You're still not getting it. Staying higher longer takes more power because you leave the throttle open longer. Then you're trying to replace it by descending faster and converting it to electricity - but you're back the the less efficient mechanical to electrical and back again conversion. You'd use less power by doing a normal descent and not trying to reclaim energy.
You'll get there eventually and then you will be telling your friends how practical and economical it is. 
Yeah, sure if you say so. You're the expert. To everybody else reading this thread, think back to the year 1992 and remember what kind of awesome batteries you had in your life that powered all your things. IIRC, back then in the consumer world, Nickle Cadmium batteries were king. They were so cool. Yep, only marginal improvements. If only Apple knew they could build their iPhones with NiCds, they could save a load of money! I doubt anybody would notice. Anybody in the construction trades... remember the old cordless tools from 1992 compared to today's cordless tools? Hardly a difference, right?
Agreed
It’s not competitive. I buy jet a, delivered to my tank for roughly 2.15 a gallon. Airlines are getting it way cheaper than I can.
Here's an interesting question: If BEVs achieve mass adoption, presumably that will result in building additional electric power plants, more demand for whatever fuels them, and building more electric distribution capability. How much will this increase the price of electricity?
Takes 5 minutes to fill a gas tank.
Of course, but isn't energy storage per pound currently much better with avgas and Jet A than it is with batteries?
A reasonable comparison of the energy used in the takeoff roll vs the amount used in cruise is not that hard to do. For piston planes like the ones I fly from sea level airports, let's assume the engine is putting out 100% power during the takeoff roll, and 75% in normal cruise. A 200 HP engine puts out about 149 kilowatts at 100% power, and about 112 kW at 75% power. The energy consumed is power multiplied by time. I've never timed my takeoff roll, but It's probably less than one minute, so to be generous, I'll use that as an estimate. 149 KW for one minute of takeoff roll = 2.48 kWh of energy consumed. 112 kW for one hour of cruise = 112 kWh of energy consumed. For four hours of cruise, it would be 448 kWh.
The take off roll is minimal. The taxi is the real fuel killer. But I think robo taxi which pulls the plane and is controlled by the pilot is more likely.
Be a sport. Imagine how big the motors would have to be to accelerate the plane to takeoff speeds. Adding that kind of weight and more multiple failure modes during takeoff is too awesome not to do. /sarcasm
After you add all the stuff you've been describing you'd be luck if you have enough useful load left for yourself and your cell phone.Yes, but with the caveat that not everybody has the same mission requirements, so while some may put the benchmark at say 500 mile range, 4 place with a say 600 lb payload, others would be thrilled with just a two place, 300 mile range and 400 lb payload. Just like the electric car of today, many don't actually have to have direct replacement of capabilities to accept it. So, many, many electric planes could be sold long before they reach the aviation communities "benchmark" for a four place single.
I am one of those people. I don't need four seats and I don't need 6 hours of endurance. My Mooney has way more capability than I really need. I would trade it in a heartbeat fro a less capable electric plane because that e-plane would likely work for me just fine. I just want it to be kinda speedy and have great visibility, that's all.
The trouble with trying to eliminate fuel used in taxiing is that the engine needs to be warmed up before takeoff. And using data from a Cessna 182S manual, the fuel used for engine start, taxi, and takeoff amounts to only about ten percent of the fuel used on a one hour flight at 6000 feet at 75% power, and about three percent for a four hour flight. I doubt that the real savings could be gotten up to even half of those percentages.
I see a lot of practical difficulties with such an idea.
Yep. Hyundai actually makes one, and it's not some crazy looking or insanely expensive boutique car either... just a simple SUV... https://www.hyundaiusa.com/tucsonfuelcell/index.aspx
What percentage of the total fuel use of a turbine occurs during taxi?
Based on flight plan: A SAAB 340 will burn about 500lbs in flight for a 42 mile flight. (I did LAX to OXR direct).
I ask again: What percentage of the total fuel use of a turbine occurs during taxi?
Wow, I'm amazed that taxiing accounts for that high a proportion of fuel use for a turbine!
