch of the prop is like the gears in a transmission. A lower pitch gives faster acceleration (thrust) and a higher pitch gives more top speed but little thrust. There is a difference between slow fly props and electric only props. The slow fly props suck up more amps but produce more thrust, but you have to watch you dont go over the rpm limits on them. That 10x7 will get you going pretty damn fast but acceleration will be pretty low. I would recommend using a 10x5E by APC. Its a good middle of the road electric only prop that also puts the motor closer to the max effeciency. Good luck!

Bobbydog

slipstick

The guys have seen you right on prop numbers but please recheck those readings.

Excellent decision on getting the inline meter (which one ?) but you may not be using quite correctly. It sounds like you may have taken the voltage (12.54V) before you started the motor. You want to open up the throttle, let it stabilise for 3-4 seconds (no longer) and then take all the readings as close together as possible.

Steve

chaupt

I took the reading again. I took the voltage before I loaded it up.
12.45 no load
11.1 full throttle
16.0 amps
177 Watts
I used the E-Flite in line meter

Rugar

That should work just fine.

chaupt

Thanks all for your help!!!