User Guide

59
Flight Instruction
58
Flight Instruction
THE BALANCE OF FORCES
Most aeronautics texts teach
that there are four forces that act on
an airplane in flight, and that they
show up in two opposing pairs. One
pair is weight, which is pretty obvi-
ous, and lift, the force exerted by
the wings in holding the airplane up
in the air (you’ll find out in a
moment that lift does a lot more than
that). The other pair is thrust, the
force that pulls or pushes the air-
plane forward through the air, and
which is usually provided by some kind of engine (but not always -
look at gliders!), and drag, the opposing force that tries to hold it
back. (Actually, all aircraft are supported by a fifth force, invisible
but all-pervasive, called money - and that’s the reason we need
flight simulators like FLY!)
As long as we’re flying along straight and level, and at a con-
stant speed, all four of these forces are in balance. The weight of
the airplane is exactly counteracted by the lift of the wing, so it
goes neither up nor down. Its drag, caused partly by the wing’s
efforts to keep everything aloft and partly by the effort needed to
push the whole airplane forward through the air, is exactly coun-
teracted by the thrust of the powerplant, so it neither speeds up nor
slows down. As soon as we try anything even the slightest bit
fancy, though - say, a turn, climb, or descent, or, worse yet, some
combination of these - things start getting a bit more complex.
The Four Forces
Lift
Thrust
Weight
Drag
Force of Money
FUNDAMENTALS OF
AERODYNAMICS
There are a number of different ways to go about learning to
fly. One - we might call it “the old school”—is to just sit down in
an airplane with an instructor and start flying. Another, however,
can make the whole experience much more rewarding: learning a
little, before you start flying, about what’s really going on, what
really makes your aircraft fly and behave the way it does. That’s
the way I try to start out my real-life flying students; and that’s what
we’re going to do here.
THE WING’S THE THING
All five of the aircraft presented in this release of FLY! have
something in common: they’re all fixed-wing airplanes. By this, I
don’t mean that they’ve been broken and repaired, but rather that
their wings stay decently in one place, rather than the unseemly
flailing about we see in rotorcraft. We could say that the wing is
really the most important part of any airplane; all the other bits,
like powerplants and control surfaces, are really there to aid the
wing in fulfilling its purpose: providing lift.
What’s lift? It’s simply the force generated by the wing as it
deflects the air through which it’s moving.
Rotorcraft