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London-Paris electric flight 'in decade'

bbc.co.uk

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Re: London-Paris electric flight 'in decade'

#131

Post by walshemj »

ams6110 wrote: post #129
fab13n wrote: post #124

Earlier quoted context omitted.

> 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.

And extinguishing a metal fire is not trivial

Re: London-Paris electric flight 'in decade'

#132

Post by yongjik »

I wonder if any company is seriously considering nuclear-powered planes? The energy density alone would make it extremely competitive.

And, let's be honest, in case of a crash, I'd rather walk away (or be hauled away without a limb or two) to die of cancer ten years later, than be burned to crisp in a huge fireball. Fear of radiation is overrated.

Re: London-Paris electric flight 'in decade'

#134

Post by asteli »

I see some back of the napkin calcs happening here, and feel compelled to point out that in addition to in-flight fuel, current regs require planes to have reserves sufficient to:

* maintain a holding pattern for 30 minutes (45 for recip. engines) PLUS

* perform a missed approach at destination, climb out again, and perform a landing at an alternate PLUS

* contingency fuel (5% of trip fuel)

Re: London-Paris electric flight 'in decade'

#135

Post by lutusp »

Airlines that switch to electrics will have to resolve a logistical issue -- do you switch batteries between flights, or do you need to buy twice as many aircraft, so half are flying and half are charging? I suspect that battery-switching will be the answer, even though the batteries will be a significant percentage of the aircraft's volume.

Re: London-Paris electric flight 'in decade'

#136

Post by verulito »

Maybe I don't understand combustion well enough but why isn't there more hype about fuel cells? They seem so much more compelling, in cars or otherwise. Just seems like if Elon Musk decided to pursue fuel cell cars rather than electric cars that those might be more dominant on the market today.

Re: London-Paris electric flight 'in decade'

#137

Post by fdej »

JumpCrisscross wrote: post #130
fab13n wrote: post #124

Earlier quoted context omitted.

> 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.

Trivia: there was about as much chemical energy in the fuel of either Boeing 767 that struck the twin towers as the gravitational potential energy released by the towers collapsing.

Re: London-Paris electric flight 'in decade'

#139

Post by J-dawg »

srssays wrote: post #67
J-dawg wrote: post #65

Earlier quoted context omitted.

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.

At some point we're going to need to stop doing that, hence the need for alternative ideas.

Re: London-Paris electric flight 'in decade'

#140

Post by J-dawg »

dredmorbius wrote: post #117
J-dawg wrote: post #42

Earlier quoted context omitted.

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…

Keep in mind that all protrusions are going to generate significant drag. So if you can find ways to incorporate the batteries within the airframe, you'd be better off. There's also the problem of mass-transfer. In general, aircraft should keep the center of mass behind the center of lift, and ... bad things happen when this isn't maintained. With liquid fuel, tanks are actively pumped to retain both forward-aft and…

Thanks for the comprehensive reply. I find it interesting to consider ideas like this, even if they ultimately turn out to be unworkable.
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