In this lesson, we will review motors and propellers.
After completing this lesson,
you'll be able to identify motor wiring,
and understand propeller variations.
For our quadcopter build,
we used a DYS motor,
a specific motor was meant for FPV racing quads,
but we're using it because of its performance.
There are a few things I want to do when talking about motors.
First, I want to note the direction.
And each motor is going to have arrows on it or dictate which direction it wants to spin.
You can reverse the direction of motors by changing the wiring going into
them but the thread pitch is going to be different on reverse direction motors.
So, two of the motors on our quadcopter are going to have
a right-hand thread and two will have left-hand thread.
It's important to orient them in the direction they're meant to spin,
so you don't accidentally loosen the nuts in flight.
So the specific motor that we're using is an MR2205-2750KV.
Now if you remember, the 22 determine
the diameter of the stator and the five determine the height of it.
So it's a relatively low profile height and it's made for a 250 series racing quad.
That's roughly the size that we're using.
And remember the 2750KV number determine the max RPM.
It's basically a constant velocity number.
So in this case, if we were on this on a three-cell battery system,
we're looking at roughly 30,000 RPM.
If we run it on a four-cell,
we're going up to about 40,000 RPMs.
In addition to the motor,
we need to talk about propellers because there are many different ones on the market.
When we were specking out the motor and the battery system,
we looked at five by four and a half props.
With the black three-bladed prop,
we have a five by four pitch.
With the orange one,
we have a five by four and a half.
And with a three-bladed orange one,
we also have five by four and a half.
There are some important things to note here about propeller choice.
The main thing that we're looking for is the amount of surface area under the propeller.
So, we're using a two-bladed five by four and a half BN prop or bull nose prop.
So, this allows us to get the most amount of
surface area underneath to give us the most amount lift.
The five by four and a half BN three-bladed prop doesn't
necessarily increase the amount of lift we're going to
get because it adds more drag in the air,
and ultimately, what will happen is we get less flight time
because we're spinning a heavier prop and we have more resistance going through the air.
So, out of these three propellers,
the two-bladed five by four and a half which falls in line
with allowing us to use the three-cell on a four-cell battery system,
is going to be the best choice for our application.
If we decide to run a three-bladed prop,
we'll be able to change directions a little bit faster in the air,
but we will sacrifice flight time.
If we decide to use a five by four with this different profile,
we're actually going to get less thrust out of it because we
have less surface area than a BN style prop.
There are lots of different props and different sizes and pitches on the market.
So, it's important that you do your research and
figure out which one works best for your application.