Hi BOAC,
the air usually comes from the 2 PACKS, whose air cycle machine is helped to cool down (beside the turbine) with the RAM air.
So my question is. If i have the packs off on take off, and the RAM air inlet/outlet closes as soon as i bring the thrust levers on TO/CLIMB position, how can the airbus prepressurize?
I hope it's a little more clear..
