Aviator90 Episode 2

Speaker: [0:31] Welcome to another episode of Aviator 90 from Angle of
Attack.
[0:36] In the last episode we discussed lift and what it is
essential for flights. Now, we will talk about the other three
forces of flight. You may have remembered one of Sir Isaac Newton’s
laws that I mentioned which is for every action there is an equal
and opposite reaction. With that said, I’ll now teach you what I
know about the other forces on the aircraft.

[1:00] Because in the last episode we talked about lift, I find it
appropriate to talk about weight. Weight is the opposite of lift.
Out of all the forces, I can consider this to be the simplest of
the forces, the flight, because it has a few key aspects that we
are both familiar with.

[1:16] First, a plane is not lighter than air; therefore, it’ll
fall without the lift component. Second, gravity. We all know what
this is, and thank goodness for it. Otherwise, this whole flying
thing just wouldn’t mean anything to us because everything would be
on the ground all the time anyway. In all seriousness, gravity is
obviously the biggest contributor to weight. You can see why it’s
opposite to the force of life.

[1:46] Thrust can be described in general terms as the force that
moves the aircraft forward. This force largely relies on Newton’s
third law, again, as you’ll see. We’ll be using a propeller, and
the aircraft will be flying in Aviator 90.

[2:02] So, let’s talk about how the propeller creates thrust. A
propeller turns at a rate determined by the pilot as a result of
engine power. The prop is at a pitch or angle of attack just like
the wing we discussed in the lift section. The propeller
essentially creates lift forward rather than up. This pulls the
aircraft forward and also sends a blast of air back that assists a
bit with air flow over the control surfaces. If an aircraft
produces enough thrust to outperform drag and we have a sufficient
air foil, the aircraft will fly.

[2:42] Drag is generally described as the forces that are upon the
airplane that are pushing it back. These forces are basically
friction, disruption and resistance to air flow created by the
forward thrust the aircraft is creating. Drag is broken up into
several different types which are friction, form, induced and
parasite drag. We’ll now talk about each one of these.

[3:07] Friction drag is caused by the air flow around the airplane.
As the air goes around the plane, it comes in contact with the
aircraft and creates friction as it touches. This, in turn, creates
drag. Form drag is actually something we’re all familiar with as it
is very prevalent in car designs. It is basically how the shape of
the aircraft interacts with the air flow around it.

[3:32] Now, a sports car will be built in such a way that form drag
is reduced, smooth, sleek and at the least resistance possible.
Aircraft, as you can imagine, are built in the same way. You don’t
see a big van again flying around now, do you? This would not work.

[3:50] Induced drag is created as a result of lift that is created
by the wing. You may or may not be familiar with winglets present
on some airliners. These winglets are in place partially to reduce
this very kind of drag because spoiled air is formed at the tips,
and these winglets reduce that spoiled air.

[4:10] Parasite drag is anything on the airplane that can produce
drag, such as rivets, antennas, pitot instruments, et cetera.
Parasite drag can even be produced by an extremely dirty airplane
or a little frost on the airplane, believe it or not.

[4:25] Let’s look at a few different phases of aircraft operation
and see how the forces relate to each other.

[4:33] Now, in straight and level flight lift is equal to weight,
and thrust is equal to the drag. When lift and weight are equal,
you stay in the same place, right? When descending, weight is
greater than lift. Why? Our gravity is getting the better part of
us, pulling us down. Obviously, angle of attack would have
something to do with this as well. When climbing, lift is greater
than weight. Why? Because we’re defying gravity in pushing through
it. Again, angle of attack does have a play in this situation.

[5:09] When on the ground and not moving, weight is greater than
lift keeping our wheels planted and thrust and drag equals zero.
You may think that these forces of flight aren’t critical to
flight. They are. Everything you do in the air is the result of the
relationship between these forces, absolutely everything. Give
yourself a big pat on the back. We can now move onto more advanced
things.

[5:35] Next, I’ll teach you about control surfaces. Until next
time, throttle on.

Transcription by CastingWords