Originally Posted by
Uplinker
Not being an aerodynamicist, my untrained mind would imagine there to be less drag if air was allowed to go through a rotating fan, than if the fan was held fixed in the airflow - presenting a huge “airbrake”. As several have said, turning the fan and engine and gearbox will take power to do, but would that be more power than the equivalent “airbrake” would absorb though?
Just to get a feel of it, the post above, of which helicopter descends faster, rotor turning or rotor stopped seems a fairly good analogy.