Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Electric Planes Usher in the Second Great Age of Aviation

wired.com

Post reply on HN
Print view View original

41–50 of 70 posts

Re: Electric Planes Usher in the Second Great Age of Aviation

#41

Post by andrewla »

masklinn wrote: post #10
sokoloff wrote: post #2

I drive an electric car and fly piston airplanes. I don't see electrics replacing internal combustion in aviation in my flying lifetime. Why? Weight. The specific energy (energy per kg, edited per masklinn) of batteries sadly lags the specific energy of gasoline or kerosene, and the airplane carries that weight for the whole flight for an electric airplane. (My gas airplane gets lighter and lands as much as 1000 poun…

> The energy density of batteries sadly lags the energy density of gasoline or kerosene Nitpick but the energy/mass density is usually called "specific energy" to differentiate it with the more usual energy/volume "energy density". And while a battery's energy density is pretty bad, they pretty universally have a higher density than petroleum fuels and thus even worse specific energy: the best batteries have 2 orders…

> And while a battery's energy density is pretty bad, they pretty universally have a higher density than petroleum fuels and thus even worse specific energy

Is there a typo in there? Energy density (MJ/L) for batteries is lower than petroleum fuels by the same order of magnitude as the specific energy.

Re: Electric Planes Usher in the Second Great Age of Aviation

#42

Post by blktiger »

srb- wrote: post #20
simonsquiff wrote: post #5

I read a piece by Elon Musk, who was saying that electric planes - whilst very far away - are the future of air travel. Why? Because they will allow planes to fly higher - increasing efficiency and speed. Apparently the normal 30,000 feet cruising altitude is not higher because the reduced oxygen levels at higher altitudes impact the gasoline combustion too much. Even at 30,000 feet the air is thick as soup at cruisi…

Like most, I originally assumed that because batteries have poor specific energy compared to fossil fuels, there was no point in considering them for aircraft. But Musk's assertion has made me reconsider. Has anyone here done the math? What I think he's talking about is NOT a conventional plane with a battery simply replacing the gas tank, but instead essentially a flying battery, where 90% of the plane's mass is bat…

At Airventure last week I listened to a talk on an electric motor glider (http://electricmotorglider.com). One of the takeaways that I had was that with current battery technology, for electric motors to make more sense than a gasoline powered motors you have to have a flight time of less than 23 minutes. Above that, the reduced weight of fuel beats out the weight of batteries. We need additional research in the battery technology space before it's going to make sense for aircraft to be electric.

Re: Electric Planes Usher in the Second Great Age of Aviation

#43

Post by stcredzero »

sokoloff wrote: post #2

I drive an electric car and fly piston airplanes. I don't see electrics replacing internal combustion in aviation in my flying lifetime. Why? Weight. The specific energy (energy per kg, edited per masklinn) of batteries sadly lags the specific energy of gasoline or kerosene, and the airplane carries that weight for the whole flight for an electric airplane. (My gas airplane gets lighter and lands as much as 1000 poun…

If you could run cargo planes on beamed power, you wouldn't have to haul your power storage (fuel) to altitude. Also, given the extreme simplicity and reliability of electric motors, such an infrastructure would save huge amounts of money and also avoid externalities like atmospheric pollution.

The big question, of course, is the ability to build such an infrastructure with enough reliability.

Re: Electric Planes Usher in the Second Great Age of Aviation

#44

Post by pingec »

alexhawdon wrote: post #39
gambiting wrote: post #34

"In a statement, Pipistrel said Siemens prohibited the use of its motor for a flight over water." I am not sure how that could happen? Surely if they bought the engines they could have done whatever they wanted with them? Unless they were leased from Siemens or something.

Maybe to get permission for your flight plan when using an experimental vehicle you have to be able to show that the manufacturers of the major components have confidence it will be able to complete the proposed route safely?

Afaik both UK & French authorities gave permission for the flight to take place. It were Siemens that wanted to prevent it.

Re: Electric Planes Usher in the Second Great Age of Aviation

#45

Post by stcredzero »

simonsquiff wrote: post #5

I read a piece by Elon Musk, who was saying that electric planes - whilst very far away - are the future of air travel. Why? Because they will allow planes to fly higher - increasing efficiency and speed. Apparently the normal 30,000 feet cruising altitude is not higher because the reduced oxygen levels at higher altitudes impact the gasoline combustion too much. Even at 30,000 feet the air is thick as soup at cruisi…

If you could make beamed power work, you wouldn't have to haul your power source up to those altitudes. Of course, this is quite a "big if."

Re: Electric Planes Usher in the Second Great Age of Aviation

#46

Post by elektromekatron »

sokoloff wrote: post #2

I drive an electric car and fly piston airplanes. I don't see electrics replacing internal combustion in aviation in my flying lifetime. Why? Weight. The specific energy (energy per kg, edited per masklinn) of batteries sadly lags the specific energy of gasoline or kerosene, and the airplane carries that weight for the whole flight for an electric airplane. (My gas airplane gets lighter and lands as much as 1000 poun…

It maybe isn't quite as bad as you think, as what really matters is the thrust for the combined weight of the engine and power source rather than just the energy density of the power source in joules per kilo. Combustion is generally pretty lousy, compared to electric, at converting joules into useful newtons.

Re: Electric Planes Usher in the Second Great Age of Aviation

#47

Post by simonsquiff »

masklinn wrote: post #16
simonsquiff wrote: post #14

Earlier quoted context omitted.

I'm not sure it's ignoring everything - as this article states, electric planes exist today, and are improving at a fast rate. Batteries are also improving (thanks to Musk and others), not that electric planes needs to be battery based - fuel cells could be the answer (though presumably these require oxygen so might have altitude issues). So whilst far away, it's an extrapolation from our current position. Nuclear pl…

> I'm not sure it's ignoring everything - as this article states, electric planes exist today Prop toys exist, not "future of aviation" anything. Props being an other issue, electric planes means no turbofans. > Batteries are also improving Batteries are not improving at a rate which would increase their specific energy by 2 orders of magnitude (the difference between the specific energy of the best batteries availab…

The original supposition was that electric planes are the future - albeit a future very far way - because electric means no oxygen concerns, which means higher altitude, which increases efficiency and / or speed.

Now, electric doesn't mean battery. Fuel cells, solar, or even hybrid might all play a part. I believe a large proportion of energy consumption is during takeoff - what if you could draw take off power needs from the airfield rather than from the aircraft? What about hybrid - use gas to get to 30,000 feet, then turn on electric to go higher than that? Yes battery energy density is miles away currently, but if we avoid batteries in part, and improve them too, where might things be in 50 years time? The point is we are on the journey with electric planes, and the goal is a good one for reasons stated. Major problems to overcome - absolutely, but this is not a short or medium term prediction. But 'Magical thinking' required, more so than Dyson spheres? That's harsh.

I think Musk said he'd like this to be a far future project for him. He said he's driven by not wanting to go backwards - how space travel was worse than the 60s, as is air travel (no supersonic public aircraft any more). Electric planes - if possible - would be the solution to faster air travel. With Tesla and SpaceX under his belt, he'd certainly got the necessary chops to tackle it.

Re: Electric Planes Usher in the Second Great Age of Aviation

#48

Post by elektromekatron »

stcredzero wrote: post #43
sokoloff wrote: post #2

I drive an electric car and fly piston airplanes. I don't see electrics replacing internal combustion in aviation in my flying lifetime. Why? Weight. The specific energy (energy per kg, edited per masklinn) of batteries sadly lags the specific energy of gasoline or kerosene, and the airplane carries that weight for the whole flight for an electric airplane. (My gas airplane gets lighter and lands as much as 1000 poun…

If you could run cargo planes on beamed power, you wouldn't have to haul your power storage (fuel) to altitude. Also, given the extreme simplicity and reliability of electric motors, such an infrastructure would save huge amounts of money and also avoid externalities like atmospheric pollution. The big question, of course, is the ability to build such an infrastructure with enough reliability.

Perhaps an orbiting network of solar powered satellites that can each manage large numbers of directed power beams. Though maybe that would be a non starter due to the large number of non-civilian applications.

Re: Electric Planes Usher in the Second Great Age of Aviation

#49

Post by 6stringmerc »

termain wrote: post #36
6stringmerc wrote: post #29

Earlier quoted context omitted.

No, I mean like the chassis components were on the outside of the car, like a bug. That was the crux of their entry, mollified by some talk of aerodynamic efficiency. From what I recall, the rendered images of their concept didn't even have a method of entry for the driver/passengers. No doors. It was...well, frustrating, as my tone probably conveyed. Re: Monocoque - my entry cited that format to give additional stre…

Ah, ok. I can definitely understand your frustration since exoskeleton and aerodynamic efficiency don't generally mix.

Thanks for being interested / opportunity to clarify. The rendering actually looked like I-Beams curved into some kind of egg-like shape. It was mathematically sound, sure, but at first glance coming up with an answer "Where can research go with this?" didn't seem apparent.

I tuned in to every Q&A session provided during the contest and time and again they reiterated certain principles for judging...when the results came in, yeah, pretty infuriating. Oh well...it did motivate me to finally meet with a Patent Attorney on a couple other ideas, so some lemonade did come out of it.

Post reply on HN