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Electric airliner

Old 22nd Mar 2017, 10:52
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Electric airliner

London-Paris electric flight 'in decade' - BBC News

I'm deeply suspicious about almost everything described here.

Apart from the obvious lack of acknowledgement of energy density....

why does it have a v-tail? There seems no good reason for a lack of vertical stabiliser. Why are there huge slots in the leading edge of the wing? that would make the wing more or less useless.

How long would London-Paris take with those weedy little electric engines?
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Old 22nd Mar 2017, 10:56
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Originally Posted by mommus View Post
Apart from the obvious lack of acknowledgement of energy density....
From the article:

"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."

Seems to address the point.
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Old 22nd Mar 2017, 11:01
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Electric propulsion makes sense in-flight where relatively little power is used - but not for takeoff. And while storage has a long way to go, using electrically powered hybrid engines may be a longer term solution.


Just look how far electric cars have come in 10 years with little financial/economic pressure and just the green lobby. Now try it with oil in 10 years time over 100 Dollars a barrel......
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Old 22nd Mar 2017, 11:05
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It looks a bit like easyJet and their ecoJET concept from last decade.

And as for batteries. Consider the meltdown that people are having because a few laptops are having to go in the hold.
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Old 22nd Mar 2017, 11:08
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It looks more like a Comet with a V tail.
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Old 22nd Mar 2017, 11:10
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Is this the same "in a decade" that we have been promised for the last 50 years for fusion power ?
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Old 22nd Mar 2017, 11:21
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Who remembers the "forked tailed doctor killer"?
https://en.wikipedia.org/wiki/Beechcraft_Bonanza

And the V tail is about the least implausible element in this fantasy.
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Old 22nd Mar 2017, 11:22
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I suspect it will need either a catapult or a conveyor belt runway, or both.

But good on them, progress isn't made without trying.
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Old 22nd Mar 2017, 11:32
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"The company is relying heavily on innovation in battery technology continuing to improve at its current rate.
I know someone involved in electric aircraft and he was telling me that battery technology is currently developing at the same rate as computers were 20 years ago.

And as for batteries. Consider the meltdown that people are having because a few laptops are having to go in the hold.
what on earth does that have to do with it??
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Old 22nd Mar 2017, 11:34
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Originally Posted by DaveReidUK View Post
From the article:

"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."

Seems to address the point.
A bit like someone in the 1960s saying - "we're expecting the speed of airliners to continue improving at its current rate... so by 2010 we'll be flying around at mach 10"
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Old 22nd Mar 2017, 11:47
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I'm sure it will use solar powered EmDrives (RF resonant cavity thrusters) by then. You could also use it to heat up the in-flight meals.

Big Yawn.
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Old 22nd Mar 2017, 12:20
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Originally Posted by foxmoth View Post
I know someone involved in electric aircraft and he was telling me that battery technology is currently developing at the same rate as computers were 20 years ago.
For a long time computing speed data capacity and price were all improving by about double every 18 months.

They might conceivably be able to gain battery breakthroughs by a factor of 10 or so from here to an unknown point in the future, using some nanotube discoveries or whatever, but multiplying battery performance by 10,000 in 20 years seems a bit improbable.
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Old 22nd Mar 2017, 12:37
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Apart from the fact it would likely have Props and therefor no one would fly on it because it is old there is the Freudien slip that the company is 'HEAVILY' reliable on battery technology. Batteries just that, heavy and unlike jet fuel they do not get lighter as the flight goes on and it burns off so take off weight and landing weight are just the same.

It is a lovely idea and I wish them success but its a real Everest of a mountain to climb even for a 70 seater that can do London-Paris. That would be a very very limited market even in little old Europe where an hour gets you quite along way to be cost effective a short hauler needs three hour endurance minimum for efficient deployment so you can do the likes of London-Berlin, Paris-Milan and in the US if it could not do NY-ATL/ORDits never going anywhere. Economy of scale is everything in the airline world and its very hard to start small and work upwards
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Old 22nd Mar 2017, 12:41
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Originally Posted by foxmoth View Post
I know someone involved in electric aircraft and he was telling me that battery technology is currently developing at the same rate as computers were 20 years ago.
Sorry, nowhere near Battery technology is improving by about factor of 2 every 10 years, this is far slower than computers 20 years ago.

In general, loose comparisons with Moore's Law (about transistors) are never valid, since the underlying principles are unique to information processing, and don't apply to other fields such as batteries.

Usually, the Moore's Law comparison is thrown out as part of marketing hype, designed to impress investors, but has no basis in reality.
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Old 22nd Mar 2017, 13:33
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Originally Posted by 911slf View Post
Who remembers the "forked tailed doctor killer"?
https://en.wikipedia.org/wiki/Beechcraft_Bonanza

And the V tail is about the least implausible element in this fantasy.
New pipe-dream concept studies often feature V-tails to make them look "futuristic", but they rarely make it through to the production versions (on the rare occasions that there actually ARE any production versions) - heck, even the early brochures of the Astude class submarine showed it with an "X-tail" for the same reasons.

But having said that - the "doctor killer" tendency of the V-35 was nothing to do with the "V", and everything to do with the "doctors" IIRC.
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Old 22nd Mar 2017, 14:41
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But having said that - the "doctor killer" tendency of the V-35 was nothing to do with the "V", and everything to do with the "doctors" IIRC.
That and a bit of a tail flutter problem that was finally addressed by an AD.
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Old 22nd Mar 2017, 14:47
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Originally Posted by GrahamO View Post
Electric propulsion makes sense in-flight where relatively little power is used - but not for takeoff. And while storage has a long way to go, using electrically powered hybrid engines may be a longer term solution.


Just look how far electric cars have come in 10 years with little financial/economic pressure and just the green lobby. Now try it with oil in 10 years time over 100 Dollars a barrel......
I think advancements in electrical switching components had more to do with it but that may have been driven by green, although I think consumer electronics had more to do with that.
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Old 22nd Mar 2017, 17:17
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what on earth does that have to do with it??
Batteries, you know, tend to catch fire even in normal operation if you're not very careful. And now we're going to replace all the jet fuel with batteries.

Maybe they'll take the 787 approach and build a huge fire-resistant box around them. Of course, then they'll need more batteries so they can life that weight off the ground.
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Old 22nd Mar 2017, 18:54
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Originally Posted by MG23 View Post
Batteries, you know, tend to catch fire even in normal operation if you're not very careful.
A bit early for panto season, but "Oh no they don't!". Amongst other things this "self-flambe-panic" stuff is generally deemed to be a "lithium issue" (mainly with Lithium-cobalt technology) and if all you have is Lithium batteries this aeroplane will never become real. If it is to happen then it will need a different (denser) battery chemistry, and there is no reason tro assume that will be any more fire-prone than a bog-standard AA alkaline.

But even for the Lithium technologies the suggestion doesn't really stand scrutiny. As far as I'm aware every single case of lithium battery fires to date has been able to be traced to one of four things:

1. Damage
2. Abuse (operation, handling or storage not in accordance with specification)
3. Manufacturing defect in the cells or the charging/conditioning system
4. Design error in the battery installation or the charger/conditioner system

As far as I am aware (and I have studied this at some length) there has *never* been an instance where a Lithium battery has caught fire "in normal operation". Subsequent investigations have always found one of causes 1-4 was involved.
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Old 22nd Mar 2017, 19:21
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As far as I am aware (and I have studied this at some length) there has *never* been an instance where a Lithium battery has caught fire "in normal operation"
Only if you define 'in normal operation' as 'not catching fire'.

The 787 batteries were in normal operation when they caught fire. The Samsung batteries were in normal operation when they caught fire. That they did so due to design flaws merely reiterates my point that they catch fire in normal operation unless you're very careful with the design.

You're right that this has mostly been a lithium issue so far. But any device that stores a lot of energy in a compact form where it's easy to extract is likely to have disastrous failure modes. We understand the disastrous failure modes of jet fuel. We don't understand the disastrous failure modes of yet-to-be-invented-mega-battery.
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