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Comment by onuryavuz | Hacker News Reader

So if the main issue is fuel economy, then we can assume that the future of air travel is an electric aircraft. I think weight is a major issue in electric aircraft design, how many batteries does it take to get an airplane off the ground ?

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When the Hyperloop stuff first being hinted at, I assumed the trick was electrically accelerating gliders in a series of hops (avoid the biggest cost of rail -- the rails).

The fact is that energy efficiency is never not going to be a factor and air travel is actually plenty fast for most purposes. The big problem is cost and external friction (getting to/from the airport, on/off the airplane).

It's like saying "phone calls haven't gotten any better in the last 50 years" -- except for cost, convenience, ease of getting a connection (e.g. you used to need to book international calls and get an operator to connect long distance calls).

How is that like air travel? "convenience, ease of getting a connection" for instance - we've screwed that up at airports for a decade now (since 2001 of course).

Not plenty fast for most purposes. Takes a day of pain to get anywhere. Used to be, you could go and get back same day. That's a huge setback.

Air travel hasn't gotten faster but it's gotten cheaper, more convenient, and far more common. Your complaints about air travel pretty much disappear if (a) you're a frequent air traveller and get pre-clearance etc. and (b) pay more for tickets (e.g. business or first class and more direct flights). So your problems are comparing incredibly discounted commoditized products to a very expensive premium product.

There are high end air-taxi and virtual private jet services around now that are probably less expensive than buying lots of regular air tickets was back in the 60s.

Car phones date back to 1946 (yep, surprised me too). So all the petty inconveniences of phones could be solved by money a long time ago (e.g. by having a secretary).

Not fair - its hasn't gotten all three of those things. Its convenient only if it isn't cheap. Ditto for common.

I don't get that conclusion - flying used to be a very expensive premium product? Not 20 years ago - ticket prices haven't changed all that much since then, at least out here in the Midwest far from any hub. I pay the same to get to the coast as I paid in the 90's to get home from school at the coast.

Last I checked, the 60s were more than 20 years ago.

Neglecting the weight of the engine / motor itself, the energy density of jet fuel is about 46 MJ/kg, and with batteries you can only get to about 1.5MJ/kg. Mobile phone batteries are about 0.5MJ/kg.

So thats at least 30 times more weight than is required with jet fuel.

Electricity is probably not it.

It's actually worse than this when you consider that aircraft become more fuel efficient the longer they fly, because they're not carrying around the fuel they've already burnt. An electric aircraft would presumably have a constant weight (stuff + batteries).

Electric cars and batteries are by no means my area of expertise, but I'd have to believe that the size and weight of the batteries needed for an electric plane would be totally unfeasible for efficient flight. Just for a comparison, a Tesla Model S weighs 4600 pounds, while a BMW 5 series weighs 3900 pounds, so the Tesla is about 20% heavier.

Plus, Jet A (kerosene) is relatively cheap compared to the cost of electricity and batteries.

Finally...imagine the range anxiety of a battery powered 777.

The range anxiety is based on not being able to fill up anywhere (electrically) even through there is plenty of alternative energy (gas) at every exit. There aren't any jet fuel stations in the sky, so planes already have this problem.

I don't think we'll see electric planes anytime soon since I see the future being a mix of all types of energy, but range anxiety isn't the problem.

Some ideas I've seen involve microwave power beamed down from space and/or up from ground stations. No batteries.

That sounds like a lot of birds would be wiped out, if it's adopted at scale.

You're better off using nuclear power or renewable energy to create carbon-neutral jet fuel than anything else. I doubt there's any other way to fly than hydrocarbons (or equivalent chemical energy). Nuclear planes are also a joke (I believe they are theoretically physically possible, but have to be huge, and of course there's the little issue of flying nuclear reactors around in the sky), all the other alternate energies are right out, and none of the non-rocket alternate thrust methods have anywhere near enough specific impulse to get a plane off the ground, to say nothing of the unpleasantness of something like ion drives taking off in the middle of populated metropolises all the time. (Any ion drive that could drive a plane would sterilize quite a bit of landscape in the process.) Rockets might theoretically work but obvious jet engines win out in practice in this use case.

Absent a breakthrough in battery technology, EV-like airliners are unlikely, and in any event would not be a complete fix for "fuel economy" problems -- it isn't just about the simple cost of fuel, but also about range, size/weight/materials, and the number of passengers (and degree of comfort).

I think the major issue is turnaround time. It takes 7 hours to recharge my Leaf. How long would it take to charge a 777? Yes, "but swappable batteries!" And how long does it take to swap batteries including the inspection and paperwork that I'm sure must be required when swapping out a major component in a commercial passenger aircraft?

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