Definition
The downward aerodynamic force produced by the horizontal stabilizer (the small wing at the tail) that holds the tail down and keeps the aircraft in proper pitch balance. In most conventional aircraft, the tail is designed to push down, not lift up, so the airplane remains stable and controllable in pitch.
Plain English
The tail of a normal airplane is actually pushing down, not lifting up. That downward push is called tail download, and it keeps the nose where it should be so the airplane flies steadily.
Context Anchor
Seen in discussions of airplane balance, pitch control, flap use, and tail icing effects.
Derivation
Download' here means a force directed downward, the opposite of 'uplift' or 'lift.' In aerodynamics, 'load' refers to a force acting on a structure, so 'tail download' literally means 'the downward load on the tail.'
Why Pilots Care
Ice on the tail can reduce this downward force, creating an unexpected pitch-up tendency that may lead to loss of control.
Grounding Statement
Picture the tail of the airplane as constantly being pushed downward by the air flowing over the horizontal stabilizer; that steady downward push is what holds the nose up at the right angle.
Intuition Check
Do not read download as anything electronic here. In this context, tail download means a downward force on the tail.
Example Sentence 1
Ice forming on the horizontal stabilizer can reduce tail download and lead to a sudden nose-down pitch.
Example Sentence 2
Maintaining proper tail download helps keep the aircraft in level flight without constant forward pressure on the yoke.