6 ms·
Fuel weight for liquid fuel at start of flight: 10x Fuel weight for liquid fuel at end of flight: 3x Fuel weight for battery at start of flight: 100x Fuel weig
by fwungy 3y ago
Fuel weight for liquid fuel at start of flight: 10x
Fuel weight for liquid fuel at end of flight: 3x
Fuel weight for battery at start of flight: 100x
Fuel weight for battery at end of flight: 100x
Batteries are not a great idea for a planes primary energy source. Liquid fueled planes get lighter and more efficient as they fly, a battery plane starts with a much larger and heavier fuel load and carries it the whole trip. Not only that, battery costs a lot more than fuel tanks.
- Johnny555 3y ago>Liquid fueled planes get lighter and more efficient as they fly, a battery plane starts with a much larger and heavier fuel load and carries it the whole trip I saw a concept once that had the plane drop the big battery after takeoff (maybe after reaching cruising altitude too) and let the battery fly back to the airport autonomously. Then it doesn't have to carry that dead weight for the entire trip. But, just like the promise of extended range batteries you could tow behind your EV for long trips, it's probably not real-world feasible.
- raverbashing 3y agoSomething like a carrier launch catapult, I think, would make more sense to be honest
- Johnny555 3y agoDoes the rollout from 0 - 200mph takeoff speed really use the bulk of the takeoff energy? I figured most of the energy went to climbing 6 miles in altitude.
- dredmorbius 3y agoI believe you're correct in this. An aircraft carrier's catapult isn't about getting an aircraft to altitude, but about getting it to flight speed, on the attenuated runway of a carrier deck. (Landing and arrestor cables are the equivalent problem in reverse.) That said, a divide-and-conquer approach to reducing overall aircraft energy use might go some way to making electrically-powered flight ... at least more feasible, for larger payloads / passenger capacities, and distances, than is now conceived. This includes ground taxiing (jet engines are quite inefficient at low speeds) via tugs, some form of take-off assist, jettisonable battery packs (after take-off and climb phases), general lightweighting of the airframe itself (already a major area of both research and accomplishment for electric aircraft), and automation and removing requirements for onboard pilots and flight attendants (the more paying bodies the more effective the business proposition). There's possibly some room for optimisation of engine and airframe efficiencies, routing, and traffic control, and possibly some gains by hybrid designs (fuel + battery with electric drives, say). As a whole though I suspect electric aircraft have been oversold, and that aviation as a whole will see reduced availability and usage in future.
- deleted 3y ago[deleted]
- raverbashing 3y agoProbably not, but takeoff is at when engines are at its most inefficient
- QuercusMax 3y agoAnd at a proper airfield it wouldn't need to use nearly as much g-force, since you can accelerate at a slower rate when you have a runway.
- MuffinFlavored 3y ago> I saw a concept once that had the plane drop the big battery after takeoff (maybe after reaching cruising altitude too) and let the battery fly back to the airport autonomously. Then it doesn't have to carry that dead weight for the entire trip. This sounds unrealistic. What if the plane needs "big energy" in the sky for emergency failure? Isn't the standard in aviation failure to the level of the 3rd degree or something (1 signal has 2 backups for 3 total or something)
- Johnny555 3y agoI agree it's unrealistic, but not because the plane might need "big energy" later -- I don't see how dropping the battery is any different than burning the fuel? If the plane burns 25% of its fuel on takeoff and climb, then that fuel is gone. If the plane drops 25% of its battery capacity (which is now depleted) after takeoff and climb, that battery capacity was already depleted, it's just acting as dead weight.
- dredmorbius 3y agoThe difference is that when you burn fuel, you burn fuel, and the mass exits the aircraft through the engine. When you discharge an electric cell, you're still carrying that electric cell with you. I suspect you're trying to express this and are fingering some other element of this concept as unrealistic, but that's not how your comment reads.
- Johnny555 3y agoI literally said that the depleted battery would be physically detached, I don't see how there is any other interpretation? I saw a concept once that had the plane drop the big battery after takeoff (maybe after reaching cruising altitude too) and let the battery fly back to the airport autonomously. Then it doesn't have to carry that dead weight for the entire trip. It's unrealistic because of all of the details in making a an autonomously flying battery pack that can detach from an aircraft in flight and do it with the kind of safety a civilian passenger aircraft demands.
- etaty 3y agoI believe dropping and catching new battery pack in the air is the way to go as well! Electric motors are smaller and can enable stationary flight. So stopping to change your pack is maybe a solution.
- fwungy 3y agoThey could use steam powered catapults like on carriers.
- okr 3y agoI hear mass catapulting passengers into the air is a thing now.
- pretendgeneer 3y agoI agree, we should limit flight to exclusively across large oceans. And replace flights over land with more practical low carbon options like high speed trains.
- freedom-fries 3y agoOr high-speed cars. I hate trains.
- itishappy 3y agoI'm just imagining the carnage from everyone barreling down the highway at 200 km/h (125 mph)...
- meepmorp 3y agohttps://alt.pavethe.earth/ https://alt.pavethe.earth/ > Today roads are narrow, you have to turn, and most governments frown at ground travel over Mach2. With endless blacktop in every direction, there will be no restriction to your movement, and rocket powered hypercars will whiz in all directions. We will be able to amuse ourselves with endless driving at incredible speeds while drinking beer and eating wonderfully juicy burgers.
- earthling8118 3y agoThe cars are the problem, not the solution.
- okr 3y agoWhat is a train? A collection of cars.
- nrb 3y agoSimply not realistic for major routes in the US for the foreseeable future. Los Angeles and New York are 2500+ miles apart across over 10 states that would need to properly coordinate and invest to make this a reality.
- lovecg 3y agoAt least in theory the battery could be used to recover some of the energy on descent (similar to regenerative braking, but with the spinning propeller instead of wheels). No idea if that’s at all efficient or if anyone experimented with this though.
- dredmorbius 3y agoThe main drawback to that suggestion is that aircraft really don't need more charge as they descend. The high-energy flight segments are take-off and climb. If you're charging batteries on descent ... the only gain is that the next take-off/climb phase can use that recovered energy. But from a mass and capacity standpoint, which seem to be the real challenges for electric flight, you're gaining very little. The ability to get rid of the battery you've spent on take-off/climb would be far more useful.
- ep103 3y agoOr solar