Why battery-powered aircraft will never have significant range

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dog

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Dec 29, 2019
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578
I think of the 400 hydrogen refueling stations all but 4 are in California?
Says there are only 40 some in california.
Different sources cite upto 500 worldwide in
2020.



 

blane.c

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capital district NY
Says there are only 40 some in california.
Different sources cite upto 500 worldwide in
2020.



Yes 40 got dyslexia I guess or something. I'll edit.
 

John.Roo

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Letohrad / Czech Republic
Show us the flying protoypes. There's a lot of talk about this stuff happening tomorrow, but don't you think there would be some flying prototypes first? Pretty hard to keep this sort of thing a secret. There is money in news stories, and some journalists are good at smelling out this sort of thing and getting actual pictures of it in flight, not the CGI stuff we see on the websites.
True.... I am personaly really sad because this "investors baits" are damaging image of electric aviation.
When Airbus reported what their eVTOL is able to fly +-5 minutes with approx. 500 kg battery (don´t remember exact numbers, but is very close) everybody was disapointed. But Airbus just shown true - actually available batteries are not able to power eVTOL like for example Lilium with parameters they report.
Unfortunatelly are investors obviously making decissions without any technical research. They spend money in rendered images and videos from short unmanned flights.
I wrote many times but again... aviation is conservative. We need approved technologies. If new super high energy density battery will be available it will take years to test it use it in certified airplanes. Even "old and known" Li-Ion cells needs to be installed and used carefully.
Way for homebuilders is not to wait - way is to use what is available and affordable.
Actualy is not a main problem the weight - problem is price.
Info from Internet....
"Tesla used to sell new units for $20,000 to $23,000, but Gruber said prices were adjusted and that you can now buy a 90 kWh battery pack for $14,000."
If I actually oder battery pack for airplane with half capacity (45 kWh) I will actually pay over 50 000 EUR. Using "TESLA prices" would be possible get 25-30 kWh battery for 4 000 - 4 600 USD.
 

dog

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Dec 29, 2019
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578
Yes 40 got dyslexia I guess or something. I'll edit.
The second article about the 1500 hydogen
filling stations that also have EV charging powered by fuel cells bieng installed,signals that we are aproaching a tipping point where
hydrogen goes from something mentioned speculativly to something seen and then normalized.
AND then we can actualy get some and put it in
our planes.
The idea of hydrogen as a fuel providing better
range than anything else is going to be what drives its implimentation in aviation.
The need for a cryogenic fuel storage is of course a big hurdle,though it is bieng done.
One other interesting bit I learned about the hydrogen filling syations,is that a large number are not open to the public!,welding/industrial gas?,any idea?
 

rv7charlie

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Pocahontas MS
Let's move this to a discussion of serious matters.
The weird carriage returns in Dog's posts are almost certainly an interaction between his posting platform (phone, tablet, computer, etc), settings buried in the browser or other software he's running (which likely he never touched), and the forum software. I've seen it happen to others on other forums; I've even seen it happen to my own posts.

And ethanol isn't that bad an idea or a political thing (but making it from corn is both, if I can believe what I read on the internet).

edit: obligatory & explanational ;-)
 

Dusan

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Canada
Show us the flying protoypes. There's a lot of talk about this stuff happening tomorrow, but don't you think there would be some flying prototypes first? Pretty hard to keep this sort of thing a secret. There is money in news stories, and some journalists are good at smelling out this sort of thing and getting actual pictures of it in flight, not the CGI stuff we see on the websites.
To develop effective VTOL aircraft is hard, as the performance for cruise is driven by L/D, that means large wetted aspect ratio - slender wings, low drag; and effective propulsion at cruise speeds. For hovering performance, the aircraft needs low disk loading, otherwise the power demand is very high. However, low disk loading means large rotors, and large rotors are inefficient for high speed operations. Several VTOL aircraft configurations are coping with this conundrum, Edgevise flying rotors - typical helicopters and multi-copters - low L/D, retreating blade stall; lift + cruise systems, stopped, stowed, folding rotors - adding drag and ‘dead weight’; Tilt wings and tilt-rotors - they are a compromise, the prop-rotor is too small for hover, but too large for cruise. Adding to this is the fact that wings are at best ‘dead weight’ in hover, but practically is the source of unwanted flow interactions - e.g. impingement, fountain flow.

Actually, only 2 designs have evolved to 'life' to be real aircraft in more than 60 years of VTOL history, and those are military aircraft. I'm of course talking about the V22- osprey - tilt-rotor, and the jet harrier/F-35, the military specification aspect to perform the mission are the reason of their success, the economic cost is secondary. The civilian marked is driven by economics, and as long that the aircraft design compromises too much, it will never be a viable option. Some people believe that the electric propulsion solves the problem, because of the high inherent efficiency, distributed propulsion and other effects, but a hidden aspect that kills the efficiency is the aerodynamics of VTOL. If the aerodynamics is not right, you end up with an inefficient aircraft, that only exacerbates the unwanted characteristics of electric propulsion. For now there isn't a solution to this.

As for "Show us the flying protoypes" I'm working on a concept - a wing to develop lift in hover and augment the rotor lift. The rotor can be smaller so it's much better performing at cruise speeds. Here is a short video showing several concepts and flying models:
 

Dan Thomas

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True.... I am personaly really sad because this "investors baits" are damaging image of electric.....
This stuff fools people like a couple of the posters here, just like Moller's endless promises fooled some of us 40 and 50 years ago. The old guys then said "Yeah, sure" when they heard us talking about flying cars. Crusty old curmudgeons stuck in the steam age, we thought.


But they were right. They had lived long enough to instantly spot malarkey that defied physics.
 

EzyBuildWing

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Join us for the biggest adventure in History...... grand unveiling commences in approx 100 minutes.....
You can be there at the gig......
Now at 99 minutes and counting.......
Here's the Link:


"Join us for the biggest adventure in History"........ tomorrow(today?) 6PM PST....... so the comms say.
Seems Archer Aviation is going to publicly-unveil something that's really going to set the world on fire......
Let's hope so.
....so be there to enjoy the ride.....

https://www.eventcreate.com/e/maker-unveil-event-livestream
 

dog

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Dec 29, 2019
Messages
578
Let's move this to a discussion of serious matters.
The weird carriage returns in Dog's posts are almost certainly an interaction between his posting platform (phone, tablet, computer, etc), settings buried in the browser or other software he's running (which likely he never touched), and the forum software. I've seen it happen to others on other forums; I've even seen it happen to my own posts.

And ethanol isn't that bad an idea or a political thing (but making it from corn is both, if I can believe what I read on the internet).

edit: obligatory & explanational ;-)
I will try and fix that.
Cheap phone,running a browser that deleets
all ads,except the ones that are hand coded into pages old school.Browser is very customisable.
HBA renders fine for me,so will try tweeking.
And as far as ethanol for fuel goes,isnt the relationship between a fuels energy per volume
unit just a bluff? As most carbon based fuels have a similar energy density per pound.
Hense the use of rubber and powdered aluminum as solid rocket fuel,heaviest per volume.
Or is alcohol less energy dense per pound.
Id ask my buddys but they might take it the wrong way and think I was dissing there shine,
and Id have to then tuck in and personaly demonstrate energy density.
 

Aesquire

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Jul 28, 2014
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Rochester, NY, USA
,
Or is alcohol less energy dense per pound.
Yep. That's the inescapable need for a bigger tank for the same power/range. Alcohol has some lovely properties. It's resistant to detonation, so you can turn up the pressure, either with higher compression, more boost, or valve manipulation. Or all of the above.

Modern Automobile Flex fuel engines typically use valve timing and fuel injection adjustment, both timing and amount, to enable using a range of booze in petrol from 0-80+%. Hot rodders sometimes just use higher compression, which limits their use of lower Octane equivalent fuel. If you built it with 14 to 1, booze runs fine but gasoline breaks things. More common in hot rods is raising the compression to barely safe on pump gas, and running lots of boost, for both racing power, and limp home cruising. ( this takes self control. It's easy to build an engine that you can wreck if you get stupid )

In any case, adding booze to gasoline, or running straight booze, you burn more for the same power. Easy to demonstrate by measuring mpg with different fuels in a Flex fuel car or minivan.

Anecdotal, but real, locally the cost at the pump ( last I did this, about 6 years ago ) for E-85 was a lot cheaper than 87 octane rating gasoline. There's a tax paid discount involved as incentive. The minivans at work were Flexfuel. The Company told us to buy E-85 when we refuel. Then they threatened to fire you for filling up with Regular gasoline. Management motivation is political and irrelevant. The Worker motivation was practical, less wasted time filling the tank. The fact that ( depending on price/local subsidy/politics/taxes ) E-85 was not actually saving money, because of higher consumption, was also irrelevant, to the workers. They had a company gas credit card. Management motivation obviously prioritized other factors than economy. ( A Lot )

My results with my personal minivan varied by the factors mentioned in parentheses above. Sometimes I saved money but spent more time at the pump, other times it was more expensive, plus more time at pump.

And it lost power with booze.

I'm sure other engines with variable turbochargers would shift the numbers and be better performers with E-85.

One warning! On top of the multiple problems with alcohol fuel, E-85 isn't consistent in content. It legally can vary from 15-85%. In reality it's worse. So building an engine that counts on high compression and/or boost means you need to test your fuel every fill up. Or compromise so you don't wreck the engine If the fuel is really 86 subregular.
 

Rhino

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Seems Archer Aviation is going to publicly-unveil something that's really going to set the world on fire......
Must be a slow burn. Nothing in the news about the world on fire. I did see an article on the intro of the Tesla Plaid S though. The reporters seemed intent on pointing out that it was overdue and over budget, but that could be said about so many products these days. 390 mile range and can recharge for another 187 miles in just 15 minutes. I like the recharge time, but they didn't mention at what speed that range is obtained. It also noted a longer range version is coming, but it'll be slower. I don't think that's necessarily a bad thing when you consider realizing all the "quickness" of the Plaid S would usually involve breaking the law and endangering lives. Slower is far more practical, as long as it isn't too slow.
 
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