Why battery-powered aircraft will never have significant range

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Dan Thomas

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This comes up all the time. So if gasoline has about 33.6 kWh/gal, this is about 12.4 kWh/kg. A typically AC ICE engine uses only about 12% of that.
You're off some. The worst aircraft engine turns about 25% of the fuel's energy into useful power, or more than twice what you say. It's still pretty sick. Another 25% is lost through cooling, and 50% goes out the exhaust, some of which is often saved by turbocharging. A EFI/EI ICE would get a lot better than 25% just through more efficient ignition and modulating of the mixture to the best efficiency at all times.
 

Dan Thomas

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Thanks for the fix. Yeah, 1020 rpm for 740 FPS.
The tip speed is also affected by the forward speed. A² + B² = C². At 250 MPH, 367 FPS, the tip speed ends up at 826 FPS, or .755 Mach, pretty close to the .8 Mach typical limit. If the C-130 goes 300 MPH it's 861 FPS, .797 Mach.
 

tspear

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You're off some. The worst aircraft engine turns about 25% of the fuel's energy into useful power, or more than twice what you say. It's still pretty sick. Another 25% is lost through cooling, and 50% goes out the exhaust, some of which is often saved by turbocharging. A EFI/EI ICE would get a lot better than 25% just through more efficient ignition and modulating of the mixture to the best efficiency at all times.
It depends. The most common comparisons are given in cruise when the ICE is at its most efficient.
However, the super majority of flights are less than an hour. When you consider taxi, climb, and descent the block numbers for ICE are much worse.
Note: I am specifically focused on the short flight here, due to the fact that battery powered planes can only do the short flight :)

Tim
 

PiperCruisin

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You're off some. The worst aircraft engine turns about 25% of the fuel's energy into useful power.
You're right. My bad. Was looking at what the typical Lycoming burn rate it for power compared to how much is "available" in the gas. Not as bad. I guess the point I was making is that the stack of soda pop should have been about 1/4 that size.
 

EzyBuildWing

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WORLD ENDURANCE RECORD ATTEMPT FOR ELECTRIC AIRCRAFT TO DEPART AUSTRALIA'S ADELAIDE-PARAFIELD AIRPORT TOMORROW

Adelaide-based Eyre to There Aviation in partnership with platinum sponsor AvPlan EFB will aim to break a world endurance record for an electric aircraft with a 7-day, 18-stop flight around South Australia, starting tomorrow.

The record attempt, flying a Pipistrel Alpha Electro plane, will start at Parafield Airport at 7.00am on Saturday June 19 with the first leg to Balaklava and the first overnight stop in Whyalla. The total distance will be 1,150km, which will shatter the previous record of 750km flown in September 2020 in Germany.

"Electric aircraft don’t yet have the range of other aircraft, but they’re perfect for short flights such as flight training and particularly circuit training, which is a core activity in obtaining a private pilot licence.

“There are more than 250 registered flight schools in Australia using more than 3,400 training aircraft. Roughly 25 per cent of flight training covers the beginner phase which involves circuit training for take-offs and landings as well as training in close proximity to an airfield. Electric aircraft are perfectly suited for this task.

“The average age of small single engine aeroplanes in Australia is 36.4 years, so many of these are reaching the end of their lifespan.

Vid below shows 15 seconds "take-off roll" . 1 hour of flying requires 1 hour and 15 minutes of charging...... so 3 battery-sets enables continuous operation of the aircraft, with a max-range of about 1 hour,

 

Aesquire

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Watched a video today on electric cars... by an engineer.

He pointed out that if we'd been using electric cars for the last century, and the New Internal Combustion Engine with Better Power to weight, etc. was hyped, they'd be very unhappy with the New Thing.

What's up with gears? Why so many? Oh, it has lousy starting torque and you have to rev the daylights out of it to move.
Lousy torque.
What? I have to go to a specialty fuel store? Can't just plug it in when I get home?
Noisy, rough, stinks...
etc. etc.

And of course it uses weapon grade fuel. Anti-tank weapon grade fuel. Some Russian guy invented it, right? Explosive, explosive fumes?!

And so forth.

I can see me arguing about storage safety, and the need for grounding straps, and other complaints.

But... One would have to assume the pressure of the market would have sped up the chemistry development to also assume we'd have Electric Airliners, and Orville & Wilber probably wouldn't have been the first to fly. Batteries were heavy, and still are. ( Lithium made a big jump )

So this would probably be the Homebuilt Airship Forum. And there'd be flame wars about which cars had the best parts to go in the Technora envelope covering the monomolecular film holding in the Hydrogen, and the advantage of semi-rigids, and which Solar Film held up best at low temperatures.
 

Vigilant1

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He pointed out that if we'd been using electric cars for the last century, and the New Internal Combustion Engine with Better Power to weight, etc. was hyped, they'd be very unhappy with the New Thing.
Two alternative history ideas for short SF stories:
1) Mankind develops text-based telecommunications (telegraph->keyboards and displays in homes->mobile text devices) before audio communications. The ability to actually hear the other person, their tone, etc, would be seen for what it is: far superior to text.

2) Automobiles never took off, we went from horses to progressively more advanced rail. Some guy proposes flat roads and cars operated by citizens. "What will stop them from crashing into each other??"
" We'll apply markings on the roads to delineate the direction of movement.'
"No tracks, no barriers? You are crazy!"
 
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EzyBuildWing

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Single-seat coaxial heli..... looks a great little machine, but needs converting to electric.....with 1 hour range!
Or say 45 minutes range with 45-minute recharge-time......then could fly it continuously around the circuit with 1 battery-pack always on charger.
It's an "air-experience-machine" for racking up hours, not a cross-country heli.
Great vid:
 

Geraldc

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We still have a bit to go.

ZK-EAL4 (c/n 942 AE 60) is owned by Electric Airline Ltd of Lyttleton and was trailered up to Paraparaumu from its Rangiora base (as it does not have the range to fly there).
Raptor flew further.

 

opcod

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Yes the beauty of silence. It's all about the mission, if you want to go Ny to CA, do you walk, take the bus, take the train ? It's about the mission. Something with short wing like Cessena eating fuel with the worst performance ever is not something called efficient. So the Alpha not efficient by itself, but put the 50ft wing on it, as an option and then it make very much sense. Just as currently, it's cheaper to swap the 912 vs than buying a new bat pack at about 2/3 the life of your rotax. People just have to adapt their kind of flying and motorglider are quite the key here.
 

BJC

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Something with short wing like Cessena eating fuel with the worst performance ever is not something called efficient.
The physics definition of efficiency is the output divided by the input. By that measure, the Cessna is not terribly efficient; nor are most TC GA aircraft.

But when one considers that a battery powered aircraft to replace that Cessna has not yet been put into production (except for powered gliders with wing spans that are problematic for many users), the Cessna’s “efficiency” at getting private owners into the air for pure pleasure with some CC utility is infinitely higher than the mythical battery powered replacement.

People who want to fly will, for the foreseeable future, be better served by purchasing a Cessna than waiting for a battery powered aircraft.


BJC
 

Vigilant1

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... It's about the mission. Something with short wing like Cessena eating fuel with the worst performance ever is not something called efficient.
Ahh, but I think the first sentence above is most important, and can falsify your second sentence above.

When I was a student pilot, I was highly focused on one measure of efficiency: Converting dollars efficiently into aeronautical skills and flying hours. For that task, the Cessna 152 with the chalky paint tied down at the end of the row was far more efficient than a slick Diamond DA-22 or any other option available to me.
 
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BBerson

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Don't need a motor glider for fast and efficient cruise. The four seat Cozy probably gets reasonable seat miles per gallon. Needs more runway than a Cessna.
 

Dan Thomas

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Single-seat coaxial heli..... looks a great little machine, but needs converting to electric.....with 1 hour range!
Or say 45 minutes range with 45-minute recharge-time......then could fly it continuously around the circuit with 1 battery-pack always on charger.
Helicopters require a lot more power than fixed-wing airplanes. The FW electric airplane already has very short range; how long do you think a helicopter will fly on whatever batteries it can lift?
 

Dan Thomas

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Watched a video today on electric cars... by an engineer.

He pointed out that if we'd been using electric cars for the last century, and the New Internal Combustion Engine with Better Power to weight, etc. was hyped, they'd be very unhappy with the New Thing.

What's up with gears? Why so many? Oh, it has lousy starting torque and you have to rev the daylights out of it to move.
Lousy torque.
What? I have to go to a specialty fuel store? Can't just plug it in when I get home?
Noisy, rough, stinks...
etc. etc.

And of course it uses weapon grade fuel. Anti-tank weapon grade fuel. Some Russian guy invented it, right? Explosive, explosive fumes?!

And so forth.

I can see me arguing about storage safety, and the need for grounding straps, and other complaints.

But... One would have to assume the pressure of the market would have sped up the chemistry development to also assume we'd have Electric Airliners, and Orville & Wilber probably wouldn't have been the first to fly. Batteries were heavy, and still are. ( Lithium made a big jump )

So this would probably be the Homebuilt Airship Forum. And there'd be flame wars about which cars had the best parts to go in the Technora envelope covering the monomolecular film holding in the Hydrogen, and the advantage of semi-rigids, and which Solar Film held up best at low temperatures.
Imagine that the electric car had been the first and successful design. The world would now be covered in powerplants, dams and other ugly stuff. In the early days of cars, coal was used for generating most power. Big dams didn't come along until later. By now, acid rain would have destroyed so much forest that houses would have to all be made of brick. Early nuclear plants would have proliferated and who knows how many meltdowns and waste contamination we'd have had by now.

And the early motors wouldn't have had the supermagnets. Batteries would have all been lead-acid. Lead and copper mining would have been a huge industry, along with all their environmental destruction and pollution. No electronic controls, either, making speed control difficult, cumbersome and inaccurate. An accident would mean acid everywhere, battery explosions, and so on.

See, there are two sides to every story.
 

Sockmonkey

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Imagine that the electric car had been the first and successful design. The world would now be covered in powerplants, dams and other ugly stuff. In the early days of cars, coal was used for generating most power. Big dams didn't come along until later. By now, acid rain would have destroyed so much forest that houses would have to all be made of brick. Early nuclear plants would have proliferated and who knows how many meltdowns and waste contamination we'd have had by now.

And the early motors wouldn't have had the supermagnets. Batteries would have all been lead-acid. Lead and copper mining would have been a huge industry, along with all their environmental destruction and pollution. No electronic controls, either, making speed control difficult, cumbersome and inaccurate. An accident would mean acid everywhere, battery explosions, and so on.

See, there are two sides to every story.
Yeah, but you're kind of missing the point. With new stuff we tend to see the downsides as being bigger than they are because the downsides of the stuff we're currently using are things we've gotten used to and don't notice anymore.
 
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