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You need the electric equivalent of a glider tug plane to get you up to altitude. It can then return to base taking its drained batteries with it while you con

You need the electric equivalent of a glider tug plane to get you up to altitude. It can then return to base taking its drained batteries with it while you continue to your destination with fully charged batteries.

nickff 2y ago
If that sort of complexity were viable for commercial aviation, we’d be air-to-air refueling airliners.
- namibj 2y ago
  Air-to-air is way more difficult than just a tug, though.
  - nickff 2y ago
    If that’s the case, why doesn’t the Air Force tug up its fighters? It’d be a huge advantage.
    - deleted 2y ago
      [deleted]
    - usrusr 2y ago
      Why? Energy density way beyond anything battery, and power headroom way beyond anything designed for frugal transport. Short haul passenger flights are not about speed but about getting directly to the stopover, without the unpredictability of ground transport. A "powered glider" with separating assist for the climbout could be a great match for that task. And the tug would obviously not really be a tug, but a winged battery directly attached to the aircraft it supports, with barely enough wing for a controlled return. An electric drop tank. Not exactly unheard of in military aviation (except for the "electric", obviously)
    - dredmorbius 2y ago
      Given a range of options for a similar problem, glider pilots generally opt for tugs, which suggests that complexity is within range of a general-aviation pilot class, let alone a commercially-certified one. But let's take your point as given. Fighter aircraft are generally built for speed and have (even relative to commercial aviation) often fairly low range. The equivalent to "tugging" would be external jettisonable fuel tanks, and we have seen those in military use since at least WWII. Given the general lack of electric propulsion in military use, that seems reasonable. The other model has been JATO packs applied to both fighter and cargo aircraft (Fat Albert, a C-130 Hercules, is often fitted with these for air-show demos). Not electrical power, but an external boost assist. For drone craft, there are deployment scenarios in which a large cargo plane drops (electrically-powered) drone swarms. I don't know the extent to which this has been deployed, but again it's similar. If a military were to adopt tugs, I'd expect them to be applied to drone or cargo missions, either with a drone tug (similar to the cargo-plane model above, but possibly with remotely-piloted / autonomous tugs), or with some capability for lofting a battery pack that could be detached and flown back to the take-off site after contributing to initial take-off and climb. That is complicated, but might fit certain mission profiles, and for a relatively slow long-haul cargo mission might make the cut. Worth also noting that most EV aviation concepts are for relatively modest cargoes and distances. The more viable range from 2--12 passengers for perhaps 100--200 km at low speeds. I've seen some more ambitious proposals, but they strike me as not especially viable.
  - TylerE 2y ago
    Very much disagree. Air to air refueling is done in a very stable manner at cruise altitude. Takeoff is a much more dynamic flight regime where things can go very wrong very quickly.
    - deleted 2y ago
      [deleted]
almostnormal 2y ago
Drop tanks, well, drop batteries, to get rid of the excessive mass.
- deleted 2y ago
  [deleted]
- jl6 2y ago
  Kinda crazy but might actually work for continental flights over cooperative areas. Parachute the empty batteries down with some minimal steering mechanism to land them at regularly spaced depots, then ship them back to airports fully charged. Turnaround time for planes is short enough that you’d need to do a battery-swap rather than a battery-charge anyway.
  - dredmorbius 2y ago
    I'd like to see what a typical widebody's fuel drain over time is, but suspect a large share is the takeoff-and-climb portion of flight. A winged battery which could drop away at ~FL20--30 or so and return to either the origin field or some secondary collection point might be all you need, rather than tossing batteries out the cargo bay throughout the flight. I also suspect that most EV aviation will be shorter haul such that a large set of drops wouldn't be necessary.
    - Galxeagle 2y ago
      You piqued my interest enough to go hunting - this StackExchange[1] question estimates ~19% of fuel is spent on initial climb-out to 30k feet for a 737-800 on a 5-hour LA->JFK flight. Without doing hard calculations, it intuitively feels pretty marginal potential flight weight savings for the operational complexity it would add [1] https://aviation.stackexchange.com/questions/47262/how-much-fuel-is-used-for-the-different-phases-of-the-flight-of-a-typical-airlin https://aviation.stackexchange.com/questions/47262/how-much-...
      - dredmorbius 2y ago

nickff 2y ago

If that sort of complexity were viable for commercial aviation, we’d be air-to-air refueling airliners.

namibj 2y ago
Air-to-air is way more difficult than just a tug, though.
- nickff 2y ago
  If that’s the case, why doesn’t the Air Force tug up its fighters? It’d be a huge advantage.
  - deleted 2y ago
    [deleted]
  - usrusr 2y ago
    Why? Energy density way beyond anything battery, and power headroom way beyond anything designed for frugal transport. Short haul passenger flights are not about speed but about getting directly to the stopover, without the unpredictability of ground transport. A "powered glider" with separating assist for the climbout could be a great match for that task. And the tug would obviously not really be a tug, but a winged battery directly attached to the aircraft it supports, with barely enough wing for a controlled return. An electric drop tank. Not exactly unheard of in military aviation (except for the "electric", obviously)
  - dredmorbius 2y ago
    Given a range of options for a similar problem, glider pilots generally opt for tugs, which suggests that complexity is within range of a general-aviation pilot class, let alone a commercially-certified one. But let's take your point as given. Fighter aircraft are generally built for speed and have (even relative to commercial aviation) often fairly low range. The equivalent to "tugging" would be external jettisonable fuel tanks, and we have seen those in military use since at least WWII. Given the general lack of electric propulsion in military use, that seems reasonable. The other model has been JATO packs applied to both fighter and cargo aircraft (Fat Albert, a C-130 Hercules, is often fitted with these for air-show demos). Not electrical power, but an external boost assist. For drone craft, there are deployment scenarios in which a large cargo plane drops (electrically-powered) drone swarms. I don't know the extent to which this has been deployed, but again it's similar. If a military were to adopt tugs, I'd expect them to be applied to drone or cargo missions, either with a drone tug (similar to the cargo-plane model above, but possibly with remotely-piloted / autonomous tugs), or with some capability for lofting a battery pack that could be detached and flown back to the take-off site after contributing to initial take-off and climb. That is complicated, but might fit certain mission profiles, and for a relatively slow long-haul cargo mission might make the cut. Worth also noting that most EV aviation concepts are for relatively modest cargoes and distances. The more viable range from 2--12 passengers for perhaps 100--200 km at low speeds. I've seen some more ambitious proposals, but they strike me as not especially viable.
- TylerE 2y ago
  Very much disagree. Air to air refueling is done in a very stable manner at cruise altitude. Takeoff is a much more dynamic flight regime where things can go very wrong very quickly.
  - deleted 2y ago
    [deleted]

almostnormal 2y ago

Drop tanks, well, drop batteries, to get rid of the excessive mass.

deleted 2y ago
[deleted]
jl6 2y ago
Kinda crazy but might actually work for continental flights over cooperative areas. Parachute the empty batteries down with some minimal steering mechanism to land them at regularly spaced depots, then ship them back to airports fully charged. Turnaround time for planes is short enough that you’d need to do a battery-swap rather than a battery-charge anyway.
- dredmorbius 2y ago
  I'd like to see what a typical widebody's fuel drain over time is, but suspect a large share is the takeoff-and-climb portion of flight. A winged battery which could drop away at ~FL20--30 or so and return to either the origin field or some secondary collection point might be all you need, rather than tossing batteries out the cargo bay throughout the flight. I also suspect that most EV aviation will be shorter haul such that a large set of drops wouldn't be necessary.
  - Galxeagle 2y ago
    You piqued my interest enough to go hunting - this StackExchange[1] question estimates ~19% of fuel is spent on initial climb-out to 30k feet for a 737-800 on a 5-hour LA->JFK flight. Without doing hard calculations, it intuitively feels pretty marginal potential flight weight savings for the operational complexity it would add [1] https://aviation.stackexchange.com/questions/47262/how-much-fuel-is-used-for-the-different-phases-of-the-flight-of-a-typical-airlin https://aviation.stackexchange.com/questions/47262/how-much-...
    - dredmorbius 2y ago