7 ms·

Just drop them before landing... There could be a batteries landing place where they'd be collected. Is it too crazy?

by kuu 7y ago

mikepurvis 7y ago
Since a big chunk of the power is expended on takeoff, the ideal would be to drop part of your battery then rather then waiting until after landing. But either way, you're stuck with the significant complexity and expense of having to prepare a parachute and landing gear specifically for the battery on each flight, plus having to collect and charge those batteries.
- tonyedgecombe 7y ago
  Perhaps you could trail a long unwinding power cable behind you which disconnects when fully extended.
  - Alupis 7y ago
    What happens when it mechanically fails and doesn't disconnect? Have a 2 mile long cable being drug behind a 200mph flying machine? That seems quite dangerous - to both the aircraft and everyone onboard, as well as to anyone on the ground in the path of this cable.
    - tonyedgecombe 7y ago
      What happens when the plane mechanically fails? Having 600 tons of metal raining down on a population sounds quite dangerous.
      - Alupis 7y ago
        > What happens when the plane mechanically fails? Having 600 tons of metal raining down on a population sounds quite dangerous Simply put, that's just not how aviation works. Mechanical failures aren't uncommon in aviation, but for an aircraft to not be able to divert and return to the ground, a lot has to go wrong all at once. It's infinitesimally rare for all systems to fail at once on an airliner. There simply isn't a problem of airliners dropping out of the sky, ever. They're incredibly robust machines. However, with your idea, we'd be relying on a single system to prevent catastrophic failure. That's a massive step backwards for aviation. That doesn't even begin covering the problems with delivering enough electricity over this cable to power an airliner at takeoff... That cable would need to be a very thick gauge of wire and very heavy - causing all sorts of it's own problems.
        tonyedgecombe 7y ago
        You can have your doubts but I'm off to the patent office tomorrow.
  - alexis_fr 7y ago
    Aircraft carrier catapults do that. When launching the aircraft, all the energy is expended from the ground. Looking forward to such gigantic machines on airports, how much they would charge per flight, and problems like terrain slowly moving due to the gigantic forces at play.
    - smileysteve 7y ago
      > Looking forward to such gigantic machines on airports, how much they would charge per flight It's actually an interesting supposition, because whether it's gasoline or electric, it should be cheaper and more reliable to run a ground operation than to pack fuel that is expelled before anything meaningful has happened.
    - hodgesrm 7y ago
      Catapults accelerate aircraft to the point of generating enough lift for powered flight. They allow you to take off from a short runway like a carrier but don't get you to altitude. You can get a sense of how much power is being used to reach cruising altitude by listening to the engines on take-off. They don't fully throttle back until you reach a high enough altitude to permit level flight.
      - pge 7y ago
        Good point - if you watch carrier launches, the planes actually fall a little as they go off the end of runway because they aren’t lifting yet. But presumably with a longer runway like you have at an airport, you could get to higher speed and truly liftoff. But having also launched from a carrier myself, I wouldnt want that g force everytime I fly commercially.
        hodgesrm 7y ago
        I would love to launch from a carrier. Was in the Air Force but not flight crew. Saw a lot of great aircraft there...from the ground. :)
        WalterBright 7y ago
  - chr1 7y ago
    Or build a several kilometers high tower, using either Space fountain or floating spheres. https://en.m.wikipedia.org/wiki/Space_fountain https://en.m.wikipedia.org/wiki/Space_fountain https://en.m.wikipedia.org/wiki/Cloud_Nine_(tensegrity_sphere) https://en.m.wikipedia.org/wiki/Cloud_Nine_(tensegrity_spher...
  - baddox 7y ago
    Heck, it might be doable to just lay the power cable in a permanent route on the ground and use electricity to propel the craft along that route! You wouldn't even need wings!
- Mountain_Skies 7y ago
  It wouldn't be viable for flights over oceans but I wonder if having batteries that eject at 95% exhaustion and then fly/glide themselves to a collection point with the last 5% of energy would work. There are too many variables for me to even do cocktail napkin math on it but with ever increasing drone tech, perhaps it would be possible.
  - mikepurvis 7y ago
    Hard to say if giving the battery its own avionics is better or worse than equipping it with a parachute or steerable glider. Either way, it's the kind of thing that SpaceX decided was worth trying for the sake of fairings worth a few million apiece. Asking them how it went is probably a good place to start. Regardless of the specifics, it's obvious that any of these schemes is a logistical and technical nightmare compared to "taxi up to the terminal, plug in the refueling hose while people and cargo are loaded onto the plane." It's unlikely that the private sector will be too enthusiastic about investing in anything like this without heavy incentives.
- tzs 7y ago
  I wonder if their are a pair of liquids that could be used to make a flow battery and that would be safe to dump they are expended?
  - quotemstr 7y ago
    The liquid is gasoline, and you can make it carbon neutral. This whole effort toward battery powered aircraft is misguided: technically, hydrocarbon fuels work better than anything else. What you want to do is make carbon neutral hydrocarbon fuels.
    - chr1 7y ago
      The real advantage of electric airplanes is simplicity of electric motors, better aerodynamical properties of a plane using many small propellers, and possibility of vertical takeoff. Ideally when we have kerosene based fuel cells we could have small electic aeroplanes that will be much easier to control, and would allow more frequent direct flights, instead of having to collect 100s of people together make them wait several hours, and drop them at an inconvenient location.
      - quotemstr 7y ago
        Sure. I have no objection to electric power trains for aircraft. But at that point, we're not talking about eliminating carbon emissions anymore, so the climate angle in this article ceases to be relevant.
- richardjs 7y ago
  Accepting that we're just throwing out interesting-sounding ideas, I wonder if having a powered runway rail (or something of the sort) to provide takeoff power could work. With that you wouldn't have to worry about dropping anything. But I do wonder how much power is actually expended at takeoff versus climbing or cruising flight. According to [1], only ~19% is used for both takeoff and climb, so electrifying the runway to save the fraction of the 19% used while in contact with the ground is probably not worth it. [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-...
  - ctack 7y ago
    Could use an electromagnetic rail to slowly but surely accelerate and launch it up to to cruising altitude https://en.m.wikipedia.org/wiki/Rocket_sled_launch https://en.m.wikipedia.org/wiki/Rocket_sled_launch
  - scottlamb 7y ago
    SupersonicScrub's comment (a sibling to yours) says that the engine can be significantly more efficient if it doesn't have to meet the power demands of take-off. Their link says "at least 30%" fuel savings on a one-hour flight (although "the fuel savings will partly come from the latest gas turbine technology"). So maybe the rail system you propose isn't such a crazy idea. Also, it's not totally different in concept from an aircraft carrier's catapult; hopefully gentler...
    - magduf 7y ago
      >Also, it's not totally different in concept from an aircraft carrier's catapult; hopefully gentler... Nah. If someone can't handle a few g's in takeoff, maybe they shouldn't be flying, and should should stay home, or maybe in a nursing home. I know it sounds mean, but seriously, think about it: aircraft transport isn't always comfortable. Turbulence happens, and it can be extremely rough at times, even injuring people severely if they're not belted in. If someone is too frail to handle being launched by an aircraft carrier catapult (which, remember, also launch those big AWACS planes, not just small fighter jets), then they're not suited for handling turbulence either. Also, don't forget, the latest generation of catapult technology is actually pretty gentle. The USS Ford's "EMALS" catapults are electromagnetic, rather than steam, and one of the big stated benefits of this is that it's gentler on the airframes than the old steam catapults. It's still going to subject the pilots/passengers to several g's, but probably lower peak acceleration than the older technology did.
- SupersonicScrub 7y ago
  There's a better electrically driven solution that takes advantage of the fact that take-off and climb-out requires the most power. Maximum power requirements come from take-off and climb-out, so the engine size is designed around the max take-off power. This means that the engine is over-designed and less-efficient for the majority of the flight. By implementing a hybrid engine, the gas-powered component and the electric powered component work together to provide take-off power requirements. By the time the aircraft reaches cruising altitude, the batteries are dead, and the gas-powered component works alone. This allows the engine to be designed for the cruise power requirements, which results in a much more efficient engine. UTC is currently experimenting with this concept. https://www.flightglobal.com/news/articles/utc-to-test-hybrid-electric-propulsion-system-on-da-456942/ https://www.flightglobal.com/news/articles/utc-to-test-hybri... Yes it's not carbon neutral, but it's a step in the right direction.
  - _ah 7y ago
    Wouldn't this also mean that full engine power is unavailable in the event of an emergency? Seems like this solution makes edge cases more likely to be fatal.
  - iguy 7y ago
    Not just for take-off, but for the possibility of finishing the take-off with one engine failure. That's quite a bit of spare capacity. However I also wonder why, if electric motors are a solution here, there hasn't been a comparable fuel-powered extra-takeoff-engine. Why would this not have the same benefits? Or are extra engines simply too complicated mechanically unless they are motors? (The liked article is about modifying a Dash 8, which is a turboprop, and perhaps it's easy to have oversize propellers for takeoff, and just connect a motor to the same gearbox.)
    - mikepurvis 7y ago
      Probably because a jet engine costs like $30MM. It may well be that the incremental cost ($, weight, complexity) of adding an electric booster to an existing engine design is much more practical than just adding more engines.
- deleted 7y ago
  [deleted]
0xffff2 7y ago
In a word, yes. Dropping the batteries out of an airliner in a way that left the batteries recoverable and reusable would add a tremendous amount of weight. It would also add a tremendous amount of danger. Neither of those things are attractive to a manufacturer.
- bdamm 7y ago
  However, reducing the cost of fuel by 1/10 would be very attractive to basically all airlines, so the manufacturers may very well step up for it. Bombs away!
  - WalterBright 7y ago
    The reason Boeing developed the 737MAX was a 15% fuel savings. Pretty darned attractive.
api_or_ipa 7y ago
It turns out that aircraft have a very sensitive centre of gravity that needs to be close to the centre of lift. If you were to design a "battery bomb" you'd have to carefully engineer the pre- and post-bombing centre of mass and ensure that your control surfaces can respond adequately. In addition, you'll need bomb-bay doors and associated mechanics which adds mass and complexity. All of this takes a toll of efficiency, cost and reliability. However, it's an intriguing idea, especially if you use steerable parachutes that can neatly fly themselves back home, maybe all the way into a recharging slot.
hyperbovine 7y ago
Here is what happens when you've got a tank rolling around downstairs: https://www.youtube.com/watch?v=7QYlueabGDg https://www.youtube.com/watch?v=7QYlueabGDg Jettisoning 200,000 lbs of batteries would be even worse.
- 0xffff2 7y ago
  I'm not sure that's relevant. Said tank was an uncontrolled and unexpected movement. Military air transports are certainly capable of doing controlled air drops of tens of thousands of pounds.
AnimalMuppet 7y ago
Batteries tend to have chemicals that are both fire and corrosion hazards. Subjecting their cases to the stresses of repeatedly landing (even on a padded catcher) could lead to containment problems. You don't want that on an airplane.

Just drop them before landing... There could be a batteries landing place where they'd be collected. Is it too crazy?

by kuu 7y ago

Just drop them before landing... There could be a batteries landing place where they'd be collected. Is it too crazy?

Since a big chunk of the power is expended on takeoff, the ideal would be to drop part of your battery then rather then waiting until after landing. But either way, you're stuck with the significant complexity and expense of having to prepare a parachute and landing gear specifically for the battery on each flight, plus having to collect and charge those batteries.

tonyedgecombe 7y ago
Perhaps you could trail a long unwinding power cable behind you which disconnects when fully extended.
- Alupis 7y ago
  What happens when it mechanically fails and doesn't disconnect? Have a 2 mile long cable being drug behind a 200mph flying machine? That seems quite dangerous - to both the aircraft and everyone onboard, as well as to anyone on the ground in the path of this cable.
  - tonyedgecombe 7y ago
    What happens when the plane mechanically fails? Having 600 tons of metal raining down on a population sounds quite dangerous.
    - Alupis 7y ago
      > What happens when the plane mechanically fails? Having 600 tons of metal raining down on a population sounds quite dangerous Simply put, that's just not how aviation works. Mechanical failures aren't uncommon in aviation, but for an aircraft to not be able to divert and return to the ground, a lot has to go wrong all at once. It's infinitesimally rare for all systems to fail at once on an airliner. There simply isn't a problem of airliners dropping out of the sky, ever. They're incredibly robust machines. However, with your idea, we'd be relying on a single system to prevent catastrophic failure. That's a massive step backwards for aviation. That doesn't even begin covering the problems with delivering enough electricity over this cable to power an airliner at takeoff... That cable would need to be a very thick gauge of wire and very heavy - causing all sorts of it's own problems.
      - tonyedgecombe 7y ago
        You can have your doubts but I'm off to the patent office tomorrow.
- alexis_fr 7y ago
  Aircraft carrier catapults do that. When launching the aircraft, all the energy is expended from the ground. Looking forward to such gigantic machines on airports, how much they would charge per flight, and problems like terrain slowly moving due to the gigantic forces at play.
  - smileysteve 7y ago
    > Looking forward to such gigantic machines on airports, how much they would charge per flight It's actually an interesting supposition, because whether it's gasoline or electric, it should be cheaper and more reliable to run a ground operation than to pack fuel that is expelled before anything meaningful has happened.
  - hodgesrm 7y ago
    Catapults accelerate aircraft to the point of generating enough lift for powered flight. They allow you to take off from a short runway like a carrier but don't get you to altitude. You can get a sense of how much power is being used to reach cruising altitude by listening to the engines on take-off. They don't fully throttle back until you reach a high enough altitude to permit level flight.
    - pge 7y ago
      Good point - if you watch carrier launches, the planes actually fall a little as they go off the end of runway because they aren’t lifting yet. But presumably with a longer runway like you have at an airport, you could get to higher speed and truly liftoff. But having also launched from a carrier myself, I wouldnt want that g force everytime I fly commercially.
      - hodgesrm 7y ago
        I would love to launch from a carrier. Was in the Air Force but not flight crew. Saw a lot of great aircraft there...from the ground. :)
      - WalterBright 7y ago
- chr1 7y ago
  Or build a several kilometers high tower, using either Space fountain or floating spheres. https://en.m.wikipedia.org/wiki/Space_fountain https://en.m.wikipedia.org/wiki/Space_fountain https://en.m.wikipedia.org/wiki/Cloud_Nine_(tensegrity_sphere) https://en.m.wikipedia.org/wiki/Cloud_Nine_(tensegrity_spher...
- baddox 7y ago
  Heck, it might be doable to just lay the power cable in a permanent route on the ground and use electricity to propel the craft along that route! You wouldn't even need wings!
Mountain_Skies 7y ago
It wouldn't be viable for flights over oceans but I wonder if having batteries that eject at 95% exhaustion and then fly/glide themselves to a collection point with the last 5% of energy would work. There are too many variables for me to even do cocktail napkin math on it but with ever increasing drone tech, perhaps it would be possible.
- mikepurvis 7y ago
  Hard to say if giving the battery its own avionics is better or worse than equipping it with a parachute or steerable glider. Either way, it's the kind of thing that SpaceX decided was worth trying for the sake of fairings worth a few million apiece. Asking them how it went is probably a good place to start. Regardless of the specifics, it's obvious that any of these schemes is a logistical and technical nightmare compared to "taxi up to the terminal, plug in the refueling hose while people and cargo are loaded onto the plane." It's unlikely that the private sector will be too enthusiastic about investing in anything like this without heavy incentives.
tzs 7y ago
I wonder if their are a pair of liquids that could be used to make a flow battery and that would be safe to dump they are expended?
- quotemstr 7y ago
  The liquid is gasoline, and you can make it carbon neutral. This whole effort toward battery powered aircraft is misguided: technically, hydrocarbon fuels work better than anything else. What you want to do is make carbon neutral hydrocarbon fuels.
  - chr1 7y ago
    The real advantage of electric airplanes is simplicity of electric motors, better aerodynamical properties of a plane using many small propellers, and possibility of vertical takeoff. Ideally when we have kerosene based fuel cells we could have small electic aeroplanes that will be much easier to control, and would allow more frequent direct flights, instead of having to collect 100s of people together make them wait several hours, and drop them at an inconvenient location.
    - quotemstr 7y ago
      Sure. I have no objection to electric power trains for aircraft. But at that point, we're not talking about eliminating carbon emissions anymore, so the climate angle in this article ceases to be relevant.
richardjs 7y ago
Accepting that we're just throwing out interesting-sounding ideas, I wonder if having a powered runway rail (or something of the sort) to provide takeoff power could work. With that you wouldn't have to worry about dropping anything. But I do wonder how much power is actually expended at takeoff versus climbing or cruising flight. According to [1], only ~19% is used for both takeoff and climb, so electrifying the runway to save the fraction of the 19% used while in contact with the ground is probably not worth it. [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-...
- ctack 7y ago
  Could use an electromagnetic rail to slowly but surely accelerate and launch it up to to cruising altitude https://en.m.wikipedia.org/wiki/Rocket_sled_launch https://en.m.wikipedia.org/wiki/Rocket_sled_launch
- scottlamb 7y ago
  SupersonicScrub's comment (a sibling to yours) says that the engine can be significantly more efficient if it doesn't have to meet the power demands of take-off. Their link says "at least 30%" fuel savings on a one-hour flight (although "the fuel savings will partly come from the latest gas turbine technology"). So maybe the rail system you propose isn't such a crazy idea. Also, it's not totally different in concept from an aircraft carrier's catapult; hopefully gentler...
  - magduf 7y ago
    >Also, it's not totally different in concept from an aircraft carrier's catapult; hopefully gentler... Nah. If someone can't handle a few g's in takeoff, maybe they shouldn't be flying, and should should stay home, or maybe in a nursing home. I know it sounds mean, but seriously, think about it: aircraft transport isn't always comfortable. Turbulence happens, and it can be extremely rough at times, even injuring people severely if they're not belted in. If someone is too frail to handle being launched by an aircraft carrier catapult (which, remember, also launch those big AWACS planes, not just small fighter jets), then they're not suited for handling turbulence either. Also, don't forget, the latest generation of catapult technology is actually pretty gentle. The USS Ford's "EMALS" catapults are electromagnetic, rather than steam, and one of the big stated benefits of this is that it's gentler on the airframes than the old steam catapults. It's still going to subject the pilots/passengers to several g's, but probably lower peak acceleration than the older technology did.
SupersonicScrub 7y ago
There's a better electrically driven solution that takes advantage of the fact that take-off and climb-out requires the most power. Maximum power requirements come from take-off and climb-out, so the engine size is designed around the max take-off power. This means that the engine is over-designed and less-efficient for the majority of the flight. By implementing a hybrid engine, the gas-powered component and the electric powered component work together to provide take-off power requirements. By the time the aircraft reaches cruising altitude, the batteries are dead, and the gas-powered component works alone. This allows the engine to be designed for the cruise power requirements, which results in a much more efficient engine. UTC is currently experimenting with this concept. https://www.flightglobal.com/news/articles/utc-to-test-hybrid-electric-propulsion-system-on-da-456942/ https://www.flightglobal.com/news/articles/utc-to-test-hybri... Yes it's not carbon neutral, but it's a step in the right direction.
- _ah 7y ago
  Wouldn't this also mean that full engine power is unavailable in the event of an emergency? Seems like this solution makes edge cases more likely to be fatal.
- iguy 7y ago
  Not just for take-off, but for the possibility of finishing the take-off with one engine failure. That's quite a bit of spare capacity. However I also wonder why, if electric motors are a solution here, there hasn't been a comparable fuel-powered extra-takeoff-engine. Why would this not have the same benefits? Or are extra engines simply too complicated mechanically unless they are motors? (The liked article is about modifying a Dash 8, which is a turboprop, and perhaps it's easy to have oversize propellers for takeoff, and just connect a motor to the same gearbox.)
  - mikepurvis 7y ago
    Probably because a jet engine costs like $30MM. It may well be that the incremental cost ($, weight, complexity) of adding an electric booster to an existing engine design is much more practical than just adding more engines.
deleted 7y ago
[deleted]

0xffff2 7y ago

In a word, yes. Dropping the batteries out of an airliner in a way that left the batteries recoverable and reusable would add a tremendous amount of weight. It would also add a tremendous amount of danger. Neither of those things are attractive to a manufacturer.

bdamm 7y ago
However, reducing the cost of fuel by 1/10 would be very attractive to basically all airlines, so the manufacturers may very well step up for it. Bombs away!
- WalterBright 7y ago
  The reason Boeing developed the 737MAX was a 15% fuel savings. Pretty darned attractive.

api_or_ipa 7y ago

It turns out that aircraft have a very sensitive centre of gravity that needs to be close to the centre of lift. If you were to design a "battery bomb" you'd have to carefully engineer the pre- and post-bombing centre of mass and ensure that your control surfaces can respond adequately. In addition, you'll need bomb-bay doors and associated mechanics which adds mass and complexity. All of this takes a toll of efficiency, cost and reliability. However, it's an intriguing idea, especially if you use steerable parachutes that can neatly fly themselves back home, maybe all the way into a recharging slot.

hyperbovine 7y ago

Here is what happens when you've got a tank rolling around downstairs: https://www.youtube.com/watch?v=7QYlueabGDg https://www.youtube.com/watch?v=7QYlueabGDg Jettisoning 200,000 lbs of batteries would be even worse.

0xffff2 7y ago
I'm not sure that's relevant. Said tank was an uncontrolled and unexpected movement. Military air transports are certainly capable of doing controlled air drops of tens of thousands of pounds.

AnimalMuppet 7y ago

Batteries tend to have chemicals that are both fire and corrosion hazards. Subjecting their cases to the stresses of repeatedly landing (even on a padded catcher) could lead to containment problems. You don't want that on an airplane.