|Jul 31, 2009, 10:39 AM|
Power-to-weight ratio for the complete power train
I have done a study, with interesting results, which are shown in graph 1. The motor data is taken from graph 2. The computation is shown in the table.
By "complete power train" I mean motor+prop+ESC+wiring+battery.
Please note the % no-load speed at which the best power-to-weight ratio occurs. 70%NLS for a 5 minute WOT motor run. 74%NLS for a 10 minute run. 78%NLS for a 20 minute run. 80%NLS fof a 40 minute run.
Note that peak efficiency is not a good operating point unless you are into long motor runs.
Graph 3 shows an example of how the data translates into powertrain weight for a particular application.
|Jan 03, 2010, 03:44 PM|
I remark that for your 70%NLS
the ratio PowerIn/motorWeight is 3W/g
(150W In for 50g motor)
It is my upper limit, generally
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