stealth916
Veteran
Location: Rocklin, CA
| Ron - thanks for the interest in this. I can't take credit of course - it has been done a lot, for at least a year on hummingbirds.
If you read my original post - you can see I discuss ramifications of all mount options.
In the case of your scenario - the motor would be running with normal timing, yes, but the prop would be running BACKWARDS - ie trailing edge first, because it is not a pusher prop. This motor is timed for clockwise rotation, but 99% of the props out there are cut for CCW.
So you choose your poison: Either a motor timed backwards, or a prop running backwards. In my experience, a motor running with reverse timing is not near as bad as a prop running backwards. In fact, I have done a lot of bench testing with motors running 'proper' timed and 'reverse' timed, and it seems that running a typical motor timed for direct drive, with reverse polarity, gives more torque and less heat than running it properly - it draws less amps. You may not get that last 300 RPM - but sometimes it's not what you need.
My testing was done with Speed 400 motors over the years, but it probably is a similar effect with these small motors.
With that said - taking a closer look at this prop, there really isn't an airfoil. It does have swept tips - but big deal. So perhaps in this case, with this particular prop - running it backwards would not produce a huge efficiency loss.
What I will do is modify a stock tail case to accept this motor, then I will try flying both scenarios. If I'm feeling patient - I may even bust out the Whattmeter and tach, and do bench testing on both setups. |
