One of the most frustrating parts about flying a quadcopter is having to regularly swap battery packs, as this massively limits what you can do with said quadcopter, never mind its effective range. Obviously, having the sun power said quadcopter during a nice sunny day would be a much better experience, but how workable is this really? While airplanes have used solar power to stay aloft practically indefinitely, a quadcopter needs significantly more power, so is it even possible? Recently, [Luke Maximo Bell] set out to give it a whirl.
His quadcopter build uses a large but very lightweight carbon fiber frame, with large 18″ propellers. This provides the required space and lift for the solar panel array, which uses 27 razor-thin panels in a 9×3 grid configuration supported by a lightweight support frame.
Due to the lightweight construction, the resulting quadcopter actually managed to fly using just the direct power from the panels. It should be noted however that it is an exceedingly fragile design, to the point that [Luke]’s cat broke a panel in the array when walking over it while it was lying upside-down on a table.
After this proof of concept, [Luke] intends to add more panels, as well as a battery to provide some buffer and autonomous flying hardware, with the goal of challenging the world record for the longest flying drone. For the rest of us, this might make for a pretty cool idea for a LoRaWAN mesh node or similar, where altitude and endurance would make for a great combo.
I’m impressed that this works at all. Makes me wonder what is possible in terms of solar powered airplanes – given that quad rotors are not particularly energy efficient things…
SPOILER: It doesn’t. There are li-pols hidden in those carbon fibre tubes.
Are you sure? The body of the quadcopter seems light enough to get by with the amount of power generated by the panels. I’m no expert and haven’t ran the numbers but it still seems within the realm of possibility.
I guess
I’ve actually met Luke and he’s showed me some of his projects. He definitely knows what he’s doing
If this was a random YouTube short, sure.
This guy has created a number of detailed projects on YouTube and nothing here looks beyond the realm of possibility.
This isn’t a small, inefficient quadcopter being powered by some heavy polycrystalline panels.
This is a big quad with large, efficient rotors carrying a very large, lightweight and efficient panel in full sunlight.
I’m surprised it works at this scale, but it’s believable.
Why would he bother with that?
He actually plans to stick to stick a lipo on this, it isn’t planned to be batteryless, this was a test flight before adding the batteries.
And if you watched the video it basically runs out of power momentarily and almost crashes after his maiden batteryless flight.
Why bother? Because youtube runs heavily with the bias of positive reporting: if there’s nothing to report, it doesn’t get clicks. That makes people fake positive results or talk failure into success far more often than admit failure.
For example, the plasma channel guy who’s now trying to extract water out of fog using high voltage. He’s spinning up this awesome creation that definitely does work, and extracts 21 ml of water per watt-hour of electricity used – and his audience eats it up because they don’t consider that it takes the entire charge of the battery to make a gallon in the optimum case, yet he’s talking like this is a real solution to agricultural irrigation or something.
Failures can be interesting too, but those are usually the preserve of “crazy mad professor” type of channels. You watch it for the performance, not the subject matter.
That’s nice, so do you then assume EVERY success on YouTube is fake? Maybe I watch different channels than you, but I see LOTS of project videos that end in failure, and they still get views.
id actually allow that. why? gives you a buffer for vertical take off and landing. in cruse the panel can be used as a wing to offset some of the lifting power. it would need to be the bare minimum needed to get off the ground and up to speed, it can charge during flight with surplus power topping off the batteries for landing. its just doing what birds do by default.
A 747-8s wingspan is 224 ft 5 in at the root they are 48.7 feet long tapering to 12.1 feet at the tips. That gives you roughly 6,824 sq ft of wing surface. Youve got ~250 feet of length in the fuselage with a width just over 20 feet. If you were to wrap it completely with solar panels, Ignoring the inefficiencies caused by indirect exposure this would cause, youd have around 15700 square feet of panels on the fuselage.
So in total a 747-8 could squeeze in around 22,500 square feet of panels. highly efficient solar panels can theoretically capture a maximum of approximately 472.5 kilowatts (kW) of power
The Boeing 747-8 has a maximum takeoff weight (MTOW) of approximately 987,000 to 990,000 pounds (447,700 to 449,056 kg). with estimated power consumption around 240 megawatts (MW) for takeoff and approximately 60 MW during high-altitude cruise.
472,5 kw of power is less than that produced by the engine of a 4729 pound Cesna 208.
So the potential of solar power for fixed wing aircraft is pretty poor unless youre talking about ultralight weight powered gliders and drones.
Not really, its certainly a more natural fit than rotational aerofoil lift of helicopter and multirotors. You just have to actually design to suit the methods you intend to use, a 747 is all about stuffing as much takeoff mass and volume as possible into a footprint that works at most international airports making use of the huge power density and performance of their fuel and engines. It is bulk transit efficiency around existing infrastructure that was considered not flight lift-drag/power requirement to surface area. Where something like an existing motorglider design or that really crazy looking Verhees delta would naturally work rather well (assuming you can make the structure work with the panels still) as already an efficient flier and has actually rather giant surface area for its size. But likely need to scale up a little from the very small lightweight aircraft they are…
If anything the ultralights are the hardest one to design as directly solar powered – you have no mass budget to speak of to start with. So even with the huge energy density and performance to weight ratios of aircraft engines they are not that easy to design. The Electric Motor might well be a touch lighter but having to pack in lots of mechanical supports for a wing surface material that isn’t really structural is probably making a functional solar ultralight on the verge of if not entirely impossible with current material science.
sorry if I confused you by saying “ultralight weight powered gliders”, That was not meant to imply a FAA section 103 eligible aircraft limited to 254 pounds.
It was merely confining the applicability of solar power to “something like an existing motorglider design would naturally work rather well” as they are already incredibly low weight in comparison to most other fixed wing aircraft designs.
Ultralight weight, powered gliders makes far more sense than Ultralight, weight powered(hows that work??), gliders and Ultralight, weight, powered gliders, leaves “weight” hanging senselessly. I neglected a comma but you seem to have neglected logic.
My point there was light weight isn’t actually the import part and that going lighter doesn’t really fix the power generation problem. Yes being light does play a part in energy demand to fly but the bit that actually matters is designing for high surface area to power required to fly – a 747 type aircraft is just entirely the wrong design for the job, as the whole point wasn’t to have a large surface area to power requirements to fly but actually rather close to the exact opposite of having minimal surface area for maximum lifting volume and mass so it fits in the airports, fuel efficiency in flight matters to the design, but only a secondary consideration to the number of sardines or parcels you can shove in.
and my point was that no matter the design the surface area to weight ratio is not favorable to the commercial applicability of solar power to fixed wing aircraft. Theres just not enough surface area to make the power captured a significant portion of the requirements. Solar powered dirigible sure. Solar powering a glider with a huge wingspan to weight ratio, sure. Its just not practical for 99% of real world use cases.
@JustSayin I’d argue that it really isn’t a slam dunk not commercial option – for instance the flying wing type concepts have huge surface area, pretty efficient lift/drag and serious volume and weight carrying potential – enough benefits they have been seriously considered in place of the 747 style jumbo jet for a long time already and really its largely the inertia of the industry that just keeps making the same thing (sometimes with big changes and disastrous results as they don’t have to actually recertify the ‘modification’ etc).
@foldione
The largest flying wing aircraft ever built is the Northrop YB-49. Its eight General Electric J35-A-15 turbojets produced a maximum of 3,750 pounds of thrust (16.68 kN), totaling 30,000 pounds of thrust (133.44 kN) for the entire aircraft, which amounts to over 15MW of power.
With a wingspan of 172 feet with an overall length of 53 feet, it has a significantly smaller surface area and hence a much much lower Solar Power harvesting potential than a 747-8.
So AGAIN, the potential of solar power for fixed wing aircraft is pretty poor unless youre talking about ultralight weight powered gliders and drones.
@JustSayin Existing and rather historic airframes designed with entirely different uses in mind and many years of technical development apart (as it seems you are using a very modern 747 variant) are not proof of anything being impossible.
Also in many ways even your very old and thus not really fair comparison actually does prove my point at least as well if not better than your own cherry picking the right stats for the argument as you are – an older smaller but still pretty giant heavy aircraft that is able to take off in half the runway space, with a MTOW to thrust ratio in its favour (or at least close depending on which 747), and a fairly comparable wing surface area despite being significantly smaller etc…
While your old delta wing doesn’t have the surface area to thrust to obviously work purely on solar its got a pretty darn close surface area to that 747 while needing massively less thrust! Actually looking like a viable level of fuel offset at the very least and it may even be entirely viable to fly just on solar power once its in the air -obviously not going to be flying as fast as it could in that case, but such a short take-off distance with relatively anaemic thrust implies it can fly just fine at relatively low air speed). And for commercial flight, especially cargo that isn’t that picky about being stuck on a plane for a few extra hours that operating at lower speed to have low/no fuel consumption is economically pretty sound. And even for passengers as Concord vs the sardine can’s rather proved most people won’t pay enough to get there faster either…
Age has no bearing on AREA. The key most important issue at hand. You can only capture as much solar energy as you have square footage to cover. When a 747 sized plane only has enough surface area to produce the power required for a tiny little Cesna, it doesnt matter how old either plane is. You can double or triple the lift efficiency and you will still be 10s if not 100s of times below the power requirements.
Double check your maths. The surface area of the YB49 is WAAAY less than a 747. It requires much less thrust, but its also a much lighter plane with a much lower payload capacity. AND ITS THE LARGEST Flying wing EVER built. So there is no better example to cite and it would come up WOEFULLY short of having enough area to significantly offset its power requirements with solar power.
You keep talking in generalizations and hypotheticals.
Feel free to “cherry pick” your own examples that attempt to support your points. Find a single real plane that has a surface area that is large enough to capture enough solar power to offset its power requirements by more than 10%. I wont hold my breath, I suggest you do not hold yours….because the potential of solar power for fixed wing aircraft is pretty poor unless youre talking about ultralight weight powered gliders and drones. IT JUST DOESNT SCALE.
I’d have to say not so much on two fronts. As while I agree age has no great bearing on area it has some as the abilities to make larger structures that are flight worthy has changed. And while I agree area is important for solar generation it really isn’t the only important consideration – adding more area in a way that changes the lift/drag ratio could easily be a big negative! The most important thing is the ratio of area to power required for sustained flight – the lift to drag ratio really matters when trying to fly efficiently, and just adding more area is in general not going to help with that.
However the main point I was trying to make is the purpose of the aircraft and technology available at the time also matters so very much for comparative purposes – a relatively high performance combat aircraft built with comparatively primitive construction so its far heavier in construction and probably packing 2x maybe even 3x the engines it actually needs to function comparably well to the 747 (even though the engines are older and rather unimpressive) is hardly a good direct comparison.
So unless somebody can come up with the flight characteristics of both the best I’ve been able to find suggests the old flying wing vs 747 is rather hugely in the flying wings favour – the 747 just needs way more sustained power to stay airborne at no matter how you figure it – It is just not an efficient flier, what it is is a relatively efficient way to stuffing lots and lots of stuff you’ll get paid enough for that it offsets it being one rather fuel hungry aircraft.
Also as purely solar flying, including being able to have enough mass and solar power supply excess to haul and actively charge the batteries has been done in RC scales (and some rather larger versions) in both something more flying wing and a more glider like form factor, but never anything even close to 747 for good reason! Then considering that generally speaking RC scale is much much harder to be efficient in than larger scales with how aerodynamics and the ability to make strong, stiff, but light weight structures actually scales in favour of building larger! (Up to a point anyway). It all rather suggests the giant commercial flying wing with significant solar derived power if not entirely powered by it is rather plausible. Though I’d doubt it will get made any time soon – between oil companies not wanting to lose so much revenue and the rather conservative bureaucracy around new aircraft it probably won’t even be worth investing in creating for some time, unless it becomes militarily useful as a more deployable rapid recon system than satellite clusters that can match its loitering ability or something.
(In RC scale these days with the insane performance of motors and batteries its pretty easy to get something to fly for a short time, but to actually fly remotely efficiently so you can fly for more than a few mins not so much.)
Also I specified WING surface area – which is very very close according to Wiki anyway. The 747 effectively just adds a big tube, which isn’t awful for solar generation, but will also likely shade some of its own panels, and have many panels on it at woefully poor angles no matter what orientation you fly in – a flying wing still will have that problem but to a much much lesser extent – in effect its surface area is ALL prime real estate for solar, which helps it be even more viable.
@foldi
So NO example of “the abilities to make larger structures that are flight worthy has changed.” to support your claims? Glad I wasnt holding my breath. The larger the plane, the heavier the weight, the greater the required thrust. Unless youre going to move into dirigible/wing hybrids youre never going to get enough surface area to capture the required power. You might as well be positing that superconducting antigravity technology will enable planes to fly with no more solar power than is required for a calculator because so far youve only managed speculation, fantasy, and the dismissal of any facts and figures that do not support your dream.
You can beat this horse all you want. It dies here for me. The potential of solar power for fixed wing aircraft is pretty poor unless youre talking about ultralight weight powered gliders and drones.
Yes, solar-powered heavier-than-air craft is difficult. Nasa managed to do that on Mars, mainly because the gravity there is so much less than it is here. But aircraft design, like most engineering, evolves toward what is useful. On his YouTube channel, RCTestFlight showed off a model plane he made that had the wings covered with solar cells. It was I think his third try at this, using different designs for the airframe, that succeeded in sustained flight. The longest flight in his series on this was several hours, like over four I think, and he eventually landed it because he got tired and bored with it. And THAT is far less of a challenge than solar-powering a quadcopter, because quadcopters are notoriously inefficient, while fixed-wing planes with high aspect ratios are in general quite efficient.
As we approach the end of the era when passenger flight could be commercially successful, designs will evolve toward lighter weight, lower-drag airfoils, and more efficient propulsion. I think we’re close to the limit on the joules/kg limit of lithium batteries, so no help there. But even with that, the focus is going to be on how to store enough energy into an aircraft to make it commercially viable, and this depends not on lightweight power generation, but lightweight power storage and lightweight structures. We’re not going to see commercial solar-powered flight for the same reasons we won’t be seeing the return of passenger dirigibles. There HAVE been experimental solar-powered, piloted aircraft, but none that I know of could carry more than one person. From this does not commercial viability emerge.
@JustSayin The most obvious example that really shows the scale of improvements in ability to create larger stronger and/or lighter wings has to be the wind turbines scaling up so hugely over the period, from the early wood and steel options that were massively out scaled in wing size by the first composites to now where every single blade on the newer turbines is longer than those old windmills were tall in its own right!
As in the world of aircraft the ability to make a 50m long wing that could actually fly exists for a long time, but that 50m long wing with vastly less internal structure mass or more stiffness and load capacity just looks like a 50m long wing. And so far very very few have tried to make bigger as their both hasn’t been a desperate need and the existing airports are likely not going to be capable of serving it – so instead of a bigger wing you just got better and better wings of the same sort of size.
@foldi
So no real world examples just more wild conjecture. Youre delusional and cant accept that the concept doesnt scale because it doesnt fit your dream. Youre convinced that you know something and wont accept any facts to the contrary. Its pointless to continue with you on this subject. Enjoy your Bliss!
Those wind turbine blades are a very much real world example, and a very very obvious undeniable one that requires aerofoils rather exceeding the requirements of most aircraft wing!
The only way to see the big improvement in construction methods and what they can do to compare modern and old in aircraft is effectively to deconstruct the aircraft components. Simply because folks have not chosen to build much bigger doesn’t mean it isn’t possible now, instead however they have made a comparable size wing much better. And if you really want to look closely you can see the improvements that mean the old 747 to the new ones and other more modern jumbo’s do have a few extra meters of wingspan, can take larger more powerful engines, have significantly more mass lift capacity etc. But its all relatively subtle, rather than big obvious headline we just built a 800meter wingspan flying wing, and as subtle details and what they mean are clearly lost on you…
But it is those construction method advances that are one of and in many cases the biggest reason why new generations of aircraft are faster/have longer ranger/ more lifting capacity etc – heck often they even have the same darn engines as the old generation and yet perform better! Just looking at the 747 each generation trends to greater range, more take off mass and higher fuel capacity than the last even though the wingspan across many of them doesn’t change at all!
@Foldi
You doorknob. A wind turbine blade is NOT an example of an aircraft. The two are not analogous. The size of wind turbine blades does not support the premise of adequate solar capture capability of a winged aircraft.
The largest wind turbine blade is 153 meters (502 feet) long, manufactured by Dongfang Electric for its 26-megawatt H2X000-31X offshore wind turbine These blades weigh approximately 83.5 metric tons (92 US tons). Thats roughly 1/5th the weight of a 747-8, PER BLADE. The blade width is not official published, and varies along its length. But even if each blade was 15 meters wide, the total area would only amount to ~2300 sq meters, giving a whopping 517kw of power potential per blade. With the 747-8’s high altitude cruise requirement of 60,000kw (60MW) Two of the worlds largest wind turbine blades would only produce 1/60th that power while weighing 1/10th the weight of a 747-8.
So AGAIN, Your “real world example” fails to support your premise. SOLAR DOESNT SCALE SUFFICIENTLY FOR AIRCRAFT POWER beyond ultralight weight powered gliders and drones..
1/5+1/5≠1/10 LMAO
Damn, I cant believe I did that. Dealing with you is numbing my brain. Im sinking to your intelligence. OH NO!
That should have read….
Two of the worlds largest wind turbine blades would only produce 1/60th that power while weighing 2/5th the weight of a 747-8.
@JustSayin
The entire point on the turbine blades is how manufacturing and material sconce has enabled these much much larger aerofoils, its not a direct analogue to aircraft as actually a wind turbine blade is a much much tougher challenge than any aircraft wing I can think of – its got to under huge and often rather less than consistent loads not flex at the tips so it strikes its own tower and unlike so many over large aircraft wings you can’t guy wire it to the fuselage! Your aircraft wing actually does flex and can be allowed to flex rather more – the only limiting factor there really is how much inconvenience in design you are willing to accept (like the take off sticks of the U2) and fatigue life.
You wanted the more directly applicable to aircraft comparison simply look at the large bodied airliners as I indicated. Not hard to spot that you get multiple versions of the same aircraft, often with the same wing span and shape and same fuselage proportions and identical engines making significant performance gains generation to generation – the wings didn’t get larger by much as a rule but the construction methods would allow it.
Actually try to build that flying wing now and it can be massively lighter than the old one was, while being structurally more capable of high loading, and if you are building it with the intention of sedately cruising the skies not intending to be shot at the wing will look ever more competitive as it doesn’t need to be nearly as strongly built when you intend to fly it as an airliner and thus won’t be opening the doors in flight…
I am absolutely not saying Passenger Solar flight is a commercial success waiting to happen, simply that it is very very plausible given the huge amount of evidence at smaller scales where aerodynamics are unfavourable of net energy positive flyingwings working. And that they are already vastly more efficient (which is why so many companies have considered the idea for passenger jets for so long now). Along with the various improvements in aero construction and computer modelling.
Personally I’d suggest solar augmented flying wing is very plausible in the not too distant future just as so many commercial ships have started fitting those rotating tube ‘sails’ – doesn’t have to fly purely on solar to be worth it, just offset enough fuel cost to be worth it. And entirely solar powered isn’t implausible at all. I’d doubt it would replace regular especially long haul passenger aircraft quickly if at all as likely flying slower but the air freight stuff.
Uhh you wouldn’t just use direct solar energy for takeoff. Also you listed a weight for a plane full of fuel. What would actually be done is likely the following. 1 definitely not for heavy cargo applications, of course. 2. Batteries fully topped up on shore power to provide the necessary acceleration up to cruising altitude. The weight of the batteries offsets the weight saving from the fuel as well as the dry mass of the jet engines. Electric motors can be much smaller and lighter. 3. Really I think with current technology the best approach might be to use a smaller more efficient turbine to provide the power to the electric motors during take off. Ascent, as well as to provide any emergency power that might be needed, kind of like a turbo button. And finally 4. I think the article was actually talking about uav’s
No one said you would use it just for takeoff. My figures included takeoff and cruise requirements.
Even if you halved the weight, disregarding all fuel, the solar power potential is 1/64 to 1/128th the necessary power for flight.
Batteries plus solar plus motors unlike fuel do not diminish with flight time, but thats inconsequential since we have now ignored fuel weight as well.
The 747-8 has 4 GEnx-2B67 engines each weight 12397 pounds. You would need a 155 megawatt electric motor to produce equivalent thrust under comparable conditions.
an 80 MW industrial induction motor roughly half the required power weighs around 150 tons (330,000 lbs) over 20 times what the turbojet does.
I dont know what sort of perpetual motion delusion you are pondering but you cannot produce an equivalent thrust by chaining inefficiencies. An electric motor driven by a generator driven by a smaller more efficient turbine will require a HIGHER power output and fuel consumption than a turbojet providing direct thrust.
and finally, Yes this article is speaking about A UAV but the comment I have responded to is “Makes me wonder what is possible in terms of solar powered airplanes” which leaves scale open to interpretation. The surface area of a large bodied jet being one of the greatest solar energy potentials yet having only enough potential for the energy requirements of a much smaller cesna provides clear support for my statement that ” the potential of solar power for fixed wing aircraft is pretty poor unless youre talking about ultralight weight powered gliders and drones.”
O and on top of the things I mentioned above, you also didn’t account for the gain in efficiency from the elevation as well as the significant decrease in temperature. Some quick Google searching showed an installation at 1900 meters elevation that generated 50 percent more power than it would at sea level.
I imagine at plane cruising altitude it would be even better
PSST learn to read ” with estimated power consumption around 240 megawatts (MW) for takeoff and approximately 60 MW during HIGH-ALTITUDE CRUISE.” The reduced power requirements for high altitude cruise factors in all of your googlefu knowledge.
Or, look at what has been done already….
https://en.wikipedia.org/wiki/Solar_Impulse
You don’t need to power the whole plane. You could use a solar wing area to supplement the jets.
1kg of JetA1 =120MJ * 20%efficiency = 24MJ work
1kG of 3.5W, 6g , 200um flexible cells, *10hrs = 19MJ
That is standard thickness Si wafers. Given the active junction is a few um, they could be much thinner, and would then be able to produce more thrust than the same weight of kerosene.
There was an ex-russian company that peeled a um thin GaAs junction cell onto (kapton?) film. They claimed significantly greater energy than kerosene, as the cells were very, very light and higher efficiency than silicon.
A 747-8 burns approximately 2.67 kg to 3 kg of fuel per SECOND during cruising flight. The wing area could provide roughly 1/1000th of the power required during cruising flight under ideal circumstances.
POINTLESS.
Let’s assume jet fuel costs $700 per ton. That’d be $2 per second. If you save a thousandth of that, you would be making $7.20 per hour. If a commercial jet plane flies for 60,000 hours, you’d estimate savings of about a quarter million dollars, considering that they don’t always fly in daylight.
It could pay back, but it’s basically peanuts compared to the total cost.
The nontrivial problem would be engineering this hybrid propulsion system in a way that was workable and did not squander that 1/1000th of an increase in efficiency through added weight or aerodynamic drag by piling even more stuff on the wings.
And then make it reliable enough to certify for commercial airline use while also doing all of that.
OMG
That amount of fuel and power could power an entire village in Africa for a year. Aeroplane is one of the most ineffective machines out there.
You can fly from LA to London in under 11 hours. By ship you would take at least a week to make that trip. And over two months by sailboat. Aeroplanes are incredibly effective.
this is starting to get annoying, there is no option of registering nick/verifying email when commenting
Second time someone uses my nick to post unusually stupid comment. Its so stupid even I wouldnt post something like that!
JustSayin’: “incredibly effective.” At converting passenger dollars into passenger miles. But this only works as long as operating costs don’t increase much compared with passenger wealth. And increase they do, and increase they will continue to do, increasingly. This is a dead end, and if an electric solution (never mind a solar one) can’t be found, then air travel will become as popular as coal-fueled steam passenger ships.
@BBJim
While leisure travelers make up the majority of air passengers (approximately 88%), business travelers are significantly more profitable, accounting for as much as 75% of airline profits. Business travelers represent about 12% of all airline passengers, but they pay higher fares for last-minute bookings, better seats, and loyalty programs
Coal fueled steamer passenger ships only fell out of popularity when a BETTER solution came into play. Until/Unless an alternative that is just as fast becomes available jets will still shuttle passengers around the world.
@JustSayin
To a large extent something better came along 30 odd years ago and is getting better and better – the internet and the ways of communication it brings to a large extent removes the need to actually go anywhere. Especially for business purposes.
Also I’d disagree with you a bit in general – there was a big boom in taking ‘fast’ ships as much for the novelty and fun when they first become affordable enough, but the demand really isn’t stable – Going places by boat or aircraft is to a large extent a luxury, and as such its the first thing to suffer when people start feeling poor.
@foldi
You disagree with me because youre desperate to find ways to argue on the internet. Try reddit. Its more your speed.
Global air travel is GROWING and is expected to continue growing at a steady pace, with some forecasts projecting nearly double the passenger numbers by 2045.
Facts do not support anything youve attempted to spew into any part of this comment section.
Indeed, but not relevant at all to my point, as what was the expectation before the Financial crash of 2008? Before the Fuel price hikes caused by various wars? Before something like SARS or COVID scares folks off flying (if they are even allowed)? -Plenty of airlines have nearly or actually gone bust because the passenger numbers cratered and/or the running costs skyrocketed causing numbers to fall many many times. Not always huge impact, but sometimes that little war here drops traffic 40% in less than a year, and often it doesn’t recover afterwards that fast either!
So while assuming the world will remain economically stable filled with roses and joy the expectation is pretty much everything will always grow, and airtravel is going to be part of that. My point is the real world very rarely actually works that way for long. And as soon as things wobble your existing business traveller is going to consider if the high cost of being their in person is worth it when the internet and all the technolgies for communication around it are getting so good (and are so very much cheaper), and so many times these days companies don’t travel much or even have never taken the business trip at all – as they can talk to the factory in Hong Kong/Vietnam/China/India/etc or the speciality engineering firm doing part of the design in Germany/USA/etc remotely…
@foldi
you do realize that the telephone was invented in 1876.
Before that, in 1865, the Pantelegraph was used to send documents between Paris and Lyon, France.
The internet didnt stop air travel at all.
Sure there have been moments in history that BRIEFLY reduced air travel. It has ALWAYS recovered and returned to its upward trend. It will continue to do so until/unless a faster and/or more efficient means of travel is discovered.
The world isnt going to turn into your isolationist dystopia where everyone stays home and only reaches out through their holodecks anytime soon.
Youre spinning your wheels and spewing nonsense because you cant make a single post with facts supporting the scalability of solar powered flight. GIVE UP ALREADY.
@JustSayin, maybe you’ve never heard of “peak oil”. Air travel is bound to certain limits, and all commercial aircraft development in the past few decades has been about getting more passenger kilometers out of a liter of Jet-A. This can only go so far, as none of the efficiencies that are being improved can ever exceed 100%. It MAY be possible with a vast investment into nuclear power, to develop synthetic fuels that don’t start with oil (Navies are already doing this), and that’s the only extension I can see working.
There has been a much more efficient mode of travel than air for a long time. It’s called “rail”. Speed is a bigger part of the equation, apparently.
@BBJ
Around 60% of global oil demand goes to transportation, with road transport alone using about 45%. Airplanes only
account for about 5% to 6% of the world’s total oil consumption.
Road transportation is shifting away from petrochemical fuels. Thats going to significantly change the consumption curve and free up many years worth of air travel/air freight allotments giving various non petrochemical synthetics time to catch up.
Until we develop antigravity or teleporters, airplanes will continue to be in service,
The problem with solar a solar powered aircraft is that mass scales with the cubs of its dimension scale while available solar power scales with the square of those dimensions. Batteries don’t have that problem. Their power scales by the cube of the size scale. For example, suppose you have a drone that is 1m wide, weighs 1kg produced 100 watts of solar power,1000 watts of battery power. You generate 100watts/kg from solar and 1000/watts/kg from the battery. If you scale it up to 2 meters, it weighs 8kg and produces 400 watts solar (50W/kg) and 8000 watts (1000/W/kg) battery power. Suppose you want to make it really big, and scale by a factor of 10, it weighs 1000kg and produces 10000watts solar (10W/Kg) and 1,000,000W (1000W/kg) from the battery. The solar panels quickly become irrelevant.
While it’s true, this doesn’t take into account the fact that for example the thickness of the solar cells doesn’t really change, etc, you can’t escape the fundamental geometry of the problem. The power available is restricted by the available surface while the mass it has to lift is proportional to the volume.
On the other hand, this leads to an interesting observation that’s relevant to microdrones. A normal sized drone CAN fly only on solar power. It’s difficult to do and you need extreme optimization to make it work, but it does work.
However, it gets easier the SMALLER you make it.
Suppose you scale our hypothetical drone by half? It’s now 50cm wide, weighs 125 grams , produces 25W (200W/kg) solar and 125W (1000W/kg) battery power.
If you want to shrink by a factor of 10, making it 10cm wide, it weighs 1g, (and is probably quite fragile) generates 1W (1000W/kg) solar and 1000w/kg battery power.
If you shrink it to 1cm, a factor of 100, it weighs 1mg , generates 10mW (10,000W/kg) solar and 1mW (1000W/kg) battery power.
Of course at the scale of a cm your going to need some pretty advanced fabrication techniques to make it. Your probably going to be using the solar panel itself as a structural component. You will also probably fabricate the controller electronics onto the back side of the solar panel die and then build the battery over that. The motors are a whole other can of worms.
You are not accounting for how lift and drag/ aerodynamic efficiency scales with size here though. Nor how the structural weight actually required as things scale changes, which as a 2x larger “solar wing” thing is likely to be built in nearly exactly the same method and materials (largely hollow construction of thin sheets) it really doesn’t actually get cubic heavier, maybe not even 2x heavier the minimum thickness of material you can actually work with to create the structure quite possibly doesn’t change between the small and large…
IMO going smaller would actually be dramatically harder – the bigger the prop you can swing the more efficient your lift generation by a large margin as a rule (though matching motor/driver to prop also matters, and in multi-rotors you need to be able to change the velocity of that prop rather quickly as it is also your control surface). Which is why those tiny pager motor drones that are almost nothing but battery and motors can barely fly for maybe 2 mins and the larger ones can fly and even fly very aggressively for considerably longer while also carrying other mass for things like cameras. To use an easy to look up example DJI claim a 2788mAH 7V battery can fly for 36 mins for a 250g drone, which gives a ballpark of energy demand for a relatively heavy and overbuilt camera drone of 6Ax7V for around 50W continuous (calling it 3AH for 30 mins, so 6A of total draw). But scale up again DJI claim a 6654mAh @14V battery on their 1Kg model is nearly an hour of flight time, so carrying 4x the mass and only in the ballpark of double the continuos wattage to fly being still around 6A but now at 14V…
I do think your idea of effectively etching the flight controller electronics onto the back of the PV module and using the panel itself as the core structure is pretty neat as a concept if you want to try and make small and solar work. Though I really don’t think it will actually work at the sizes you are thinking at all. To take the earlier examples neither seems an entirely unreasonable amount to get from a reasonably small and potentially light enough in construction ’75-100W’ or the ‘200W’ ballpark solar panel reliably, so while it would need to be more like a meter square thin thing and probably end up much more wind effected by using lightweight composites to support the silicon rather than the usual for a fixed install thick glass and aluminium protection while also stripping out the extra mass, and the battery mass can probably get the usually 4kg(ish) panel down to the right ballpark… Wouldn’t be very durable, but then a multirotor that can only just about stay airborne and only during the day near the peak hours was never exactly a reliable flyer.
Darn I didn’t mean to post that one yet, as I know I’m too darn tired to really trust my maths was right… But hopefully the point is made at least.
gb2reddit, your not welcome here.
So it sounds like maybe bumblebees COULD fly. But regarding microdrones, what is the application? In most cases transportation – and aircraft are mainly about transportation – the important thing is how many kg of payload you can carry how far, and to a lesser extent, how quickly. The only practical application I can think of for microdrones is surveillance. I don’t think Amazon will stay relevant by delivering individual potato chips.
IMHO, NASA’s Helios Flying Wing reincarnated as a copter on a shoestring budget. Add some aerodynamics and it will be Osprey on a budget.
“Osprey on a budget”
Don’t give me war flashbacks…
what if they used “double-side” pv panels aligned vetrtically below the cruciform struts?
Double-sided PV panels are only incrementally better than single-sided ones. Like in the 10-25% range of improvement, and that’s mainly because you can have a PV panel facing the sun, who’s back side is facing a bright sky. On an aircraft, the back side of your panels faces … the ground. Which is fine if you’re flying over a desert or a field of snow…
I agree mostly, though being able to capture even 5% more energy from the ambient scattering over lower albedo surfaces, and at no additional weight cost potentially if you assume the solar surface of the wings on both sides shares a substrate – as it might be with wing designs similar to a Blériot monoplane, that is ‘free’ power so it is not a bad idea.
Also the OP seems to be implying vertical panels under a drone in the place of the motor mounting struts, which I’d think could work rather well at increasing solar generation for the mass the multi-rotor needs to lift. However the windage means I expect it couldn’t fly at all most of the time as the winds are too high.
Yeah, it’s the same problem that killed dirigibles. Literally.
Random idea, use a weather balloon covered in solar panels, then hang a drone below it on an umbilical. Use the drone to tow it around or to keep it on station. — google say it already exists, https://en.reset.org/this-helium-powered-h-aero-drone-can-fly-for-24-hours/
Why on earth use a drone for a LoRaWAN node when a tethered balloon would work so much better and so much more reliably???
To not be where they are looking for you… don’t worry about that whole broadcasting as loud as possible.
Although it could be a limited use version, only used when necessary and kept up in the air waiting otherwise. Kinda cool.
Consider using a mesh network (whether LoRaWAN, meshtastic or something higher bandwidth so you could provide full internet connectivity…) to transport data in and out of an authoritarian state. And furthermore to transport data, once it has crosed the border of that state, across the land until it reaches major population centres where your subscribers actually are. Jack booted goons will be going round cutting down any balloon tethers they find. But they, at ground level, can’t reach a solar powered drone. Furthermore, for a small drone hovering at fairly low altitude hitting it with a missile could be difficult for the regime to acomplish. And the drone would cost so much less than a missile that (so long as your anti-censorship effort has half-adequate funding) the authoritarian regime (however rich they were to start with) would go bankrupt from the price of missiles long before you couldn’t afford to build new drones. Authoritarian states are everywhere thesedays, looking to do things like outlaw cryptography, so the need for such a physically uncensorable network is not entirely theoretical.
Also: I really like that other comment suggesting pairing it with a balloon for even better endurance.
I was out last week with a 250 gram toy quadcopter and struggling with trying to bring it back in what I had thought was a light breeze.
I expect this solar panel thing will flip over and fly better as a kite.
Brilliant! Why not use a kite as LORA wan node?
Is there practical lower weight limit for solar panel construction? my understanding is that the semiconductor making actual electricity is just few atoms thin and rest is there just as thickness to provide strength and prevent the crystal structure from cracking. or maybe accomodate quarter wavelength of the converted light, which is waaaaay shorter than thickness of panels available nowadays.
Im no expert, but i beleive that while we might be reaching practical limit to how much energy can panels make per square meter, there is still huge margin of how much energy can panels make per gram. just imagine mylar-like solar panels. maybe with graphene? that would be crazy light compared to what we have now.
There are folks that have ‘printed’ perovskite type solar onto crisp packet material rolls, not as efficient as regular solar and far as I know nobody has yet made a perovskite last more than a few years in theory before the degradation in performance through age renders it useless. But in power per gram and skinning an aircraft that might actually be the right tech – servicing the covering ‘fabric’ every year when the stuff is relatively cheap and actually pretty resilient mechanically despite its light weight in a way silicon probably never can match would be plausible.
This is a tough sell. To a large extent, aircraft can be built, sold, and used commercially because they can last a long time. If you’re comparing the cost of silicon and perovskite PV, you start with lower efficiency than add the ongoing maintenance and if falls right off the bottom of the spreadsheet. Which is also why we’re also not seeing that dominating rooftop solar.
It was never going to dominate rooftop solar with the current quality and price and established market being so different – rooftop is build and forget for decades like most large static infrastructure, entirely different thing to flying!
All aircraft are rather maintenance heavy. It might be the expensive rebuild of the engine every few hundred flight hours or in this case peeling the outer skin off to then recover it with fresh perovkite ‘fabric’. Really not a big deal if the process is cheap/fast enough to keep flying.
Great project. Maybe combine it with a small helium balloon? Other than lift, the balloon could help support the fragile panels.
Looks like you could save alot of weight in the mounting hardware for the panels. The 3 sets of branching mounts seems inefficient. I might try just 3 horizontal bars that overlay the x of the drone. Maybe an additional support for the middle bar out to the edges of the x. Additionally I would put as much spacing in between the panels as I could to try and stop your drone from becoming a kite.