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Jet fuel has the advantage that it is consumed as you fly. Some planes can start with full tanks, but not land. If they need to do an emergency landing, they ha

by geon 5y ago

Jet fuel has the advantage that it is consumed as you fly. Some planes can start with full tanks, but not land. If they need to do an emergency landing, they have to dump the fuel. I imagine that would be difficult with batteries.

pkdpic 5y ago
Thats an excellent point. I wonder if flight batteries could be developed in small distributed cells with a weight / surface area that would allow them to hit a non-dangerous terminal velocity. And I wonder what the financial and environmental impact would be as compared to dumping jet fuel.
- adrianN 5y ago
  Dumping solids along flight routes doesn't really sound like a good idea. People don't like getting hit by small pellets, so matter how non-dangerous their terminal velocity is. Just imagine all the broken windshields for example.
- ehnto 5y ago
  We are making the assumption that dropping the batteries would actually be useful in an emergency situation. Considering that the plane needs to be designed to land fully loaded, since you're not dumping the batteries every flight, I think you would need to be way outside the operations planned safety envelopes to ever need to do that. I think building battery cells designed to fail safely in an accident is probably a more reasonable option than trying to dump them.
  - rich_sasha 5y ago
    Planes are safe to land fully loaded, but not designed for doing it repeatedly. The undercarriage, IIRC, needs a separate inspection after such landing. This is why, time permitting, planes will first burn off or drop fuel before doing an unplanned landing.
    - chrisandchris 5y ago
      While it‘s technically true that they can land fully loaded, using the word „safe“ is not ideal [1]. They _can_ land fully loaded but you are exceeding the maximum weight for landing which is neither advised by the manufacturer nor is it guaranteed that nothing will break. So if you it‘s not an emergency that requires immediate landing, you won‘t go for it. [1] https://aviation.stackexchange.com/a/33253 https://aviation.stackexchange.com/a/33253
      - rich_sasha 5y ago
        Yeah that’s better said.
guntars 5y ago
Easy, the battery bank is a separate drone ship that can be detached at any time. In fact, you could have booster electric aircraft to help the planes reach cruising altitude and then return to the same airport it left from to do it again.
- ginko 5y ago
  That doesn't sound easy at all.
  - guntars 5y ago
    You're right, I should have said "solvable" instead. Maybe some people wouldn't react so poorly to the comment. The point was that dumping the combustion products into the atmosphere and as a result reducing the total mass of the plane as it flies isn't some unsolvable advantage of jet fueled planes compared to the electric ones. 1) Detaching heavy objects while in-flight is a tried and tested technology. We've been doing it ever since flight was invented. 2) UAVs are not making the news anymore and fully autonomous landing has been commercially available since the mid-60s, granted, for very different type of aircraft, but it's becoming more common for light aircraft too. Dropping UAVs from airplanes is of course a whole different ball game, but wouldn't you say it's.. doable? Ultimately whether the added complexity is worth it depends on the proportion of energy used during taxi, takeoff and climbing compared to the total which varies wildly depending on distance and other factors, but tends to be highest for very short (but also very long) flights which is where electric aircraft currently stand a chance.
newsclues 5y ago
Do planes use most energy to get airborne? If so catapults like aircraft carriers maybe a good idea. Or extension cords that pop out when it gets airborne?

by geon 5y ago

pkdpic 5y ago

Thats an excellent point. I wonder if flight batteries could be developed in small distributed cells with a weight / surface area that would allow them to hit a non-dangerous terminal velocity. And I wonder what the financial and environmental impact would be as compared to dumping jet fuel.

adrianN 5y ago
Dumping solids along flight routes doesn't really sound like a good idea. People don't like getting hit by small pellets, so matter how non-dangerous their terminal velocity is. Just imagine all the broken windshields for example.
ehnto 5y ago
We are making the assumption that dropping the batteries would actually be useful in an emergency situation. Considering that the plane needs to be designed to land fully loaded, since you're not dumping the batteries every flight, I think you would need to be way outside the operations planned safety envelopes to ever need to do that. I think building battery cells designed to fail safely in an accident is probably a more reasonable option than trying to dump them.
- rich_sasha 5y ago
  Planes are safe to land fully loaded, but not designed for doing it repeatedly. The undercarriage, IIRC, needs a separate inspection after such landing. This is why, time permitting, planes will first burn off or drop fuel before doing an unplanned landing.
  - chrisandchris 5y ago
    While it‘s technically true that they can land fully loaded, using the word „safe“ is not ideal [1]. They _can_ land fully loaded but you are exceeding the maximum weight for landing which is neither advised by the manufacturer nor is it guaranteed that nothing will break. So if you it‘s not an emergency that requires immediate landing, you won‘t go for it. [1] https://aviation.stackexchange.com/a/33253 https://aviation.stackexchange.com/a/33253
    - rich_sasha 5y ago
      Yeah that’s better said.

guntars 5y ago

Easy, the battery bank is a separate drone ship that can be detached at any time. In fact, you could have booster electric aircraft to help the planes reach cruising altitude and then return to the same airport it left from to do it again.

ginko 5y ago
That doesn't sound easy at all.
- guntars 5y ago
  You're right, I should have said "solvable" instead. Maybe some people wouldn't react so poorly to the comment. The point was that dumping the combustion products into the atmosphere and as a result reducing the total mass of the plane as it flies isn't some unsolvable advantage of jet fueled planes compared to the electric ones. 1) Detaching heavy objects while in-flight is a tried and tested technology. We've been doing it ever since flight was invented. 2) UAVs are not making the news anymore and fully autonomous landing has been commercially available since the mid-60s, granted, for very different type of aircraft, but it's becoming more common for light aircraft too. Dropping UAVs from airplanes is of course a whole different ball game, but wouldn't you say it's.. doable? Ultimately whether the added complexity is worth it depends on the proportion of energy used during taxi, takeoff and climbing compared to the total which varies wildly depending on distance and other factors, but tends to be highest for very short (but also very long) flights which is where electric aircraft currently stand a chance.

newsclues 5y ago

Do planes use most energy to get airborne? If so catapults like aircraft carriers maybe a good idea. Or extension cords that pop out when it gets airborne?