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
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.
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.
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 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.
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.
what if they used “double-side” pv panels aligned vetrtically below the cruciform struts?
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.
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.