Why battery-powered aircraft will never have significant range

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Jay Kempf

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I assume we can fly 6 hrs with an electric plane that costs 20 k in two years.
That wouldn't be a very good assumption. People make assumptions based on other electric applications. LED lights are really bright and use no power. Lots of electric power tools and cars make it look like airplanes are the same and the whole industry will fall to this amazing new technology. It is creating a flood of people investing in pipe dreams.

Truth is airplanes need to make power, continuous power, Watts are Watts, HP is HP. Batteries are only as good as the chemistry. When you push the chemistry they get dangerous. When they get dangerous they need to be contained. When they have to be contained and managed the energy density starts to plummet. When that gets solved, tested, and gets in volume production then it still at the moment needs heavy containment.

So how is the chemistry going to change? Lithium is the current workhorse. What other technologies are leading the charge. You have exactly one periodic table to work with. Volatility is what it is.

Have you ever been around a Lithium based battery that started to overheat and run away. I have. You don't want that inside your fuselage. Boeing found out the hard way and they are really smart people. And they weren't using it for thrust.

$20k will not buy you the batteries, or the motor right now, nor in 10 years. You will not produce an airframe, especially certified and sell it for less than, I'll guess $250k, for the next 10 years.

So you can stop assuming.
 

pictsidhe

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As usual, that article has a lot of "mights" and "coulds" and "long ways to go(s)." And 40% or 70% improvements. Yes, advances are being made, but they're still relatively small. We need advances in orders of magnitude, as we've seen in information storage. It will probably happen but, as both you and the article's author state, it might not be in our lifetimes.

I sure do appreicate the lithium batteries, though. I grew up with carbon batteries powering incandescent flashlights that were seldom more alive than dead. Cordless tools were unimaginable. Now I have cordless drills that lasted me a week of aircraft inspection panel removals and installations and other maintenance stuff, all on one charge. LED flashlights that run a LONG time on a pair of AA cells and have awesome light for my old eyes. Wonderful stuff.
Batteries are a different kettle of electrons to information storage. Moore's law does not apply!
 

SlowFlight

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My impression of battery pricing no matter what the battery is made of, would be materials plus assembly is usual, plus uniqeness that can't be matched to the most cost flush market. If someone comes up with a battery that is half the cost, half the weight, of current batteries, it is unlikely to sell at half the cost until the market that needs it is saturated to oversupply. Size market with half the weight? Cars, Trucks, aerocopters, phones, tools, battery packs everywhere. Already developed waiting on a small drop in weight. Time to cheap batteries will likely extend far beyond patents and ability to produce, it will be time to saturation of excess supply or the next better battery. Lion I believe only can have a spare Ion per molecule, so figuring out to store 2 ions would double capacity quickly, then there is the problem of heat. Even stable ssingle compostion copper gets quite warm when you move more than the outer most electrons. Multiple problems.
 

Dan Thomas

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Electra One actually ought to do it, but costs way more.
Another airplane called the Electra?? That makes three of them in aviation history. The Lockheed 10, the type that Amelia Earhart disappeared in, the Lockheed L-188 Electra, the big old airliners I worked on a few years ago, used as fire bombers, and now this one. So original.
 

Yellowhammer

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I agree, I don't think battery powered aircraft will ever get over the hump. Maybe the best they will ever see is a two hour flight time. I wish all the folks throwing their tine and money at these electrically powered airplanes would divert their attention to creating an inexpensive jet/turbo prop or a solid, super affordable 4 stroke replacement for a Rotax 582.
 

pictsidhe

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Another airplane called the Electra?? That makes three of them in aviation history. The Lockheed 10, the type that Amelia Earhart disappeared in, the Lockheed L-188 Electra, the big old airliners I worked on a few years ago, used as fire bombers, and now this one. So original.
She's a popular girl!
 

pictsidhe

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Beryllium can do two electrons at not much more atomic weight. But it has lower electrode potential, so gains small. Pricey and toxic, too. Magnesium and aluminium are cheap and possibly useable, but lower specific energy density than lithium. I don't know of anything better than Lithium. It's why it was the holy Grail for so long. Better lithium cells could certainly be developed.
 

Speedboat100

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Not a chance. Not big enough to carry enough batteries. It would need a lot more wing area/aspect ratio. $250k a copy at least.
I recall their design goal was 100+100+100...weight.batteries and payload. 2012 their claim was 3 hours. Now the batteries are double effective than 2012.
 
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Geraldc

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I just a watched video from Fisher Flying products about electric propulsion.
He (Dave) was talking about standardized battery packs.
I can see the future being where you go to an airfield and swap out your battery with a charged one and carry on.Sort of like 15kg aa cells.
Same would go for cars. Pull in to the fill up station and swap your batteries. Fuel company owns the batteries and you pay per swap.
 

Jay Kempf

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I just a watched video from Fisher Flying products about electric propulsion.
He (Dave) was talking about standardized battery packs.
I can see the future being where you go to an airfield and swap out your battery with a charged one and carry on.Sort of like 15kg aa cells.
Same would go for cars. Pull in to the fill up station and swap your batteries. Fuel company owns the batteries and you pay per swap.
Except those batteries are huge, heavy, somewhat dangerous when chargine, and you have to manage charge cycles. Most last about 1000 charges which seems like a lot until you put an entire infrastructure in place using them. They have to be available at whatever depot you want to charge and have to be charged meaning keeping inventory of expensive batteries and they would always be in the wrong depot cause that's how transportation works. Ships go back empty to Asia. That cost has to factor in. Electric bike city vendors are already figuring that out. They have a contract army to go collect them, charge them and put them back into the popular racks. Devil is in the details. Details cost real money. Ask the hydrogen fuel cell people about building infrastructure. We have a huge, mature and well figured sorted infrastructure to deliver fossil fuels to the point of use with little geographic spacing. How that got to be such a bad thing eludes me still. Saving the planet with Teslas is not happening.
 

Voidhawk9

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Dan Thomas

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Details cost real money.
So true, and only one little detail can completely wreck an idea. Just look at the Moller Air Car, the four-seat thing with over 1400 horsepower (eight 180 hp engines) driving tiny fans that made an awesome noise and still couldn't prove itself to fly even after an investment of 100 million dollars over 50 years. The little detail was those tiny fans. A two-seat helicopter can fly quite handily on a seventh of the power. Four seater helicopter need a little more, like the R44 that has 245 HP. Rotor size matters. Seriously matters.
 

Jay Kempf

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The Elektra one needs to have a lot more span and area to lift more batteries to get a lot more hours. It's structural fraction is already in the bottom of the possible range. But commercially there really aren't any customers for the plane as it is. It isn't a glider. It isn't a transport airplane. The people that have bought one are companies researching electric aircraft designs like a couple of my customers. Those types of businesses use an aircraft like that to test their own systems.

The UAS version "might" be viable but it still needs more endurance. Electric conversions of some existing glider designs can lift more batteries and have more aero refinement and can be had used for much less money albeit without the solar panels and motor already installed. UAS control systems are pretty mature right now and batteries, motors, props are pretty well sorted as well. So why would the Elektra-One have any industry changing innovation to offer?

The two place high altitude version they are working on for altitude records is closer but they went manned, incorporating pressure suits, so that's a little off spec for commercial products as well.
 

Speedboat100

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The Elektra one needs to have a lot more span and area to lift more batteries to get a lot more hours. It's structural fraction is already in the bottom of the possible range. But commercially there really aren't any customers for the plane as it is. It isn't a glider. It isn't a transport airplane. The people that have bought one are companies researching electric aircraft designs like a couple of my customers. Those types of businesses use an aircraft like that to test their own systems.

The UAS version "might" be viable but it still needs more endurance. Electric conversions of some existing glider designs can lift more batteries and have more aero refinement and can be had used for much less money albeit without the solar panels and motor already installed. UAS control systems are pretty mature right now and batteries, motors, props are pretty well sorted as well. So why would the Elektra-One have any industry changing innovation to offer?

The two place high altitude version they are working on for altitude records is closer but they went manned, incorporating pressure suits, so that's a little off spec for commercial products as well.

I recall Voyager had 4:1 loaded to empty weight ratio.

So 60 kg / 60 kg / 120 kg is doable. Not easy but doable.

With aspect ratio of 16 and L/D of 25 and wing loading of 25 kg/m2 I bet a 3-4 kw usage at 100 mph is doable too....so 3,5 hr endurance with 60 kg of batteries and 120 kg payload.
 

Dan Thomas

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With aspect ratio of 16 and L/D of 25 and wing loading of 25 kg/m2 I bet a 3-4 kw usage at 100 mph is doable too....so 3,5 hr endurance with 60 kg of batteries and 120 kg payload.
Assumptions again. So why isn't anyone doing it?
 
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