5 ms·

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? Ri

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? Right now, we have relatively large, relatively fast, jet planes. Do we need that size and that speed to be commercially viable? Could we also run a larger fleet of smaller, more automated planes or helicopters? If there was no kerosene left by tomorrow morning, would there really be no alternative?

djrogers 6y ago
> 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.
- onion2k 6y ago
  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.
  - tomalpha 6y ago
    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 https://en.wikipedia.org/wiki/Kangaroo_Route#Multiple_stops
  - Animats 6y ago
    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/ClipperSchedule.jpg https://tripsintohistory.com/wp-content/uploads/2012/10/Clip...
  - nopzor 6y ago
    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..)
- dreamcompiler 6y ago
  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.
  - Gh0stRAT 6y ago
    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.
    - tatersolid 6y ago
      > 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.
      - DennisP 6y ago
        Bailing out seems a bit problematic for passenger aircraft.
ReptileMan 6y ago
I kinda enjoy the ability to get to the other side of the world in 24 hours.
baq 6y ago
the problem with jets is stratospheric water vapor in addition to all the CO2 they emit (quite a lot in itself).
pjc50 6y ago
> If there was no kerosene left by tomorrow morning I suspect the medium term solution would be to make some, either from other hydrocarbons or plant cellulose, or even by the US Navy seawater CO2 to liquid fuel process.
kokey 6y ago
I probably have a skewed perception because I play with small fpv drones, but any weight saving like this usually opens up a whole world of new possibilities we never bothered to imagine before. This will certainly help existing delivery drones and drone taxi projects.
ashtonkem 6y ago
You probably don’t need gasoline density equivalents for short haul flights, but we’re still really far off from where we need to be.
Gibbon1 6y ago
I keep seeing numbers around 500 miles range floated for 8-12 passenger electric aircraft. Fire up google earth and start drawing 500 mile radius circles around metro areas.
bfieidhbrjr 6y ago
> if you can build batteries with the energy density of gasoline Actually significantly worse than that. A plane gets lighter the longer it flies, especially at takeoff when everything is at max thrust. A battery becomes more and more dead weight the longer you fly.
- bitdotdash 6y ago
  I wonder if this could be solved for with detachable take-off booster. Gets you up in the air, then returns to the airport.
  - ginko 6y ago
    Couldn't you just start with a cable that detaches and is pulled back to the landing strip?
    - noodlesoups 6y ago
      Just make sure it detaches properly, you don't wanta a dozen wire to yank you in mid ascend
    - mPReDiToR 6y ago
      A "third rail" along the runway and a dodgem/Scalextric type conductor springs to mind.

djrogers 6y ago

> 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.

onion2k 6y ago
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.
- tomalpha 6y ago
  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 https://en.wikipedia.org/wiki/Kangaroo_Route#Multiple_stops
- Animats 6y ago
  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/ClipperSchedule.jpg https://tripsintohistory.com/wp-content/uploads/2012/10/Clip...
- nopzor 6y ago
  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..)
dreamcompiler 6y ago
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.
- Gh0stRAT 6y ago
  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.
  - tatersolid 6y ago
    > 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.
    - DennisP 6y ago
      Bailing out seems a bit problematic for passenger aircraft.

ReptileMan 6y ago

I kinda enjoy the ability to get to the other side of the world in 24 hours.

baq 6y ago

the problem with jets is stratospheric water vapor in addition to all the CO2 they emit (quite a lot in itself).

pjc50 6y ago

> If there was no kerosene left by tomorrow morning I suspect the medium term solution would be to make some, either from other hydrocarbons or plant cellulose, or even by the US Navy seawater CO2 to liquid fuel process.

kokey 6y ago

I probably have a skewed perception because I play with small fpv drones, but any weight saving like this usually opens up a whole world of new possibilities we never bothered to imagine before. This will certainly help existing delivery drones and drone taxi projects.

ashtonkem 6y ago

You probably don’t need gasoline density equivalents for short haul flights, but we’re still really far off from where we need to be.

Gibbon1 6y ago

I keep seeing numbers around 500 miles range floated for 8-12 passenger electric aircraft. Fire up google earth and start drawing 500 mile radius circles around metro areas.

bfieidhbrjr 6y ago

> if you can build batteries with the energy density of gasoline Actually significantly worse than that. A plane gets lighter the longer it flies, especially at takeoff when everything is at max thrust. A battery becomes more and more dead weight the longer you fly.

bitdotdash 6y ago
I wonder if this could be solved for with detachable take-off booster. Gets you up in the air, then returns to the airport.
- ginko 6y ago
  Couldn't you just start with a cable that detaches and is pulled back to the landing strip?
  - noodlesoups 6y ago
    Just make sure it detaches properly, you don't wanta a dozen wire to yank you in mid ascend
  - mPReDiToR 6y ago
    A "third rail" along the runway and a dodgem/Scalextric type conductor springs to mind.