Q-121: I noticed in your first book, Clean and Quiet, that you
suggest the use of fuses and arming switches. Yet in your second book,
Getting Started in Backyard Flying, you make no comments on these items. Am
I missing something or did you forget to include this information?
A-121: Clean and Quiet – A Guide to Electric Powered Flight was
published in the 1995 timeframe, making it now nearly 10 years old. The degree
of sophistication in electric power back then was well described in many of Bob
Kopski’s electric columns appearing in MA. Bob was always concerned first
and foremost with safety issues, so it wasn’t any surprise that he recommended
things such as fuses (to prevent fires due to over-current situations) and
arming switches (to make sure you didn’t experience an accidental startup at a
full throttle setting).
But 10 years later the technology has changed tremendously thanks to the
availability of microchips that can be programmed with all kinds of features.
Most present-day ESCs will cut off the motor if an overload situation occurs
with the motor such as in a crash landing where the throttle is still on, but
the propeller is prevented from turning, causing a stalled motor.
New programming techniques will prevent the motor from starting if the throttle
is at any other position than dead idle or off! We even have ESCs that sense
radio interference or an out-of-radio-range situation and turn the motor off,
preventing a fly away.
With all of these built-in features, it is no wonder that we no longer see fuses and arming switches. Quite honestly without these components there is less voltage drop in the motor circuits which makes for a lot more power system efficiency. So no I didn’t forget to describe these items, it’s just that they have essentially become extinct.