Definition
The forward force produced by the airplane's engine and propeller (or jet exhaust) that propels the aircraft through the air. In energy-management discussions, T represents the thrust input the pilot commands through the throttle, which adds energy to the airplane.
Plain English
T is the letter used to stand for thrust — the pushing force the engine produces to move the airplane forward. When pilots talk about energy and how the airplane gains or loses speed and altitude, T is the symbol they use for that pushing force.
Context Anchor
Seen in Airplane Flying Handbook discussions and diagrams about the forces acting on an airplane and how a pilot manages the airplane’s energy state.
Derivation
T is simply the first letter of 'thrust.' The word thrust comes from Old Norse 'thrysta,' meaning to press or push — which describes exactly what the engine does to the airplane.
Why Pilots Care
Thrust is one of the four forces of flight; balancing it against drag determines whether the airplane can maintain speed, climb, or accelerate.
Grounding Statement
When the pilot advances the throttle and the airplane begins to pull harder forward, that forward pull is engine thrust.
Intuition Check
Do not read T as throttle position. Throttle is the control the pilot moves; T - engine thrust is the actual forward force the engine produces.
Example Sentence 1
In the energy diagram, T represents the thrust the engine adds to the airplane when the pilot advances the throttle.
Example Sentence 2
In level cruise, thrust must equal drag so speed stays constant.