@deonb ,
@Salty
You guys are making this way to complicated.
When you are sitting on the ground and/or taxing with a traditional turboprop you are burning significant fuel. Especially when you think about the average 15 minutes taxi at a class B airport. That does not include any hold times....
In addition, to meet FAR Part 25 requirements, the engines need to be massively oversized. Which means that either are very inefficient in cruise, on the ground, descent, or in the climb. Current engines are only optimized for a single condition. When moving around the airport, and in descent you need minimal power, but turboprops and turbofans generally require above 60% fuel flow to just stay lit (this is based on what others have posted on the PT6, Garrett turboprops, and Airbus and Boeing airliners).
I would think the extensive bean counters at both JetBlue and Boeing have crunched the numbers. When you read the article, they state they have the estimates for the battery pack using current tech, airframe, engines, fuel... and yet it will save a lot of operational cash for the select and limited mission.
Further, airliners do not use speed brakes as a general rule because it is inefficient. You are just throwing away energy. In this case, using windmilling props you can recharge the battery, so there is no reason to not use regen in descent and stay higher longer (if ATC allows).
And so far you have yet to prove that the stated assumptions, math and other information in the article does not save the airlines money. You just have your assumptions.
I do not know the answer; I think it is an interesting concept, and in the specific mission it may make sense.
Stop thinking inside the current box and assumptions about the kind of flying in GA applies to short hop airliner missions that is the target market.
Tim