(11 Dec 2016, 4:37 pm)South Tyne Lad wrote Ah right I see, Bigger fans like that take more energy from the engine to run, Which explains the loss of power.But aren't the eFans driven by electricity (when required) rather than a constantly-running hydraulic motor?
Will no doubt explain people's complaints on here that the Red Arrows B9s lack power, As they are indeed equipped with them too.
This would result in lower parasitic drag - allowing 'more' power to drive the bus.