Slashdot Mirror
The Electric Airplane Is Coming
An anonymous reader writes "The electric car is so yesterday; electric airplanes are coming. A battery electric-powered ultralight aircraft has been flying for the last year. A series-hybrid motor glider and a concept for an all-electric, 50-seat passenger plane were introduced at the Paris Air Show."
Writing from my Alienware laptop while running Crysis, powered by the cig. port! This is so much fu^H^H NO CARRIER
"When information is power, privacy is freedom" - Jah-Wren Ryel
So does this mean I can stop seeing those ads and comments stating that we don't have anything to run our planes on other than oil based products.
Time to offend someone
The personal flying car is here.
A battery electric-powered ultralight aircraft has been flying for the last year.
Flying FOR A YEAR? Crap. My Volt only goes 35 miles then I have to charge it or burn gas. I want one of those airplane batteries!
We need this more than any other technology right now, and it's a solvable problem.
Want something to stimulate the economy? That'd do it.
..don't panic
From TFA: 'The power capacity of battery technology, he continued, would have to grow by “at least a factor of four before we are near where we need to be to accomplish this.'
This is when electric aeroplanes would become really feasible.
Not in any practical sense. Weight is critically important in aviation, and kerosene has an order of magnitude higher specific energy than the best batteries.
http://en.wikipedia.org/wiki/Energy_density#Energy_densities_ignoring_external_components
That's why airlines charge for luggage now.
If you could do the whole trip on battery, it's going to take many, many tons of batteries -- far more than fuel as you said -- and depending on your electricity generation source you could be putting out more pollution in the end anyway.
If it augments fuel in a hybrid configuration, then every pound of battery makes you burn fuel faster. Where are the savings? You don't get to do regenerative braking either.
This electric plane looks promising too, even though it's only a model airplane so far. Not sure there are many partners interested though...
In Soviet Russia, our new overlords are belong to all your base.
"A battery electric-powered ultralight aircraft has been flying for the last year."
And boy, are its batteries tired!
What you're describing will not work. You're trying to violate the laws of physics, similar to proposals of perpetual motion machines. It's a neat thought experiment, in order to identify the problems, but it won't work in the real world.
From basic Newtonian mechanics, we know that for every force there will be an equal and opposite reactive force. A closed system will not be able to achieve motion without an external force: either a force applied to other objects (e.g. pushing against the ground, or pushing against (a.k.a. 'blowing') a fluid like air or water) or by ejecting matter (as in a rocket).
Specifically regarding your design: As I understand it, you basically want an object where internally forces are applied to inclined planes, in order to push the planes 'upwards'. You imagine that this can be done in a way where there is no corresponding opposing force also pushing the object downwards. You try to get around this problem by imagining a decoupling where internal masses are momentarily not touching the main mass: so you have one piece that fires a 'bullet' horizontally, which hits the inclined plane (pushing it upwards). You imply that this means there is no corresponding opposing force. However you mention offhand that you will recover the 'bullets' and reuse them. But if the bullet hits the inclined plane, and pushes it upwards, then the bullet will be correspondingly deflected downwards. When the bullet hits the recovery mechanism, it will impart to it a downward force equal and opposite to the upward force that the inclined plane felt. The two forces will cancel out: the plane is pushed up, the recover mechanism is pushed down.
You can imagine putting the recovery mechanism further away from the inclined plane. But, at best this just creates a time lag between when the inclined plane is pushed upwards, and the bullet-recovery mechanism is pushed downwards. So the vehicle will jolt up-down but on average will stay in the same place and thus will not hover against the constant force of gravity. This is inescapable since the planes and the recovery mechanism are mechanically coupled to one another. The only way to solve this is to remove the recovery mechanism, and let the bullets shoot out the bottom of the object, so that the planes are pushed upwards and the opposing force is carried away by the bullets, out of the object. Of course 'flying' by shooting a gun downwards is generally inefficient, which is why we've invented things like helicopters, which push air downwards instead. That way you don't have to carry around a bunch of bullets; you just use the mass and hydrodynamic properties of the fluid you're flying through.
The opening post implies that this electric aircraft revolution is right around the corner, but in reality, it will be decades before any practical implementation by any major aerospace company; I would dare say the 20-30 years the article estimates may be a bit generous. Weight is one of the biggest drivers in aircraft design (and one of the biggest factors of aircraft fuel efficiency), and until they can develop batteries with sufficient power to offset their massive weight, these planes will continue to be limited to small hobby craft. Nothing in this article indicates that these technological barriers have been overcome yet.
Even if the technology were all in place today, it would take a good five to ten years to design and certify a cargo or passenger aircraft. I'm hopeful with this technology, but I temper that hope with the reality of implementation.
A safe compact limited need to fuel power source is needed and only one thing fits the bill, fusion. Current planes already give up an immense amount of their weight for fuel so why would we want to continue that practice? If we are going to break from fossil fueled aviation then go all out.
* Winners compare their achievements to their goals, losers compare theirs to that of others.
No, batteries behave like a bomb even under normal use. Remember the rash of exploding laptop batteries a few years ago?
Chances are any form of energy crammed into a tiny space that can be easily converted to electricity has some inherent danger to it.
There's no -1 for "I don't get it."
Not sure, but I bought some of them US made LEDs when I moved into my new house. I didn't, however, buy all LED because they are incredibly white light (vs the halogen replacements I got for the normal bulbs.)
Every time I start to have faith in humanity, I ruin it by driving to work between 7 and 8 am.
It's been a while since I left the airplane scene, but from what I remember, the FAA requires small-engine airplanes to have reciprocating engines.
I've never seen a reciprocating electric motor, so are electric airplanes even legal?
http://www.youtube.com/watch?v=YINO0aoSAGg Terry
Of all the modes of transport available to humans, air travel would be hit hardest by a true fuel shortage. If we were to run out of oil in the next few years the we'd just transition to electric cars. Many, if not most, trains already run on electricity. There are alternatives for shipborne travel, coal, wind, nuclear and possibly even electric. There is, however, no viable alternative for air travel except for dirigibles. Unless, I suppose, someone were willing to give nuclear-powered aircraft a shot. Needless to say, intercontinental travel would get significantly slower for quite a while.
The linked article does describe the efforts to create but it emphasizes that they need many advances to make it happen and that it isn't coming for at least twenty years.
Democracy Now! - your daily, uncensored, corporate-free
I thought the primary problem with electric cars was the amount of power that can be stored for the weight of the batteries? Weight is an even more important issue for planes.
I would have thought batteries would need to be able to store twice (or thereabouts) the energy per kg since presumably they wont be allowed to jettison spent batteries. True aeroplane fuel is expensive but then it's saving costs on weight, something that also translates into emissions.
I guess the research is valuable regardless, but every time I hear about some electric vehicle the problem seems to always return to the batteries.
You could use superconductive storage today and get the right battery-weight. It would actually weigh much less than jet fuel to add enough power to a series of superconductive coils and store the power. A typical coil of SMES in current use can get about a 1 MW/h which is 3600 Megajoules, typically a kilo of jetfuel has something like 44 megajoules of power, so one coil would replace 81 kilos of jet fuel. You'd need like 57 thousand kilos of jetfuel to go a typical 3,500 statute mile flight. Which is 705 superconductive coils, which would weigh less than the jetfuel currently does and would cost less after being built on a per flight basis and could be refueled as quickly as one could give it new electric power.
It might however have clear health effects with that much localized magnetic fields and break a lot of electronic devices, and refrigeration is a giant pain in the ass without having it 30k feet in the air.
It is no longer uncommon to be uncommon.
I''m researching this as I go, so I don't know what the result will be, but I have a good guess.
Take the General Electric GE90, a powerful, efficient turbofan. It produces a wide range of thrusts, but I'll stick with the simple 500 kN near the top. It weighs 8,283 kg.
An EMD 710 diesel locomotive engine used in an efficient V20 configuration produces 3,098 kW and weighs 18,365 kg dry.
It obviously gets complicated from there because we're comparing power to thrust. How about, since you're thinking diesel-electric, I compare to a turboshaft? They're both rated in power, and both numbers would be converted to thrust in some manner, with whatever attending losses of the thrust system (propeller/ducted fan/etc.) being equal.
If you want fuel flexibility, the Honeywell AGT1500 from the M-1 tank can produce 1,120 kW running on, from what my tanker friends tell me, "greasy kid's stuff." However, it's not an aircraft design so it's quite heavy at 1,134 kg (for example, it sits in a heavy steel frame so it can be quickly plucked out to change engines).
So we use the later aviation version, the PLT27 that produces 1,434 kW and weighs 145 kg.
That's half the power at 1/127th the weight. No, diesels aren't going to work in airplanes. Far too low of a power/weight ratio. The equivalent weight in turbines would give you 182,118 kW, or almost a quarter-million horsepower.
Why do we still use diesels in locomotives then? The diesel is more reliable, long-lived and requires less maintenance. We don't care so much about an extra dozen tons since it doesn't matter much when it gets up to speed.
Scroll down
http://www.everythingpanam.com/1960_-_1970.html
Don't be dumb; there's an infinite number of molecules out there that can be made from the elements on the periodic table. For instance, carbon nanotubes have only been discovered relatively recently, and have all kinds of interesting and useful properties, yet carbon the element has been known since ancient times, and is probably one of the first elements named and understood by scientists when they first invented chemistry. More recently, it's been discovered that you can make nanotubes with boron and boron nitride, which have very different properties from the carbon variety (BN tubes are insulators, whereas carbon tubes are conductors).
http://www.newscientist.com/article/dn13143-boron-nanotubes-could-outperform-carbon.html
This is just the tip of the iceberg. There's an untold number of "metamaterials" out there waiting to be discovered, things which don't occur in nature in any significant quantity, have all kinds of amazing properties, and are made from simple elements that we've known about for ages (boron and nitrogen aren't exactly new discoveries).
I'm sorry, but you seem to be an idiot.
Who cares if something dissolves in air? If its properties are useful enough, then you put it in an air-free environment, or you put something on top of it to keep air away. We invented this thing a while ago that does this, it's called "paint". Works great for keeping steel and iron from rusting.
The bulk properties of carbon nanotubes have already been demonstrated, and they're not very far away from making composites with them that enough tensile strength for a space elevator cable. You only need nanotubes about 1cm long for that.
Elements we don't have in huge amounts? What, like carbon, boron, and nitrogen? I can't think of anything that's more plentiful on the earth's surface except for hydrogen and oxygen.
Manufacturing? You have to manufacture everything else out of raw materials. It's not like you can dig up aluminum out of the ground; you have to refine it from ore, which requires tons of electricity.
You're either a troll or a fool.
The thing that's most spectacular is that the regenerative braking means you'll never hit the ground in a fall!
"There is more worth loving than we have strength to love." - Brian Jay Stanley
Commercially, I don't see batteries working, simply because it would affect the turnaround time of aircraft drastically, an aircraft on the tarmac charging it's batteries is an aircraft that is not making money.
NZ Electronics Enthusiasts: Check out my Trade Me Listings
Really???
JP4 has an energy density of 42.8 MJ/kg A fully loaded 747 carries 139200 kg of JP4.
That is 5,957,760 MJ of energy. Got a fuel cell that can do that?
Just for fun lets say you use VERY cool propellers and you get 20% bump in efficiency, that is still not going to come anywhere even close.
Hey KID! Yeah you, get the fuck off my lawn!
It is easy to create a picture of a cool craft based on technology that does not exist yet. The trick is in implementing the technology.
Did you not see his reply? Sorry, but that kind of post deserves belittling. For most posts, yes I try to avoid belittling people since people can have genuine disagreements, and I've certainly been mistaken from time to time, but that one was so over-the-top stupid I couldn't help it.
While this is really cool, it simply cannot scale to 747 size.
Hey KID! Yeah you, get the fuck off my lawn!
Fuel cells can burn JP4 or whatever you want to have it convert to electricity. The fuel energy density is therefor the same for fuel cells as it is for "ordinary" internal combustion engines.... the only difference is how the fuel is burned and how the oxygen is applied to the fuel.
That said, the efficiency of the fuel being burned and being able to supply the motor with sufficient energy given the size of the fuel cell is something to argue about. Fuel cells work fine for astronauts, but then again you wouldn't want to have an ICE in that kind of environment nor are you needing that energy to keep you aloft either.
Unless you have put a whole bunch of effort into creating high power fuel cells, it seems like you would need a whole bank of the things which would add both bulk and mass to the plane.... both of which are things in very short supply on most aircraft. Unless you can improve upon the power plant weight and size of a normal turbofan jet engine, it seems like it would be a waste of effort.
Is how incredibly huge and strong a transmission would have to be. Diesel-electric lets them eliminate the transmission.
In a perfectly still atmosphere (zero wind), the energy requirement grows like dV^2 to travel a distance d at speed V.
Batteries' specific energy (J/kg) being much less than current hydrocarbons', this approach is conceivable only for travel at very slow speeds.
And as a reminder, zero energy flying has been practiced for quite a while: it uses gliders or balloons.
Columbus to DC.
A Cessna 140 has about an 85 hp engine, which translates to 62 kW as you said. It has 15 sq/m of wing area, say we can use even 10 at 1 kW/sqm. That's about 13 hp. I doubt you'll even be able to cruise with that. Think about it, that's the power of two average lawnmowers, it's not going to keep a Cessna in the air.
Forget batteries. The gross weight of the Cessna is only 250 kg higher than the empty weight. Say person weight of 75 kg, two people, you have 100 kg left for batteries. Cruise is usually 50% power, 31 kW. The 24 kW/h battery in a Nissan Leaf weighs 300 kg. Take 1/3 of that to fit it and you have 8 kW/h for flight. That means 15 minutes cruise. The full-power takeoff probably more than offsets the 2.5 kW/h you'll charge in-flight with the solar cells.
Oops, I forgot to calculate in the weight of the solar cells...
Batteries just can't carry their own load in a commercial transport or passenger airplane. It's a great idea for a recon drone-type vehicle that's almost all wing, slowly circling above on solar power, using batteries to stretch between clouds. But then the cargo is only a few cameras and sensors, and the batteries.
I think it's pretty obvious he's talking about MWh, one megawatt of power for one hour, even with the added "/".
This need for better batteries reminds me of the Robert A. Heinlein novel Friday.
The guy who owned most of the country did so because he invented basically a super-battery. And it's true. Someone who could invent a 50-lb briefcase-sized brick that could give a car 150 hp and a 300-mile range in adverse conditions (A/C or heater on) would be a zillionaire.
I make the mistake too sometimes. I know the concepts, I just rarely have need to use the abbreviations, and don't always bother to look them up.
OTOH, the very idea of superconducting coils in an airplane sounds like quite the flight of fancy. Even if it worked, I wonder about charging them at the airport in any reasonable amount of time. An average 747 carries around 150,000 kg of fuel. Jet A has 42.80 MJ/kg, so we need 6,420,000 MJ to fuel up equivalently.
Since 3,600 MJ = 1 MWh, we need 1,783 MWh to fuel a plane. That's an entire gigawatt power plant running for almost two hours just to fuel one aircraft.
If you wanted the ability to fuel just five aircraft at a time, that's more power output than all but the the three largest dams in the world. To fuel just three at a time you need the world's largest coal or fuel power plants, or a top 10 nuclear plant.