Editing Thrust-to-weight ratio (section)

==Calculation==
The thrust-to-weight ratio is calculated by dividing the thrust (in SI units &ndash; in [[newton (unit)|newton]]s) by the weight (in newtons) of the engine or vehicle. The weight (N) is calculated by multiplying the mass in [[kilogram]]s (kg) by the acceleration due to gravity (m/s{{sup|2}}). The thrust can also be measured in [[Pound (force)|pound-force]] (lbf), provided the weight is measured in pounds (lb). Division using these two values still gives the numerically correct (dimensionless) thrust-to-weight ratio. For valid comparison of the initial thrust-to-weight ratio of two or more engines or vehicles, thrust must be measured under controlled conditions.

Because an aircraft's weight can vary considerably, depending on factors such as munition load, fuel load, cargo weight, or even the weight of the pilot, the thrust-to-weight ratio is also variable and even changes during flight operations. There are several standards for determining the weight of an aircraft used to calculate the thrust-to-weight ratio range.

* '''Empty weight''' - The weight of the aircraft minus fuel, munitions, cargo, and crew.
* '''Combat weight''' - Primarily for determining the performance capabilities of fighter aircraft, it is the weight of the aircraft with full munitions and missiles, half fuel, and no drop tanks or bombs.
* '''Max takeoff weight''' - The weight of the aircraft when fully loaded with the maximum fuel and cargo that it can safely takeoff with.<ref>[https://ntrs.nasa.gov/api/citations/19850010645/downloads/19850010645.pdf?attachment=true NASA Technical Memorandum 86352 - Some Fighter Aircraft Trends]</ref>