17 years ago
The book explains the basic physics of hobby-motor
operation, but there is only a 1 page discussion on
brushless motors. This left me with many questions.
According to the book, brushed-motors have greater
efficiency at lower (high-load) rpms, whereas brushless
motors have greater efficiency at high (low/no-load) rpms.
Is this still true?
The book doesn't talk about magnets (gauss) and their
effect on motor performance. All things being equal,
does a stronger (cobalt) magnet increase efficiency, or does it
just increase the power-dissipation through the windings?
And what is a "wet" magnet (I see that term in advertisements
for RC/Car stock-motors)?
My last question is more of a motor-design question
than anything else. The book's graphs show various
plots for Astroflight's product-line (circa 1994.) The
common trend was smaller-sized motors had *higher* no-load
RPM than the larger-sized motors. Is this a freely-made
decision, or was there a conscious trade-off/compromise
involved in choosing the Kv constant?