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Old 9th July 2021, 09:05 PM   #1161
dirtywick
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Originally Posted by RecoveringYuppy View Post
I'd like to know this, not assume this. Just repeating it is possible in your opinion is not the least bit interesting. I'd like to understand it.
Well you're asking me to design an airplane.

A battery is a box of various shapes and sizes with a positive and a negative lead. It strains my credulity to believe that it would be impossible to design a plane that has a panel that pops off that you can't hook a lift up to and drop a battery out and put a new one in. It's electricity, not fuel, it can be literally anywhere in the plane. You really don't think that's possible? My question is how could it not be?
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Old 9th July 2021, 09:07 PM   #1162
RecoveringYuppy
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Originally Posted by dirtywick View Post
Well you're asking me to design an airplane.
No, I'm absolutely not asking that.
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Old 9th July 2021, 09:11 PM   #1163
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Originally Posted by RecoveringYuppy View Post
That is just too stupid. Cars aren't airplanes. Fuselages need integrity, they try to minimize openings in them. Applying that idea directly to a plane might have the entire bottom half of the plane being opened up on each turn around. If you're not willing to put some thought in to this why not stop posting??
lol this is getting weirdly aggressive. have a good night
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Old 9th July 2021, 09:52 PM   #1164
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Originally Posted by RecoveringYuppy View Post
Is replacing batteries quickly going to be feasible? Ziggurat addressed the ownership/"chain of custody" issues, but do we know planes can be designed in a way that makes frequent replacement feasible? Constantly replacing a large component of the plane is not obviously a simple thing. Weight/strength and other requirements might make easy replacement hard to design for.

As you say, we can't replace fuel tanks. If the batteries have to be just as integrated for similar reasons it might be just as difficult to change batteries.
Fuel tanks on a 737 contain about 40,000 liters of fuel which is about 1400 cubic feet and weigh over 40 tons when full. Batteries to replace that are going to be on a similar scale given where battery technology is.
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Old 9th July 2021, 11:22 PM   #1165
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Originally Posted by dirtywick View Post
Well you're asking me to design an airplane.

A battery is a box of various shapes and sizes with a positive and a negative lead. It strains my credulity to believe that it would be impossible to design a plane that has a panel that pops off that you can't hook a lift up to and drop a battery out and put a new one in. It's electricity, not fuel, it can be literally anywhere in the plane. You really don't think that's possible? My question is how could it not be?
It should be possible to design a fuselage that keeps its integrity even if the battery box fell out (or one of them; probably best to have more than one.) But I can see a couple of problems with that:
  • It would require extra weight, and weight is an enemy in aircraft design.
  • The process of changing the batteries would subject the frame to bumps and bangs, which over time could weaken the fuselage.

I'm not saying it's impossible, but it might be rather difficult to do correctly.
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Old 9th July 2021, 11:40 PM   #1166
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Airbus going for hydrogen power

probably because of the problems noted above
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Old 9th July 2021, 11:41 PM   #1167
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KIA EV6 looks nice

Again, another expensive car
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Old 10th July 2021, 01:31 AM   #1168
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I have a test drive booked for October (October!). By then, no doubt, I will be drooling over the next "challenger to Tesla"

Head still says, for us, the Fiat is the sensible EV to buy
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Old 10th July 2021, 02:08 AM   #1169
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Originally Posted by dirtywick View Post
Well you're asking me to design an airplane.

A battery is a box of various shapes and sizes with a positive and a negative lead. It strains my credulity to believe that it would be impossible to design a plane that has a panel that pops off that you can't hook a lift up to and drop a battery out and put a new one in. It's electricity, not fuel, it can be literally anywhere in the plane. You really don't think that's possible? My question is how could it not be?
Batteries in a plane could power propellers, no problem, but for large-scale commercial flights would that be enough? If not, what would provide the motive force?
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Old 10th July 2021, 02:14 AM   #1170
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Hydrogen, see about three posts up
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Old 10th July 2021, 02:24 AM   #1171
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Originally Posted by Filippo Lippi View Post
Hydrogen, see about three posts up
Right, but the hydrogen is being burned and the exhaust gases move the plane. In the case of batteries, what is moving the plane?
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Old 10th July 2021, 04:19 AM   #1172
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Am I the only one imagining an electric plane that gets its battery swapped in half an hour, followed by a two day shakedown and test flight to recertify it?
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Old 10th July 2021, 05:57 AM   #1173
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Like they do after they've refuelled with kerosene?

I suspect that we will have small, light, prop planes powered by batteries and big jets powered by hydrogen
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Old 10th July 2021, 06:20 AM   #1174
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Originally Posted by GlennB View Post
Batteries in a plane could power propellers, no problem, but for large-scale commercial flights would that be enough? If not, what would provide the motive force?
they use them in military cargo planes.
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Old 10th July 2021, 07:35 AM   #1175
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Originally Posted by Blue Mountain View Post
It should be possible to design a fuselage that keeps its integrity even if the battery box fell out (or one of them; probably best to have more than one.) But I can see a couple of problems with that:
  • It would require extra weight, and weight is an enemy in aircraft design.
  • The process of changing the batteries would subject the frame to bumps and bangs, which over time could weaken the fuselage.

I'm not saying it's impossible, but it might be rather difficult to do correctly.
This is what I was getting at. Note the numbers I cited in the post just before you posted. Tens of tons, over a thousand cubic feet. It's a massive part of the plane being changed frequently. It's not the same problem for a planes as it is for a car. You have to add a structure that can support the battery and retain the structural integrity of the fuselage while tens of tons roll in and out. Passengers and cargo are of the same magnitude but note that they are 100s of individual components that can come and go through small openings. For the 737 I cited as an example, if the design goal for access to the battery is 10 square feet of fuselage then the battery is going to be about 100 feet long. If the battery is more the form factor of a car, then you will have an opening that basically splits the fuselage on a large scale.


Originally Posted by Jack by the hedge View Post
Am I the only one imagining an electric plane that gets its battery swapped in half an hour, followed by a two day shakedown and test flight to recertify it?

Yes, swapping out a battery is comparable to major maintenance on a plane.

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Old 10th July 2021, 07:41 AM   #1176
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There was a documentary series that first aired in the sixties where the air transport section of the organisation operated an aircraft that could swap the majority of its fuselage and still be more than airworthy. It was called "Thundersomething."
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Old 10th July 2021, 07:54 AM   #1177
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Originally Posted by dirtywick View Post
they use them in military cargo planes.
I had a search for battery-powered planes but could only find a Cesna test model and a bit of 'coming soon' from articles dated 2020. Do you have a reference for commercial use in planes?
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Old 10th July 2021, 05:09 PM   #1178
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Originally Posted by GlennB View Post
I had a search for battery-powered planes but could only find a Cesna test model and a bit of 'coming soon' from articles dated 2020. Do you have a reference for commercial use in planes?
I meant they use propellers.
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Old 10th July 2021, 05:12 PM   #1179
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Originally Posted by RecoveringYuppy View Post
This is what I was getting at. Note the numbers I cited in the post just before you posted. Tens of tons, over a thousand cubic feet. It's a massive part of the plane being changed frequently. It's not the same problem for a planes as it is for a car. You have to add a structure that can support the battery and retain the structural integrity of the fuselage while tens of tons roll in and out. Passengers and cargo are of the same magnitude but note that they are 100s of individual components that can come and go through small openings. For the 737 I cited as an example, if the design goal for access to the battery is 10 square feet of fuselage then the battery is going to be about 100 feet long. If the battery is more the form factor of a car, then you will have an opening that basically splits the fuselage on a large scale.





Yes, swapping out a battery is comparable to major maintenance on a plane.
They could put multiple batteries in
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Old 10th July 2021, 06:42 PM   #1180
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Originally Posted by dirtywick View Post
They could put multiple batteries in
Did you have a thought you wanted to finish there?
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Old 10th July 2021, 06:52 PM   #1181
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Probably that those multiple batteries could be smaller? Like you said...

"100s of individual components that can come and go through small openings"

If people and fuel can do it maybe batteries can too. In fact, every passenger can carry a battery into the plane and plug it in themselves

ETA:
What if people are the batteries! Put 'em on treadmills maybe too!
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Old 10th July 2021, 07:26 PM   #1182
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Originally Posted by mgidm86 View Post
Probably that those multiple batteries could be smaller? Like you said...

"100s of individual components that can come and go through small openings"

If people and fuel can do it maybe batteries can too. In fact, every passenger can carry a battery into the plane and plug it in themselves

ETA:
What if people are the batteries! Put 'em on treadmills maybe too!
Pardon me while I imagine a Boeing board meeting in which a team of aeronautical engineers give a detailed technical analysis on the physics of Chicken Run.
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Old 10th July 2021, 08:50 PM   #1183
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And if you plug in your battery-people to a direct neural interface with an artificial intelligence, you can just make them think they've gone on their journey and returned, so you don't even need to fly them at all!
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Old 10th July 2021, 09:49 PM   #1184
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Originally Posted by RecoveringYuppy View Post
Did you have a thought you wanted to finish there?
No. I think my point was plainly made.
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Old 11th July 2021, 12:20 AM   #1185
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Originally Posted by Delvo View Post
Planes in the air always need to apply some forward thrust; they slow down by applying less of it. So the effect on your energy budget is not even a potential net gain but a decrease in your net rate of loss.
Originally Posted by RecoveringYuppy View Post
How do gliders avoid that requirement? I don't think there is such a requirement.
Passenger & cargo planes carry a lot more weight with a lot less wingspan & wing area per weight at much higher speeds against much stronger drag.

To replace them with something that did the same job with a different power source, you'd still need to carry the same load at the same speed. To start simply, let's skip speed for a moment and just look at load. A 787 carries 423 times as much weight as a DG-800, for a total weight 380.7 times as heavy when the weights of the vehicles are included, but it does that with only 32 times as much wing surface area to generate lift with. That's about a factor of 12 as much weight per wing surface area, so it needs another lift-generating factor in its favor to help it generate roughly 12 times as much lift as it could generate if it were a 787's size but trying to operate like a DG-800. That other factor, without somehow giving it 12 pairs of wings or making its wings 12 times as wide or such, is more forward speed. Conveniently, the plane's forward speed is one of the two requirements we started with in this paragraph's first sentence anyway. So, let's design this thing for more forward speed. Well, that means running engines.

How much speed difference? The world record for fastest that a specially built-for-speed glider has ever even briefly peaked at was 180 MPH. The DG-800 I used in that comparison above was one of the fastest, with a top speed of 170. But including the whole time from the beginning of a flight to the end so the ups & downs cancel out, any enclosed glider typically goes at about 50-60. A loaded 787, under most realistic atmospheric conditions, can't even get/stay off the ground at less than roughly 140-150, and typically cruises at over 560, possibly up to almost 600 in a pinch. That means fighting a wind of hundreds of miles per hour in its face the whole time. One of the most basic flight equations is that if you're maintaining speed & altitude then your thrust equals your drag, because if thrust were greater you'd be speeding up or rising and if drag were greater you'd be slowing down or sinking. So keeping a vehicle that size & weight going means maintaining thrust equivalent to the drag being caused by that amount of wind in its face. If the thrust were to go to zero (actually a negative number if you start trying to "regenerate"), all that drag would make speed and altitude get very dire very rapidly.

Less/no thrust, at any time during a plane's flight, means much much less speed or lift or both, which means simply not doing the job. Doing the job means maintaining thrust at all times. There's no way out of the basic physics. Gliders, as you put it, "avoid that requirement" by simply not having anywhere near such a demanding job to do: carrying a tiny fraction of the load at a small fraction of the speed.

Another way to look at it that's a bit word-gamey but a fair enough simplification: regenerative braking is a type of braking, passenger/cargo planes don't brake in flight or even have flight-brakes, so there's nothing to try to apply the word "regenerative" to.

Originally Posted by dirtywick View Post
Itís a big heavy box with a positive and negative terminal. Itís electricity. Unlike a giant vat of liquid you can put it wherever you want.
You have the difference between a fuel tank and a solid shape exactly backward. The fact that fuel is a liquid is exactly why you can make a tank in any shape and put it wherever there's some leftover space space for it that you can't put something else. That tends to end up being the insides of the wings & tail fins. (This is especially easy to see in a diagram comparing the A, B, & C models of F-35. What goes in the extra wing space that the one with the biggest wings has and the others don't have? Fuel. What goes where the lift fan would be in the ones with no lift fan? Fuel. What goes where the built-in gun would be in the ones with no built-in gun? Fuel. Fuel tanks are what you use to fill the spaces that aren't needed for something else.)

Fortunately for the battery-replacement concept, you're also wrong about the shape of batteries. They're really paired chemical tanks with some wires in & out of them, so, again, just like fuel, you could make the tanks just about whatever shape is convenient.

Unfortunately for the battery-replacement concept, you're also wrong about what their solidness means for replacing them. Being solid, even in the most ideal shape for the given application, makes replacement harder to design for and harder to do, not easier, than with a liquid.

Originally Posted by dirtywick View Post
Well I guess you could design a plane where the batteries are hard to get at as easily as you could a car. You could also design it to be really easy.
Yes, it would be easy. It would also mean the plane had no baggage space, because the place where replacing batteries would be easy is the bottom of the fuselage, which is where baggage goes in liquid-fuel planes. It would also add lots of weight to the plane, not only because batteries are just heavy anyway (which also makes battery cars heavier than liquid-fuel cars), but also because of structural reinforcements that would be needed to handle the attachment & detachment mechanisms and make sure that both parts are structurally sound enough both separate and together. And those reinforcements would also cut into the cabin space as well.

You could instead keep the baggage space and make the batteries the shape & size of current planes' fuel tanks and put them where the fuel tanks currently are, which is primarily in the wings... but that's the most horrible place you could come up with to be trying to attach & detach solid objects. They'd instantly become the weakest, least-stress-tolerate points in the whole plane's structure. Even lots of reinforcement all over the place would only eat into your battery space and add more weight while still not really fully solving the problem of how badly you'd just compromised the structural integrity of the wings. You could avoid this by making the batteries a more permanent fixture as part of the wings, but then once they'd been used what would you do? If only electricity were something that could easily flow in & out of any shape without needing to physically move the container anywhere, almost like a liquid...

Originally Posted by GlennB View Post
Batteries in a plane could power propellers, no problem, but for large-scale commercial flights would that be enough? If not, what would provide the motive force?
A passenger/cargo jet engine's thrust is about 30% from exhaust gas rushing out the nozzle and 70% from the main fan at the front of the engine, which is driven by a turbine (like a small portable windmill) that takes its power from the exhaust gas on its way to the nozzle. An electrical system could spin a ducted fan easily enough. I'm not sure what it would do about the other 30%. Spin the fan 43% harder?
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Old 11th July 2021, 03:31 AM   #1186
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Originally Posted by Delvo View Post
A passenger/cargo jet engine's thrust is about 30% from exhaust gas rushing out the nozzle and 70% from the main fan at the front of the engine, which is driven by a turbine (like a small portable windmill) that takes its power from the exhaust gas on its way to the nozzle. An electrical system could spin a ducted fan easily enough. I'm not sure what it would do about the other 30%. Spin the fan 43% harder?
Cheers, I didn't know that. Essentially the fan is doing the job of a prop?

If so it brings us back to my original question - could a battery-powered prop (ignoring for now the weight/storage issues of batteries) power a commercial passenger plane, where speed is essential?
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Old 11th July 2021, 06:04 AM   #1187
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Tesla FSD ver 9 beta is out.

First test I’ve seen:

https://youtu.be/KeMM1oyboMc


Pretty impressive.
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Old 11th July 2021, 08:25 AM   #1188
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Originally Posted by GlennB View Post
Right, but the hydrogen is being burned and the exhaust gases move the plane. In the case of batteries, what is moving the plane?
I guess the question is, would the hydrogen actually be burned (in the way jet fuel is currently burned)?



I believe hydrogen cars simply use the H2 to power electric-generating fuel cells (so in effect, a hydrogen vehicle is just an electrical car without the big-ass battery.) In theory, you could build a plane along the same principle... hydrogen powering a fuel cell to generate the electricity that powers either propellers, or some sort of electric-based jet engine (if such a thing ever becomes feasible).
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Old 11th July 2021, 08:31 AM   #1189
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Originally Posted by Delvo View Post
Another way to look at it that's a bit word-gamey but a fair enough simplification: regenerative braking is a type of braking, passenger/cargo planes don't brake in flight or even have flight-brakes, so there's nothing to try to apply the word "regenerative" to.
Thanks for the informative post. One clarification about your simplification here though please: During descent, are the flaps on a commercial jet not generating excess drag? Excess meaning drag that isn't introduced solely as a trade of keep the lift during slow speed flight.

Would it be accurate to say that the only place regenerative braking might apply is when the spoilers deploy?
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Old 11th July 2021, 08:37 AM   #1190
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Originally Posted by Segnosaur View Post
I guess the question is, would the hydrogen actually be burned (in the way jet fuel is currently burned)?
Theoretically it could go either way. The hydrogen powered zero emission (Airbus ZEROe) concept plane I saw mentioned earlier in this thread is actually a hybrid. I don't have details on the exact nature of where the fuel cells enter in but their blurbs do say the engines themselves will be hybrid. Since the plane is only tentatively planned for 2035 at the moment I don't even know if reliable details actually exist.

ETA: https://www.airbus.com/innovation/ze...gen/zeroe.html

Not much of substance at that link, here's the meat:

Quote:
.... resulting in a highly efficient hybrid-electric propulsion system.

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Old 12th July 2021, 04:13 PM   #1191
P.J. Denyer
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Originally Posted by Wowbagger View Post
Almost. There are a few options I am mulling over. I will announce my final decision upon its delivery.



That's my other vehicle, though.

I should get a bumper sticker for my Tesla that says "My Other Car is a Spaceship".
Surely it should say "My other Car is a Spaceship and you're a Jerk, a complete Kneebiter"

You know, two birds/one stone.
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Old 14th July 2021, 05:39 PM   #1192
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Originally Posted by acbytesla View Post
Really? My buddy's Tesla has a range of 400 miles. That's plenty
And no, the range is unlikely to stay low. Every issue you just mentioned are being addressed. Cobalt is being phased out for example. And methods are being created to effectively recycle and reuse the elements. Batteries are also getting lighter. Aviation is going to be harder to replace "electrically" but that doesn't mean mined petroleum fuels won't be able to be replaced through carbon capture created fuels.

But even if we can't replace aviation fuels in 30 years, we should able to replace petroleum and fossil fuels in passenger vehicles, trucking and industrial heat applications such as making concrete. If we can do that, we will have done a lot.

I'm convinced that it's important to get the ball rolling. Once we do, it's going to be a lot easier.
I think it should be said that a 400 mile range for an electric vehicle is not quite the same as a 400 mile range for an internal combustion vehicle. This is due to the difference in time to refill or recharge. For the gas or diesel vehicle, this is a few minutes, and by the time you have driven that far, you probably need to pee, grab a bite to eat or just take a break from driving anyway. But with an electric vehicle, you're probably done for the day. I'm very conflicted abut electric vehicles. I recognize the necessity, due to global warming, of replacing ICE powered vehicles with electric, and, when push comes to shove, I could live with 400 miles per day. OTOH, if the weather requires heating or cooling the interior, that range is probably more like 300 or 350 miles. Cooling of course, reduces the range of an ICE vehicle too, but heat is free (an actual benefit of the inefficiency of the ICE).

Electric vehicles are quickly becoming viable, and are the only realistic alternative to doing away with cars entirely(assuming that the electricity is generated by low or zero carbon means). But damn it, from the standpoint of personal practicality, they are inferior in pretty much every way to gas or diesel vehicles. I suspect that my current gas powered pickup truck. is the last ICE powered vehicle I will own. But damn it I'm going to hang on to it until I die, it dies, or I can no longer buy fuel for it at an affordable price.
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Old 14th July 2021, 09:27 PM   #1193
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Originally Posted by CORed View Post
Electric vehicles are quickly becoming viable, and are the only realistic alternative to doing away with cars entirely(assuming that the electricity is generated by low or zero carbon means). But damn it, from the standpoint of personal practicality, they are inferior in pretty much every way to gas or diesel vehicles. I suspect that my current gas powered pickup truck. is the last ICE powered vehicle I will own. But damn it I'm going to hang on to it until I die, it dies, or I can no longer buy fuel for it at an affordable price.
It depends on the person. I personally rarely travel to anywhere that takes more than 3 hours, don't need to go offroad, have no reason to haul heavy loads, and have a place to garage a vehicle. I'm low-hanging fruit as far as an electric vehicle is concerned, and my next car will certainly be electric. Won't be able to afford one for a while yet, though.
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Old 14th July 2021, 10:03 PM   #1194
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Originally Posted by CORed View Post
I think it should be said that a 400 mile range for an electric vehicle is not quite the same as a 400 mile range for an internal combustion vehicle. This is due to the difference in time to refill or recharge. For the gas or diesel vehicle, this is a few minutes, and by the time you have driven that far, you probably need to pee, grab a bite to eat or just take a break from driving anyway. But with an electric vehicle, you're probably done for the day. I'm very conflicted abut electric vehicles. I recognize the necessity, due to global warming, of replacing ICE powered vehicles with electric, and, when push comes to shove, I could live with 400 miles per day. OTOH, if the weather requires heating or cooling the interior, that range is probably more like 300 or 350 miles. Cooling of course, reduces the range of an ICE vehicle too, but heat is free (an actual benefit of the inefficiency of the ICE).

Electric vehicles are quickly becoming viable, and are the only realistic alternative to doing away with cars entirely(assuming that the electricity is generated by low or zero carbon means). But damn it, from the standpoint of personal practicality, they are inferior in pretty much every way to gas or diesel vehicles. I suspect that my current gas powered pickup truck. is the last ICE powered vehicle I will own. But damn it I'm going to hang on to it until I die, it dies, or I can no longer buy fuel for it at an affordable price.
Electric Cars are becoming more viable! I purchased a Tesla Model Y Last December, and I documented on this thread the trip my wife and I took from Seattle to Yellowstone. The Tesla Supercharge network makes long trips *very* viable.

But at the moment it's really only Teslas that have that advantage, and I hope a more universal fast charging network is expanded quickly.
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Old 14th July 2021, 10:43 PM   #1195
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Originally Posted by GlennB View Post
Essentially the fan is doing the job of a prop?
Pretty much... in fact, most propeller engines these days are essentially jets with a propeller instead of a fan at the front: no cylinders, no pistons, just a single tube with air getting sucked in the front, compressed, mixed with fuel, ignited, and blown out the back through a turbine which draws power from it to drive a propeller instead of a fan. Similarly, helicopters' rotors are also now usually turbine-powered. It's all one engine type, with different spinny things attached for moving air. Because they're all based on the turbine, the names of the three categories are cleverly called "turbofan", "turboprop", and "turborotor". For both propellers and helicopter rotors, the bigger the vehicle is and the more engine power is needed, the more likely it is to be turbine-driven; smaller lighter weaker slower models can still have car-like engines. With propellers, the difference is pretty visible: an air intake in the shape of a ring around the base of the propeller means pistons, and one or two small air intakes off-center from the propeller means turboprop.

Another type is the turbojet, not to be mixed up with turbofans even though most "jet" engines are turbofans, not turbojets. A turbojet has no fan, propeller, or rotor connected to be driven by it; the turbine powers only the compressor. Those are only useful for higher speeds than turbofans usually work at, but they're uncommon even in planes that are faster than most; Concorde used turbojets, but its Russian counterpart and all fighters use skinny turbofans. (Their fans are smaller than passenger/cargo plane engine fans, but they're still there.) Some missiles use a turbojet instead of a rocket.

At an even higher speed range, the air becomes self-compressing, so you don't need the compressor and thus you don't need the turbine to drive it; this would be a ramjet. Some have been built, but their use is limited by their lack of ability to get themselves started from zero, which makes them dependent on being dropped from another aircraft. Compression by the ram effect is still important because combustion needs to happen in air that's moving through the engine at subsonic speed. An engine that can get combustion to happen in supersonic air instead of needing to slow it down first is a scramjet (Supersonic Combustion ramjet), but those have only been built for testing so far, not put in a plane that anybody was actually going to use.

Originally Posted by GlennB View Post
could a battery-powered prop (ignoring for now the weight/storage issues of batteries) power a commercial passenger plane, where speed is essential?
Not for planes of the size, speed, & range that we currently use jets for. A big part of the reason why we switch from propellers to fans in bigger & faster planes is about the stress on the blades, not the power source. Long & skinny is just not as able to withstand the forces as short & wide. To replace turbofan engines with electrical engines, they would need to be electrically-powered ducted fans... electrofans. What an electroprop could replace is a turboprop, which is still a pretty common engine type for smaller planes that take shorter flights at lower speeds, because we've already found that propeller blades do OK in that setting.

Originally Posted by RecoveringYuppy View Post
One clarification about your simplification here though please: During descent, are the flaps on a commercial jet not generating excess drag? Excess meaning drag that isn't introduced solely as a trade of keep the lift during slow speed flight.
Not that I know of.

Originally Posted by RecoveringYuppy View Post
Would it be accurate to say that the only place regenerative braking might apply is when the spoilers deploy?
Brakes in the wheels could be regenerative any time they're being used. In theory, spoilers could also draw some regenerative power, but I currently can't picture how to design a mechanism that would do it without losing some of its effectiveness at its primary job of slowing down the plane once it's on the ground. Another part of the slow-down-we're-on-the-ground process that feels like a potential lost opportunity is the thrust reversers, but again, I can't picture how to design a regenerative element there that doesn't diminish their use for reversing thrust. And in any of these three cases, we'd be talking about adding equipment, which adds weight, which is dead weight for the entire flight, which actually makes the engines or batteries use more power throughout the whole flight, all so we can put it to use for about a minute.
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Old 15th July 2021, 01:13 AM   #1196
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Originally Posted by CORed View Post
I think it should be said that a 400 mile range for an electric vehicle is not quite the same as a 400 mile range for an internal combustion vehicle. This is due to the difference in time to refill or recharge. For the gas or diesel vehicle, this is a few minutes, and by the time you have driven that far, you probably need to pee, grab a bite to eat or just take a break from driving anyway. But with an electric vehicle, you're probably done for the day. I'm very conflicted abut electric vehicles. I recognize the necessity, due to global warming, of replacing ICE powered vehicles with electric, and, when push comes to shove, I could live with 400 miles per day. OTOH, if the weather requires heating or cooling the interior, that range is probably more like 300 or 350 miles. Cooling of course, reduces the range of an ICE vehicle too, but heat is free (an actual benefit of the inefficiency of the ICE).

Electric vehicles are quickly becoming viable, and are the only realistic alternative to doing away with cars entirely(assuming that the electricity is generated by low or zero carbon means). But damn it, from the standpoint of personal practicality, they are inferior in pretty much every way to gas or diesel vehicles. I suspect that my current gas powered pickup truck. is the last ICE powered vehicle I will own. But damn it I'm going to hang on to it until I die, it dies, or I can no longer buy fuel for it at an affordable price.
I think it all comes back to what I've been saying earlier in this thread about usage and infrastructure.

I've been driving a TM3 LR for the best part of two and a half years now and it is absolutely perfect for my needs. I rarely drive more than 300km in a day and I can trickle charge overnight in my garage or on my drive. Long trips only require the same amount of planning in respect of recharge and comfort stops as they always did. I used to own a diesel Audi A6 which was a glorious motorway barge that could do the best part of 900km on a single tank, but even then I'd stop for 20 minutes every two and a half hours or so because of joints and bladder and caffeine addiction. Two summers ago I drove the TM3 alone from Slovenia to eastern France in a single day with no issues at all: this was 1000km across five countries in several chunks with no range anxiety or anything, just a big feeling of unease on the Autobahn in Bavaria where even driving at 150kph you feel you're in reverse.

In terms of infrastructure, it's improving all the time. This Monday we went to visit a grotto with a fierce underground river flowing through it in the middle of nowhere and I was surprised to see that since my last visit they'd installed 22kW charging points in the car park. I like to look at the numbers for the growth of the petrol station network in the US every decade from 1890 to 1940: slow start but then a massive snowball effect.

I should have mentioned context as well. Not only are EVs viable but traffic patterns are being modified around them. The two cities I visit the most frequently now have exclusion zones reaching a fair way out of the city centres whereby at certain times only EVs will be allowed in. At the beginning this was on days of pollution peaks, now it's being extended to times of extreme heat, and there are proposals around to make this increasingly frequent.

TL;DR: it's true that EVs don't yet meet the daily usage requirements and budgets of everybody, nor is the support infrastructure there yet. But in my case, and that's the only one I'm qualified to talk about, there has not been a single occasion in the last 30 months and 35K km where I've thought that I'd have been better off with one of my old ICE cars.
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Old 15th July 2021, 02:26 AM   #1197
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Mrs Don and I recently went on the longest trip we have had for a couple of years. Since my father's death I don't have to regularly do a 600 mile round trip and Covid has meant that last year I cycled further than I drove.

We drove from Don Towers to Coniston in the Lake district on Day 1 which we could easily have done on a single charge in a modern long-range EV. We would have been able to charge in Coniston (we drove less than 20 miles while there) and again in Keswick before setting off for Kirkby Stephen (where we could have charged again) and Barnard Castle (to have our eyesight tested). We had a day out on the North Sea coast which involved about 70 miles of driving.

The only time when we might have had to stop driving to recharge was on the journey home. It's around 275 miles so we would likely have stopped for a 20 minute "splash and dash" at one of the fast chargers close to the motorway. We stopped for a comfort break in any case so we wouldn't have lost any time.
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Old 15th July 2021, 05:20 AM   #1198
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Electric cars seem to be the ultimate goal, but electric bicycles are also a very interesting case, especially for city dwellers.

The added electric motor really takes a lot of the negatives out of bicycling. The added motor power makes it easier to travel longer distances, higher speeds, and through hilly areas without requiring the rider to be physically fit, and you don't arrive at your destination covered in sweat.

At least in the warmer months, it's a pretty great way to cover distances in between subway stops and is faster in many cases than riding the bus.

There's already existing infrastructure for the storage of bicycles everywhere and ebikes are still light and small enough to be taken on public transit or carried into buildings.

Obviously they still suffer from the lack of weather protection, making them not a year round solution except for the die-hards willing to ride in the Boston winters.
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Old 15th July 2021, 09:05 PM   #1199
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I'd love an eScooter, but I don't really travel anywhere within eScooter range, maybe the football, but I am not in a fit state to drive any sort of motor vehicle on the way back.
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Old 15th July 2021, 09:12 PM   #1200
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I agree with CORed that an EV isn't an option at the moment given the journey described, though that sounds hellish and I hope that isn't typical, let alone routine.
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