View Single Post
Old Oct 11, 2012, 11:27 AM
yomgui is offline
Find More Posts by yomgui
Registered User
yomgui's Avatar
France, RA, Cormaranche-en-Bugey
Joined Feb 2011
633 Posts
Originally Posted by flylowfast View Post
Any ideas on why the big difference between the calculators and real life ?
Those calcs use a too simple motor model, they forget a big part of the losses that can be seen as a resistance in series, increasing with rpm... Rm (internal resistance of the motor) is not enough !, so it results in increased rpm predictions, so over-estimated thrust, higher amps draw and better efficiency than real life. Also the propeller "drag" might be incorrectly estimated by the calcs, and Io also increases with rpm... the batteries Ri can be wrong too...
yomgui is offline Find More Posts by yomgui
Reply With Quote