Flat-rated

Flat -rated is a technical term used in aviation. Flat -rated or flat- rating refers to where the thrust no longer increases with decreasing temperature at aircraft engines a special field of functional linear relationship between the engine thrust and the temperature of the surrounding air. This power limit ensures that the specific stress limits (design limits ) of a turbine design are not exceeded and thus minimizes the risk of damage and the life of the engine is not reduced unnecessarily.

The two major factors that limit the maximum output of a turbine, the compression and the turbine inlet temperature. With sinkernder air temperature increases, the maximum achievable boost the performance of a turbine but is capped at the top by the maximum allowable compression. The thrust is not increased, but remains constant (flat). Typically, an engine is designed so that it can deliver up to a temperature of 29 ° C or the maximum static thrust. At higher ambient temperatures, however, reaches the maximum allowable turbine inlet temperature as a limiting factor.

In order to protect the engines by a minimum -held compression and turbine inlet temperature, the pilots determine each time on the basis of flight performance tables or using the on-board computer which is sufficient for a safe take-off engine power that far at low load and low temperatures below the maximum thrust may be (flexible rating ).