Originally Posted by
tdracer
Pattern, that's simply nonsense. It takes energy to pressurize the aircraft - regardless of the fuel source - but the lower the altitude the higher the drag and the more thrust required. The reason we normally cruise at 30k and above is simple - the reduction in drag means less fuel (energy) is required to fly a given distance, overwhelming the relatively small amount of extra fuel (energy) needed to warm and pressurize the aircraft. That is simple physics - going to electric propulsion doesn't change the physics.
Bingo! Reward yourself two Pesos from petty cash.
In fact, the plane may well carry high pressure air tanks that can be filled with ground power and serve as a backup air supply or even backup power source since it would already be there... but maybe not if its too hard to make the air compressors dual purpose: high volume low pressure for cabin air, high pressure low volume for tank air.
Anyway, with modern turbojet planes is it is much easier and fuel efficient to fly M .8 at FL 32+ than 12k. Drag being a drag with still be true no matter the propulsive force... in fact, electrics should have an advantage considering they can make their full power at altitude versus SL minus the any cooling capacity loss. Combustion engines lose much more power, but the reduction in drag more than offsets this. The main stumbling block for electrics now is the ability to carry enough juice for flights lasting more than an hour. I somehow doubt that battery tech will magically achieve a 2x energy density improvement in any time less than a couple of decades.
However, for those missions of an hour or less, like short regional flights or training flights, I think electrics will be great.