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London-Paris electric flight 'in decade'

bbc.co.uk

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Re: London-Paris electric flight 'in decade'

#41

Post by JustSomeNobody »

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 sounds like something that could go very wrong and either cause the plane to crash or hurt/kill people on the ground.

Re: London-Paris electric flight 'in decade'

#42

Post by J-dawg »

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.

Speaking as someone with no aviation knowledge at all this seems like an awesome idea.

The plane could take off with battery packs slung under the wings which are jettisoned and become drones, gliding down to a depot.

I'm now waiting for someone who actually knows what they're talking about to point out the flaws. One that springs to mind is the logistics of collecting the drone-batteries and transporting them to be reunited with the parent aircraft.

Re: London-Paris electric flight 'in decade'

#43

Post by FungalRaincloud »

JustSomeNobody wrote: post #34
ptaipale wrote: post #11

TL;DR: If I read things right, the BBC article is highly misleading and the plane still uses jet fuel. Longer version: The article mentions "removing the need for jet fuel" but does not explain how the engines of this "electric" plane work. Propellers run by electric motors, or what? No. Wright Electric's own site is scant on technical details and concentrates on praising the great team in its blog. From browsing oth…

So, basically, PR to get a stock bump? Anytime I read anything that says 5 - 10 year, my initial reaction is, baloney.

I feel the same way, and yet, so much happens every single year that I never expected to see in my lifetime. I'm young (and in a tech field), tech isn't supposed to surprise me as much as it does. It's just that the media gets it so wrong so much of the time.

Re: London-Paris electric flight 'in decade'

#44

Post by taneq »

alex_duf wrote: post #28
ptaipale wrote: post #11

TL;DR: If I read things right, the BBC article is highly misleading and the plane still uses jet fuel. Longer version: The article mentions "removing the need for jet fuel" but does not explain how the engines of this "electric" plane work. Propellers run by electric motors, or what? No. Wright Electric's own site is scant on technical details and concentrates on praising the great team in its blog. From browsing oth…

I think the image you can see on the electrek article is from this blog post: https://weflywright.com/2017/02/12/wright-weekly-weport-feb-... The legend for that image is: >This image shows the potential subsystems that could be powered electrically. (Note: an fuel plane can also install electric subsystems – for example the 787 is making headway in this direction – but the subsystems in an electric plane will be all…

Wow, apparently I've been driving an electric car for years! It uses quite a bit of petrol too though.

Re: London-Paris electric flight 'in decade'

#45

Post by cjrp »

blutack wrote: post #25
tankenmate wrote: post #8

Earlier quoted context omitted.

The equation isn't just energy density; it's also the efficiency of harnessing that energy. Good electric motors are way more efficient than a turbofan.

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…

> There's also the issue of the mass of batteries not going away during the flight

Excellent point; currently as fuel is burned off, planes can climb to higher, more efficient altitudes (known as a step climb). What's the performance penalty for not being able to do this as your batteries aren't getting lighter as the flight progresses.

Re: London-Paris electric flight 'in decade'

#46

Post by martijn_himself »

ptaipale wrote: post #11

TL;DR: If I read things right, the BBC article is highly misleading and the plane still uses jet fuel. Longer version: The article mentions "removing the need for jet fuel" but does not explain how the engines of this "electric" plane work. Propellers run by electric motors, or what? No. Wright Electric's own site is scant on technical details and concentrates on praising the great team in its blog. From browsing oth…

Their site and blog reminds me of the Mars One project: a lot of talk and no substance. I hope I'm mistaken.

Re: London-Paris electric flight 'in decade'

#47

Post by jacquesm »

aphexbr wrote: post #3
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

FTA: "The company is relying heavily on innovation in battery technology continuing to improve at its current rate. If not, the firm will not be able to build in enough power to give the plane the range it needs." So, it presumably can't work now but they're putting their money on the idea that it will in the near future.

At which time everybody and their brother will be doing the same. The hard part is the batteries.

Re: London-Paris electric flight 'in decade'

#48

Post by jacquesm »

pale-hands wrote: post #40
CalRobert wrote: post #17

They picked the one city pair already served well by rail??? One where there will be substantial time lost to immigration queues anyway, thus reducing the relative benefit of high speed travel? SF-LA, London-Dublin, etc would have made a lot more sense.

Good point, but this is just the BBC giving an example of a distance that its audience can easily grasp.

I hope the took the requirements of two alternates to heart in their range calculations otherwise - bad pun - this won't fly.

Re: London-Paris electric flight 'in decade'

#49

Post by IanCal »

ptaipale wrote: post #11

TL;DR: If I read things right, the BBC article is highly misleading and the plane still uses jet fuel. Longer version: The article mentions "removing the need for jet fuel" but does not explain how the engines of this "electric" plane work. Propellers run by electric motors, or what? No. Wright Electric's own site is scant on technical details and concentrates on praising the great team in its blog. From browsing oth…

> TL;DR: If I read things right, the BBC article is highly misleading and the plane still uses jet fuel.

I don't think there's a clear description of the plane, so I don't think you can say what it "does" use.

Their blog says they'll go all-electric if batteries progress fast enough or they describe taking a hybrid approach "like a chevy volt".

> From browsing other sites [0] it appears that the engines are still using conventional jet fuel to generate the thrust; it's just that the external systems (pressurization, de-icing, landing gear mechanics, fuel pumps etc) that are powered by electricity are using battery power instead of generator in the current jet engines.

The clip I think you're referring to comes from this: https://drive.google.com/file/d/0B5dHV3MyeeBjN1BoU3hHclFYd3M...

which is not describing their proposal but they bring it up in one of the reports as a side opportunity for electric aviation.

Re: London-Paris electric flight 'in decade'

#50

Post by Retric »

notahacker wrote: post #33
Retric wrote: post #12

Earlier quoted context omitted.

Retrofitting an existing jet seems like a vastly more viable option in 10 years. But, with sufficient funding it's possible to start from scratch and get there in 10 years.

Not when you're dependent on (i) aviation authorities to certify your aircraft and (ii) third parties to improve battery technology to the point where it can happen

Based on another article they are not doing 100% electric. They are basically using battery's to replace the alternator/APU attached to the jet engine. That still adds up to a lot of jet fuel, but is only something like 5% total fuel savings.
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