back to article Giant solar-powered aircraft to begin cross-country flight

The photovoltaics-powered Solar Impulse HB-SIA aircraft has arrived at the NASA Ames Research Center in Silicon Valley's Moffett Field to prepare for a flight across the US. After it has been offloaded in pieces from its Boeing 747-100 transporter, the Swiss-made HB-SIA will be reassembled in a Moffett Field hanger, then embark …

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Neat!

I can't wait until it comes to D.C. It'll be great to see it in person.

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Anonymous Coward

Success

Will ultimately be dependant on the weather, something that can only be predicted with inaccuracy. If the wind blows in the wrong direction he may find himself in a hover, or worse going backwards.

Who's betting his first stop will be Hawaii?

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Re: Success? Weather

This was the problem with the US Airship "aircraft carriers". They were destroyed by weather.

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Pint

Re: Neat!

It is DC already.

Get it? Sorry...

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At the risk of being too pedantic,,

Beyond just being tired, what does the pilot do about food and water, and what about going to the bathroom?

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Re: At the risk of being too pedantic,,

Yellow Ice.

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Re: At the risk of being too pedantic,,

And brown meteors, one presumes?

Either that or a bucket full of the blue water under the seat.

Though if weight is that much of a concern... adult nappies?

The mind reels back in horror contemplating it. I wouldn't want to be the people opening the hatch on the ground.

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Trollface

Re: At the risk of being too pedantic,,

Ah, this is probably where they've come up with a nifty idea to raise additional capital.

Farmers all across the nation will pay a small amount each to have their fields fertilized. So the GPS turns on the green light, the pilot sticks his posterior out the hatch and... bombs away!

Can't wait for the movie...

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Anonymous Coward

Re: At the risk of being too pedantic,,

... and as it spends much of it's time above 12000 ft, what about all the oxygen that the pilot needs?

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Re: At the risk of being too pedantic,,

Same as on a commercial jet - the low-pressure external air is compressed to create cabin air.

It's obviously a special compressor on an airscrew craft as there isn't any bleed air from the jets, but it's still pretty simple.

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Boffin

Re: At the risk of being too pedantic,,

Well when the 2 person Voyager team flew around the world they used the tech of the Gemini programme with bags they dropped over the side when over open country.

Outside of general aviation things get a bit involved for long flights but they have to be faced.

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Pint

Re: At the risk of being too pedantic,,

http://en.wikipedia.org/wiki/Gemini_7

14 days, two men in a can.

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Re: At the risk of being too pedantic,,

In fact, why have a human pilot at all? Remote control + semi-autonomous and it REALLY could stay up forever. Could be very useful for comms links in remote areas etc.

Even if the ultimate aim is to develop this to a point where it can carry passengeres, the pilot is still extra weight. Stick 2-4 passengers in and pilot it from the ground.

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Units and comparisons...

At the risk of point out El Reg's own guidelines, altitude of aircraft (especially, but not exclusively when operating in US and European airspace) are reported in FEET. Feel free to quote meters for those who like such things, but the applicable unit is FEET!

And, while we're at it, a two class 747-400 doesn't really carry 524 passengers; to get that many people in, you need to use short-haul style "business class" seats, the sort of thing that British Airways calls "Club Europe". For serious long-haul flights, which is what the 747-400 is designed for, a more typical two-class layout yields something like 406 passengers (e.g. the Qantas 747-400 fleet here: http://www.qantas.com.au/travel/airlines/aircraft-seat-map-boeing-744/global/en describes a variety of seat plans, all in the 350-406 passenger range. Plus, of course, about 20 crew.

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Re: Units and comparisons...

And speeds should be in knots. km/h is not metric and is an abomination. If you must use metric then m/s would be correct.

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Re: Units and comparisons...

Km/h for air or sea travel is indeed an abomination but not for the reason you stated. A knot is one nautical mile per hour, and a nautical mile is one minute of an degree of latitude. A pilot will know that for every 60 knots of groundspeed they travel east (or west), they will travel 1 degree of longitude every hour.

It's one of the few 'old' measurements that makes better sense than metric, and quite frankly any change towards km/h should be resisted.

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Anonymous Coward

Re: Units and comparisons...

"A knot is one nautical mile per hour, and a nautical mile is one minute of an degree of latitude"

Actually no. A nautical mile is defined as exactly 1852 metres.

"A pilot will know that for every 60 knots of groundspeed they travel east (or west), they will travel 1 degree of longitude every hour."

I think you'll find you're missing a cos(φ) somewhere in there.

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Anonymous Coward

Re: Units and comparisons...

I presume you mean latitude? As longitude is /very/ wrong.

-D

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Re: Units and comparisons...

Almost right! But traveling East or West at 60 knots will move you 1 degree of longitude only if you are flying on the equator. Any non zero lattitude will give you more than a degree, 1 / cos( Lat ) degrees actually.

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Re: Units and comparisons...

But if possible flights take a great circle route so calculating flight speed in degrees of that circle makes sense.

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Headmaster

Re: Units and comparisons...

Not quite true. I degree of longditude is only 60 nautical miles at the equator. As you go towards the poles. the longitudinal lines get closer together until they meet. Latitude lines are 60 miles apart in all cases though, so the statement "A pilot will know that for every 60 knots of groundspeed they travel north (or south), the will travel 1 degree of latitude every hour." is correct.

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Re: Units and comparisons...

Sorry firefly, but that attempt of reasoning is simply rubbish. I am pretty sure that

a) the vast majority of flight is not in a straight east/west (and vice versa) direction, and

b) the actual distance on the ground for a degree of longitude varies with the latitude. The internationally defined 1852 meters per nautical mile is only valid for a distant straight along the equator.

Once again, using the more sane metric values makes much more sense than using another set of Fred Flintstones units...

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Anonymous Coward

So this has a real pilot not a Lego/Playmobile one?

Unless you pick the right stuff.........

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FAIL

I love stuff like this..

Because it proves so conclusively why renewable energy is such a load of pants.

Right at the bleeding edge of technology, a renewable aircraft the size of a jumbo, can just lift one man, and if lucky, get up to 30mph.

I hope he doesn't hit a downdraught. or CAT.

"Engineers are confidently predicting that a wind powered vessel 'could sail indefinitely, at 2-3 knots average, depending on weather conditions"

WOW!

"Greenpeace says 'walking will be the way we travel in the brave new green world, walking needs no expensive roads, and if there is access to enough brown rice and hiking boots, can be carried on almost indefinitely",

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Anonymous Coward

Re: I love stuff like this..

Seems to me the tech will eventually be put to use in some kind of drones rather than for passenger/piloted flights.

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Anonymous Coward

Re: I love stuff like this..

So the few feet the first airplane made were indicative of the future of flight? Yeah, get a brain.

While not small, it manages further than the first flight did. So it's again a proof of concept.

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Devil

Re: I love stuff like this..

"Engineers are confidently predicting that a wind powered vessel 'could sail indefinitely, at 2-3 knots average, depending on weather conditions".

Bollocks.

Last time I remember the "pinnacle of wind" - the steel hull, steel mast windjammers from the end of the 19th century outsailed with ease german cruisers at the start of WW1. Germans could not catch up even with the sorry hulk which was Cutty Sark by that time (it had a mast missing and had 1/4 of the crew it needed).

The speed of these 4-5 mast monsters was ~ 15 knots. That is in fact on par with most cargo fleet till this day (only ferries and some container ships sail faster and only on short haul). It was not speed or carrying capacity that terminated the windjammer fleet - it was a combination of the canals (Panama and Suez) and manpower costs.

The saddest part about attempts to reintroduce windpower in ships is that none of it gets even close to where we were 120 years ago. Parachute sails/kites my a**e. A proper "salty dog" rig of the kind which took the route around cape Horn to California or Cape Good Hope to Australia in the 1890-es can run circles around it any day.

The only reason for wind to be slower in the end-to-end play is that it requires different routes. You usually cannot sail straight from A-Z. That is why the canals decimated it in the first place. From that perspective, considering where the Suez/Middle East situation is going lately we will be considering wind again very soon (same as we did during the previous Suez problems).

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Rol
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Re: I love stuff like this..

and when the new ion drive planes that can travel faster than the Earth rotates, start whipping round the globe, always in sun, you'll see how short sighted, short sighted, really can be.

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Headmaster

Re: I love stuff like this..

Ion drives don't work like that.

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Black Helicopters

Re: I love stuff like this..

"Seems to me the tech will eventually be put to use in some kind of drones rather than for passenger/piloted flights."

What makes you think it hasn't already?

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Pint

Re: I love stuff like this..

World's biggest ship (under construction now) will be going 17.5 kts, to double fuel efficiency.

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Rol
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Re: I love stuff like this..

Not yet.

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FAIL

Re: I love stuff like this..

in a far wind yes, a sailing ship was fast.

The problem comes when you look at the average journey time between ports. A tramp chugging at 7 knots could provide a reliable service in far less time than a clipper. Whose route would be longer, having to seek and find the trades, and the westerlies, and often being becalmed in between.

The myth of 'wind is fast' is similar to the myth surrounding wind turbines. Just quote the top speed and forget the abysmal average and pretend its superior.,

"Nevertheless, the Sovereign of the Seas, the Cutty Sark and other fast sailing ships did not average such speeds. The Cutty Sark set a record for a passage from Plymouth to Sydney of 72 days, when a fast passage was considered to be anything around 100 days. Even on the record setting voyage, however, the Cutty Sark actually only averaged around 8 knots. The ships which made “fast passages” of 100 days averaged around 5 knots. The Flying Cloud on her record setting voyage between New York and San Francisco ol 89 days, likewise averaged around 7.5 knots.

The reason that average speeds of so many clipper ships were often low had to do with the doldrums, the regions of light air just South of the Equator. Even the fastest sailing ships are slow when the wind is light or non-existent. But what of ships that did not have to traverse the light air of the doldrums? The fastest passage ever recorded by a sailing ship between New York and Liverpool was made by the clipper Red Jacket in 13 days, 1 hour and 25 minutes. During the voyage she reached speeds of over 17 knots. Nevertheless her average speed was around 10.5 knots.

These are the record speeds set by the fastest sailing ships. It is probably fair to say that most sailing ships in the 19th and early 20th centuries averaged between 5 – 8 knots on average depending on the size of the ship, the route and the weather. There are nothing wrong with these speeds but they are not comparable with container ships, even those slow steaming at 12 knots."

( http://www.oldsaltblog.com/2012/09/are-modern-ships-slower-than-sailing-ships-probably-not/ )

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Meh

Re: I love stuff like this.. @ itzman

You are sort of correct buy have made the error of failing to consider the rest of the environment, the structural limitations of the ships and the fleshy crew.

Wind is not, and has never been, the sole bottleneck in vessel speed. The ships were more limited by the state of the seas than the winds themselves. It is/was terribly easy to exceed the hull speed on a sailing ship (on a modern vessel with deeper keels and efficient sails almost no wind is necessary to scoot along) but you get into stresses (hull and mast breakages, cargo displacement, loss of steerage, and generally unacceptable levels of throwing humans overboard/breaking them). The voyages could have been much faster but the ships fell apart from the sheer beating they took. Steel hulls helped a lot with this as did internal power which made maintaining steerage easier, but even the largest ships afloat today can't overpower the power of the seas and are regularly forced just to point into the storm, try to keep her into the waves and hope.

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Re: I love stuff like this..

Yep. See:

http://en.wikipedia.org/wiki/Qinetiq_Zephyr

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Devil

Re: I love stuff like this..

What I love most is the thought of all those twisted little goblins in HM Treasury trying to work out how the hell they can quantifiably tax sunlight.

HeHeHe...

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Re: I love stuff like this..

"...how the hell they can quantifiably tax sunlight."

The same way they've taxed fresh air in Australia - aka the "Carbon Tax". Trust me, the greedy fuckers will find a way.

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Go

I , for one, am fascinated with this

Just like first combustion planes had laughable performance, but looking at them ,someone with vision could imagine their amazing future ...

Today solar-powered craft can take only 2 passengers and fly at laghauble speed, but imagine thats just first iteration in a row of succesive designs, with a commercial one available in next few years, when solar cells will be much more efficient.

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Stop

Re: I , for one, am fascinated with this

"when solar cells will be much more efficient"

I've been hearing that refrain for decades, along with "when batteries will be much more efficient/lighter/smaller/less dangerous"

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Meh

Re: I , for one, am fascinated with this

Efficiency in both PV and batteries has increased dramatically, even in the last decade.

Fear of risk, vested interests, and pure ignorance have been a major component in developing both. No one wants to try and make things better so the Govt has to step in and subsidize stupid ideas hoping at least a few will work out. It is nice to see someone pushing current limits with the plane.

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Re: I , for one, am fascinated with this

Efficiency has increased somewhat and not as much as the hype. But interestingly not life. Also curiously if we consider volume and not weight NiMH is as good as Lithium when new and after 6 months of cycles may beat Lithium of same volume on capacity. Easily beat on life. Much heavier though.

Water heating at home from solar is still far better than photovoltaic and will repay costs without subsidy. The photovoltaic only repays cost for user if subsidised.

A photovoltaic aircraft is likely only suitable as high altitude "drone". Even at 100% efficiency the photovoltaic aircraft would not have commercial carrying capacity nor cope with weather to land and take off.

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Boffin

Re: I , for one, am fascinated with this

Solar PV can't ever work for large airliners, here's why:

The Boeing 787 Dreamliner is supposed to be one of the most fuel-efficient passenger aircraft yet developed.

It uses two Rolls-Royce Trent 1000 engines.

A single Rolls-Royce Trent 1000 engine delivers 39,400 kW at takeoff.

There are two of them, so your batteries have to be able to provide that 78,800kW during takeoff - no batteries can do that, but we'll ignore that for the moment.

For the sake of argument, let's say 1/4 that at cruise altitude.

Maximal insolation is 1.3kW per sq metre at the top of the atmosphere.

Let's give you 100% efficient PV cells. So your aircraft needs to have a PV cell surface area of approx. 15,100 m2.

Boeing's Dreamliner's total wing area is 325 m2, let's say 650 m2 for the full aircraft (bigger than reality).

Yet we're still only at 23% of the required power by using 100% efficient cells.

Oh dear. Not going to work then, is it?

Like helicopters, this technology is interesting and likely to be useful in specific situations (eg very long loitering drones), but it cannot replace the jet airliner.

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Meh

Re: I , for one, am fascinated with this

"Just like first combustion planes had laughable performance, but looking at them ,someone with vision could imagine their amazing future ..."

True but they had a reason to innovate which drove many cycles of engine and structures development.

It was roughly 24 years between the Wright brothers at Kill Devil hill and Lindberg flying the Atlantic.

BTW I upvoted you. Improvement is possible, the question is how much will people want?

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Anonymous Coward

Re: I , for one, am fascinated with this

You might not need the power of a couple of RR Trent 1000s. Remember you won't have to be lifting umpteen tons of aviation fuel and its associated infrastructure. Secondly, being on the ground there should be no problem with the acreage required for solar takeoff power. The area of the runway itself feeding electrified rails might be one possible scenario.

I'm not saying this can definitely work, just saying don't be too hasty writing off a viable solar passenger flight system sometime in the future. After all, bumblebees refuse to believe they can't fly.

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FAIL

Re: I , for one, am fascinated with this

"with a commercial one available in next few years, when solar cells will be much more efficient."

I love a good larf when non engineers prattle on about subjects they dont understand.

Weight and power for heavier than air flight are inextricably linked. it takes about 10W/lb to just stay in the air floating. It takes about 30W/lb to actually be able to climb at anything other than a snails pace, and most aircraft are in te 70-150W/lb area which allows them to fly out of trouble, get up to cruise quiclkly and so on.

This aircraft already has a third of its weight in lithium batteries to get the peak power to actually take off. At night it depends on those to keep it aloft. Solar panels are already better than 20% efficient, and the wingspan of this - needed to actually generate enough to stay up - is already bigger then a jumbo jet. once the batteries motors and structural weight are taken into account, it has just adequate margins for a single passenger.

It would need solar cells that generates at least 30 times more to be any commercial proposition.

You cant change the insolatin and you cant get 60-0-% efficient batteries, no matter how smarty you are.

I've been flying electric (model) aircraft for years. I know all the formulae. I've used the best technology there is. I can outperform fuel engines. For three minutes. Then the battery is flat and its time to land. And solar panels of the same size as the aircraft if they were 100% efficient still would not have the ability to recharge them faster than they need to be drained.

This is an amazing feat, don't get me wrong - its a very large model electric sailplane which has been massively compromised in every way to get its weight down, and the solar panel area up. IN order to achieve flight at all. The slow speeds reflect that.. the slower te speed the slower the sink rate and the less power you need to get the machine up, and that means building for a very low wing loading - that also gives you the largest area of wing to put the panels on. Been there done that to achieve ultra low power flight, BUT the flip side is it will inevitably be dog slow - speed takes power - and it will crumple like a wet tissue in turbulence. Nor will it be able to run away from it.

I t is suffering from exactly the same problems as airships. Yes they use very little fuel and stay aloft indefinitely, but with the issues of buoyancy/payload being insoluble except by making them bigger, and the strength of materials versus their weight sadly remaining constant, you necessarily and inevitably end up with a structure that is large and fragile. Most airships didn't catch fire and crash in a blaze: Most got ripped to pieces by turbulence.

So its possible to say with absolute certainty that using this technology,. or any derivative of it, no matter how efficient, you will never see a commercial solar plane, ever. There simply isn't enough energy from the sun to fly one.

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Re: I , for one, am fascinated with this

If you look at the numbers, a WWII fighter had about 75W/lb. A 450mph hawkerTyphoon at the end of WWII had 150W/lb.

There was no amazing leap forward in engine design: The engines just got about twice as good - the key was in the ability to build BIGGER engines. around 100bhp bought you a top of the line WWI fighter. 1000bhp nets you a spitfire.

And in accepting the far higher landing speeds that the massive increase in speed necessitated.

A WWI biplane nips into the air at 50mph or less, and a 100 yards of runway.

A 747 needs to be doing the best part of 150mph and needs two MILES of runway.

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Re: I , for one, am fascinated with this

"I'm not saying this can definitely work"

But I am saying that it definitely categorically cannot work.

Because I am an engineer who designs builds (albeit smaller) aircraft and flies them.

I could probably - given the cash - build you an electric aircraft that could break the sound barrier. If you found a magic battery with 100 times the energy density of the best theoretical battery that ever could be produced using any elements that exist in the periodic table, it might even stay up for half an hour doing that.

But, using wing area to collect sunlight, the mathematics are simple. There simply is not enough power arriving there to give you anything more than the ability to carry the weight of the panels and enough battery after dark to keep the aircraft aloft at a very slow and massively vulnerable speed in a structure that would almost certainly fail commercial tests.

Its one of the abiding myths perpetrated by the eco lobby that 'technology will improve' And so it will, but there are always theoretical limits, and only if you are well away from them is dramatic improvement possible. For example, Moore's law represents strides in technology and miniaturisation of etching on silicon that can produce exponentially more memory and circuitry on a single silicon die. But you cannot go to smaller components than the size of a few atoms. If you want more you have to look at a totally different technology.

This isn't he start of a new technology, this is - rather like a formula one car - the absolute bleeding edge of an old technology. Heavier than air flight, batteries, solar panels and electric motors. All well understood, all getting very close to 'as good as it gets' .

The problem is there are no new technologies on the horizon. Oh there are claims, but in the end they are all old technologies dressed up to be 'new' and marketed as the next great hope of the future.

The appalling thing is that we haven't had any significant new technologies in the last 50 years.

atomic and Quantum theory in the early 20th century gave us atomic power, lasers and the semiconductor.

And that's the only stuff I can think of that was a total breakthrough. Everything else is simply refining stuff that was already known about. Leonardo could have built an aeroplane if someone had given him a moped engine and a few gallons of fuel.

As is this.

Now if someone were to hand me a 'quantum engine' that would silently destroy and turn matter directly into electrical energy..without destroying me, I could build you a ship to take you to the stars..well the nearer ones anyway..

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Anonymous Coward

Re: I , for one, am fascinated with this

Solar hot water is NOT still far better economically than solar PV. The optimistic scenarios for solar thermal ignore the fact that if you're not at home using hot water, heating your water isn't very efficient so it looks pretty bad compared to on-demand natural gas water heating. Grid-tied PV can use all the electricity it generates with only 10-15% conversion and transmission losses and it generates power during periods of high demand when spot prices are highest. The thermal over PV view is outdated.

Back to topic: yes it's primarily a high-altitude drone technology for now, but as thin film keeps improving efficiency and prices keep falling the question is not whether you can have electric airliners but whether there will be a point where you can economically run low-altitude drones in some locations some of the time or add solar to aircraft wings in order and lower long-term overall costs. Fuel is expensive.

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Anonymous Coward

Re: I , for one, am fascinated with this

Solar hot water is NOT still far better economically than solar PV. The optimistic scenarios for solar thermal ignore the fact that if you're not at home using hot water, heating your water isn't very efficient so it looks pretty bad compared to on-demand natural gas water heating. Grid-tied PV can use all the electricity it generates with only 10-15% conversion and transmission losses and it generates power during periods of high demand when spot prices are highest. The thermal over PV view is outdated.

Back to topic: yes it's primarily a high-altitude drone technology for now, but as thin film keeps improving efficiency and prices keep falling the question is not whether you can have electric airliners but whether there will be a point where you can economically run low-altitude drones in some locations some of the time or add solar to aircraft wings in order and lower long-term overall costs. Fuel is expensive and people are expensive.

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