How feasible are electric planes?
They work, but not as well as fossil fuel powered aircraft.The problem is that fossil fuels are almost the perfect chemical fuel. They're about as energy dense as you can get without becoming explosive. Batteries still weigh more per unit energy delivered. Even if they could match fossil fuels, fossil fuels's weight disappears as you use it, while the battery remains a constant weight when depleted.Alternatively, if you don't use batteries, you could use solar cells. This has two problems.What do you do at night (you still need a pretty big battery)Solar cells are not particularly energy dense, either. The wings and back of a plane is not that much real estate. We're talking low energy output and slow speed.The conclusion I come to is that electric heavier than air flight is quite possible, but not particularly practical.Lighter than air flight, however, is an entirely different proposition. Lighter than air blimps actually have a problem using fossil fuels: they can't remain neutrally buoyant and burn fossil fuel at the same time. They become too light and, unless you vent some precious lifting gas, you will float off and be unable to land.Most blimps solve this by being heavier than air, then using engine power to create the bit of lift they still need to actually get off the ground. The constant weight of the battery is actually an advantage because you can accurately remain neutrally buoyant. When you consider that lighter than air craft have minimal energy demands and a lot of real estate on the top for solar cells, electricity makes perfect sense.The reason lighter than air vehicles aren't popular (besides the Hindenburg, which we could prevent these days, even if we did fill blimps with Hydrogen) is that they are slow. The Hindenburg went 80 MPH/ 130 KPH. Modern jet liners go about seven times faster.