Futurology

Ah, AOPA. I wonder if they spent more or less on printing and postage on the junkmail they still sometimes sent me than they ever got from me in membership fees.

They don't hold a candle to the EAA though. Holey cheese grater.

I haven't read this article yet, but I did recently read about electric planes. There are a shockingly large percentage of flights in the US (and probably the world) that are that short. Not a percentage of passengers, but percentage of flights. Lots of islands that don't have a routine ferry service, or small rural communities in places like Alaska that may be separated from the road system by a mountain range.

Those small communities couldn't support constant rail (or ferry) service, so small planes are actually the most economical way to serve them. Even places like Hawaii could use electric planes to good effect.

The first I read about them was for flights to Nantucket Island, which absolutely gets ferry service, but it's also where a lot of rich people have homes, and they are going to fly. https://nantucketcurrent.com/news/cape-air-to-buy-electric-planes

You ever tried to travel by train here? Long or short distance. The rail infrastructure isn't there

There's plenty of places where an electric shorter range plane makes sense. Alaska and Australia come to mind immediately.

Well it did say it was a milestone flight, as well as 68 miles not necessarily meaning on a straight road you could drive 70mph on.

There are a lot of good arguments for rail or other means of transportation, but the travel volume vs the infrastructure required are vastly different in the US than in many parts of Europe/Asia. Think 'lots of medium distance low volume routes' that aren't economically feasible since there are existing routes. If you went through the effort of building a train route, you would have to charge so much per person to make it pay for itself that no one could afford it and they would take other methods.

I'm Europe, there seem to be enough 'short, high volume routes' that are economically feasible that considering adding other legs to them make sense, or they just already work.

have you seen the state of their rail system? Americans might be dumb but they're not fucking stupid.

"Woke commie company out to make us all gay with electric plane!"

Better?

Why? It's probably just an ad.

It’s absolutely not impossible. Airplanes are more efficient than drones, and efficiency grows with scale. Drones fly. Of course an airplane can do the same.

The problem is one of speed and range. The best form of propulsion we have for electric airplanes is the propeller, which has a lower top speed potential than a turbofan. The energy density of batteries is also lower.

Realistically, an electric airplane will have reduced range and speed compared to a modern jet.

Havent read the article yet, but I recall reading that with modern battery architecture electric planes were physically impossible.

Something something bumblebees.

Another issue is batteries don't change (significantly) in mass during flight. Most airliners have greater takeoff weight than landing weight, because after flying a jet for a few hours you're going to burn many tons of fuel. Batteries don't do that, so you'd have to have an airplane capable of landing at it's MTOW.

I think it is more specifically electric planes as large as commercial airline passenger planes are impossible. It has a lot to do with battery mass to energy content ratio. Kerosine is about 46.4 MJ (megajoules) per kilogram. Lithium-air batteries, for example, only have about 6.12 MJ/kg.

So, that means you need 7 times as much battery (in mass) to have the same energy content of kerosine fuel. Naively, we can maybe say that means electric planes only have 1/6 of the range of an equivalent kerosine plane.[^]

Interestingly, lithium-air batteries theoretically have the largest possible energy density for any battery at 40.1 MJ/kg.

^ The calculations are really basic and probably only slightly reflect reality (since there are many other important factors. For example, Hydrogen has a lot more energy per kilogram than kerosine, but because it is much less dense, it has much less energy per m^3 than kerosine. This has made hydrogen gas very impractical for either internal-combustion engines, or planes), but I think it gives an idea of what the problem is.

Assuming $8 for energy, let’s say $0.12/kWh you’re looking at 64kWH. That’s like 1kWh/mi, which is pretty fucking bad. There’s no way they’re scaling this up, because the battery has to weigh at least 1 Ton. So to double the distance you’d need to initially add double the battery, but that’s equivalent of adding 8 fat fucking Americanos to the payload, there by reducing the distance you can travel.

Meanwhile a Cessna Jet gets like 27/mi per gallon. So 2.5 gallons of fuel gets the same travel distance, and that only weighs like 20lbs.

Also, haven’t looked lately, but last I remembered, jet fuel was like $11/gal.

It's a problem of range. Jet planes have the advantage that they get lighter as the flight goes on, so for shorter flights, the battery issue is not as big of a problem. It's not a physical impossibility to achieve flight with lithium ion, it's a question of how far.

They envisioned travelling on the Autobahn?

Reminds me a lot of a Cessna Mixmaster. No front propeller, and the horizontal tail attaches to the engine cowling rather than crossing behind the propeller.

My instinct would be to go full Rutan, build a canard. If we're going with a single engine pusher. No need for the tail booms, everything produces lift, the main problem is flaps really aren't a thing with canards, you land them clean. But, if you're going to bolt VTOL to it somehow, who cares?

Does say that vertical takeoff is part of the plan. Probably worth an awkward looking plane if the goal is to eliminate the need for infrastructure like modern airports.