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Re:Ultralight lithium-sulfur batteries for electric airplanes by tenuousemphasis on Wednesday August 19, 2020 @03:22PM (#24214964)
>Meanwhile, gasoline / petrol / benzin (wherever your are in the world) has an energy density of 12200 Wh/kg.

Electric motors are 90% efficient, ICE are less than 20%. So in reality gasoline is 2-3x as energy dense, when you look at how much of the fuel's energy can be used to do useful work.

Re:Ultralight lithium-sulfur batteries for electric airplanes by tengbretson on Wednesday August 19, 2020 @03:25PM (#24215027)
You also have to factor in the weight reduction as petroleum fuel is consumed vs the fixed weight of a battery.
Re:Ultralight lithium-sulfur batteries for electric airplanes by outworlder on Wednesday August 19, 2020 @03:29PM (#24215092)
This is a huge deal for aircraft. Not much for cars, as EVs are not carrying a lot of extra baggage that ICE cars require.

When was the last time you saw an ICE with both a trunk and a frunk? :)

Re:Ultralight lithium-sulfur batteries for electric airplanes by ScottBurson on Wednesday August 19, 2020 @05:48PM (#24217087)
> When was the last time you saw an ICE with both a trunk and a frunk?

Seconds ago -- there's one in my carport :-) (A 1993 Toyota MR2; it's mid-engine. The frunk is small, and completely filled by the spare tire and aftermarket stereo amp.)

Re:Ultralight lithium-sulfur batteries for electric airplanes by throwaway189262 on Wednesday August 19, 2020 @04:06PM (#24215593)
Modern gasoline engines are not as heavy as you may think. I once transported 2 liter car engine in the back seat of my civic. Only ~150 lb and quite manageable.

Even monster SUV motors are only ~350 lbs. That doesn't include cooling, oil, accessories, or transmission but EV's have those too.

Re:Ultralight lithium-sulfur batteries for electric airplanes by Tuna-Fish on Wednesday August 19, 2020 @03:28PM (#24215065)
True, but the effect of this is less than it sounds like, as while the fuel is consumed, in an ICE car the engine is the heavy part and that isn't consumed.
Re:Ultralight lithium-sulfur batteries for electric airplanes by klyrs on Wednesday August 19, 2020 @04:23PM (#24215851)
Don't discount this so easily. You can't land a jumbo jet immediately after takeoff because its maximum allowed landing weight is much less than its maximum allowed takeoff weight. So you'll need a stronger fuselage and landing gear for electric plans, which means even more weight
Re:Ultralight lithium-sulfur batteries for electric airplanes by gibolt on Wednesday August 19, 2020 @03:37PM (#24215198)
I'd love to see a future where part of a plane's battery pack is a detachable drone that could fly back right after takeoff (most taxing on energy use) and thus decrease the weight of the plane.

You could also have battery swaps during flight as they pass over drone battery depots.

Sounds crazy. Might not be worth the gains for the complexity, but could be worth it across a whole fleet.

Microwave laser groundstations (or solar satellites) could come first, removing much of the battery requirement.

Re:Ultralight lithium-sulfur batteries for electric airplanes by tengbretson on Wednesday August 19, 2020 @03:40PM (#24215244)
Hah, now you've got me imagining a gentle rain of 18650 batteries following a plane as it travels across the sky.
Re:Ultralight lithium-sulfur batteries for electric airplanes by gibolt on Wednesday August 19, 2020 @04:00PM (#24215528)
Yes, gentle :D
Re:Ultralight lithium-sulfur batteries for electric airplanes by usrusr on Wednesday August 19, 2020 @07:18PM (#24217978)
Another crackpot idea:

Instead of a catapult or a flying battery pack, go for a tethered launch. The plane taxis onto a platform that is actually a powerful "cable laying UAV" with powerful ducted fans for propulsion and some lift and two big powered spools of copper as heavy as it can carry. The platform arrests the plane's main undercarriage, connects power lines to the plane and raises itself on its own set of wheels. They accelerate together, leave the ground together, all while the powered spools are unrolling the wires to the ground station exactly as fast as needed to avoid mechanical drag (the wires are effectively in free-fall, perhaps issues with the cable landing could be evaded by sending up a chain of "cable carrying (T)UAVs" that take the role of virtual poles). In time before the spools run out, the platform disconnects from the plane slows down the spools so that the inertia and main motors of the platform start pulling on the wires, then reels itself back in while it maneuvers to a point above the base station, finishing the circle with a tail-landing followed by dropping into "platform" position controlled by its secondary fans. Meanwhile, the plane flies of into the sunset on a fresh set of batteries.

But the battery tender UAV actually sounds far more practical, I guess I just like ideas involving tethered UAV.

(and somehow I feel almost entitled do spew out the most improbable ideas, since seeing footage of the successful dual suicide burns of the Falcon Heavy boosters - if that's possible, why isn't everything else as well?)

Re:Ultralight lithium-sulfur batteries for electric airplanes by mikeyouse on Wednesday August 19, 2020 @03:58PM (#24215494)
Seems like you'd be better off with a ground-based catapult system to get the plane up to speed and in the air where the on-board motors could take over.
Re:Ultralight lithium-sulfur batteries for electric airplanes by klyrs on Wednesday August 19, 2020 @04:19PM (#24215787)
Catapult really paints the wrong picture... but if you say ballista and actually mean a maglev rail accelerator then I'm down
Re:Ultralight lithium-sulfur batteries for electric airplanes by gibolt on Wednesday August 19, 2020 @04:01PM (#24215538)
If these are passenger aircraft, that probably wouldn't fly
Re:Ultralight lithium-sulfur batteries for electric airplanes by microcolonel on Wednesday August 19, 2020 @04:17PM (#24215756)
> If these are passenger aircraft, that probably wouldn't fly

Well, it doesn't need to have the same rate of acceleration as a carrier's, but honestly it just doesn't make sense in general.

Re:Ultralight lithium-sulfur batteries for electric airplanes by mikeyouse on Wednesday August 19, 2020 @04:50PM (#24216241)
Right -- you could use the full length of an existing runway to have a gentle acceleration , bt I'd argue this makes a lot more sense than some sort of drone delivered jettisoned/retrieved battery if your goal is to reduce on-board energy expended for takeoff. Much less complex and the wear parts would be fixed at the airport rather than on every single airplane.
Re:Ultralight lithium-sulfur batteries for electric airplanes by microcolonel on Wednesday August 19, 2020 @08:42PM (#24218643)
> I'd argue this makes a lot more sense than some sort of drone delivered jettisoned/retrieved battery..

Oh absolutely, it compares favourably to one of the most asinine first-pass approaches to this problem I've ever seen, heheh.

The real solution is to find a way to produce good liquid fuel from a cheap and abundant source of overprovisioned baseline power (maybe make hydrogen† from your nuclear power in off-peak hours).

Batteries are mostly composed of matrix, so even if you could extract energy as efficiently from the non-matrix materials in the battery as you can from hydrocarbon combustion, you would still be lugging around all that matrix.

† Yes, I get that it's 3 times less energy dense than good hydrocarbons, but it's a start when compared to batteries.

Re:Ultralight lithium-sulfur batteries for electric airplanes by K0balt on Wednesday August 19, 2020 @08:16PM (#24218457)
Might make more sense that you suspect. An airport designed to land uphill and takeoff downhill actually makes huge a difference in operating costs for heavy aircraft. Takeoff and initial climb are huge fuel burners.
Re:Ultralight lithium-sulfur batteries for electric airplanes by oh_sigh on Wednesday August 19, 2020 @03:50PM (#24215375)
My SUV is 4500 lbs and has a 17 gallon tank. Gasoline weighs ~6lbs/gallon, so it only factors for about 2% of total mass between a full and empty tank. Seems safe to mostly ignore it.
Re:Ultralight lithium-sulfur batteries for electric airplanes by tenuousemphasis on Wednesday August 19, 2020 @03:29PM (#24215085)
Yes, that's true. And the cost of electricity vs. fuel. Safety is another factor. The point is there's a lot more to it than Wh/kg of the energy source.
Re:Ultralight lithium-sulfur batteries for electric airplanes by throwaway189262 on Wednesday August 19, 2020 @04:00PM (#24215529)
Electric vehicles have range problems in cold climates because you don't have waste heat.

On a very cold day 60% of that waste heat might be used to warm the cabin. This translates to up to 50% range reduction in electric vehicles.

Re:Ultralight lithium-sulfur batteries for electric airplanes by DarmokJalad1701 on Wednesday August 19, 2020 @04:17PM (#24215748)
This is a myth. It is not nearly that bad. I own a Model 3 in a place where it is frequently below 30F in the winter. My last road trip when it was 17F throughout I consistently got around ~250-270 miles out of 310 rated range. The new hybrid heat-pump based system in the newer models makes it even more efficient.
Re:Ultralight lithium-sulfur batteries for electric airplanes by hansvm on Wednesday August 19, 2020 @07:54PM (#24218299)
I'm not sure how much it would matter, but it's probably worth pointing out that 17F is nearly shorts weather in the middle of the brutally cold winters a lot of places experience.
Re:Ultralight lithium-sulfur batteries for electric airplanes by DarmokJalad1701 on Wednesday August 19, 2020 @09:07PM (#24218811)
It shouldn't matter that much in that case too, especially if you have home charging. The lowest I have gone is minus 40 F during a cold snap last year. I had no problems starting up the car and going. The acceleration/regen was limited for a bit in the beginning to protect the battery. I lived in an apartment at the time and so I couldn't "pre-condition" the battery and interior from wall-power. But even then I had no problems after everything warmed up. Sure I used a bit more energy at the beginning to warm up the interior since I couldn't plug in.

On longer trips, the waste heat from motors are cycled through the battery to bring it to ideal temperatures. Even in extreme cold weather, you get full "regen" capability (meaning battery is warmed up), just from the waste heat from the motors. There is also an option to pre-condition the battery for fast charging by intentionally driving the motors less efficiently to generate more heat.

Re:Ultralight lithium-sulfur batteries for electric airplanes by throwaway189262 on Wednesday August 19, 2020 @04:20PM (#24215807)
Isn't the range penalty a lot worse on short trips? When I was researching Leaf I noped out of buying one because range penalty in the cold for daily commutes was almost 50%
Re:Ultralight lithium-sulfur batteries for electric airplanes by DarmokJalad1701 on Wednesday August 19, 2020 @09:02PM (#24218773)
Depends on the generation of Leaf. The older ones had a big problem with thermal management. Teslas on the other hand has a cooling loop that takes in excess heat from the motor (in some cases, intentionally running the motor inefficiently to generate more heat), to "condition" the battery to the ideal temp. Ideally this is done while plugged in if for short trips. The car essentially stalls the motor with just enough current to generate heat. On long trips, the heat generated during the drive is enough to take care of this and the battery stays at the optimum temperature even if it is extremely cold outside.