What does it mean to be financially responsible? It's a complex question with a complex answer, but at its core is a simple truth: To be financially responsible, you need to live within your means. And to live within your means, you must spend less than you make.
longitudinal axis. A straight line running fore and aft through the center of gravity. It is horizontal when the airplane is in the rigging position. The aircraft rolls about this axis. See axes.
Longitudinal Waves. To see a animations of spherical longitudinal waves check out: In a longitudinal wave the particle displacement is parallel to the direction of wave propagation. The animation at right shows a one-dimensional longitudinal plane wave propagating down a tube.