Battery powered Skyhawk
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Hands up now all those who bought a Prius, do you feel like a tit?
The biggest have in automotive history.... with the exception of the PT Cruiser (hey want an older looking new car... heres one we mangled earlier) you burn exactly how much less fuel a year... a thimble... well done
, unless you just bimble to shops it useless... I'm all for planet saving gadgets but don't put a pigs ear in a box and sell me a purse.
When you can do a X-country land and 're-fuel' at a remote airfeild- (an extension cord will do) then i'd be interested.
but why oh why put this technology into and airframe designed 50+ years ago. take advantage of the advances in composites and aerodynamics, build somethign really slippery, then you'd save a lot more power than dragging an in-effecient airframe through the sky.
The biggest have in automotive history.... with the exception of the PT Cruiser (hey want an older looking new car... heres one we mangled earlier) you burn exactly how much less fuel a year... a thimble... well done
, unless you just bimble to shops it useless... I'm all for planet saving gadgets but don't put a pigs ear in a box and sell me a purse.When you can do a X-country land and 're-fuel' at a remote airfeild- (an extension cord will do) then i'd be interested.
but why oh why put this technology into and airframe designed 50+ years ago. take advantage of the advances in composites and aerodynamics, build somethign really slippery, then you'd save a lot more power than dragging an in-effecient airframe through the sky.
A new airframe is a high risk development. A new mode of propulsion is a high risk development. Put them together and the whole program is just asking to fail. Better to try out the new propulsion technology on a proven platform than to try to design a brand-new airplane around what is effectively a prototype. History shows us that, for the most part, the big successful companies have tried to avoid putting a brand-new engine on a brand-new airframe in order to avoid putting too much risk in the program. An example of what happens when you try to put a new engine on a new airframe: 787. Boeing took a huge risk on that program, and while they're about to finally get it finished up (it's turning out quite well, too), it's been riddled with delays.
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I'm willing to bet an efficient gas turbine running a generator and having an electric motor drive the prop, would be much lighter than any combustion engine.
Let's aim for 160 hp. A brushless motor for a C172 would weigh about 15kg (yes, the deliver about 7-10Kw/Kg). A generator that could provide such power would weight about the same (as a motor is a generator in reverse), so add another 15kg. Add electronic controls for both and you have maybe 10kgs on top of that. How much does a gas turbine weigh that can produce about 160 shaft horsepowers? Well, the venerable helicopter turbine the Allison C18 delivered 317 shp on 70kg (140lbs), which would make it a fair assumption that half that power output could reduce the weight to about 50kgs. Let's add it up: 15+15+10+50=90kg. Now, that's less than any combustion engine.
So why isn't this available?
Well, you could as well ask yourself why a PT6 costs 10 times more than a combustion engine when it's simpler and cheaper to manufacture? Nothing makes sense in aviation, that's why. No normal amounts of logic apply, because the regulatory organs have a stranglehold on the market. It's an oligopoly. Want an alternative to that PT6 in your TBM? You're out of luck - it's been certified with that engine and that engine only and now they have you over a barrell. They can charge whatever they want.
They will fight electric tooth and nails. GE, RR, P&W will bring out everything they got and the FAA and EASA will listen. The revolution will not happen within the "big" industry, military or certified planes, it will happen with the grassroots, EAA, homebuilts and nutjobs in sheds. Just like it's always done - you look at most big inventions in the flying industry and it's almost always from the small enthusiasts and tinkerers in garages. There would be no composite 787 Dreamliner without the Windecker, there would be no B2 Stealth Bomber without the Horten brothers etc, etc.
Let's aim for 160 hp. A brushless motor for a C172 would weigh about 15kg (yes, the deliver about 7-10Kw/Kg). A generator that could provide such power would weight about the same (as a motor is a generator in reverse), so add another 15kg. Add electronic controls for both and you have maybe 10kgs on top of that. How much does a gas turbine weigh that can produce about 160 shaft horsepowers? Well, the venerable helicopter turbine the Allison C18 delivered 317 shp on 70kg (140lbs), which would make it a fair assumption that half that power output could reduce the weight to about 50kgs. Let's add it up: 15+15+10+50=90kg. Now, that's less than any combustion engine.
So why isn't this available?
Well, you could as well ask yourself why a PT6 costs 10 times more than a combustion engine when it's simpler and cheaper to manufacture? Nothing makes sense in aviation, that's why. No normal amounts of logic apply, because the regulatory organs have a stranglehold on the market. It's an oligopoly. Want an alternative to that PT6 in your TBM? You're out of luck - it's been certified with that engine and that engine only and now they have you over a barrell. They can charge whatever they want.
They will fight electric tooth and nails. GE, RR, P&W will bring out everything they got and the FAA and EASA will listen. The revolution will not happen within the "big" industry, military or certified planes, it will happen with the grassroots, EAA, homebuilts and nutjobs in sheds. Just like it's always done - you look at most big inventions in the flying industry and it's almost always from the small enthusiasts and tinkerers in garages. There would be no composite 787 Dreamliner without the Windecker, there would be no B2 Stealth Bomber without the Horten brothers etc, etc.
Last edited by AdamFrisch; 15th Mar 2011 at 23:36.
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Adam - there is no such thing as an 'efficient' gas turbine. They are used in aircraft due to very high power to weight ratios - exactly the opposite to electrical power!!!!
The specific fuel consuption of gas turbines is terrible, the numbers give you a clue gas turbine around 0.8 lbs/hp hr, a petrol engine 0.4 and diesel 0.32 - the basic thermodynamic cycles that these engines use predetermine these 'efficiencies' and wishful thinking will never outdo physics.
People who actually understand these things are the main reason why some of these outlandish ideas have not seen the light of day.
LArgely I~ would agree that the 'Pious' is largely a confidence trick. If Toyota had genuinely wanted to advance the state of the art it would have been diesel powered. But it was aimed squarely at the US market - where cars are petrol powered and so the marketing people waved its partially green credentials and the somewhat gullible public bought them - giving them fuel consumption almost as good a a standard diesel car........
Why do turbines cost so much? Try the engineering and materials. There will never be a 'cheap' turbine. Removing them from the aeronautical industry would help but in essensce most of a turbine needs to be made from very high specification materials and the slightest design or operational error reduces them to scrap - a massive difference to cast iron and standard aluminium alloys.
The specific fuel consuption of gas turbines is terrible, the numbers give you a clue gas turbine around 0.8 lbs/hp hr, a petrol engine 0.4 and diesel 0.32 - the basic thermodynamic cycles that these engines use predetermine these 'efficiencies' and wishful thinking will never outdo physics.
People who actually understand these things are the main reason why some of these outlandish ideas have not seen the light of day.
LArgely I~ would agree that the 'Pious' is largely a confidence trick. If Toyota had genuinely wanted to advance the state of the art it would have been diesel powered. But it was aimed squarely at the US market - where cars are petrol powered and so the marketing people waved its partially green credentials and the somewhat gullible public bought them - giving them fuel consumption almost as good a a standard diesel car........
Why do turbines cost so much? Try the engineering and materials. There will never be a 'cheap' turbine. Removing them from the aeronautical industry would help but in essensce most of a turbine needs to be made from very high specification materials and the slightest design or operational error reduces them to scrap - a massive difference to cast iron and standard aluminium alloys.
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Any new technology is not going to be perfect right off the bat.
Maybe somebody will invent something but you are looking at totally blue sky research. It might happen tomorrow, in 100 years, or never.
The electric motor drive train has not been an issue and could have been done decades ago (brushless motors with AC drives have been around for yonks, with the electronics gradually getting a little better). The obvious formula is a motor per wheel but mounted inboard of the drive shaft to avoid the unsprung weight. The rest is just straight electronics.
The lesser issue is that the electricity grid would not be able to cope if all normal cars suddenly went electric. But at least there are obvious (if hugely expensive) ways to solve that one... but I bet you that electricity prices would go through the roof; they would have to increase by 5x to 10x to match the cost of petrol or diesel, and that would be done by sticking a huge tax on it. But this would be tricky because it would make household electricity very expensive. But the govts would have no option because they need the tax from people driving around.
The Prius is a crap car and a straight diesel car would be every bit as economical, and a lot cheaper to make and buy.
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I know they're inefficient, but the way things are going with 100LL availability and pricing, it will end up being cheaper. Any hybrid solution is going to involve some sort of turbine until power storage gets there.
a SMALL 275 HP engine? You US'ans really must have a different vocabulary. My BIG campervan has a BIG 2,8 litre diesel engine producing just a meagre 128 HP - how's that for small?
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Wing tip generators re-capturing the vortex energy and turning it into electricity.....yea right, something for nothing, perpetual motion sir?, well of course, please invest 10 million and we guarantee your place in the future fantasy-marketing cr@p, americans just love it
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My problem with the Prius is not the MPG savings, urban yes it maybe better, highway MPG theres bugger all difference.
The issues is ethos around the thing, its the idea that its planet saving technology. its bollox the Prius is a giant marketing ploy pulling on the guilty heart strings of over consumers.
The Nickel used to make the battery is far more harmful to the environment than the emissions from a diesel! it would be more environmentally sound to buy a Hummer. and what do you do with it when the cars life is over, leave out in the rain to dissolve like a berocca? give it to the magic recycling pixies?
Totally off thread but people really need to experience the pitfalls of things like like solar energy before evangelising it. i deffinately use it it and i know its limitations.
The issues is ethos around the thing, its the idea that its planet saving technology. its bollox the Prius is a giant marketing ploy pulling on the guilty heart strings of over consumers.
The Nickel used to make the battery is far more harmful to the environment than the emissions from a diesel! it would be more environmentally sound to buy a Hummer. and what do you do with it when the cars life is over, leave out in the rain to dissolve like a berocca? give it to the magic recycling pixies?
Totally off thread but people really need to experience the pitfalls of things like like solar energy before evangelising it. i deffinately use it it and i know its limitations.
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My problem with the Prius is not the MPG savings, urban yes it maybe better, highway MPG theres bugger all difference.
The issues is ethos around the thing, its the idea that its planet saving technology. its bollox the Prius is a giant marketing ploy pulling on the guilty heart strings of over consumers.
The Nickel used to make the battery is far more harmful to the environment than the emissions from a diesel! it would be more environmentally sound to buy a Hummer. and what do you do with it when the cars life is over, leave out in the rain to dissolve like a berocca? give it to the magic recycling pixies?
Totally off thread but people really need to experience the pitfalls of things like like solar energy before evangelising it. i deffinately use it it and i know its limitations.
The issues is ethos around the thing, its the idea that its planet saving technology. its bollox the Prius is a giant marketing ploy pulling on the guilty heart strings of over consumers.
The Nickel used to make the battery is far more harmful to the environment than the emissions from a diesel! it would be more environmentally sound to buy a Hummer. and what do you do with it when the cars life is over, leave out in the rain to dissolve like a berocca? give it to the magic recycling pixies?
Totally off thread but people really need to experience the pitfalls of things like like solar energy before evangelising it. i deffinately use it it and i know its limitations.
Also, car batteries are recycled (and all batteries should be recycled).
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Hi!
The electric Skyhawk is planned to fly for 2 hrs, seat only two people, and be used almost exclusively for flight training. In flt training, most of the flights are out and back, and ususally .9-1.5 hour sorties.
The batteries will either be able to be recharged in the time it takes to debrief and brief a student, and/or they will be set up for a battery swap, which will take about 10" or so.
The electric motor, and associated accessories, are MUCH less weight than the comparable ICE equipment. The electric plane won't need the tanks and fuel. It, obviously, will need a battery. The solar cells on the wings, which won't be on the earlier models and/or will be an option, will help recharge the battery.
They picked the -172 because it is the most popular trainer. When you need to overhaul the ICE powerplant, you swap it out for the electric motor.
For those of you who feel it is a pipedream, there were many, many carriage and horse-type people who knew that the new "horseless carriage" would never take off: For example, they were too difficult to operate, they were loud, dirty and stinky, there was no where to drive them (not enough suitable roads), there was no where to maintain them, and there were no places to refuel them. Because of the lack of infrastructure, and the fact that it was a new technology, many, many people were 100% sure that the automobile would never take the place of the horse carriage.
cliff
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The electric Skyhawk is planned to fly for 2 hrs, seat only two people, and be used almost exclusively for flight training. In flt training, most of the flights are out and back, and ususally .9-1.5 hour sorties.
The batteries will either be able to be recharged in the time it takes to debrief and brief a student, and/or they will be set up for a battery swap, which will take about 10" or so.
The electric motor, and associated accessories, are MUCH less weight than the comparable ICE equipment. The electric plane won't need the tanks and fuel. It, obviously, will need a battery. The solar cells on the wings, which won't be on the earlier models and/or will be an option, will help recharge the battery.
They picked the -172 because it is the most popular trainer. When you need to overhaul the ICE powerplant, you swap it out for the electric motor.
For those of you who feel it is a pipedream, there were many, many carriage and horse-type people who knew that the new "horseless carriage" would never take off: For example, they were too difficult to operate, they were loud, dirty and stinky, there was no where to drive them (not enough suitable roads), there was no where to maintain them, and there were no places to refuel them. Because of the lack of infrastructure, and the fact that it was a new technology, many, many people were 100% sure that the automobile would never take the place of the horse carriage.
cliff
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I think the evangalists need to be careful with their historical 'learnings'.
The reason technologies like the motor car and internal combustion in general advanced as rapidly and as far as they have is because technology 'savvy' people could see those nascent technologies offered great potential.
They meant that greater power, less weight, more speed etc were potentially on offer.
The situation with all 'green technology' is fundementally different. In the vast majority of cases large costs and other significant disadvantages means that the 'green' version will under perform the present situation until there is either a massive technical breakthrough or legislative or some other external influence.
In short it is the Prius argument - it looks good for the planet but actually it is not green, it promises fuel economy but does not delivery, it is not genuinely sustainable - it is marketing.
I know a chap with an electric glider - it is a thing of beauty - the best our technology can offer at the moment. It self launches and can climb to 3000m - once. It can give full throttle for 13 minutes - after which it can 'self sustain' for maybe another 10 - if the cells recover. He has had some problems with the cells but loves the idea of the machine.
List price is just short of $300,000 so it carries some pretty significant downsides. Incidentally the manufacturers say there is no point in using solar cells to increase the self sustaining mode - too heavy, too little power......
The reason technologies like the motor car and internal combustion in general advanced as rapidly and as far as they have is because technology 'savvy' people could see those nascent technologies offered great potential.
They meant that greater power, less weight, more speed etc were potentially on offer.
The situation with all 'green technology' is fundementally different. In the vast majority of cases large costs and other significant disadvantages means that the 'green' version will under perform the present situation until there is either a massive technical breakthrough or legislative or some other external influence.
In short it is the Prius argument - it looks good for the planet but actually it is not green, it promises fuel economy but does not delivery, it is not genuinely sustainable - it is marketing.
I know a chap with an electric glider - it is a thing of beauty - the best our technology can offer at the moment. It self launches and can climb to 3000m - once. It can give full throttle for 13 minutes - after which it can 'self sustain' for maybe another 10 - if the cells recover. He has had some problems with the cells but loves the idea of the machine.
List price is just short of $300,000 so it carries some pretty significant downsides. Incidentally the manufacturers say there is no point in using solar cells to increase the self sustaining mode - too heavy, too little power......
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A battery powered C172 may well work for 1hr training flights in the battery endurance sense.
However the overall economics will be a different thing. Nobody has got anywhere near 1000 cycles especially with rapid charging. Anybody with experience of laptops, model planes, etc, will know this. You get 100-200 cycles out of a LIPO battery and it is going downhill. And this battery won't be a £100 LIPO
It will cost many thousands. The real life will be a major cost factor.
The motor and control electronics are relatively trivial and could have been done 20 years ago in pretty much the same way as today. But even there, the reliability won't be 100%. It could be very high indeed, but there is very little electronics expertise in GA today. It looks like the combined might of Lycoming manages to knock up an electronic ignition box not incomparable to ones I used to build for Yamaha bikes in the 1970s.
If I was running a school I would look at this seriously but only on a "pay per flying hour" basis so the vendor would be forced to back up his battery life and other claims. After the Thielert fiasco, I can't see any flying school owner doing much else...
However the overall economics will be a different thing. Nobody has got anywhere near 1000 cycles especially with rapid charging. Anybody with experience of laptops, model planes, etc, will know this. You get 100-200 cycles out of a LIPO battery and it is going downhill. And this battery won't be a £100 LIPO
It will cost many thousands. The real life will be a major cost factor.The motor and control electronics are relatively trivial and could have been done 20 years ago in pretty much the same way as today. But even there, the reliability won't be 100%. It could be very high indeed, but there is very little electronics expertise in GA today. It looks like the combined might of Lycoming manages to knock up an electronic ignition box not incomparable to ones I used to build for Yamaha bikes in the 1970s.
If I was running a school I would look at this seriously but only on a "pay per flying hour" basis so the vendor would be forced to back up his battery life and other claims. After the Thielert fiasco, I can't see any flying school owner doing much else...
Battery technology is predicted to continue to increase. Boeing believe this and have scetched out some ideas for an electric motor assited turbo-prop, subject to a massive step change in battery efficiency.
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subject to a massive step change in battery efficiency.
A 1000HP 3-phase brushless motor is tiny. At a guess, about 1ft long and 2ft diameter if you want a low-RPM direct-drive solution. Weight perhaps 50-100kg (i.e. a fraction of a PT6).
The controller would be about 1ft cube; weight about 10kg.
Just need a battery................
Oh BTW you will need one other thing in the long term, to generate the electricity if this idea becomes popular:
Nuclear fusion
Actually that will prob99 come, within our lifetimes. It already works, for a short while.
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A battery powered C172 may well work for 1hr training flights in the battery endurance sense.
Assume a C172 that's normally running on a 160 HP engine, at 70%. One HP = ~750 W. So in one hour, this aircraft uses 160 * 70% * 750 = 84 kWh. (Maybe a little less because of increased efficiency. But that doesn't change the discussion significantly.)
This energy needs to be replenished somehow. A typical European circuit can deliver 240V at 16A, which is 3.8 kW. This means that recharging that aircraft using a normal circuit will take a little over 22 hours.
So in essence, with that setup, the flight school can squeeze a single flight out of that airframe on any given day. Assuming they max out the 240V circuit for the rest of the day to recharge the aircraft.
Of course that's not a setup that's practical. But you need the equivalent of 22 average household circuits, all maxed out, to get a more-or-less workable charge rate of about one hour for each flight hour - assuming your batteries can charge that fast.
10 aircraft charging simultaneously and you're looking at values approaching one Megawatt. That's the unit that we normally express powerplant capacities in. (Fukushima Unit 1 was 460 MW, to give you an idea.)
As others have said, before electric flight really takes off, there are a few things that need to happen:
- Battery storage capacity needs to improve significantly
- The power grid needs to be upgraded significantly
And even then I think automotive technology is going to reap the rewards first, and aviation last.
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Just a thought for those who equate electric power with milk floats and mobility scooters.
The fastest lap time round the Isle of Man TT course on an electric motorbike is I believe 94.7 mph.
And I've got a little £40 battery powered model helicopter which I'm sure would have been impossible to build at any price 25 years ago.
Electric devices are getting much better very quickly. But where will all the "clean" electricity come from? Errrrrrrrrr......
The fastest lap time round the Isle of Man TT course on an electric motorbike is I believe 94.7 mph.
And I've got a little £40 battery powered model helicopter which I'm sure would have been impossible to build at any price 25 years ago.
Electric devices are getting much better very quickly. But where will all the "clean" electricity come from? Errrrrrrrrr......
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A typical European circuit can deliver 240V at 16A, which is 3.8 kW. This means that recharging that aircraft using a normal circuit will take a little over 22 hours.
) which I wired up for a 3-phase swimming pool heat pump, and some other stuff. The company charged about £800 for bringing in 3 x 35mm2 cable which was good enough for at least 100A per phase, so that's 72kW. In fact I recall allowing for a 40kW 3-phase pool heater, and some other stuff; on Economy 7 this was not much dearer than oil which was the only other option. They installed a 3 phase electricity meter for free. The quarterly rental was the same, as Seeboard did not have a 3 phase domestic tariff The cost per kWh was the same too (they obviously hoped you would buy lots of them ).So I think, in a city scenario, 100kW is really easy.
Out in the sticks, miles from nowhere, it would be expensive (5 figures+ perhaps) but not much training takes place from remote strips.
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I recently saw some marketing material, presumably the sort that has been used to persuade my very own government of the value of electric cars. I seem to recall that it suggested there is a payoff in favour of electric cars if you assume that the regular sort get about 35-40mpg at best.
(Let me at this point say I'm a total amateur in this area, so treat my comments accordingly)
I drive an unmodified 2005 Peugeot 307 HDI Sport. I'm one of these nerds that actually knows what mileage I get, and keeps a close eye on it. I get 54mpg in the city, and at least 63mpg out of town - yes, it beats a Prius by a substantial margin in both environments :-)
Not that I don't like the idea of electric transport - I do, and I'd love an electric car and matching aeroplane. I just think the hype is a bit ahead of reality at the moment.
(Let me at this point say I'm a total amateur in this area, so treat my comments accordingly)
I drive an unmodified 2005 Peugeot 307 HDI Sport. I'm one of these nerds that actually knows what mileage I get, and keeps a close eye on it. I get 54mpg in the city, and at least 63mpg out of town - yes, it beats a Prius by a substantial margin in both environments :-)
Not that I don't like the idea of electric transport - I do, and I'd love an electric car and matching aeroplane. I just think the hype is a bit ahead of reality at the moment.