MAKE Terry Kilby - 3;Power Train; Propellers; Direction

3/Power Train
The power train is the group of components that generate
power and transfer it in a fashion that creates movement. In
your car, the engine creates power that is transferred to the
transmission that sends it through the axle system and
finally to
the wheels which make the car move. Our quadcopter also has a
power train system that helps us to create movement. Let’s
have a look at those components now.
Propellers
The best place to start is at the end, at the propeller. The prop,
as it is usually called, is often compared to the tire in automobile
power trains; just as the tire “grips the road” to create move-
ment for the car, the propeller “grips” the air, moving the drone.
And like tires for your car, props come in all shapes and sizes,
and should be selected according to the rest of the power train
that will drive them. There are three main specs you want to
look for when selecting props: direction, size, and pitch.
Direction
Look carefully at the props in your kit. Notice that the propellers
come in two dierent shapes with opposite angles of pitch.
These props are meant to be spun in reverse directions from
each other. Each type has the ocial name of pusher or tractor.
Pusher props, sometimes called left-handed props, generate lift
when spun in a counterclockwise direction. Tractor props,
sometimes called right-handed, generate lift when spun in a
clockwise direction. Together, these two props work to keep the
aircraft balanced and level. We will discuss how this works in
greater detail later in the book.
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