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London-Paris electric flight 'in decade'

bbc.co.uk

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Re: London-Paris electric flight 'in decade'

#121

Post by jpm_sd »

koolba wrote: post #27
dredmorbius wrote: post #23

Earlier quoted context omitted.

That buys you roughly a factor of three. Subtract again for the fact that you're not shedding half your takeoff weight in fuel over the course of a flight. You land with as much battery as you started with. More if you're using metal-air batteries.

Not necessarily! Imagine a system where the plan actually jettisons the spent batteries along the way. They could glide/parachute down to a collection depot to be recharged and sent back to the airport for installation.

That's called a "bomber".

Re: London-Paris electric flight 'in decade'

#122

Post by jpm_sd »

notahacker wrote: post #57
JustSomeNobody wrote: post #36

Earlier quoted context omitted.

What's the turnaround for the aircraft though? If they can't turn around an aircraft in 15-30 min, we'll need more aircraft or prices will skyrocket (no pun).

Any sensible proposal for electric systems for commercial aircraft is going to aim for batteries to be safely swappable in 10-15 minutes. (Though they can still make delays from unexpected diversions to airports without a stock of batteries worse)

The structural penalties for making "most of the weight of the aircraft" removable will probably lead to a plane that doesn't fly.

Re: London-Paris electric flight 'in decade'

#123

Post by jpm_sd »

Entangled wrote: post #91
D_Alex wrote: post #75

I am really quite confident that no serious development of electric passenger aircraft will take place during the coming decade. And it is not a question of feasibility, but rather of priorities. There is so much low hanging fruit to be collected! By the end of the decade, if all goes well, we will be in the middle of replacing petroleum fuelled cars and busses with electric ones, and maybe turning our attention to o…

Siemens disagree http://www.siemens.com/press/electric-aircraft

They specifically mention "hybrid-electric propulsion systems", which means electric propulsion powered from a fuel-burning generator.

Re: London-Paris electric flight 'in decade'

#124

Post by fab13n »

mikro2nd wrote: post #110
fdej wrote: post #26

Earlier quoted context omitted.

That's correct, but note that an electric motor is about twice as efficient as a combustion engine, reducing the factor to about 25x (at least ideally). Typical medium range aircraft burn about 3 kg fuel per km [1], so to fly 1000 km you would need about 3 * 25 * 1000 kg = 75 tonnes of batteries. This should be in the ballpark of what we can pack into an aircraft already, but I guess at least another 2x improvement i…

There are other considerations, though... The thought of a Li fire on board an aircraft is something that would keep me awake nights. I'd guess that anybody wanting to put Li technology batteries aboard aircraft is likely to spend the next 10 years jumping through regulatory hoops, so unless rechargeable battery technology is "ready to deploy" right now on aircraft, I don't see any way this is happening within a deca…

> The thought of a Li fire on board an aircraft is something that would keep me awake nights.

Whereas you wouldn't think twice about jet fuel fires, because you're used to it rather than because fuel isn't a fire hazard :-)

Re: London-Paris electric flight 'in decade'

#125

Post by fab13n »

JustSomeNobody wrote: post #36
fdej wrote: post #26

Earlier quoted context omitted.

That's correct, but note that an electric motor is about twice as efficient as a combustion engine, reducing the factor to about 25x (at least ideally). Typical medium range aircraft burn about 3 kg fuel per km [1], so to fly 1000 km you would need about 3 * 25 * 1000 kg = 75 tonnes of batteries. This should be in the ballpark of what we can pack into an aircraft already, but I guess at least another 2x improvement i…

What's the turnaround for the aircraft though? If they can't turn around an aircraft in 15-30 min, we'll need more aircraft or prices will skyrocket (no pun).

They say they plan to package batteries are packaged as standard freight containers.

Since current turnarounds include freight container swaps, I don't see why a battery swap wouldn't fit in it.

Re: London-Paris electric flight 'in decade'

#126

Post by Loic »

oskarth wrote: post #81
fridek wrote: post #72

Currently the shortest LGW-CDG flight is 1h. There is LCY-CDG lasting 1h 20m. For both cities it takes 30 - 60m to get to the airport from central location and you should be there at least 1h before the departure (for a total of 2-3h non-flight time). This makes total travel 3h - 4h30m. For comparison, the fastest train is 2h 25m. I guess you need to travel to and from the train station too, but it's definitely more…

Not to mention that taking the train between London and Paris is actually very pleasant, unlike taking a flight. When I worked in London I often used to go to Paris over the weekend, and it felt so luxurious to be able to wake up in Paris on Monday morning and be at my desk just after 9am in London (due to the time difference). The time on the train is all quality time that you can spend working, reading or eating a…

I do the same between Paris and Essen in Germany. There is a direct Thalys train connection. Door to door, it takes me the exact same time to reach Paris La Défense with the train as with flying from Düsseldorf. In the Thalys I have a good meal and place to work productively on my code or simply relax and read a good book.

Re: London-Paris electric flight 'in decade'

#127

Post by anovikov »

kgabis wrote: post #102
anovikov wrote: post #71

Why not, a jet powered plane can fly 17,300km, electric plane must have about 2x energy efficiency (70-80% vs 35-40% overall) because it's not a heat machine, so with 50x less energy density it translates to 700km. Actually it can be more because batteries are a lot denser than jet fuel so plane will be thinner, thus having a lot less air resistance, so 800km is possible. As you can see they are shooting for 500km, m…

You've contradicted yourself by saying that batteries are both less and more dense than jet fuel...

LOL energy density is much much lower, but volumetric density is several times higher. Meaning, they take less space for same weight -> airframe can have smaller profile and have less air resistance.

Re: London-Paris electric flight 'in decade'

#129

Post by ams6110 »

fab13n wrote: post #124
mikro2nd wrote: post #110

Earlier quoted context omitted.

There are other considerations, though... The thought of a Li fire on board an aircraft is something that would keep me awake nights. I'd guess that anybody wanting to put Li technology batteries aboard aircraft is likely to spend the next 10 years jumping through regulatory hoops, so unless rechargeable battery technology is "ready to deploy" right now on aircraft, I don't see any way this is happening within a deca…

> The thought of a Li fire on board an aircraft is something that would keep me awake nights. Whereas you wouldn't think twice about jet fuel fires, because you're used to it rather than because fuel isn't a fire hazard :-)

Jet fuel isn't very flammable unless it's atomized or vaporized, something which only happens in the engine. And it's pretty straightforward to extinguish an engine fire, and all aircraft engines have systems to do this.

Re: London-Paris electric flight 'in decade'

#130

Post by JumpCrisscross »

fab13n wrote: post #124
mikro2nd wrote: post #110

Earlier quoted context omitted.

There are other considerations, though... The thought of a Li fire on board an aircraft is something that would keep me awake nights. I'd guess that anybody wanting to put Li technology batteries aboard aircraft is likely to spend the next 10 years jumping through regulatory hoops, so unless rechargeable battery technology is "ready to deploy" right now on aircraft, I don't see any way this is happening within a deca…

> The thought of a Li fire on board an aircraft is something that would keep me awake nights. Whereas you wouldn't think twice about jet fuel fires, because you're used to it rather than because fuel isn't a fire hazard :-)

Doubly surprising given the fear is expressed in a thread specifically about the 50x energy-density differential between jet fuel and Li-on batteries.
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