Quote Originally Posted by rwanttaja View Post
..."As fuel is consumed the conventional aircraft gets lighter, battery planes stay the same weight" is some sort of drawback, and am curious why folks think that's a problem.
The Holy Grail of electric propulsion research is a battery powered airliner. Let's do a thought experiment, using the Boeing 737-900ER, for which I happen to have performance data.

We climb to 35,000 feet and arrive at a gross weight of 180,000 lbs. We select a cruise speed of 0.79 Mach and hold that speed until we've burned 30,000 lbs of fuel and our gross weight is 150,000 lbs. As we fly along losing weight the aircraft gets more efficient, which the flight computer uses to reduce fuel burn rate at our constant speed. At level-off, burn rate is 6,842pph but at the end of the experiment it's only 5,554pph (with a 6% total reduction in power setting). That's a change in burn rate of 1,288pph or nearly 21.5 pounds per minute.

That advantage would not accrue to a hypothetical electric version of the same aircraft; over the course of our cruise segment example, weight remains the same so energy consumption rate cannot decline. To achieve identical payload, range and speed, the electric aircraft would have to have batteries with energy density better than that of jet fuel.

Whether you call that a petroleum advantage or a battery problem is up to you!

The next problem is an electric motor/fan no heavier than a CFM56-7B that's capable of ~27,000 lbs of thrust.