exchemist
Valued Senior Member
I read an article in the Financial Times last week claiming that we may be on the verge of a revolution in aircraft, whereby electric power will become the future. The obvious objection that battery energy energy/weight ratio is terrible for aviation seemed to be dismissed and there was a lot about something described as a gas turbine/electric hybrid. However the basis on which this would provide an advantage over a conventional gas turbine only was not explained.
I don't get it. The principal advantage of a hybrid car, bus or commuter train, surely, is to recapture kinetic energy during braking for re-use. So, in stop-start operation, a lot of energy can be saved. But one cannot do this with an aircraft, given that air resistance alone provides the braking during descent and it is about as far from stop-start operation as it is possible to imagine. I can see that during take-off one uses more power than in the cruise, so maybe one can fit a smaller turbine and use a battery to boost during take-off, but then the battery will have to be recharged by the turbine, because descent won't give any energy back to the battery. (Not to mention the absence of any safety reserves of power, once the battery is depleted.).
I struggle to see how, given the inherent weight penalty of a battery, this can possibly be worth doing. But evidently I must be missing something. Does anyone know what the logic is behind this idea?
I don't get it. The principal advantage of a hybrid car, bus or commuter train, surely, is to recapture kinetic energy during braking for re-use. So, in stop-start operation, a lot of energy can be saved. But one cannot do this with an aircraft, given that air resistance alone provides the braking during descent and it is about as far from stop-start operation as it is possible to imagine. I can see that during take-off one uses more power than in the cruise, so maybe one can fit a smaller turbine and use a battery to boost during take-off, but then the battery will have to be recharged by the turbine, because descent won't give any energy back to the battery. (Not to mention the absence of any safety reserves of power, once the battery is depleted.).
I struggle to see how, given the inherent weight penalty of a battery, this can possibly be worth doing. But evidently I must be missing something. Does anyone know what the logic is behind this idea?