View Single Post
Old Dec 16, 2010, 07:38 AM
canard addict is offline
Find More Posts by canard addict
Registered User
Joined Jun 2005
2,576 Posts
Thanks, Don for the great discussion on propeller pitch and pitch speed requirements. It would be interesting to hear of those requirements on a Long EZ.
A few years ago when the "Calc" programs were used, my motors were set up to run at maximum efficiency and nothing else. They are now set up to consume a conservative 100 watts per pound with a prop size which looks good to me on the model. Ampere draw is never allowed to exceed 30 amps with speed controllers at double the amp draw. Roughly speaking, the details on models from 1.5 pounds to 5 pounds use from 6-5 props at 18k rpm to 11-8 props at 8k rpm. the motors are from 1800 kv to about 900 kv and the batteries are from 3 to 5 cells respectively. The prop pitch is selected for amp draw below the motor's maximum with a minimum of 4. I try to limit battery amps to the 1/10th hour or 6 minute depletion rate. That would be 22 amps on a 2200 mah battery.
Charles
canard addict is offline Find More Posts by canard addict
Reply With Quote