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A comment on Vertically aligned carbon nanotubes triple the density of lithium batteries. Parent comment

Re:Vertically aligned carbon nanotubes triple the density of... by djrogers on Wednesday October 07, 2020 @11:11AM (#24709057)
> I don't know. Sure, if you can build batteries with the energy density of gasoline, you can build an electric plane with them. But is this really necessary?

Only if you value overseas travel... It currently takes ~16 hours to fly from SF to Singapore depending on weather. Any longer, and you're going to see a lot of that travel disappear.

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Re:Vertically aligned carbon nanotubes triple the density of... by onion2k on Wednesday October 07, 2020 @11:17AM (#24709123)
Only if you value overseas travel... It currently takes ~16 hours to fly from SF to Singapore depending on weather. Any longer, and you're going to see a lot of that travel disappear.

It takes that long because it's more efficient to do it in a single flight. Taking off and landing are a massive waste of time and fuel. If we only had short range planes people would change their destinations in some cases or they'd plan layovers as part of the trip. I don't think you'd see that many people just stop travelling abroad.

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Re:Vertically aligned carbon nanotubes triple the density of... by Animats on Wednesday October 07, 2020 @02:51PM (#24711352)
In the era when planes had to do that, there was not much trans-oceanic travel. The Pan Am flying boats, the "China Clippers", went from San Francisco to Hawaii to Midway to Wake to Guam to Manila to Macao to Hong Kong. It took a week.[1]

[1] https://tripsintohistory.com/wp-content/uploads/2012/10/Clip...

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Re:Vertically aligned carbon nanotubes triple the density of... by tomalpha on Wednesday October 07, 2020 @12:11PM (#24709640)
Indeed. Though like in the olden days the large number of stopovers might cut down demand somewhat:

https://en.wikipedia.org/wiki/Kangaroo_Route#Multiple_stops

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Re:Vertically aligned carbon nanotubes triple the density of... by nopzor on Wednesday October 07, 2020 @06:28PM (#24713554)
it's not really true that ultra long range direct flights (eg. from sfo to sin) are more efficient.

the efficiency gain by not taking off and landing is eaten away by the efficiency loss of having to carry so much fuel (which also comes at the expense of useful load..)

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Re:Vertically aligned carbon nanotubes triple the density of... by dreamcompiler on Wednesday October 07, 2020 @01:50PM (#24710772)
It's not difficult to imagine in-flight recharging from something like a KC-135 running a big fat generator. If you're recharging capacitors, connect time would probably be a minute or two.
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Re:Vertically aligned carbon nanotubes triple the density of... by Gh0stRAT on Wednesday October 07, 2020 @02:39PM (#24711246)
I'm not so sure about that being an acceptable solution for civilian transportation… Even assuming automation can eliminate the risks and training overhead associated with in-flight refueling, there are still be some major hurdles that would need to be addressed before this could be considered a viable solution. The 3 big ones that come to mind are:

What happens if the KC-135 misses the rendezvous? What if the charging port fails to work for some reason? What about the carbon footprint of these airborne generators?

Plus, now you have the weight of the capacitors to carry around all the time, further reducing the effective payload.

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Re:Vertically aligned carbon nanotubes triple the density of... by tatersolid on Thursday October 08, 2020 @12:00AM (#24715622)
> What happens if the KC-135 misses the rendezvous? What if the charging port fails to work for some reason?

The same thing that happens today with combustion aircraft: the crew makes an emergency landing if they can, or bails out and waits for a Seahawk to pick them up.

This actually happens with fuel-driven aircraft regularly today.

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Re:Vertically aligned carbon nanotubes triple the density of... by DennisP on Thursday October 08, 2020 @09:59AM (#24719136)
Bailing out seems a bit problematic for passenger aircraft.
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