Why battery-powered aircraft will never have significant range

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BJC

Well-Known Member
HBA Supporter
Add a servo to position the anti-servo tab.

BJC

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Speedboat100

Banned
Add a servo to position the anti-servo tab.

BJC
I like cri cri set up in elevator just wanna know if there is a easy way out.

Speedboat100

Banned
5 plus and 3 minus ?

John.Roo

Well-Known Member
5 plus and 3 minus ?
Hello!
If you planning to stay in UL (MTOM between 450-600 kg depending on EU country) than you should calculate with G forces range from -2G to +4G. That is with safety factor 1 so for airframe design you have to multiplied by min. 1,5. For new construction I would not go below safety factor 1,875 and for main parts (wing, tail surfaces etc.) better use safety factor 2-2,25.
However, if your design looks more like a glider (with with high aspect ratio) then better use range for gliders = G forces from -2,65G to +5,3G. And than again you have to use safety factor.
Finally you will find out that you have to calculate with ultimate loads a least from -5G to +10G.
Take a look here:
https://www.easa.europa.eu/sites/default/files/dfu/CS-22_Amendment 1 revised.pdf
(from page 1-C-1)
Best regards!
Martin

BJC

emotodude

Active Member
It's hasn't flown and kits are being sold. Not my idea of responsible development and testing. I am old enough to remember too many cases of this sort of thing.
Regardless, the man has built several world record setting vehicles. You are switching topics here. My point was 300+ mile battery electric aircraft is totally possible. Not wheather we approve of someones business strategy...

Speedboat100

Banned
Hello!
If you planning to stay in UL (MTOM between 450-600 kg depending on EU country) than you should calculate with G forces range from -2G to +4G. That is with safety factor 1 so for airframe design you have to multiplied by min. 1,5. For new construction I would not go below safety factor 1,875 and for main parts (wing, tail surfaces etc.) better use safety factor 2-2,25.
However, if your design looks more like a glider (with with high aspect ratio) then better use range for gliders = G forces from -2,65G to +5,3G. And than again you have to use safety factor.
Finally you will find out that you have to calculate with ultimate loads a least from -5G to +10G.
Take a look here:
https://www.easa.europa.eu/sites/default/files/dfu/CS-22_Amendment 1 revised.pdf
(from page 1-C-1)
Best regards!
Martin
Good morning Martin !

Doesn't that requirement make the lite structure....less light?

And thanks for the information.

My design will be under 300 kg gross weight in all circumstances.

Does that make a difference ?

---

EDIT: I can make it easily into +10 G and -5 G.

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John.Roo

Well-Known Member
Good morning Martin !

Doesn't that requirement make the lite structure....less light?

And thanks for the information.

My design will be under 300 kg gross weight in all circumstances.

Does that make a difference ?

---

EDIT: I can make it easily into +10 G and -5 G.
Even if your MTOM is under 300 kg it doesn´t change nothing on G forces.
But still please check your local UL requirements - for example required range of pilot weight (typically between 65-110 kg). And try to be realistic (or a bit pesimistic) with weights. Finally is weight of prototype airframe nearly always a bit higher than expected

Speedboat100

Banned
Even if your MTOM is under 300 kg it doesn´t change nothing on G forces.
But still please check your local UL requirements - for example required range of pilot weight (typically between 65-110 kg). And try to be realistic (or a bit pesimistic) with weights. Finally is weight of prototype airframe nearly always a bit higher than expected

I agree, but I am trying to really make a small and especially light aeroplane.....and as we know even metal bird Cri Cri weighed originally just 68 kg.

There are few design aspects that allow this to have pretty steep G-loads...albeit Cessna 172 is just + 4,4 and - 1,76 G...as it is utility AC.

I just had a session with my structural engineer..to be on the safe side.

His biggest concern is that 1 seater AC has very little customers in general.

kubark42

Well-Known Member
The discussion of battery-powered aircraft has a blind spot when it considers only rechargeable batteries. I would humbly suggest that the real solution is a combination of rechargeable batteries with prime batteries. Most people's GA flying habits are not to head off into the sunset for a 500nm cruise. Painting with a broad brush, and with nothing but anecdotal experiences as way of proof, I feel that for most GA we want to fly 20-30 minutes to a nearby airport. This can be accomplished with standard airplanes with standard rechargeable battery packs.

However, we still want the ability to fly off a long distance if the occasion arises. This is where prime packs come to play. Their energy and power density is far, far higher. At the cutting edge, you have aluminum batteries, where
4Al + 3O2 + 6H2O → 4Al(OH)3. This releases 20-30x more energy than even a cutting edge Lithium rechargeable pack.

I'm not saying this will come to fruition anytime soon, it's just a counterpoint to an argument that battery-powered can never happen because rechargeable batteries are too heavy and therefore there's no route forward.

Vigilant1

Well-Known Member
The discussion of battery-powered aircraft has a blind spot when it considers only rechargeable batteries. I would humbly suggest that the real solution is a combination of rechargeable batteries with prime batteries. Most people's GA flying habits are not to head off into the sunset for a 500nm cruise. Painting with a broad brush, and with nothing but anecdotal experiences as way of proof, I feel that for most GA we want to fly 20-30 minutes to a nearby airport. This can be accomplished with standard airplanes with standard rechargeable battery packs.

However, we still want the ability to fly off a long distance if the occasion arises. This is where prime packs come to play. Their energy and power density is far, far higher. At the cutting edge, you have aluminum batteries, where
4Al + 3O2 + 6H2O → 4Al(OH)3. This releases 20-30x more energy than even a cutting edge Lithium rechargeable pack.
Cost per watt/hour for these one-time-use batteries? The "green" case will also be hard to make, even with recycling.
I suspect we'll see practical fuel cells before we see use of prime batteries and a network of places to swap them out.

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kubark42

Well-Known Member
Cost per watt/hour for these one-time-use batteries? The "green" case will also be hard to make, even with recycling. I suspect we'll see practical fuel cells before we see use of prime batteries and a network of places to swap them out.
Agreed that fuel cells are much closer to practical usage.

And I have no idea what the practical cost per W/hr of recycling an aluminum prime battery. It's basically undoing the conversion of bauxite to Al, so the Bayer process can be straightforwardly reapplied. But the practicalities of this are many years, if not decades in the future.

However, if we're comparing overall sustainability to H2, then my hunch is it's going to greatly favor recycling aluminum. The well-to-wheels efficiency of H2 is one of the worst in the transportation industry, and AFAIK there's nothing on the horizon which will fundamentally change how efficiently we can generate, ship, and store H2 in mass scale.

Vigilant1

Well-Known Member
Agreed that fuel cells are much closer to practical usage.

And I have no idea what the practical cost per W/hr of recycling an aluminum prime battery. It's basically undoing the conversion of bauxite to Al, so the Bayer process can be straightforwardly reapplied. But the practicalities of this are many years, if not decades in the future.

However, if we're comparing overall sustainability to H2, then my hunch is it's going to greatly favor recycling aluminum. The well-to-wheels efficiency of H2 is one of the worst in the transportation industry, and AFAIK there's nothing on the horizon which will fundamentally change how efficiently we can generate, ship, and store H2 in mass scale.
I agree that H2 is entirely impractical, and for that reason it is a bit of a strawman. Methanol fuel cells will probably be practical first (but are still many years off).
Unless energy gets very cheap and clean, recovering AL from something akin to bauxite will remain pricey and have a big emissions pricetag, too.

emotodude

Active Member
Agreed that fuel cells are much closer to practical usage.

And I have no idea what the practical cost per W/hr of recycling an aluminum prime battery. It's basically undoing the conversion of bauxite to Al, so the Bayer process can be straightforwardly reapplied. But the practicalities of this are many years, if not decades in the future.

However, if we're comparing overall sustainability to H2, then my hunch is it's going to greatly favor recycling aluminum. The well-to-wheels efficiency of H2 is one of the worst in the transportation industry, and AFAIK there's nothing on the horizon which will fundamentally change how efficiently we can generate, ship, and store H2 in mass scale.
On-site H2 generation from electrolysis and grid connected renewables. Agreed not the most efficient overall process, but has a nice side of effect of load leveling the grid. Making H2 when demand and cost is low greatly improves the situation. As energy costs approach zero, who cares how efficient the process is?

Dan Thomas

Well-Known Member
As energy costs approach zero, who cares how efficient the process is?
Oh. Since when are energy costs approaching zero? Wind and solar are no cheaper than any other source and in most cases they're a lot more. The taxpayer is footing massive subsidies for these things, making them look cheap, but you can only pull that off for so long before they get wise to it.

Vigilant1

Well-Known Member
And once you've got this "renewably-produced" hydrogen (Ha! Look at the >lifecycle< environmental impact of wind and solar), we'll need to compress, transport and store it. Not easy. And you'd best start with clean water--something that isn't in universally abundant supply--good for drinking, producing food, etc.
Most hydrogen produced today is made using natural gas as a base stock--that's a LOT less expensive than electrolysis, and environmentally more sound (considering that electricity--from any source--would be best used to displace electricity produced by dirtier/more expensive sources.)
For fuel cells, expect that the first practical ones in widespread use will use fuels that are liquid at/near typical ambient temperatures--just like our present hydrocarbon transportation fuels. It's an incredibly compact and convenient way to transport energy.

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BBerson

Light Plane Philosopher
HBA Supporter
The quickest path to carbon neutral is to produce hydrogen with the lowest carbon and scalable energy source, which is nuclear. Then extract carbon dioxide from air and use it to make a stable hydrocarbon like propane.
Large experimental carbon dioxide extractors from air are being built currently.

emotodude

Active Member
Oh. Since when are energy costs approaching zero? Wind and solar are no cheaper than any other source and in most cases they're a lot more. The taxpayer is footing massive subsidies for these things, making them look cheap, but you can only pull that off for so long before they get wise to it.