Aerodynamics Index

Definitions

Aircraft Axis
CG definition
Define Up and Down
Define Pitch, Bank, Hdg
Define: Lift, drag, etc.
Define Power

Physics Review

Newton's First Law
Newton's Second Law
Newton's Third Law
Reaction = Lift
Reaction = Drag
Conservation of Energy
What is a Vacuum
Action at a Distance
Rotation Rate

The 4 Forces

Spotting Forces & Moments

Performance

Drag Overview
Induced Drag
Induced Drag Equation
Total Drag

Jet Climb Performance
Prop Climb Performance
Range Jet
Range Prop

Forces in a Turn

Misc

Pitch Controls
Roll Controls

Configurations

Up/Down and the Horizon

In the animation to the left the airplane flies around and around the earth. Its weight always acts toward the center of the earth. By definition the direction gravity acts is DOWN.

Up is simply the opposite of down.

The horizon is the plane that is exactly perpendicular to the up/down axis. The horizon lies exactly at the surface of the earth. Up and down are therefore measured perpendicular to the horizon.

Local Horizon and Vertical Speed

In the simulation to the left a "local horizon" has been drawn in. This is an imaginary plane parallel to the real horizon but passing through the c of g of the airplane.

As you can see weight always acts perpendicular to the real and local horizons.

You can pitch the nose of the airplane up and down using the up and down arrow keys on your keyboard (you may have to click on the animation to wake it up first.)

The green arrow that appears is the vertical speed. By definition the vertical speed is the component of the true airspeed (TAS) that acts up or down.

It is important to realize that vertical speed is NOT a thing independent of TAS. Vertical speed is simply the component of TAS that acts up or down. If the airplane flies straight up or down then vertical speed = TAS. In all other cases vertical speed is less than TAS and given by the formula:

vertical speed = sin(c) x TAS [c is the angle of climb (negative when descending)]

In summary: The airspeed indicator in your airplane tries its best to tell you the length of the blue vector and the VSI tells you the length of the green vector, as best it can. The indications of those two instruments are tied together by the formula above and together tell you your angle of climb. We will return to this again later in the course.