| Regenerative braking is only one advantage of the hybrid approach. The other significant advantages are: 1. The engine can be sized for average output, not peak output, which makes it more efficient. 2. The engine can stay closer to its optimally efficient RPM. 3. Because RPM variation is smaller, and because power requirements are smaller, you can use more efficient engine cycles like the Atkinson cycle. I'm doubtful that the advantages will be worth the extra weight. #1 is not going to be as big of a deal for an airplane, since as you note, power output is a decent fraction of the maximum during cruise. (In contrast with a car, which might have a 200hp engine but only use 30hp of that in cruise.) But it should count for something. #2 might make a nice difference paired with a variable-pitch propellor. #3 gives a decent efficiency boost. Put it all together and it doesn't seem likely to be worth the extra weight, since that counts for so much in an airplane, but it's not completely absurd. Note for the Tesla comparison that the limiting factor in the P85D's power output is the battery, not the motors. Lighter motors would certainly be good, but it'll be a small effect. If you really want more power, you either need a bigger battery, or a battery chemistry that can discharge faster. |