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Electric powered commercial aircraft -- here we go!

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Electric powered commercial aircraft -- here we go!

Old 24th Dec 2019, 06:32
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Not Electric or wind

Originally Posted by Ancient Mariner
LNG, electric and hybrid in operation, autonomous being built right now, wind assisted tested. Then we'll see.
Per
for large cargoships batteries are not an option too heavy and expensive. The only financially viable option is new fuels for large two stroke engines lng, lpg, methane, even emulsified fuels with up to 70% water will be possible, hydrogen is also an option. Wind will only ever be a supplement.
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Old 24th Dec 2019, 08:59
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Have seen a few of these large parasails in use........



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Old 25th Dec 2019, 12:51
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Originally Posted by ETOPS
Have seen a few of these large parasails in use........


An example of a supplement, this is only a relatively small ship no more than 20000 tdw
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Old 25th Dec 2019, 15:22
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What could have been, unfortunately killed off before it caught on. would this technology cross over?
Volkswagen’s XL1 hybrid.
https://www.thedrive.com/sheetmetal/...les-per-gallon
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Old 25th Dec 2019, 21:34
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Originally Posted by cappt
What could have been, unfortunately killed off before it caught on. would this technology cross over?
Volkswagen’s XL1 hybrid.
https://www.thedrive.com/sheetmetal/...les-per-gallon
I don't think car hybrids have got very much to do with aviation. I sit in my Nissan Note serial hybrid and glance happily at the gauge showing the battery recharging as I coast down a hill or slow to a stop at the traffic lights, and that's where most of the efficiency comes from: there isn't really anything like that in aviation. Electric motors have lots of advantages, some of which probably would apply in aircraft, and there might be wins in a hybrid configuration from having a reservoir of electric power (battery or capacitor) for peak loads, but not the big advantage of regenerative braking in city driving (hybrids are not any more efficient than ICEs at steady-speed highway cruising, which is a better analogy to most aviation). Also, that VW prototype applies standards of light-weight construction and aerodynamics which are already in use in aircraft design.

Further, solar panels are not going to make a big contribution. I gather that NASA estimates the total solar power available at the "top of the atmosphere" (this is a quick google-search, so I don't know exactly what height that is, but presumably above normal flight altitude) as 1,360 Watts per square metre. Just for a quick guide to the limits, I worked out a solar panel DC-3 replacement. The DC-3 has a wing area (according to Wikipedia) of 91.7 square metres, so the maximum available solar power, if the whole of the upper wing surface is harvesting power, is about 125kW. The engines on a typical DC-3 are rated at 1,200 hp each = 890 kW. I believe an assumption of 65% power for the cruise is reasonable, which means the venerable aircraft, flying much slower than modern airliners, is using 1,157 kW. So the available energy is less than the needed energy by an order of magnitude even before beginning to account for losses. The 1.36 kW per square metre is available energy: the best panels at the moment would only actually gather about 25% of that, and then there would be other losses in the motor(s) and transmission. Oh, and this is only for daytime operations, too, which might be a further problem.

It looks like aviation is one of those areas where there is no alternative to fossil fuels except for synthetic hydrocarbons made in a carbon-neutral way, or just maybe hydrogen. Making synthetic aviation fuel would be an inefficient way of using sustainable power (wind, solar, hydro, geothermal, nuclear, whatever), but sometimes you have to accept inefficiency, and the power might be used in a form of load spreading.

The consequence of this is that the aviation industry and its supporters should not be engaged in climate change denial (which only encourages the flight-shamers), but instead should be making the case for aviation as a (temporary) special case, while at the same time investing heavily in realistic sustainable alternatives that are not defeated from the start by physical constraints. The sad present state of the Boeing company shows the consequences of short-termist denial of social responsibility.
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Old 25th Dec 2019, 21:42
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Any sort of hybrid system is of minimal benefit on an aircraft and probably not worth the weight. The big advantage of hybrid for cars (and trucks) is regenerative braking - eliminating much of the penalty in stop/go driving. Any use of the friction brakes is lost efficiency that you can't get back.
Aircraft use a lot of energy climbing to cruise altitude, but they get most of that back when they throttle back for descent. If properly planned, very little fuel is used in the last ~100 miles of a typical flight since the engines are at idle from top of descent until they start setting up for approach and landing. The only time regenerative braking could be used is during landing, and the potential energy recover is too small to compensate for the weight of the needed hardware on any but the shortest range flights.

Bottom line, unless there is massive breakthrough in battery energy density, aviation will remain dependent on hydrocarbon based fuels for other than short range operations (hydrogen is light, but it's energy density is horrible - combined with it's inherent packing difficulties it's also unsuitable for long range aircraft). We might be able to make the hydrocarbon based aviation fuels renewable and carbon neutral, but there is no current or foreseeable technology that has the realistic ability to replace it.

Edit: I see Flightless Parrot has posted pretty much the same thing while I was composing mine.
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Old 26th Dec 2019, 19:26
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Originally Posted by FlightlessParrot
I don't think car hybrids have got very much to do with aviation. I sit in my Nissan Note serial hybrid and glance happily at the gauge showing the battery recharging as I coast down a hill or slow to a stop at the traffic lights, and that's where most of the efficiency comes from: there isn't really anything like that in aviation. Electric motors have lots of advantages, some of which probably would apply in aircraft, and there might be wins in a hybrid configuration from having a reservoir of electric power (battery or capacitor) for peak loads, but not the big advantage of regenerative braking in city driving (hybrids are not any more efficient than ICEs at steady-speed highway cruising, which is a better analogy to most aviation). Also, that VW prototype applies standards of light-weight construction and aerodynamics which are already in use in aircraft design.

Further, solar panels are not going to make a big contribution. I gather that NASA estimates the total solar power available at the "top of the atmosphere" (this is a quick google-search, so I don't know exactly what height that is, but presumably above normal flight altitude) as 1,360 Watts per square metre. Just for a quick guide to the limits, I worked out a solar panel DC-3 replacement. The DC-3 has a wing area (according to Wikipedia) of 91.7 square metres, so the maximum available solar power, if the whole of the upper wing surface is harvesting power, is about 125kW. The engines on a typical DC-3 are rated at 1,200 hp each = 890 kW. I believe an assumption of 65% power for the cruise is reasonable, which means the venerable aircraft, flying much slower than modern airliners, is using 1,157 kW. So the available energy is less than the needed energy by an order of magnitude even before beginning to account for losses. The 1.36 kW per square metre is available energy: the best panels at the moment would only actually gather about 25% of that, and then there would be other losses in the motor(s) and transmission. Oh, and this is only for daytime operations, too, which might be a further problem.

It looks like aviation is one of those areas where there is no alternative to fossil fuels except for synthetic hydrocarbons made in a carbon-neutral way, or just maybe hydrogen. Making synthetic aviation fuel would be an inefficient way of using sustainable power (wind, solar, hydro, geothermal, nuclear, whatever), but sometimes you have to accept inefficiency, and the power might be used in a form of load spreading.

The consequence of this is that the aviation industry and its supporters should not be engaged in climate change denial (which only encourages the flight-shamers), but instead should be making the case for aviation as a (temporary) special case, while at the same time investing heavily in realistic sustainable alternatives that are not defeated from the start by physical constraints. The sad present state of the Boeing company shows the consequences of short-termist denial of social responsibility.
"The real downside of biofuel for aircraft is the amount of arable land that would have to be taken away from growing food crops to provide the materials for biofuels.
Fuel consumption for international aviation could be as high as 852 million tonnes (Mt) by 2050 (ICAO, 2016), and could require 426 Mt of bio-jet to meet the GHG emissions-reduction goals. Current production, however, is currently very limited, at less than 0.1% of global total consumption of all types of jet fuels."
Foillowing is a goto to a paper on the subject: https://www.irena.org/documentdownlo...ation_2017.pdf
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Old 26th Dec 2019, 19:48
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It could be done partly by biofuels but is much more likely to be done by reforming other fuels, the Nazis did it on a large scale in the 1940s, it would of course be much more expensive which would make air travel less attractive. There is not likely to be the travel options we have today, the lifestyles of future generations are going to change a great deal
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Old 27th Dec 2019, 03:53
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Originally Posted by Longtimer
"The real downside of biofuel for aircraft is the amount of arable land that would have to be taken away from growing food crops to provide the materials for biofuels.
Fuel consumption for international aviation could be as high as 852 million tonnes (Mt) by 2050 (ICAO, 2016), and could require 426 Mt of bio-jet to meet the GHG emissions-reduction goals. Current production, however, is currently very limited, at less than 0.1% of global total consumption of all types of jet fuels."
Foillowing is a goto to a paper on the subject: https://www.irena.org/documentdownlo...ation_2017.pdf
Biofuel seems likely not to be a good idea. But the use of sustainable power and commonly available substances to manufacture hydrocarbons seems more open to technological development than electric power by batteries.
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Old 27th Dec 2019, 09:13
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Maybe von Zeppelin got it right. RIGID airships, not blimps. Solar panels across the top, power only required for propulsion. (standing by for flak)
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Old 27th Dec 2019, 09:51
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If in any doubt...

Fuel / Energy by mass (Wh/kg)
Hydrogen (350 bar) / 39,300
Gasoline, diesel, natural gas (250 bar) / 12,000–13,000
Body fat / 10,500
Black coal (solid), Methanol / 6,000–7,000
Wood (average) / 2,300
Lithium-ion battery / 100–250
Lead acid battery / 40
Compressed air / 34
Supercapacitor / 5
Table 2: Energy densities of fossil fuel and batteries.

Source: https://batteryuniversity.com/learn/..._an_ev_battery
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Old 27th Dec 2019, 10:10
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https://www.youtube.com/watch?v=Mb_8DJF6Hp0&t=112s

We wont need fossil fuel in the near future.
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Old 27th Dec 2019, 10:45
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Originally Posted by cattletruck
Interesting use of figures in that article, graph shows volume of H2 plus tank.
Table just shows energy per weight of fuel ignoring the weight of the tank.

An A size cylinder (180 Bar) weighs ~ 50kg and contains 43.9 L of H2 (STP) which is 4gm so cylinder is ~ 12,500 times the weight of the H2

From stuff I did on large CH4 tanks you can do a lot better if the tanks are not thrown around like cylinders are but you would still be looking at least 100 times the weight of the hydrogen. Two points to note:
- Up the pressure and the thickness (weight) of steel goes up in proportion
- The steels required aren't cheap moreso for Aluminium, Kevlar etc

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Old 27th Dec 2019, 11:24
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Originally Posted by Herod
Maybe von Zeppelin got it right. RIGID airships, not blimps. Solar panels across the top, power only required for propulsion. (standing by for flak)
Not wishing to attack, just exploring the limits of physical possibility.

Hindenburg: Wikipedia figures are 245m length, 41.2m diameter. The square box that encloses those dimensions has an area of 10,290 sq. m. Taking the NASA figure for insolation, far higher than airships flew, as 1,360 W gives a maximum available power of 13,994 kW. Hindenburg had installed power rated at 4 x 890 kW: take a cruise power output of 2,500 kW. Taking into account all the gross rounding errors in that approximation, and a 25% efficiency of the solar panels, and ignoring the extra weight of the panels, it is just about within the limits of physical possibility in the brightest daylight. Which is a hell of a lot better than comparable calculations for aerodynes, but still adds a further dimension of marginality to a highly marginal mode of transport. Alas. I could really get behind the idea of travelling at a stately 150-200 kph in a solar powered airship, but I don't think it's going to happen.
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Old 27th Dec 2019, 14:33
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Originally Posted by tdracer
Any sort of hybrid system is of minimal benefit on an aircraft and probably not worth the weight. The big advantage of hybrid for cars (and trucks) is regenerative braking - eliminating much of the penalty in stop/go driving. Any use of the friction brakes is lost efficiency that you can't get back.
Aircraft use a lot of energy climbing to cruise altitude, but they get most of that back when they throttle back for descent. .... The only time regenerative braking could be used is during landing, and the potential energy recover is too small to compensate for the weight of the needed hardware on any but the shortest range flights.
About 10 years ago, the German LSA manufacturer presented a hybrid Rotax 912 + electric motor/generator combination. The latter would generate an additional 40 hp for take-and climb, and function as a generator during descents. I believe it was also flown, but don't know why the project was apparently discontinued. Now, when you think how far battery technology has come in the last ten years?

https://www.google.de/url?sa=t&rct=j...IQC80m9FDoBeqY
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Old 27th Dec 2019, 18:11
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Lightbulb Don't they call that . . . . .

Originally Posted by EDMJ
About 10 years ago, the German LSA manufacturer presented a hybrid Rotax 912 + electric motor/generator combination. The latter would generate an additional 40 hp for take-and climb, and function as a generator during descents. I believe it was also flown, but don't know why the project was apparently discontinued. Now, when you think how far battery technology has come in the last ten years?
And the generator re-charged the batteries when descending too, so it could go on up and down for ever !
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Old 27th Dec 2019, 21:59
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A very elegant solution to climate change if they can make the chemistry work on a large scale
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Old 27th Dec 2019, 22:09
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Originally Posted by EDMJ
About 10 years ago, the German LSA manufacturer presented a hybrid Rotax 912 + electric motor/generator combination. The latter would generate an additional 40 hp for take-and climb, and function as a generator during descents. I believe it was also flown, but don't know why the project was apparently discontinued. Now, when you think how far battery technology has come in the last ten years?

https://www.google.de/url?sa=t&rct=j...IQC80m9FDoBeqY
That's the sort of use that might be possible: specify an ICE with just enough power for cruise, and use electrical storage for peak power demands. It might or might not turn out to be a win, depending on specifics, but the fact that this project, at the right scale for trials, was discontinued, is suggestive.

On the ground, electric is great for cutting carbon emissions: in the air, alternative solutions are necessary.
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Old 29th Dec 2019, 13:04
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A very interesting video. I have no doubt that the future for aircraft is biofuel, not electric. However, apart from the obvious question of cost there is the problem that jet fuel is much harder to synthesise than motor fuel being a blend of many types of hydrocarbons. It ought, however be possible to synthesise each of these and then blend them. How long will it take to do this at a large scale and more important take to do it at an acceptable cost? I suspect decades. If, however, it were given the urgency of the moon programe in the 70s, well within the next decade?

I did a doodle and calculated that at a 6% conversion rate the sunlight hitting 1 sq km of land could produce around 7,000 tonnes of biomass per year. Obviously some would be lost in conversion but if we could end up with 5,000 tones / km^2 / year we could solve both our energy and greenhouse gas problems. Algae farms in the sea or in the Arabian desert?

Last edited by Pilot DAR; 29th Dec 2019 at 16:09. Reason: fixed typo
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Old 29th Dec 2019, 20:33
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As land transport becomes electrified in the next few decades, that will free up fossil fuels for aircraft use, so we are looking a long time into the future. The technology exists now to reform using renewable or nuclear power any carbon compound into liquid hydrocarbons, the only obstacle is economics.

Carbon capture from the atmosphere, is new technology, air contains around 400ppm CO2, so 2500CuM of air has to be moved to move 1CuM CO2, the power needed to do that produces its own heat, used on a large scale might well be self defeating. It will certainly be massively costly, in fact it may well cost less to plant trees to achieve the same result.
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