Electric GA - what would it take?

Challenged

Challenged

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Challenged
I'm curious as to what capabilities and costs would it take for you get rid of your 100LL plane, and replace it with an electric. Do you think this is something we'll see in the next 10 or even 20 years, or will we all move to burning Jet-A, take for example Cessna's 182 NXT.
 
No. Not until someone perfects the battery.
 
Maybe never. Google Antares motorglider. Electric power that works quite well. Not exactly a C 182.
 
From what I understand, battery technology is really coming along fast. There are some seriously amazing batteries being built in labs that could have applications to this with regard to charge time and capacity. Not sure about weight, though...and that's one of the most important factors.
 
I don't know what it will take to get it to C182 levels, but I will certainly jump on it once it gets here. I love the idea of electric power.

It's not if, but when.
 
The breakthroughs required, in energy storage vs. weight and charging times, and cost, initially, are probably bigger hurdles than what the Wrights were up against (mostly just finding a gasoline engine with the appropriate power-to-weight ratio), but it's worth remembering that they got over that hurdle, despite the fact that in their day, some of the biggest brains on the planet said that such an engine was impossible, in addition to stuff about the whole design being unviable... even after it had flown successfully.

As for what it would take for me personally, since I can't afford even the most modest of the new breed of certified aircraft that use basically the same system that's been around since the Wright Flyers... if I live long enough to get a nice 30-year-old electric Champ or something, I'll be all over that. :D

All the electrics have to do is compete effectively with the new $100K Champs and Skycatchers and $1/4 million 4-place singles available now, and pilots will be tossing their fuel samplers aside in droves. They might even make a dent just competing with all the much cheaper piston aircraft that are no longer in production but commonly used. They are still plentiful, pretty cheap to buy, and more capable than any existing electric airplane, but they are slowly dying out and getting pretty expensive to feed these days.
 
A gasoline or diesel generator.
 
Micro turbine generator running on JET-A powering some batteries and an electric motor. The batteries would be there in case the turbine quit.
 
It's all about energy density. The energy stored in gasoline or diesel is more than 20 times that stored in a battery of the same weight.

So you need a 20-fold improvement in battery chemistry, which isn't going to happen.
 
Fuel cells has been successfully used by NASA on the way to the Moon and other space flights to provide electrical power. They provide greater amount of power than conventional batteries. Their only drawback is that they run on hydrogen and cannot be charged like batteries.

Boeing researchers and industry partners throughout Europe conducted experimental flight tests in February 2008 of a manned airplane powered only by a fuel cell and lightweight batteries. The Fuel Cell Demonstrator Airplane, as it was called, used a Proton Exchange Membrane (PEM) fuel cell/lithium-ion battery hybrid system to power an electric motor, which was coupled to a conventional propeller.[106] In 2003, the world's first propeller driven airplane to be powered entirely by a fuel cell was flown. The fuel cell was a unique FlatStackTM stack design which allowed the fuel cell to be integrated with the aerodynamic surfaces of the plane.[107]

There have been several fuel cell powered unmanned aerial vehicles (UAV). A Horizen fuel cell UAV set the record distance flow for a small UAV in 2007.[108] The military is especially interested in this application because of the low noise, low thermal signature and ability to attain high altitude. In 2009 the Naval Research Laboratory’s (NRL’s) Ion Tiger utilized a hydrogen-powered fuel cell and flew for 23 hours and 17 minutes.[109] Boeing is completing tests on the Phantom Eye, a high-altitude, long endurance (HALE) to be used to conduct research and surveillance flying at 20,000 m (65,000 ft) for up to four days at a time.[110] Fuel cells are also being used to provide auxiliary power in aircraft, replacing fossil fuel generators that were previously used to start the engines and power on board electrical needs.[110][not in citation given] Fuel cells can help airplanes reduce CO2 and other pollutant emissions and noise.

José
 
MSPAviator said:
Micro turbine generator running on JET-A powering some batteries and an electric motor. The batteries would be there in case the turbine quit.
Click to expand...

This has been the most interesting to me for a while, but I suspect the weight of batteries PLUS fuel, is more than just a regular engine plus fuel.
 
Dilithium crystals.
 
Mrfusion.png
 
rottydaddy said:
The breakthroughs required, in energy storage vs. weight and charging times, and cost, initially, are probably bigger hurdles than what the Wrights were up against (mostly just finding a gasoline engine with the appropriate power-to-weight ratio
Click to expand...


I'd say that the problem is exactly what the Wrights were up against...finding a power source of an appropriate energy/weight ratio.

Someone else said it - the problem is almost entirely one of energy density. Today, you can replace the 300 lbs of avgas with 300 lbs of battery, but you only go for 1.5 hours before the big spinny thing stops.

So the original question - what would it take? The same thing it would take for electric cars:

1) 5.5 hours endurance on 300lbs of battery
2) charging stations at enough airports that you can make it work
3) portable charging options when you can't.
4) low cost availability.

We won't get all four in the next twenty years.
 
2) charging stations at enough airports that you can make it work
Click to expand...

2.1) Real world practical recharge times.

Let's say you can get 2 hours of useable power out of a charge before it's not enough remaining for a go around. You're on a 6 hour flight that day. That's 2 rechargings you need. If the recharge time is 6-12 hours, the half day flight is now 2-3 days minimum.
 
That's an ultralight.

It only takes 5 or so HP to power an ultralight, not 160+ for a four-place on takeoff.

And they aren't that tolerant of weather.

People have been demonstrating solar cars since the 70s, but there still isn't a practical one, for the same reason.
 
A complete re-write of the laws of physics for conductivity and charge storage.
 
Simple. Follow power lines to your destination. When the batteries get low, lower the pantograph from the belly of the plane and charge up!

Sent via teletype
 
Think we could do a hybrid airplane? You can take off and climb to altitude on the battery and then start up an advanced automotive based engine to run off car gas to keep the current levels up enough for cruise and descent - and then you plug it in again.
 
The power density of electric sources is still an order of magnitude too low to be useful. But it will improve if the price of fuel keeps going up.....
 
Challenged said:
I'm curious as to what capabilities and costs would it take for you get rid of your 100LL plane, and replace it with an electric. Do you think this is something we'll see in the next 10 or even 20 years, or will we all move to burning Jet-A, take for example Cessna's 182 NXT.
Click to expand...

800px-Energy_density.svg.png


In my picture posted above, it's easy to see the relative specific energy (energy density or power density) of various sources of power. What's less simple to understand is the relationship of powerplant efficiency to real world output.

Put another way, a gasoline engine at 33% efficiency will consume 3 times more energy than a battery/motor combination at 100% efficiency (silly example, I know)

So, while the differences are not as great as the chart shows, battery powered aircraft will remain quite limited.

Electrochemical energy and it's physical - theoretical limits are well known and understood. For practical, real world parity, electrochemical energy would have to improve beyond the limits of physics.

Consider powering an airliner by batteries, for example. The level of energy required is massive. And, no matter how fast you could drive the fan with an electric motor, you still don' have the heat, pressure and thrust of the core engine (all key factors in high speed flight) .
 
cujet said:
Consider powering an airliner by batteries, for example.
Click to expand...

Thanks for the chart, and the information.

However as for this line. You would never power an airliner with batteries. As technology improves, the way we will use that technology will change.

If electricity is ever the way we eventually chose to move mass quantities of people through the air. The physical means in which we do that will most likely be something yet imagined.
 
Running the math, the absolute, theoretical, practical maximum output of the universe's ultimate battery still falls far short of the energy of petro fuels.

The "max" is about 6600KWH/KG. Factor in the necessary conductors, housings, rechargability, depth of discharge limits and lifespan and that number becomes 1200KWH/KG. So, 1200KWH/KG is the holy grail of batteries. With that in mind, the Chevy Volt's 16KWH, 200KG battery (10KWH usable) (82KWH/KG) could be improved to 16 times it's current capacity. Enough to power an airplane! But still well short of the energy density of the fuel it would replace.

Again, put another way, that "perfect battery" (by weight) could provide a Chevy Volt with nearly 600 miles of real world range. But, that battery weighs as much as 73 gallons of gas, which could push a similar car to a whopping 2500 miles!
 
Challenged said:
I'm curious as to what capabilities and costs would it take for you get rid of your 100LL plane, and replace it with an electric. Do you think this is something we'll see in the next 10 or even 20 years, or will we all move to burning Jet-A, take for example Cessna's 182 NXT.
Click to expand...

As for the diesel piston aircraft, it currently has economic advantages. As Jet fuel is slightly cheaper per gallon, and the diesel burns fewer gallons. However, as we all know, the price per gallon could change. Diesel fuel, for example, rivals "super unleaded" in price now. Where as years ago, diesel was cheaper than regular gasoline. (reducing the sulfur pushed the price up too)(those requirements could happen to Jet-A too)

But, we must always remember aircraft fly by weight, not by gallons. Avgas is about 6 pounds per gallon and Jet-A is about 6.7+ per gal.

By weight, there is precious little difference in energy content between the two fuels. Economic factors aside, the only real diesel aircraft engine advantage is the diesel engine's greater efficiency. Those thermodynamic differences between diesel and gasoline engines have been getting smaller, year by year.

It's my belief that a direct drive gasoline aircraft engine, based loosely on current designs, could approach diesel efficiency. Direct injection and electronic ignition would be required.
 
bbchien said:
The power density of electric sources is still an order of magnitude too low to be useful. But it will improve if the price of fuel keeps going up.....
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That is exaclty what the Feds want to happen. If you artificially raise the price of fossil fuels enough, suddenly, other alternatives seem more viable. Gasoline and diesel engines are fine for aviation. I don't see the value in trying to make electric work especially with current or near/mid term technology. Until you can generate more electricity with much, much smaller batteries, with much longer duration, it a silly endeavor.
 
cujet said:
Again, put another way, that "perfect battery" (by weight) could provide a Chevy Volt with nearly 600 miles of real world range. But, that battery weighs as much as 73 gallons of gas, which could push a similar car to a whopping 2500 miles!
Click to expand...

Agreed it will never catch up. But if mogas was $150 a gallon, it doesn't need to catch up.
 
Even when lightweight batteries capable of holding lots of energy come around, shouldn't we be thinking about where the power comes from to charge said batteries? We tend to think of batteries as power sources, but they're only containers (like the gasoline fuel cells in my wings today) holding energy, created elsewhere.

The energy used to manufacture the battery, and the energy used to create the electricity to charge the battery with, and the energy used to destroy the battery at the end of its life... vs. a wing full of gas...
 
Lots of people think about that.

A single large thermal engine is much more efficient than a bunch of smaller thermal engines producing the same power. This is why we have power plants, rather than Diesel (or coal or natural gas) generators on every house. There is a net gain, and it can be large.

You also don't have to haul the fuel around. Just the energy container. Electrons are very light, but the matrix that holds them isn't yet. Change that, and you change the game. For a large airliner, half its weight can be fuel for a maximum-duration flight. It's enough of an effect to make a huge difference in the service ceiling (good luck getting an 830,000 lb 747 to FL450).

But it's all speculative. Using "magic" to motivate changes has a tendency to continue to sound exactly the same for decades. Like fusion power. It's the power of the future, and always will be. Commerical fusion powerplants are 40 years away. They were 40 years away when I worked in the field 30 years ago. Amazing how 40-30=40, eh? And "everybody knows" what it takes. They knew in the 50s, too, but it was a different set of tasks.
 
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The 2011 Green Flight Challenge sponsored by Google marks an historic achievement in aviation—the first demonstration of practical, cross-country emission-free flight. Team Pipistrel-USA.com’s winning 4 seat, electric-powered aircraft, the Taurus G4, flew nearly 200 miles non-stop while achieving 403.5 passenger MPG! Its astounding efficiency was more than twice that of the piston-powered aircraft in the competition. Equally promising: Team e-Genius won the Lindbergh Prize for Quietest Aircraft, with a peak take off noise of just 59.5 dBA at a 250 foot sideline. This achievement heralds the real transformative potential unique to electric powered aircraft—the capability to be quiet enough to land very near dwellings and businesses.

Years from now, these first Green Flight Challenge team members will be recognized as the pioneers of the Age of Electric Flight.
 
kimberlyanne546 said:
The 2011 Green Flight Challenge sponsored by Google marks an historic achievement in aviation—the first demonstration of practical, cross-country emission-free flight.
Click to expand...

Were there no emissions from the energy used to manufacture the batteries, or when generating the electricity used to charge the batteries?
 
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