The age of electric flight is finally upon us • Hacker News Board

Re: The age of electric flight is finally upon us

#11

Post by markab21 » Fri, Jun 21, 2019, 2:14 PM UTC

As someone who regularly pilots a piston-single, I'm looking forward to what hybrid or full electric can do for us little guys. The takeoff phase of flight is a high-risk situation in events such as fuel contamination which could prove fatal.

Having a small buffer, even a few minutes of battery power to rely on while trying to get back to the field to land the "impossible turn" [1] would make me feel a lot better and could be the difference between life and death.

There are various groups (Pipstrel[2], Diamond[3]) that I'm aware of that are working on electric GA aircraft. For young pilots that are looking to train, the cost of jumping in a Cessna 172, the gold standard in GA trainers will cost at best $120-200/hr. Electric costs should be 1/5 (or better) of that in reality due to the absolute bargain of replacing a TBO electric engine, scheduled maintenance and relatively low level of complexity.

[1] https://www.aopa.org/training-and-safety/air-safety-institut...

[2] https://www.pipistrel-usa.com/electric-propulsion/

[3] https://www.flyingmag.com/diamond-da40-hybrid-electric-proto...

Re: The age of electric flight is finally upon us

#12

Post by acdha » Fri, Jun 21, 2019, 2:16 PM UTC

iambateman wrote: post #10

From the article: conventional fuel for a 100 mile flight costs $400, while electric energy would cost $12. This seems like such a tremendous difference that the market would be in an arms race to make it a reality. Especially considering electric motors have fewer moving parts and so require less maintenance. Oh and it would be so quiet.

I think the big question would be how much the base equipment costs and the significant power density limitations. It takes time to get established against a very mature technology and batteries are a big limiting factor:

“Even assuming huge advances in battery technology, with batteries that are 30 times more efficient and "energy-dense" than they are today, it would only be possible to fly an A320 airliner for a fifth of its range with just half of its payload, says Airbus's chief technology officer Grazia Vittadini.”

I'm sure everyone would like to switch for environmental reasons but that sounds like a really big gap to fill.

Re: The age of electric flight is finally upon us

#13

Post by wlesieutre » Fri, Jun 21, 2019, 2:17 PM UTC

afiori wrote: post #4

wlesieutre wrote: post #3

Earlier quoted context omitted.

To store enough hydrogen to be useful you probably need it in liquid form like rockets use. Hydrogen is energy dense by mass, but not by how much space it takes up compared to liquid fuels. Otherwise you'll have a really giant bag of gaseous hydrogen which does help your bouyancy, but then you've made an airship instead of a plane and a spark accidentally turns it into the Hindenburg.

Is it so much less energy dense per liter to offset the gain in weight? In a plane energy per weight is rather important afterall

As a gas at 1 atmosphere, wikipedia says 0.011 MJ/L, compared to jet fuel at 35 MJ/L. You'd save weight (it weighs less than air so this would make you float) but need 3000x as much space if it's not compressed.

Compressed at 690 bar (about 680 atmospheres) it goes all the way up to 5 MJ/L, only 7x as much volume of fuel required compared to jet fuel. But the tanks to pressurize something that much are presumably very heavy and not a reasonable solution in an airplane.

Liquifying it gets that up to 10 MJ/liter and I don't think you need as much pressure to store that (as long as you keep it very very cold).

Per weight instead of volume you beat jet fuel (by 3-4x), so that aspect is a win. Having enough volume to store it and keeping the storage equipment light are the challenges.

Re: The age of electric flight is finally upon us

#14

Post by davidrm » Fri, Jun 21, 2019, 2:18 PM UTC

iambateman wrote: post #10

From the article: conventional fuel for a 100 mile flight costs $400, while electric energy would cost $12. This seems like such a tremendous difference that the market would be in an arms race to make it a reality. Especially considering electric motors have fewer moving parts and so require less maintenance. Oh and it would be so quiet.

> Oh and it would be so quiet.

would it? I was under the impression that proppelers were much louder!

what is the biggest source of noise in an aircraft/type?

Re: The age of electric flight is finally upon us

#15

Post by base698 » Fri, Jun 21, 2019, 2:21 PM UTC

iambateman wrote: post #10

From the article: conventional fuel for a 100 mile flight costs $400, while electric energy would cost $12. This seems like such a tremendous difference that the market would be in an arms race to make it a reality. Especially considering electric motors have fewer moving parts and so require less maintenance. Oh and it would be so quiet.

Own a single engine piston that's fuel efficient. In my plane 100 miles would be about $40 in fuel conservatively. Amortized maintenance costs are much higher than $40, but still not even close to $400. The article mentions a Caravan which is a bigger single engine turbine, not piston.

Fewer moving parts doesn't mean reliable and not subject to catastrophic unforeseen failures. If it hasn't been out for five years you're a test pilot.

Re: The age of electric flight is finally upon us

#16

Post by SeanBoocock » Fri, Jun 21, 2019, 2:22 PM UTC

iambateman wrote: post #10

From the article: conventional fuel for a 100 mile flight costs $400, while electric energy would cost $12. This seems like such a tremendous difference that the market would be in an arms race to make it a reality. Especially considering electric motors have fewer moving parts and so require less maintenance. Oh and it would be so quiet.

From the article:

> Even assuming huge advances in battery technology, with batteries that are 30 times more efficient and "energy-dense" than they are today, it would only be possible to fly an A320 airliner for a fifth of its range with just half of its payload, says Airbus's chief technology officer Grazia Vittadini.

> "Unless there is some radical, yet-to-be invented paradigm shift in energy storage, we are going to rely on hydrocarbon fuels for the foreseeable future," says Paul Eremenko, United Technologies chief technology officer.

> The big problem with this is that 80% of the aviation industry's emissions come from passenger flights longer than 1,500km - a distance no electric airliner could yet fly.

The market would be in an arms race if energy density was sufficient for long haul flights. Electric flight is awesome but until energy storage/density gets closer to hydrocarbons, conventional planes aren't going anywhere for the majority of travelers and cargo.

Re: The age of electric flight is finally upon us

#17

Post by NickM » Fri, Jun 21, 2019, 2:23 PM UTC

ginko wrote: post #2

I'm surprized hydrogen fueled flight isn't looked into more. Hydrogen can be produced using electrolysis and it's packs significantly more energy per weight even than kerosene. The main drawback is the low density which would require larger fuselages, but that should be offset by the significantly lower weight.

Yeah I have wondered about this option as well. Hydrogen fuel cell cars make very little practical sense for a lot of reasons, but most of those reasons don't seem to apply so much when you're dealing with air travel:

- It'll be a long time before fuel cells are cost competitive with gas or electric cars, but for planes the cost of fuel and operation is much more significant than with a car, so the upfront cost for building the plane seems less significant in comparison

- Refueling infrastructure is much easier to implement at a (relatively) small number of airports than it is to build many small consumer refueling stations everywhere

- Space is more important than weight in a car, but the opposite may be true for a plane

- Crash safety is a much bigger problem for cars than planes - plane crashes are rare, and if a plane crashes there's a good chance everyone dies anyway, but if you're designing a car you're going to have to be really careful to make sure every other fender bender doesn't result in a hydrogen explosion

Of course there's the issue that most hydrogen today is created from fossil fuels, but perhaps there are ways to generate it sustainably and still remain competitive with the cost of jet fuel?

Electric cars can be a very competitive alternative to gasoline cars, but electric batteries are not yet energy-dense enough to make long-distance air travel viable, so it feels like hydrogen planes might be the least bad solution if we want to get off of fossil fuels.

Re: The age of electric flight is finally upon us

#18

Post by mrfusion » Fri, Jun 21, 2019, 2:24 PM UTC

ginko wrote: post #2

I'm surprized hydrogen fueled flight isn't looked into more. Hydrogen can be produced using electrolysis and it's packs significantly more energy per weight even than kerosene. The main drawback is the low density which would require larger fuselages, but that should be offset by the significantly lower weight.

How about using carbon atoms to store your hydrogen? May I suggest methane.

Re: The age of electric flight is finally upon us

#19

Post by nradov » Fri, Jun 21, 2019, 2:24 PM UTC

ginko wrote: post #2

I'm surprized hydrogen fueled flight isn't looked into more. Hydrogen can be produced using electrolysis and it's packs significantly more energy per weight even than kerosene. The main drawback is the low density which would require larger fuselages, but that should be offset by the significantly lower weight.

Hydrogen is hardly ever produced by electrolysis. It's very inefficient.

https://en.wikipedia.org/wiki/Hydrogen_production

Re: The age of electric flight is finally upon us

#20

Post by marvin » Fri, Jun 21, 2019, 2:34 PM UTC

I fly gliders. Absolutely can't wait until my local club finally decides to get an electric single-seat self-launching glider, preferably with enough endurance to do some additional tens of kilometers after the launch, in order to avoid landing out if the weather dies out. It's a gamechanger with regards to both costs and convenience. No towplane, towplane pilot, no outlandings.