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Comment by mikeash | Hacker News Reader

Waste heat can help keep the batteries warm. For example, Teslas have a battery heater which really eats power when you start out in the cold, but after you're cruising it reaches a steady state. Range still suffers, but at that point it's cabin heating and air resistance. Assuming the batteries are in the wings, you'll probably have voids between the batteries and the skin (since batteries don't have very a aerodynamic shape) which could be insulated without too much of a weight penalty.

Battery weight is a huge problem, of course. A Tesla battery pack is 1200 pounds. That's more than many light airplanes weigh total! The motor and inverter are only about 350 pounds, by comparison.

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It looked like the battery pack was just behind the motor, in the nose, on the test plane. Easy to let the heat just flow back from the motor.

Of course, it's a small battery pack.

FYI: I've ridden a few regional flights from Sacramento to the bay that are only about 15 minutes in the air, so the battery life might be as huge an issue as it's made out to be. Use electric for regional hops, and jets for longer "traditional" flights.

The motor won't produce much heat, since it's really efficient, but that will definitely help.

And yes, there are certainly use cases which come up as the technology improves. Actually, the airplane I want to buy when I win the lottery is electric: the Antares 20E. It's an electric self-launching glider, so it really just needs enough to get airborne and to a decent altitude, then you use the weather to stay up. Short hops like you describe would work too.

It's much like cars. The Nissan LEAF was useless for driving across the country but great if you just need to get around the city, and then better technology and range increase the number of scenarios where the cars are useful.

Some flights may only be 15 minutes in the air, but that doesn't reflect the fuel requirements for aircraft. I believe you're required to keep something like 30-45 minutes worth of fuel beyond what you need to get to your destination.

I've noticed that people who work on electric aircraft express some annoyance with this.

> I believe you're required to keep something like 30-45 minutes worth of fuel beyond what you need to get to your destination.

> I've noticed that people who work on electric aircraft express some annoyance with this.

As someone who was just on a plane who was recently on a plane that was diverted to another airport due to dangerously bad weather, I'm glad those requirements are there. There's all kind of things that can go wrong that could delay a landing for a half hour or more.

That's right. It's 30 minutes for VFR, 45 for IFR. Minimum. Nearly all commercial flights are IFR.

Thanks for pointing that out, you two. Still, it's probably doable to increase the battery capacity a bit to get cruising time (vs high powered climbing time).

Not there yet, but probably within spitting distance of a few of the use cases on the edges.

Unfortunately, no. For IFR you have to be able to fly an approach at the primary airport, then fly to the alternate airport, do an approach there, and then fly an additional 45 minutes. After each approach you have to be able to fly the missed approach procedure, which necessarily involves climbing. Just being able to cruise for 45 minutes is not enough.

https://www.law.cornell.edu/cfr/text/14/91.167

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