When calculating takeoff performance, which factor is not directly affecting groundspeed?

When calculating takeoff performance, engine RPM does not directly affect groundspeed in the same way that factors like wind speed, aircraft weight, and density altitude do.

Groundspeed is primarily influenced by the speed of the aircraft relative to the ground and can be affected by external environmental factors. For instance, wind speed can either aid or hinder the aircraft during takeoff by adding or subtracting from the true airspeed. Similarly, weight impacts the aircraft's thrust-to-weight ratio, which can influence the acceleration during takeoff, thereby affecting when the aircraft reaches a certain groundspeed. Density altitude represents the air density affecting engine performance and lift, which ultimately influences the aircraft's acceleration and takeoff capabilities.

While engine RPM is important for determining the thrust produced by the engines, it does not have a direct correlation with groundspeed at the moment of takeoff since groundspeed is the resultant effect of all forces and conditions acting on the aircraft during its acceleration down the runway.