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London-Paris electric flight 'in decade'

bbc.co.uk

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Re: London-Paris electric flight 'in decade'

#61

Post by wlll »

jakozaur wrote: post #39
koolba wrote: post #2

I'm not at the forefront of this field so maybe I missed some great advances in battery technology or airplane efficiency, but how could this possible work when the energy density of a battery (.3-.9 MJ/kg) is 50x less than that of jet fuel (46 MJ/kg)[1]? Or is that simply enough for (very) short haul flights? [1]: https://en.wikipedia.org/wiki/Energy_density

Maybe we should think outside of the box. What if, aircraft doesn't need to store all of the required energy on-board? E.g. transmit energy wirelessly through microwave and just have enough fuel for emergencies.

Planes I've been on regularly fly above the clouds, I wonder how much energy could be generated by covering the entire top of the aircraft with solar panels? I don't work in this field so as far as I know it could be a drop in the ocean.

Clearly only possible during the day though.

Re: London-Paris electric flight 'in decade'

#62

Post by nradov »

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.

You've got to be kidding. The civil aviation authorities would never allow airlines to jettison solid objects over populated areas for safety reasons.

Re: London-Paris electric flight 'in decade'

#63

Post by ericd »

neolefty wrote: post #53
blutack wrote: post #25

Earlier quoted context omitted.

Electric motors would need to be orders of magnitude more efficient than turbofans (which they aren't). You also need to compare the overall efficiency developed as thrust, not just thermal efficiency. There's also the issue of the mass of batteries not going away during the flight, unlike fuel, which will require maximum landing weight to equal maximum takeoff weight - this will impose a structural penalty versus IC…

Maximum efficiency is ... 100%. So if a turbofan is 30% efficient, then the best you can do is about 3x.

Good point, but something to keep in mind is that the efficiency of the motors in turning stored energy into motion is only one part of the efficiency of the aircraft. If a plane is able to fly much higher due to the engines no longer being air breathing, that would also change the equation, as drag would be much lower with the thinner atmosphere.

Re: London-Paris electric flight 'in decade'

#64

Post by ulfw »

notahacker wrote: post #29
thriftwy wrote: post #10

What's the point if you can just take an electric train? Isn't it basically 'a flight' on rails? They should have chosen a better city pair.

Tell that to the double-digit number of airlines already flying between London and Paris... It's a [hypothetical] aircraft, not a hyperloop. It can fly other routes.

Please list that 'double digit' number of airlines that fly between Paris and London. I get to max 7 (British, Air France, easyjet, Vueling, Transavia, flyBE, cityjet)

Re: London-Paris electric flight 'in decade'

#65

Post by J-dawg »

nradov wrote: post #62
koolba wrote: post #27

Earlier quoted context omitted.

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.

You've got to be kidding. The civil aviation authorities would never allow airlines to jettison solid objects over populated areas for safety reasons.

What if the jettisoned objects were autonomous aircraft that could land accurately at a specified location?

Re: London-Paris electric flight 'in decade'

#66

Post by aninhumer »

lorenzhs wrote: post #52
notahacker wrote: post #29

Earlier quoted context omitted.

Tell that to the double-digit number of airlines already flying between London and Paris... It's a [hypothetical] aircraft, not a hyperloop. It can fly other routes.

Eurostar have around 80% market share on Paris–London for good reason. At 2hrs 15mins from city centre to city centre it's faster, less hassle, and more comfortable than flying. Security is less strict (you can take liquids) and you don't have to check your bags. Two large items of luggage are also included for every passenger. It's not even more expensive than flying if you book in advance if you include the price f…

I assume that's just market share of travel specifically between the two cities? There's also the market of connecting flights to consider.

Re: London-Paris electric flight 'in decade'

#67

Post by srssays »

J-dawg wrote: post #65
nradov wrote: post #62

Earlier quoted context omitted.

You've got to be kidding. The civil aviation authorities would never allow airlines to jettison solid objects over populated areas for safety reasons.

What if the jettisoned objects were autonomous aircraft that could land accurately at a specified location?

A better idea would be to dig oil out of the ground, process it into kerosene, and use that to power jet turbines on the aircraft.

Re: London-Paris electric flight 'in decade'

#68

Post by baldfat »

mirimir wrote: post #32
baldfat wrote: post #20

Add it to the list of 10 years from now 1) Dozens of new battery technology 2) Graphine will change our world 3) Genetic cures for thousands of diseases and birth defects 4) Linux Desktop :(

> 4) Linux Desktop :( Have been using one for 10 years :)

I've been since 2004 :)

Re: London-Paris electric flight 'in decade'

#69

Post by mathw »

lorenzhs wrote: post #52
notahacker wrote: post #29

Earlier quoted context omitted.

Tell that to the double-digit number of airlines already flying between London and Paris... It's a [hypothetical] aircraft, not a hyperloop. It can fly other routes.

Eurostar have around 80% market share on Paris–London for good reason. At 2hrs 15mins from city centre to city centre it's faster, less hassle, and more comfortable than flying. Security is less strict (you can take liquids) and you don't have to check your bags. Two large items of luggage are also included for every passenger. It's not even more expensive than flying if you book in advance if you include the price f…

Does depend where you are though. If you're in London or Paris or in easy reach of the Eurostar stations by train, then Eurostar is amazing.

If you're in the north of England, it'll take you longer to get to London than it will to get from London to Paris afterwards. At that point flying starts to look a lot more attractive.

Re: London-Paris electric flight 'in decade'

#70

Post by selectodude »

aninhumer wrote: post #66
lorenzhs wrote: post #52

Earlier quoted context omitted.

Eurostar have around 80% market share on Paris–London for good reason. At 2hrs 15mins from city centre to city centre it's faster, less hassle, and more comfortable than flying. Security is less strict (you can take liquids) and you don't have to check your bags. Two large items of luggage are also included for every passenger. It's not even more expensive than flying if you book in advance if you include the price f…

I assume that's just market share of travel specifically between the two cities? There's also the market of connecting flights to consider.

There aren't any flights to anywhere in the world out of London that would connect through Paris unless you require a flight on Air France.
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