Captain Piccard's planet-orbiting solar aircraft in warped drive drama An airplane powered by nothing more than the Sun's rays has completed its 42,000-km (26,098-mile) journey around the world after landing in Abu Dhabi on Tuesday. The Solar Impulse 2, piloted by Bertrand Piccard for its final leg, made the trip in 17 legs, flying around the Northern hemisphere with stops in nine countries. Its …
It won't replace 787's or whatever is plying the skies these days, but it's a start, and new technology has to start somewhere.
How long did it take for planes to replace ships for long distance travel? My Dad emigrated to New Zealand from the UK on a ship in the 1950's, so at least 50 years.
It's a dead end. The air transport industry we currently have only works through a combination of the energy density of kerosene, the efficiency of jet engines at the end of a nearly 80 year development cycle, and similar improvements in the application of aerodynamic design.
Electric aircraft have to replicate that. They will benefit from the aerodynamic advances, but we must be getting reasonably asymptotic on that. Energy will still need to be stored as we can probably only expect a factor of 2 or 3 improvement in solar cell energy conversion and we fly at night. So we need a big step in battery energy density. Plus either an incredibly fast charge process (2 nuclear power stations at Heathrow), or a quick battery swap-out process and a slower recharge (1 nuclear power station at Heathrow)
Then how do we make an 'electric jet engine'? I guess the technique would be to replace the jet core in a high-bypass turbofan (e.g. Trent 900) with a similarly specified electric motor (about 56 MW at takeoff).
Stick with the kero & manufacture it from CO2, H2O and nuclear energy when the oil & gas runs out.
Re the electric Hi-bypass fan, Rolls-Royce are investigating just this idea in relation to an hybrid propulsion system, with Airbus. In this approach a gas turbine powered generator produces electricity which is used by the electric fans.
Whether this actually comes about is another question.
"It's a dead end. The air transport industry we currently have only works through a combination of the energy density of kerosene, the efficiency of jet engines at the end of a nearly 80 year development cycle, and similar improvements in the application of aerodynamic design."
I think a lot of commentards here are missing the point of what Mr. Piccard is saying - it's not that in 10 years time we'll all be flying merrily round the world in solar powered jet aircraft, but that in the next decade or so battery mass & efficiency will be at a point where smaller, electric propellor powered aircraft will start to become commercially viable.
I think you're absolutely right in that the development of electronically powered jet turbine engines will take decades, as will the development of electronic storage with enough energy density and robustness to carry hundreds of people across the Atlantic, but its precisely by flying round the world in a solar powered aircraft that we learn about the technologies required e.g. how not to 'cook' the batteries as happened with the Solar Impulse 2 and which grounded it last year. Don't forget, electric microlight aircraft are already in the air, electric aircraft will just get bigger over time as electronic storage and lightweight material technology improves.
And to change the subject completely, I'm sure I'm not the only one who hopes that at some point in the flight, Captain Piccard uttered the words "Make it so..."
"in the next decade or so battery mass & efficiency will be at a point where smaller, electric propellor powered aircraft will start to become commercially viable."
You'd need a factor of 5-10 improvement in battery energy density to make this viable. That's probably more than is physically possible, even if you use flow batteries. One of the reasons airliners can fly more than a few hundred miles is because they don't have to carry their own oxygen
505 days. Puh. People have 'run' around the world in 621 days.
No. Solar-powered aircraft are not the future of airliners, due to basic physics. Solar Flux, and Scaling Laws.
This stunt is similar to the Human-Powered Helicopter. "Someday soon, we will all get to work in our own Human-Powered Helicopter." Sigh...
No. Solar-powered aircraft are not the future of airliners
Orville's and Wilbur's 1903 airplane wasn't the future of airliners. Just about every engineering concept embodied in the plane was tossed out on the path to the A380 and 787. But it was an important proof of concept, just like Piccard's plane. At a minimum, it showed it could be done.
, due to basic physics. Solar Flux, and Scaling Laws.
Yes, that's true. But the future of high-endurance solar-powered heavier-than-air flight isn't necessarily in airliners.
Hmmn.. the only heavier than air aircraft I can see maybe going all-electric for its propulsion is something like the Skycat, a Hybrid Air Vehicle, which gets some of its lift from helium, some from its steerable fans, and the rest from the aerofoil shape of its envelope. Cover the upper surface of a Skycat with solar panels and you might get enough power to be worthwhile with next generation solar cells and power storage.
I still uspect the way to go in the forseeable would be with synthetic petrol/avgas made by recycling atmospheric CO2, unless some kind of system that stores as much enrgy per unit volume as petrol does and is less polluting than current batteries are is developed.
It is for autonomous and continuous craft.
I'll sorta buy that. It's more likely that a uav (hence no need for pilot safety & life support stuff) could be engineered within current & <10yr future constraints. That's OK for mapping/surveillance but wifi/tv transmitters will rapidly eat into the power budget. There is still the issue of energy to manufacture solar cells (and batteries) but that's the price to pay if the business benefits outweigh that.
Add to that for charging the batteries on the ground before take-off if for no other reason than to take-off and run into cloudy weather. Wouldn't want to do that with low battery power.
Actually, this type of plane might well work for private aviation and small, charter firms. I can't see a scheduled airline using them until there's some advancements to make them all-weather aircraft.
It's not just the disposal, Sebastian. The EROEI (energy return on energy invested) of solar cells operating at temperate latitudes (like the UK) is negative - that is, the energy generated during their working life is only ~83 % of the energy consumed during their manufacture.
You can think of solar cells in the UK as giant batteries, charged up (most probably in China, using coal and oil) and then gradually releasing their stored energy as the sun shines. So not very good at reducing CO2 emissions, but very effective at transferring money to wealthy landowners from those in fuel poverty.
"Halve the CO2 emissions, sure, until the time comes to dispose of end-of-life solar panels."
And by not taking into account the environmental and/or CO2 costs of making the things.
(You can reduce CO2 by polluting, as is happening in china. Cleaning up the byproducts generates even more CO2)
The key is in that last paragraph: "You may be ending your around the world flight today, but the journey to a more sustainable world is just beginning." - UN Secretary-General Ban Ki-moon
"Sustainable development", i.e. "sustainable world", is globalist speak for destroying private property rights. That means ALL private property rights from home ownership to private enterprise. See U.N. Agenda 21. Their point of view is that only global government can provide responsible management of planet's resources so they must control everything and everyone.
http://blog.heartland.org/2014/04/u-n-agenda-21-impacts-private-property-rights-and-freedom/
Think that's foolish? They have organizations all the way down to the city and county governments promoting "sustainable development". If you see any of your local government leaders promoting "sustainable development", get rid of them sooner rather than later. Many times the individuals aren't from an Agenda 21 organization but use or hire "consultants" who are. Once you start looking for it, you'll find it everywhere.
Agenda 21 is a non-binding, voluntarily implemented action plan of the United Nations with regard to sustainable development. It is a product of the Earth Summit (UN Conference on Environment and Development) held in Rio de Janeiro, Brazil, in 1992.
https://en.wikipedia.org/wiki/Agenda_21#United_States
The Republicans oppose it, so it must be dangerous!
Meanwhile: https://www.youtube.com/watch?v=wFNO2sSW-mU
Quite - but I don't expect it will be "voluntary" for the plebs upon who it is "voluntarily" inflicted by the great and the good.
cf. Blighty's Climate Change Act - voluntarily voted in by MPs, with the consequent costs inflicted on the poor (but with nice subsidies to the rich).
No we won't.
This experiment requires a 2.3-ton plane with the wingspan of an Airbus A380 to transport 2 guys and 633 kilos of lithium batteries at a speed of max 90km/h. During the night it goes slower to save on energy.
Add 50 passengers with their luggage, stewardesses and in-flight entertainment, not to mention active radar, ILS and autopilot (with the assorted computers and black boxes) and you'll need a football stadium-sized wing to just keep it in the air, to say nothing about taking off.
I salute the accomplishment. It demonstrates improvements in solar cells and is certainly a feat of engineering. But let's not get carried away, this toy is not the future.
These sort of predictions tend to extrapolate revolutionary advances in the next <insert convenient timespan> based on the Moore's law-like rapid advance we can plainly see today in aerodynamics, electric turbines, solar cells and battery technology. Commencing any second now, honest, guv. Any second...
"This experiment requires a 2.3-ton plane with the wingspan of an Airbus A380 to transport 2 guys and 633 kilos of lithium batteries at a speed of max 90km/h. During the night it goes slower to save on energy."
Luckily, not all flights require flying non-stop from Japan to Hawaii (4300 miles). Maybe, just maybe, they could swap some of those batteries for cargo/people and still do the 200 miles DC-NYC or London-Paris non-stop.
I can't remember if I read this in Accidental Empires or Where Wizards Stay Up Late but the author was telling a story about the creation of postscript. He was working with one of the men responsible for creating it. The short version is that the author kept trying to tell the other person that postscript was too complex and resource hungry to work with their computers and printers. It was only years later that he understood the other man's point that there would soon come a time when that was not the case but he had lacked the vision required to lay the foundations for that time.
I see your point about vision but I just can't accept that this technology will be ready in 25 years, certainly not in 10.
The first flight of a jet pack was claimed in the 1950s and certainly happened (tethered) in 1960. Some claimed we'd all be using them in the future but we aren't. The technology works but only at the bleeding edge. There have been small incremental improvements over the decades but a step change in fuel energy per unit mass is still needed to make it remotely practical.
Solar powered flight is the same, it works but every component is at the bleeding edge. Incremental improvements are not going to change that. If someone invents solar cells that can harvest 10x the energy for a given area and battery technology with 10x the energy storage for a given mass then it's game on. Incremental improvements every few years are not going to deliver 50 passenger aircraft in 10 years.
I agree there is going to be a long lead time but if we don't lay the ground work for replacement technologies we'll never see the improvements which are required. Even if we don't jump straight to all solar planes, they might inform the design of the next generation of planes.
"Even if we don't jump straight to all solar planes, they might inform the design of the next generation of planes."
This is the best point about all of this. Large, fully solar-powered planes are way, way off, maybe even an impossibility. But hybrid planes are a more realistic concept. Current planes spend much of their time above the cloud layer and have a large amount of real estate available on which to place solar panels. I can certainly see a future where jet-powered planes take off and reach cruising altitude, where they begin to harvest solar energy. They could then use it to boost engine performance and power the in-flight entertainment systems etc.
That may be the key. Keep the entire in flight entertainment etc running of solar and a small battery system. Could it keep weight down? Or is the petroleum equivalent just so much higher density in power storage that it negates any savings in "recharging" mid flight?
The time the craft spend taxing etc is also one to consider.
Photovoltaic is a crude, one time molecular erosion parlor trick that never recovers 10% of it's initial investment energy. PV produces 1.5 watts per sq-ft at 1.5 volts DC, great for pocket calculator, useless for grid.
One horsepower is 757 watts, or 600 sq-ft of collector. One horse power is also 550 ft-pounds, the work necessary to lift one cubic foot of dirt, four feet high. Tons of material is mined, refined, shipped, melted for the Silicon, Boron, Phosphorous to make a few solar cells.
There is NO Carbon forcing, NO 'sustainable' energy and NO 'peak' oil.
Well, no matter how reluctant I am to agree with FSS but he is right - there is no sustainable energy in the world, in principle. All energy is depleted and turns into entropy. That's why eventually there will be the Heat Death of the Universe.
If you want to fight false science, which is a worthy cause, it helps to understand the basics yourself.
Horsepower and watts are units of power, not work/energy. "the work necessary to lift one cubic foot of dirt four feet high" is, as you say, work. I guess foot-pounds is a valid way to express that, though joules is less confusable with torque. What you probably meant to say is that one horsepower is 550 foot-pounds per second.
Can someone calculate the power output of the engines on a typical 747
And compare it with the power generated by covering it with solar cells.
That should give some idea of the energy requirements and how far away they are.
That ignores the battery problem of course.
RR Trent engines >50MW, so a 747 is >200MW max power. Solar cells produce ~200W/m2, so you'd need a square km to power a 747. If you could achieve 100% efficiency at the equator, there's 1300W/m2 of sunlight available compared to just over 500m2 wing area on a 747 and you're still over two orders of magnitude short. Now, about these trans-polar routes ...
PS Hybrids work in cars, where the additional weight of the battery isn't too crucial to performance - add 20% to the weight of a car and it will still drive (possibly a bit more slowly). On an aircraft every kilo of extra weight is vital - add 20% to the weight of an airliner and it could never leave the ground. Even so, very few pure hybrids achieve better fuel efficiency than an equivalent-sized diesel powered vehicle.
"very few pure hybrids achieve better fuel efficiency than an equivalent-sized diesel powered vehicle."
In open road cruising that's true and unarguable.
For urban warrior work, it's a completely different story.
The issue with car engines (diesel or petrol) is that they only work efficiently at full load and even than that's only ~35% maximum and only when at operating temperature.
The average petrol engine runs around 2-4% efficiency most of the time and 0% when idling in traffic.
Stop/start engine technology has made quite a difference for dense urban traffic fuel consumption but in the suburbs where most runs are less than 2 miles in light traffic you can expect your 50mpg diesel to be making more like 25-28mpg (real world figures) - and BOTH these areas are where hybrids win.
Using a smaller, lighter engine with more tightly defined operational parameters means you can cut the emissions control weight and complexity too, so there are engine/battery tradeoffs you can exploit for a win-win situation, but don't expect to see many hybrid longhaul trucking rigs. (On the other hand hybrid trucks are ideal for drayage work)
The further advantage in dense urban environment is that you can switch the engine off entirely and roll on electric power during pollution blackouts, but it's worth noting that London's NOX levels are now only 40-45% caused by vehicle emissions and have been like this for a while (predating Euro5 cars), so you get a law of diminishing returns unless you go after the largest pollution sources.
offtopic: The largest source of NOX in London is old-school gas and oil-fired boilers and for the most part they're also the largest source of HC and particulate emissions. Modern condensing ones are almost zero emission, which is one of the unstated reasons councils trend to mandate the things but their complexity is the very thing which causes owners of older massively polluting installations to refuse to update (until they get CO poisoning and the system is condemned, as happened to some friends of mine).
That said - London NOX (and other pollution levels) are only problematic inside the inner london ring road and virtually non-existant outside the North/South circular roads. A lot of automotive pollution control technology is being produced and sold with efficiency and cost penalties everywhere, to nail issues that only occur in small areas when there are probably better ways of tackling the issues, such as adaptive technology which restricts emissions when actually needed or simply mandating zero emission vehicles in zone 1.
No seriously. If they can get weight-for-weight equivalent solar cells to aircraft skin, why not make use of them? There's lots of electrics on board a modern aircraft, and there's always the possibility of adding energy into the mix from an alternative source... the turbines on a 787 are started electrically using one of the twin generator sets per engine rather than by a traditional ground based pneumatic system. They're developing electrical alternatives to some of the engine components all the time. So why not do it? It might happen, it might not; that's not to say you shouldn't try.
" If they can get weight-for-weight equivalent solar cells to aircraft skin, why not make use of them?"
Complexity, fragility, extra wiring mass and charge control complexity, certification for about as much extra energy as is consumed by the inflight entertainment gear of a half-dozen seats.
It's much more profitable to reduce seat mass, the weight and power consumption of the IFE kit (which is what's being done) as well as the mass and complexity of aircraft wiring (which is why some busbars and wiring are being run in Aluminium or F/O instead of copper, despite the increased fragility of the former and the extra transceivers for the latter and why switched networks/control busses are proliferating instead of hundreds of miles of individual control/power wires.)
Seriously. Just the extra wiring for solar panel skins means they'd need to weigh 1/10 of existing skins to be worth replacing on a like-for-like bases.
How dare anyone try something new? We only want tried and tested solutions, none of this new fangled science stuff!
Unless I'm missing something, this project hasn't cost any of us any money so what's the problem. Maybe something useful will come out of it, maybe it won't. Who cares. At least people are still trying.
I don't think many people are saying that it shouldn't be tried. Like the Gossamer Albatross, it's an impressive piece of technology. It's all the idiots (including many journos) saying "in 20/50/100 years time all passenger aircraft will fly on solar power" in utter defiance of the laws of arithmetic, never mind physics, that are annoying.
"The entire trip took 505 days to complete, with the delays mainly due to it having to wait for good weather before taking off and the entire mission had to be put on hold to allow for repair work to be carried out"
And no commercial interest ... surely Michael O'leary will have been straight on the phone to find out how they are avoiding paying compensation for the delayed flights to Bertrand Piccard in case they've found a loophole he hasn't! I expect to find solar panels on RyanAir jets in the near fuure with any delays being attributed to overcast conditions not providing enough solar power which was out of their control.
Too many tech illiterates conflating 'solar' with 'electric' aircraft. Even BBC's John Amos conflated the two, and twisted Piccard's words.
Solar-powered aircraft technology will have precisely two practical applications. 1) Long duration UAVs orbiting high above for some surveillance or radio platform purpose. 2) Sport gliders with stowable electric driven props for self-powered take-off could recharge while flying. Anyone think of a #3? No, the technology doesn't scale to airliners. Basic physics.
Electric airplanes, recharged from the grid, might find niche applications for smaller aircraft for short haul flights. Unless a miracle happens in battery technology, the "future of aviation" hype will never happen.
Step one is to avoid conflating the one with the other.
keep in mind that the energy density of fossil fuels is STILL much better than electric storage batteries, and is likely to be so for a VERY! LONG! TIME! to come.
besides, CO2 isn't killing the planet. CO2 is depleted by rain, and kept at a chemically balanced equlibrium level in the atmosphere, forming carbonates in the ocean (and other bodies of water) when it reacts with Mg, Ca, etc.. Higher water temperatures cause the oceans to EFFERVESCE CO2, and zealous "scientists" take measurements and try to prove the CO2 caused the warm, but it was really the WARM that caused the CO2. Besides, CO2 has 1/10 the absorption spectrum for infrared than does WATER, and I don't see anyone complaining about WATER VAPOR. The blanketing effect of WATER VAPOR could be 100 times or more than CO2, and it changes so unpredictably (whereas CO2 tends to be a constant by comparison).
But this kind of common sense analysis is NOT what the warmists want to hear.
So I'll say "Solar plane, COOL! Geek-factor-major" and I think it's a fun thing to accomplish, too. But for practical energy storage, particularly for FLIGHT, it looks like good old-fashioned FOSSIL FUELS will be the way to go, for a long, long time.
Wrong. What can be achieved by combining wings with an engine and a propeller was unknown at the time of the Wright brothers. What can be achieved today with combining solar cells, batteries, and engines with wings is exceedingly well known today, which is coincidentally why nobody in their right mind bothers anymore.
A 'great thing' was NOT achieved.
Do the math. See just how deep the hole that solar-powered aircraft have to climb out of is. The solar constant is 1300 watts per square meter. That's all there is, there will never be more. Worse, that's 1300 W/m^2 _outside of the atmosphere_. The atmosphere blocks a lot of that (and a good thing too, or we'd all be fried dead by ultraviolet and x-rays). The sun only shines in daylight. (Yes, it had to be said...) and clouds exist. This means that not only does there need to be a _LOT_ of surface area devoted to solar power collecting thingies (photovoltaics, solar steam, whatever, I don't care) but now you must more than double it to make up for darkness or bad weather or both, _AND_ you have to add (heavy!) batteries to store the power in. Volume and weight are very important in aircraft.
This means that unless you can do something to the Sun to increase the solar constant (which would have interesting secondary effects) you absolutely must get both better solar power collecting thingies, the current set won't do at all, and better batteries, the current set won't do either. Physics and chemistry say that this is unlikely. (Well, you could get energy storage which would do the job if you could get room-temperature superconductors. People have been trying for those for a while, no end in sight, but perhaps there could be a break-through. Now all that's necessary is a break-through wrt solar power collecting thingies.)
Practical _electric_ aircraft might be around in a few decades. Even without radical updates in power storage it should be possible to move limited payloads (say, a dozen or two or three passengers and their baggage) a short distance (say, a few hundred miles) at a reasonable speed (say, 200 mph) within 10-20 years. Large payloads ain't happening any time soon. Long ranges ain't happening any time soon, not with anything resembling a reasonable payload. High speeds might be possible... .for a very short time. Practical _solar_ aircraft are gonna take a while, unless there's a sudden break-through. Yeah, you could get electric drones capable of carrying 10 kilos of payload 50 km at 25 kph. You could even get solar drones, though your payload, range, and speed might be noticeably lower than that. Trans-oceanic passenger service is multiple decades off, and not small multiples either.
Look, there are very powerful electric motors available right now; some torpedoes, for example, are electric. Torpedo motors are short-ranged, and tend to be designed for just one use. This can change. They can be made longer ranged, they can be made to last longer. But that will take time and money. And there are limits as to how far you can go, limits due to physics and chemistry.
Airships have a problem with weather. Heavier than air craft can fly in weather airships can't. Worse, slow airships (which would include electric airships, hobbled by the weight of those batteries) aren't fast enough to get out of the way of weather. Worse yet, one reason why airships can't compete with heavier-than air craft at many tasks, including long-distance passenger and freight hauling, is that they have quite limited payloads relative to their sizes. Possibly the most famous airship, the LZ129 Hindenberg, was, according to Wiki, 245 meters long and 41 in diameter, and had four 1200 hp motors giving a max speed of 135 kph. It could carry 72 passengers across the Atlantic. I repeat, it was 245 meters long and could carry only 72 passengers (plus 60 crew...) trans-oceanic. To compete with existing heavier-than-air craft, a modern electric airship would need to be smaller, faster, to carry more passengers, and to require a smaller crew. One reason why Hindenberg required so large a crew was precisely because it wasn't very fast. It took days to travel a long distance, so that meant that it needed a crew large enough to stand watches, as the crew couldn't possibly stay awake and alert over multiple days if they didn't have relief watchstanders. A faster airship going shorter distances would not require a large crew. Even a slower airship wouldn't require a large crew if it could stop for the night somewhere along the way. Stopping along the way when going trans-Atlantic and even trans-Pacific can be, and has been, done. It's just annoying and time-consuming and people won't pay to do it if they can go non-stop. And they can, if they fly on a modern heavier-than-air craft.
For reasons a number of people have pointed out electric airplanes will never become viable alternatives to conventionally powered planes unless something dramatic happens (say a REALLY compact and light bacitator).
However what could happen is a return of the airship (dirigible), only with electric motors that could be powered by fuel cells supplemented by solar panels on the top of the ship.
Something like that could dramatically lower shipping costs over conventional freight hauling planes while offing much greater speed than ships. Passenger versions could offer comfort and room to stretch out not possible in an airliner and at much lower cost.
Plus they are just plain cool!
The first thing this technology is going to be used for is low earth orbit spying - the lifting capacity for a high resolution camera and storage doesn't need to be much - the slow speed is in fact a bonus, and the ability to stay aloft for days is critical. What needs to happen is to make it a drone.
So, basically, Solar Impulse 2 circumnavigated the globe in 2015-2016 at basically the same rate at which the Vin Fiz crossed the United States in 1911. Both in terms of average speed in the air, and average miles per day. Perhaps just a little slower actually. https://airandspace.si.edu/collection-objects/wright-ex-vin-fiz
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