One of the things i have learned about MPPT controllers is that you never attach a load directly to them. Instead, just connect your load to the battery directly. The advantage between a MPPT solar controller and the voltage regulator is that MPPT or maximum power point tracking controller is that it actually operates the solar panel at the maximum power and efficiency whereas the voltage regulator doesn't. This is especially important in the evenings and mornings where the MPPT controller will actually be charging the battery and the voltage regulator will not. Unlike a battery, the solar cell produces the highest voltage (Voc) at open circuit and the highest current (Ia) at dead short and the MPPT controller adjust the voltage of the incoming solar to find the maximum voltage to get the maximum power (Vmmp and Immp). Sorry for the long explanation:( Great project and great engineering!!
This didn't make sense to me either. Seems like the solution was as simple as connecting the ESC directly to the battery and leave the MPPT how it was.
Came here to say exactly this. The previous mppt setup was like driving screws with a screwdriver. Completely fine but not quite practical for the application. Instead of going for a drill (aka connecting the battery directly to the flight controls and continuing to use the mppt) though he just decided to use a hammer to drive the screws. Yeah the voltage regulator idea works but you loose all the benifits of having a solar system since the efficiency is now much worse.
This guy is right, this is what we do in solarboat racing. It works well, very efficient and super simple to set up. Just use the genasun for charging, its literally the best on the market and connect your load direct to battery.
Judging by that large coil on the regulator, it appears to be a boost converter with a regulated output. If so, it does a similar function as an mppt controller without the active tracking.
@@Andy-df5fjit literally isn't as the name of the mppt implies theres a point where you can pull the most power out of the cells since wattage of the cells isn't consistent across voltages
@@pleck7059 Yep. No tracking. The maximum power point would need to be dialed in manually. No it's not as good as having active tracking for varying sun conditions, but it's still way better than a resistive regulator.
The fact that the motor mount broke off so easily probably isn’t a bad thing. It saved the airframe, maybe even the motor. It’s a lot easier reprinting the motor mount than rebuilding the plane or replacing the bent motor shaft.
You're right! Although the crash did actually break the motor. It wasn't shown in this video, but Emma managed to fix the copper wires that had snapped on one of the coils. Pretty lucky as we only had one motor!
@@Project-Air On all my pusher designs flying wings like that I used folding propellers. This saves any mounts and props and the CF props were so expensive back in 2004.
I would try making it airtight, and use helium for stiffening, and extra lift. At least the stiffening part works for rockets. Get some extra lift by pushing some air out of the wings. No part is the best part.
It's funny how much time and effort goes into these projects and they tend to fail on such annoying mistakes. Watching him is very relaxing and extremely frustrating at the same time 😂
2:40 Well, the simple regulator lacks the capacity to do maximum power point tracking, literally the meaning of MPPT. More efficient would be to have the MPPT in the loop, but connect the load (and maybe the regulator) directly to the battery-terminal of the MPPT along side the battery.
Exactly. The MPPT makes sense - it's just the low voltage cutoff that's the issue. Powering the load directly from the battery avoids that problem. I also wonder if the voltage regulator they are using has an appropriate current limit. If not, it could exceed the charge current rating of the battery. It would be particularly prone to doing this when the battery is low and/or at low throttle settings.
Definitly an mpp controller would make sense, espessially when stripped of the heatsink and installed a more lighteight, high airflow appropriate cooling system
@@dack42 This is what I came to say; if they fly for too long in the clouds (and the battery discharges significantly lower than the regulator's setpoint) then it would likely cause damage to the battery when they reenter sunlight.
I’ve done a few solar projects on my own time, definitely not an expert. I would keep the MPPT rather than the voltage regulator though, by connecting the load directly to the battery rather than into the load connection on the MPPT, the other two connections remain the same. In this case the MPPT can charge the battery without worry of disconnecting the load. Keep up the good work Love the projects!
As stated previously here, keep the MPPT controller. Run your flight controls off the battery, not off the MPPT. If you’re going to reinforce with an aluminum spar, use a thinner box extrusion as it will be stiffer in torque than angle for the same weight. Run as many prop motors as you like; the amount of motors does not dictate your power consumption in level (break even) flight. In fact, running more props at lower RPM with more propelled surface area will increase your efficiency dramatically, and also give you the ability to climb when you need it. Your penalty will be weight of course - but not power. I flew in a two-seater solar plane with 5kw on the wings, and a 15kw motor.
Hi! I really love such solar plane projects and plan to implement it one day. You have made a good progress, although I see some problems in your design. If I were you, I would do the following: 1. Replace a bulky LiPo battery with more lightweight DIY Li-Ion pack. It would be like 30% lighter and you can arrange it into a long narrow pack, which would allow to make a smaller hull, minimising frontal area and drag. 2. Mount the motor inside the hull. It will greatly minimise drag. Mounting it may be a bit more challenging, but solvable with 3d printed bracket. Or you can just change your existing motor mount with a more aerodynamic one, that would be an easy fix. 3. As others have already mentioned, MPPT controller’s purpose is adjusting current which is pulled from solar cells in such a way that generates more output and it works more efficient than a simple converter. I suggest you ignoring load output in your MPPT and pulling power from the battery instead. 4. Improve hull aerodynamics. It looks too big, has no front cone (I don’t see any reasons to keep it open from both sides, except for cooling (which is unreasonable and may be improved by having an ESC outside)). Reducing frontal area and adding a nose cone is quite simple. 5. Issue with motor mount being broken off on landing: use folding props. It will fold on landing and while soaring/gliding (and reduce drag). Be sure that not every folding prop mount suits pusher configuration, as props may fold «inwards» and won’t fold out when spinning. 6. Reinforcing. Aluminium is lightweight, but not as lightweight as carbon fiber rods. They may be harder to find and definitely not as cheap as aluminium rods, but far stiffer. Bonus points for making a special battery pack which may be inserted into a carbon rod (I doubt you have a wing thick enough to implement this idea, as 18650 cell and wiring will be quite large, but that’s just an idea). AFAIK AtlanticSolar did this to distribute load on its wings, thus allowing to have higher aspect ratio and thinner hull (by moving batteries to wings). Also, your L-shape aluminium extrusions may be drilled out in places which don’t bear load (for example a side which goes flat on the wing bottom side) which will allow to shed some weight. I also worried if your aluminium extrusions are connected in the center, if not the wing can snap. 7. Top-sided winglets may cast a shadow on solar cells, reducing overall power output. Mounting them inverted will solve this issue, but will certainly break off on landing. There might be a way to make them detach on touchdown, but it sounds more like the least priority to do. 8. Wing profile. That’s probably the most complicated thing in the whole build. I can’t see it clearly, but assume your bottom side is flat, and the top is also flat. Making top flat is probably the only solution to mount solar panels which can’t be bent, but such geometry (that’s my guess, I’m not even close to being an aerospace engineer) produces lift only when an angle of attack is not zero. This means higher drag by keeping nose up. I’ve seen a solution on rctestflight channel which looks like a ladder: solar panels are put on these «ladders» and form somewhat nice aerodynamic shape. Btw your idea with joining two gliders is cool, but these gliders are based on real life gliders which have a thick cockpit for a pilot, which adds excess drag. I’ve bought a Voluntex ASW28 for endurance flights and plan on getting rid of stock hull and replacing it with custom narrow carbon fiber one. Anyway, I’m waiting to see new videos with the solar plane!
Yes, this a probably a lot more. You keep calling this an engineering challenge, but you seem to be neglecting a lot of the engineering part. Engineering mainly happened before you take flight, not afterwards. You're just doing stuff and then troubleshooting it. Troubleshooting certainly happens at this stage, but it's not an excuse or valid design technique (as opposed to doing more proper work up front). This was your second airborne design. It should have gone MUCH better than this. This was practically a step backwards. You're designing something based on work that's been done countless times already. You're missing the basics. (I know you're just a kid, and this is just a youtube video, but no one should look at this the way to conduct a project.) Seriously, good luck going forward. I hope you have great sucess. I love seeing young people doing this kind of thing, but you are also a role model. Up your game.
All lithium batteries are li-ion (lithium-ion), regardless of whether they are packaged as a pouch or a cylinder. Pouch cells are probably actually the best option since cylinder cells (like 18650s) would waste more weight on packaging.
@@glenmiller1437 I'm certain you bounced back and forth on whether or not you should post this. It's easy to be seen as being critical even when your intention is to help. IMO you made the correct choice. Almost none of this is new ground and a good deal of this information is readily available online. Be patient, do your research, and most importantly don't be afraid to ask other engineers for help.
"so I hopped on my Mac" "and yes, this is all running on a Mac" (shows B-roll of it running on Windows) Very interesting video(s) and project, but I couldn't help but laugh at this part.
Does Emma actually work with you on design and/or construction? If so, we need more Emma, if she's comfortable with that... always great to see a (historically) stereotypical "male profession/hobby" performed by stereotype-busters. =)
Seems like a very backwards step to eliminate the MPPT charge controller, due to it having a load safely cut-off. Use the MPPT still, but only for charging. Connect the load directly to the battery. A DC-DC converter wont be nearly as efficient in varying sun conditions. Another recommendation I would say is to introduce a BMS in front of the battery. RC batteries don't feature one for weight and cost reasons, but in an application where you are continuously charging and discharging a lithium pack, you are very likely to introduce gradual cell imbalance, which your charge controller cannot fix. At some point, the cells *will* go out of balance enough to cause damage, if not a fire. At the very least, add an active cell balancer to ensure imbalances in the cells are handled quickly. They are fairly inexpensive & light as well. They won't have the OCP, OVP, UVP and so on of a proper BMS, but that could even be an advantage as there is no chance of powering being shut off abruptly. Great video!
The BMS+balancer should in this case only be used while charging on the ground between flights. If used during flight, the total power cut problem comes back and it adds weight.
@@HL65536 This is not necessarily true. An active balancer board has no means to cut power, only equalizes cell voltages. Given LiPo and Lion cells voltage are (fairly) linear in relation to state of charge, there is no risk of balancing voltage causing an actual state of charge imbalance, which is the real goal. This technique cannot be done with Lifepo4 for this reason until at ~95% SoC for this reason. As for a BMS, I would really only recommend a 'smart' BMS that is configurable, such as a JBD BMS. That way all of the protections can be configured to trigger (or not) at whatever point you like. Realistically you should only be operating a lithium battery within its safe operation bounds, with margin for error, and that is what a BMS can provide.
16 years ago I cut my right hand on a Deltawing K10 with a pusher prop. I was badly hurt. 3 weeks sick leave. I was shocked when I saw your friend Emma throwing the plane. Since that day I use only folding propeller and start the engine when the hand is safe. For your monster that configuration would not work. Ok ... I am 61 years old :-D which can also be a reason to be slightly shocked 😀 In real life I am an aircraft technician and what I also saw is that the wing cord is very small for that length. To make it stronger, a long carbon tube with a wooden spar glued into it would also be lighter. OK ... to make that can be a challenge. However, it is a good decision to go for a delta wing or double glider configuration. I am sure you will get it happen. best wishes from Hamburg Germany
I also got a bit worried at this part. Saw a guy at the field get his hand too close to an idling motor just the other day. Several deep cuts probably some stitches required. I’ve luckily only got caught in rubber powered props but even they hurt like hell.
Totally agree. Very risky. And no gloves even. And not great that he leaves his girl friend to do that. 😢 I had 4 days in hospital and came close to losing my thumb after a prop strike. 😥
Nah, you're completely right to be shocked. The project is cool and everything but launching that plane by hand with the propeller that close is just plain stupid. Not to mention while running through uneven grass... -.-
I would like to second your worries about pusher prop and hand launch. It is accident waiting to happen. Bungy take off is a simple and safer alternative in my opinion. Greetings from Hamburg too :)
Congrats for this partial success. You really stepped up your video production game. There is a reason people use MPPT-Chargers instead of DC regulators. The reason is that we do not really care about voltage but power and the power from solar cells gets really low if the current is too high. This happens when the battery voltage drops, e.g. when there is voltage sag when more motor power is needed. It may be worth testing your charging setup with the actual solar cells and changing lighting conditions and motor power. Also, with a plane that valuable it is always a good idea to provide a small extra battery for the receiver and servos so the plane can be landed as a glider if push comes to shove.
@@JojitBuenaventuraJr A parachute with failsafe release system would weigh a lot more than a tiny battery. Plus it is better to land the plane than to have it come down uncontrolledly, maybe into a tree or water.
Charging a lithium pack with a voltage regulator is a recipe for disaster, and also fails to properly load the solar panels for maximum efficiency. Put the mppt back in the loop, but power the motor directly from the pack. I'd personally run the receiver and servos using a separate pack that is either wired up with a passive failover circuit (custom) or continually charged from the motor battery using a small liion charger rated for the average draw of the receiver +servos
Use carbon and glass fiber laminates to form the wings. No additional reinforcements are needed, probably gives you the lightest fuselage. Composite materials also make it easier to produce more aerodynamic joints. For your solar powered plane, efficiency matters
There's a company called PowerFilm that makes super thin and flexible solar panels. I don't know if they are as efficient as the ones you are using, but they could possibly be placed over a frame or even just wrapped around foam or something.
Your design, as I see it, has several things working against it: 1. That aluminum spar is probably more than the wing actually needs in terms of stiffening. You'd probably have better luck with a less-substantial aluminum or carbon-fiber reinforcement, or you could build a torsion box out of balsa. The challenge isn't making the wing strong enough, it's making it just barely strong enough. If it didn't break in the first test flight, chances are good that a very minute amount of reinforcement would be enough to stand up to most turbulence. Your wing probably only really needed any real reinforcement towards the root. 2. Swept wings inherently have poor lift properties at low speeds. Your wing is actually swept well into jet airliner wing territory - unless you're in the mood to start adding high lift devices, you're kinda working against yourself. 3. There's no reason why the chord of the wing inboard of the elevons shouldn't be extended to match the chord at the elevons. Sure, the overall aspect ratio of the wing would decrease, but I doubt it'd create enough drag or weight to offset the lift benefit, especially since I'd wager increasing the chord at the tips is adding to induced drag... 4. You're going to have to optimize the powerplant for efficiency with respect to thrust... a ducted fan of the same diameter as your propeller is probably the best approach. While the duct imposes a drag penalty at high speeds, you're low and slow. I don't think a delta wing is going to solve your problem - in fact I think it might make it worse. Delta wings are low aspect ratio by nature, so you're going to be sacrificing a lot of efficiency to no real benefit since your airplane isn't meant to fly at supersonic speeds. You're designing a low-speed airplane. High aspect ratio straight wings are the way to go.
Rctestflight made it work. Though he was following quite a different design with much wider wings More wing = less efficiency However More panels = more power
A hollow tubular spar would give better strength for the weight. Also, the spar doesn't need to extend the entire length of the wing. Some wing flex is perfectly fine. You just need enough strength to prevent catastrophic failure. I assume you made the wings swept because of the center of gravity. Otherwise, straight wings would be better for the low speeds.
The electronics are not only a fire hazard, but also not ideal. First of all the purpose of an MPPT controller is to squeeze out as much juice as you can from the solar cells, something that seems vital in your case. Secondly, lithium batteries degrade rapidly without a proper charging curve, and could even explode. Source: am an aerospace Electrical Engineer.
How would a lithium battery explode if the voltage that it's being charged at is lower than the threshold needed to trigger thermal runaway? If you have a battery whose nominal voltage is 14.4 volts and you supply it with 14.4 volts, how would the battery ever get a voltage above 14.4 volts? Especially if it's connected in parallel with a motor?
Your source isn't good enough. It is a logical fallacy called the argument from authority, you may well be knowledgeable but there is always more to learn and mistakes like human error are common place.
What exactly do you mean, that li-ion batteries degrade w/o proper charging curve? I am not criticising in any way but I am trying to learn from someone with practical experience. Let's divide my question into three simpler ones. 1. Can li-ion or li-poly work in buffer regime at constant voltage, say 4.1v/cell, given they remain there most of the time and they are occasionally discharged and finally charged in cccv mode? 2.Do the batteries NEED regular charge/discharge for longer lifetime? 3.Should someone keep some state-of-charge (e.g. charge in amper*hours) constant instead of voltage?
@@WhoIsTheEdman In nominal operation, the cheap chinese DC/DC module they are using might not be a problem. But it is your single point of failure regarding battery safety. Who is to say that its output is temperature compensated ?
You could try to mount the solar cells inside the wings with a transparent cover. This should reduce air drag and help (somewhat) to protect the cells in case of a crash. (Yes, this will slightly reduce the efficiency of the cells).
I tried to charge my phone with a solar panel on the inside of the windscreen in my car covering the entire window, I got about 30% of the charge on the inside compared to when I put it on the outside of the window...
I can't see up close, so I'm not sure, but I think the propeller is facing the wrong way. Since you are using the motor as a pusher, the propeller should be facing the other way. This could lead to a significant loss of power. This might be one of your biggest problems. I believe this design should be able to fly comfortably at lower powers. Congratulations, you're doing great!
The simple solution would be connecting battery and ESC to the same terminals on the MPPT. Skip the "Load" terminals as they have a cutoff. Ideally you can find an MPPT controller for 4s lipo. The one in the video has a slightly lower voltage limit,so wont start charging until voltage drops a bit, but should work just fine after that. That voltage regulator has no MPPT, this reduces panel efficiency, likely by a significant amount. you could use MPPT + regulator, but this adds weight and extra losses.
Her magical hair almost distracted me from the epic mission undertaken. This is wildly ambitious, and bro just keeps on smashing it, video after video.
Hey buddie, i am working with composite materials and CAD prototyping. That being said, reach out and we can do some carbon-fiber or aramid shenanigans😊 also, i would not have made the motor mount stronger because now more force will be applied to the plane body and the rotor. I would just print 5 of these and just use them as a "failure point"😊
I agree with the top comment here. I have been living totally off-grid for over six years now on a solar setup, and none of my loads are connected to my MPPT; all the loads are connected directly to my batteries. I would still use the MPPT as it has an inbuilt battery charging profile and will reduce the charge voltage if the battery is getting full and avoid you cooking it. The voltage regulator will just keep pumping in power which could be catastrophic.
Couldnt you take those aluminum L brackets and maybe cut triangles out of them to maintain rigidity while reducing the mass of the brackets significantly?
For motor mount, you need some ribs. And also print orientation is crucial. You snapped mount along layer lines, just print your mount on the side and you'll be fine.
At least the plain landed flat on the ground better than a nose dive . I agree the delta wing design should be more stable and carrie the load better can't wait to more on the future project keep up the great work 😊
I also have a solar charge controller that protects my batteries by shutting off. The thing is, I really *really* must keep my navigation lights on at night, or risk being run down (and killed) by a ship. So I have an override switch that bypasses the controller. It might damage my battery, but on the other hand, I'm a lot less likely to die. When your plan fell out of the sky, I was 90% sure I knew why!
As others have noted, carbon fiber rods would likely be a better choice than aluminum L-channel. You can also attach them to one another with a custom printed 3D bracket to extend rigidity across the entire wingspan (though you might consider reinforcing that with a layer of fiberglass).
I like the idea of the 'ready made' twin conversion, I think you should also explore other aircraft types as well before settling on the next iteration of your project
Here's what I would do for your electronics: - Keep/reintroduce the mppt as its way more efficient in harvesting power from the solar cells. Also add a small BMS for battery safety. - Group your systems into different levels of criticality. Your power will eventually run out, so what you wanna do about it? You need to know what systems need to run till the absolute end even if it kills your battery (these are likely radio + flight controls). At the moment you just keep discharging your battery, which wil likely kill it - thats what the disconnect precents after all. - Set the disconnect to the lowest safe voltage for the battery if possible. - cut off the motor if power is lost, effectively turning your plane into a glider. - manually or automatically switch on a little reserve battery for flight controlls so you can land safely.
The width of the plane's wing should keep them from wobbling front to back too much which means you don't have to use L-shaped aluminium profiles, use flat profiles and mount them vertically in the wing. This will provide up-down stability while cutting the weight of the reinforcement in half
Why don't you use pre-tensioned kevlar string to prevent wing flexing? Of course, string will cause some little air drag but it weights about to nothing and does significant stabilisation efficiency as a triangular element. Just tight it in between winglet tips and the center of the wing.
You are doing a great job with the channel! Keep it up! Also I feel like a delta wing is the way to go. Good luck! Can’t wait to see what you come up with.
The two of you need to come to California for your next experiment. We have a lot of beautiful deserts where the sun always shines and the wind is minimal
My guess is to avoid having the extra drag of tail surfaces. That's the main benefit of flying wing designs, reduced drag. But it requires a fair bit of wing sweep to get sufficient moment arm for the elevator control surfaces.
Really a video that deals with an interesting topic, that of solar powered aircraft, a much discussed topic in recent years. Well done and congratulations for bringing this very current content to TH-cam
Saw you two at project air on the bbc today so glad everythings going well on the channel and and glad me and all the followers are part of your journey 👍
Lengthen the nose a bit more. Make a sharper front nosecone and place angled canards on the front to bring down the stall speed. Move the verticals to mid wing, and add small wingtips to the end of the wings to add efficiency.
I remember a few years ago seeing somebody created a solar hovercraft, but the technology has advanced quite a bit in the last couple of decades, so it might be worth you exploring it a bit.
Knowing the wing load of first version and final version of the aircraft would be nice. I always keep track of my R/C aircraft g/dm². For roughly 1m wingspan planes, I had 10g/dm² as the target for slow planes, 20g/dm² for faster trainers and +30g/dm² for really fast and heavy planes.
I'd rethink a few things: Flying wing is not as efficient or stable as a conventional tail setup. Pusher prop is not as efficient, quiet, or safe as a tractor. MPPT is more efficient than a charge controller, just hook load up to battery. MPPT should prevent overcharge, and ESC should prevent undercharge. I'd love to see those RTF glider wings attached to a wide lifting body for extra cell space.
If you aren't flying at high subsonic speeds, I'm confused why you're using a swept wing design. perhaps consider a slight dihedral as well for stability.
I would personally bring back the mppt cobtroller just as a battery charger maybe even add more than one. Basically my idea is section the wing in such a way as to minimize the drop of performance during partial shading of series panels. For example using a separate mppt controller for each wing or maybe something like the external parts of both wings go to one controller while the internal ones to another. The mppt charge controllers shouldn't have any issues charging the same battery. Also ardupilot have a cool looking charge controller on their wiki that can talk directly over can and provide a ton of useful information.
Idea: -Use thinner but wider wings to increase lift without increasing drag. -Take one or both fuselage parts from the gliders and reinforce the wings with 2-3 thin carbon or aluminum tubes. -Theoretically, you could also cover the gliders fuselage in a thin but stable layer of fiberglass and then dissolve the Styrofoam with acetone so that a hollow ultra-light shell remains These are just ideas and I would love to be able to implement something like this
Keep it up. Properly invested in this now and even if we have to wait until next June for the maximum sunlight it’s worth persevering with. Finally taking it way north for 24 hours of sun and a whole day of flight
Using a battery balancer would be a good idea. There are standalone breakout boards that you can hook up to the battery for that. As just using a voltage regulator is not really ideal for battery charging. Using proper charge circuitry would be better for safety and battery health. But balancing the cells would make it at least less bad. Really Looking forward to the twin gliders tho!
Use carbon fibre SHS for your wing stiffener and print the motor mount on its side to increase its strength, you can also coat the printed parts with super glue, this will increase strength and reduce wind drag.
Wing structure can be made lighter and stronger by having thinner support beams in wing tip and and tail and bottom and top centre instead of one thick beam in the centre. Wing skin can be made of mylar foil glued to airfoil rib structure of the wing to massively reduce the weight
You should try these wing that have the shape of a staircase, apperently they help reduce drag at low speed, I think this would be perfect for your plane
For one I really like the foam board design.. but you also could mold the solarcels in a glass fiber composite wing (under vacuum). "Simply": 1. build a negative wing mold. 2. lay a thin layer of glasfiber 3. Lay in the rest of the lamiate. 4. Close up the wing with its underside and internals. The vacuum pressure should hold the solar cells in place and you can build a structurally more sound wing, while keeping the turbulence from the solar cells to a minimum. Obviously it is more expensive, more complex, more waste full, if you damage one cell the entire wing is trash, the efficiency goes down by a bit (I wonder how much though). But the wing, could be overall lighter/larger, and the reduced drag could eventually made up for the loss in solar efficiency. (Therfore a negative mold, where the vacuum pushes the cells into the curvature, rather than on to it, like it would be if you mold it over a positive or a wing directly.) And at last, I know it is your channel but I think you really should start to say "we" instead of "I" when you also state that Hannah worked on the project as well. I See forward to your next project and the continuation of the solar plane.
Why not cutting some rectangles in the aluminium bars to make it a lot lighter and still durable and resistant. You should try first cutting small amount and try cutting more till the resistance is too low then you get new bars and cut them to the desired measure. Also you should let the batteries be in recharge only up to like 90% to not encounter fire/explosive hazards and similar and start recharging at like 70% or so. I would lastly suggest using at least 2 batteries to be safer in case one shutdowns or worse (could happen with lithium batteries). Source: I’m a student of Physics engineering at the Politecnico di Milano in Italy.
build it like a normal glider. Take one of the ASW-17 you have and just add more wing span, you don't need it to be fast, just add lift until it can handle the weight. also mostly use the rudder to turn so you don't bank away from the sun. I guess you could even mix it to bank a little in straight flight to maximize solar input 😉
If you look at real life flying wings, their rear tends to be more of a W shape instead if a V. Maybe having a longer wing root and having actual elevators on it would help. The increased wing area also makes space for more panels and inherently increase rigidity.
I would stick to the MPPT for solar, as it is much more efficient in suboptimal conditions and just have a small backup battery just for telemtetry and avionics, so when there's not enough charge left to power the motor, you can atleast bring it down safely.
To reduce weight, you can punch holes into the aluminum L bracket, retaining the edge for rigidity. And also remove amy unneccesary plastic covering the controllers.
Probably makes sense to try carbon fiber rods instead of the heavy aluminium. Kite shops have them in all shapes and sizes for pretty cheap and the beefier ones are strong enough to withstand heavy winds (and the resulting crashes) on large wingspan kites.
A few tips: Use distributed propulsion, twin, or 3 or 4 or more motors, low KV, and high pitch props. Ditch the aluminum L extrusions. They are heavy and offer very little torsional resistance. Use carbon tubes instead, 1mm wall thickness, and as large diameter as are practical. for a tech demonstrator, you can use direct charging, if you get the ratio of solar cells to lithium cells about right, it will work well. use a simple electronic switch to disconnect in case you succeed in charging more than you use, and for use on the ground when not flying, to avoid over-charging the battery. use a moderately high aspect ratio wing with a real airfoil. about 12 percent thick would be good. you may have to make your own airfoil or modify one that already exists. for instance start with a SD7034 or something like that and thicken it. something with a deep drag bucket in polars, and that can still conform solar cells is about ideal. use open frame construction, and place cells under the covering material. use a design with a lifting stabilizer, a triangular fuselage, and place solar cells on the rear fuse, and also the horizontal stab. Glider wings are usually too thin, and are not optimal for endurance, as they are optimized for L/D instead, which is the equivalent of a distance optimization. of all the gliders, the super light weight thermal ships would be the closest.
If you find you need to drop more weight but worry about a 'wobble', I wonder if using something like Ultem line to pre-stress the wing might help provide some additional stiffness.
One of the things i have learned about MPPT controllers is that you never attach a load directly to them. Instead, just connect your load to the battery directly. The advantage between a MPPT solar controller and the voltage regulator is that MPPT or maximum power point tracking controller is that it actually operates the solar panel at the maximum power and efficiency whereas the voltage regulator doesn't. This is especially important in the evenings and mornings where the MPPT controller will actually be charging the battery and the voltage regulator will not. Unlike a battery, the solar cell produces the highest voltage (Voc) at open circuit and the highest current (Ia) at dead short and the MPPT controller adjust the voltage of the incoming solar to find the maximum voltage to get the maximum power (Vmmp and Immp). Sorry for the long explanation:( Great project and great engineering!!
This didn't make sense to me either. Seems like the solution was as simple as connecting the ESC directly to the battery and leave the MPPT how it was.
Came here to say exactly this.
The previous mppt setup was like driving screws with a screwdriver. Completely fine but not quite practical for the application. Instead of going for a drill (aka connecting the battery directly to the flight controls and continuing to use the mppt) though he just decided to use a hammer to drive the screws. Yeah the voltage regulator idea works but you loose all the benifits of having a solar system since the efficiency is now much worse.
Hey James, listen to this guy. This is your solution. Get rid of that voltage regulator and just make everything draw power directly from the battery.
This is what I was thinking.
This guy is right, this is what we do in solarboat racing. It works well, very efficient and super simple to set up. Just use the genasun for charging, its literally the best on the market and connect your load direct to battery.
now we need a cross country waypoint mission, like RC testflight
Those two are literally polar opposite
Not sure how legal it is in this country though
Possibly across Scotland? 🤔
@@Project-Air Maybe across Vatican city?
Do a GeoWizard and try to cross the country in a completely straight line!
This project NEEDS efficiency to work. To go from maximum power point tracking (MPPT) to a regulator you lose a LOT of efficiency from solar.
Judging by that large coil on the regulator, it appears to be a boost converter with a regulated output. If so, it does a similar function as an mppt controller without the active tracking.
@@Andy-df5fjit literally isn't as the name of the mppt implies theres a point where you can pull the most power out of the cells since wattage of the cells isn't consistent across voltages
@@pleck7059
Yep. No tracking. The maximum power point would need to be dialed in manually. No it's not as good as having active tracking for varying sun conditions, but it's still way better than a resistive regulator.
You could use a row of Super Capacitors instead of the lipo?
@@lynnwilliam technically yes but theres still the mppt missing
The fact that the motor mount broke off so easily probably isn’t a bad thing. It saved the airframe, maybe even the motor. It’s a lot easier reprinting the motor mount than rebuilding the plane or replacing the bent motor shaft.
You're right! Although the crash did actually break the motor. It wasn't shown in this video, but Emma managed to fix the copper wires that had snapped on one of the coils. Pretty lucky as we only had one motor!
@@Project-Air On all my pusher designs flying wings like that I used folding propellers. This saves any mounts and props and the CF props were so expensive back in 2004.
You could always use carbon fibre rods to stiffen the airframe 👍 Great video!
Carbon spars at least. Would be a fraction of the weight of aluminum
Exactly what I was thinking
I would try making it airtight, and use helium for stiffening, and extra lift.
At least the stiffening part works for rockets.
Get some extra lift by pushing some air out of the wings.
No part is the best part.
It's funny how much time and effort goes into these projects and they tend to fail on such annoying mistakes. Watching him is very relaxing and extremely frustrating at the same time 😂
You beat me to it. Exactly! I'm building a rc plane now that uses Aluminum. Not those Monster Girders! Carbon Fiber is Prefect for His Wing!!!!!!
2:40 Well, the simple regulator lacks the capacity to do maximum power point tracking, literally the meaning of MPPT. More efficient would be to have the MPPT in the loop, but connect the load (and maybe the regulator) directly to the battery-terminal of the MPPT along side the battery.
Exactly. The MPPT makes sense - it's just the low voltage cutoff that's the issue. Powering the load directly from the battery avoids that problem.
I also wonder if the voltage regulator they are using has an appropriate current limit. If not, it could exceed the charge current rating of the battery. It would be particularly prone to doing this when the battery is low and/or at low throttle settings.
Yeah this part was particularly frustrating. Especially as they got someone with apparently more experience to help.
The mppt should be between the solar cells and the voltage regulator
Definitly an mpp controller would make sense, espessially when stripped of the heatsink and installed a more lighteight, high airflow appropriate cooling system
@@dack42 This is what I came to say; if they fly for too long in the clouds (and the battery discharges significantly lower than the regulator's setpoint) then it would likely cause damage to the battery when they reenter sunlight.
Great effort! Please dont let Emma keep hand launching like that. She is going to get hurt by the prop.
I’ve done a few solar projects on my own time, definitely not an expert. I would keep the MPPT rather than the voltage regulator though, by connecting the load directly to the battery rather than into the load connection on the MPPT, the other two connections remain the same. In this case the MPPT can charge the battery without worry of disconnecting the load. Keep up the good work Love the projects!
As stated previously here, keep the MPPT controller. Run your flight controls off the battery, not off the MPPT. If you’re going to reinforce with an aluminum spar, use a thinner box extrusion as it will be stiffer in torque than angle for the same weight. Run as many prop motors as you like; the amount of motors does not dictate your power consumption in level (break even) flight. In fact, running more props at lower RPM with more propelled surface area will increase your efficiency dramatically, and also give you the ability to climb when you need it. Your penalty will be weight of course - but not power. I flew in a two-seater solar plane with 5kw on the wings, and a 15kw motor.
Hi! I really love such solar plane projects and plan to implement it one day. You have made a good progress, although I see some problems in your design. If I were you, I would do the following:
1. Replace a bulky LiPo battery with more lightweight DIY Li-Ion pack. It would be like 30% lighter and you can arrange it into a long narrow pack, which would allow to make a smaller hull, minimising frontal area and drag.
2. Mount the motor inside the hull. It will greatly minimise drag. Mounting it may be a bit more challenging, but solvable with 3d printed bracket. Or you can just change your existing motor mount with a more aerodynamic one, that would be an easy fix.
3. As others have already mentioned, MPPT controller’s purpose is adjusting current which is pulled from solar cells in such a way that generates more output and it works more efficient than a simple converter. I suggest you ignoring load output in your MPPT and pulling power from the battery instead.
4. Improve hull aerodynamics. It looks too big, has no front cone (I don’t see any reasons to keep it open from both sides, except for cooling (which is unreasonable and may be improved by having an ESC outside)). Reducing frontal area and adding a nose cone is quite simple.
5. Issue with motor mount being broken off on landing: use folding props. It will fold on landing and while soaring/gliding (and reduce drag). Be sure that not every folding prop mount suits pusher configuration, as props may fold «inwards» and won’t fold out when spinning.
6. Reinforcing. Aluminium is lightweight, but not as lightweight as carbon fiber rods. They may be harder to find and definitely not as cheap as aluminium rods, but far stiffer. Bonus points for making a special battery pack which may be inserted into a carbon rod (I doubt you have a wing thick enough to implement this idea, as 18650 cell and wiring will be quite large, but that’s just an idea). AFAIK AtlanticSolar did this to distribute load on its wings, thus allowing to have higher aspect ratio and thinner hull (by moving batteries to wings). Also, your L-shape aluminium extrusions may be drilled out in places which don’t bear load (for example a side which goes flat on the wing bottom side) which will allow to shed some weight. I also worried if your aluminium extrusions are connected in the center, if not the wing can snap.
7. Top-sided winglets may cast a shadow on solar cells, reducing overall power output. Mounting them inverted will solve this issue, but will certainly break off on landing. There might be a way to make them detach on touchdown, but it sounds more like the least priority to do.
8. Wing profile. That’s probably the most complicated thing in the whole build. I can’t see it clearly, but assume your bottom side is flat, and the top is also flat. Making top flat is probably the only solution to mount solar panels which can’t be bent, but such geometry (that’s my guess, I’m not even close to being an aerospace engineer) produces lift only when an angle of attack is not zero. This means higher drag by keeping nose up. I’ve seen a solution on rctestflight channel which looks like a ladder: solar panels are put on these «ladders» and form somewhat nice aerodynamic shape.
Btw your idea with joining two gliders is cool, but these gliders are based on real life gliders which have a thick cockpit for a pilot, which adds excess drag. I’ve bought a Voluntex ASW28 for endurance flights and plan on getting rid of stock hull and replacing it with custom narrow carbon fiber one.
Anyway, I’m waiting to see new videos with the solar plane!
Yes, this a probably a lot more. You keep calling this an engineering challenge, but you seem to be neglecting a lot of the engineering part. Engineering mainly happened before you take flight, not afterwards. You're just doing stuff and then troubleshooting it. Troubleshooting certainly happens at this stage, but it's not an excuse or valid design technique (as opposed to doing more proper work up front). This was your second airborne design. It should have gone MUCH better than this. This was practically a step backwards. You're designing something based on work that's been done countless times already. You're missing the basics. (I know you're just a kid, and this is just a youtube video, but no one should look at this the way to conduct a project.) Seriously, good luck going forward. I hope you have great sucess. I love seeing young people doing this kind of thing, but you are also a role model. Up your game.
All lithium batteries are li-ion (lithium-ion), regardless of whether they are packaged as a pouch or a cylinder. Pouch cells are probably actually the best option since cylinder cells (like 18650s) would waste more weight on packaging.
@@glenmiller1437 I'm certain you bounced back and forth on whether or not you should post this. It's easy to be seen as being critical even when your intention is to help. IMO you made the correct choice. Almost none of this is new ground and a good deal of this information is readily available online. Be patient, do your research, and most importantly don't be afraid to ask other engineers for help.
@@genephipps6421 Lol, yep, you read my mind. Well stated.
"so I hopped on my Mac"
"and yes, this is all running on a Mac"
(shows B-roll of it running on Windows)
Very interesting video(s) and project, but I couldn't help but laugh at this part.
I mean parallels on M1/M2/M3 mac runs solidworks well enough...
he showed both Mac and Windows versions
Does Emma actually work with you on design and/or construction?
If so, we need more Emma, if she's comfortable with that... always great to see a (historically) stereotypical "male profession/hobby" performed by stereotype-busters. =)
I reckon she's a kickass engineer! Love to see more of her
Seems like a very backwards step to eliminate the MPPT charge controller, due to it having a load safely cut-off. Use the MPPT still, but only for charging. Connect the load directly to the battery. A DC-DC converter wont be nearly as efficient in varying sun conditions.
Another recommendation I would say is to introduce a BMS in front of the battery. RC batteries don't feature one for weight and cost reasons, but in an application where you are continuously charging and discharging a lithium pack, you are very likely to introduce gradual cell imbalance, which your charge controller cannot fix. At some point, the cells *will* go out of balance enough to cause damage, if not a fire. At the very least, add an active cell balancer to ensure imbalances in the cells are handled quickly. They are fairly inexpensive & light as well. They won't have the OCP, OVP, UVP and so on of a proper BMS, but that could even be an advantage as there is no chance of powering being shut off abruptly.
Great video!
The BMS+balancer should in this case only be used while charging on the ground between flights. If used during flight, the total power cut problem comes back and it adds weight.
@@HL65536 This is not necessarily true. An active balancer board has no means to cut power, only equalizes cell voltages. Given LiPo and Lion cells voltage are (fairly) linear in relation to state of charge, there is no risk of balancing voltage causing an actual state of charge imbalance, which is the real goal. This technique cannot be done with Lifepo4 for this reason until at ~95% SoC for this reason.
As for a BMS, I would really only recommend a 'smart' BMS that is configurable, such as a JBD BMS. That way all of the protections can be configured to trigger (or not) at whatever point you like.
Realistically you should only be operating a lithium battery within its safe operation bounds, with margin for error, and that is what a BMS can provide.
16 years ago I cut my right hand on a Deltawing K10 with a pusher prop. I was badly hurt. 3 weeks sick leave. I was shocked when I saw your friend Emma throwing the plane.
Since that day I use only folding propeller and start the engine when the hand is safe. For your monster that configuration would not work.
Ok ... I am 61 years old :-D which can also be a reason to be slightly shocked 😀
In real life I am an aircraft technician and what I also saw is that the wing cord is very small for that length.
To make it stronger, a long carbon tube with a wooden spar glued into it would also be lighter. OK ... to make that can be a challenge.
However, it is a good decision to go for a delta wing or double glider configuration.
I am sure you will get it happen.
best wishes from Hamburg Germany
I also got a bit worried at this part. Saw a guy at the field get his hand too close to an idling motor just the other day. Several deep cuts probably some stitches required. I’ve luckily only got caught in rubber powered props but even they hurt like hell.
Totally agree. Very risky. And no gloves even. And not great that he leaves his girl friend to do that. 😢
I had 4 days in hospital and came close to losing my thumb after a prop strike. 😥
Gardening gloves at a bare minimum, I winced when I saw it nose up and drop as she released it.
Nah, you're completely right to be shocked. The project is cool and everything but launching that plane by hand with the propeller that close is just plain stupid. Not to mention while running through uneven grass... -.-
I would like to second your worries about pusher prop and hand launch. It is accident waiting to happen. Bungy take off is a simple and safer alternative in my opinion. Greetings from Hamburg too :)
Congrats for this partial success. You really stepped up your video production game. There is a reason people use MPPT-Chargers instead of DC regulators. The reason is that we do not really care about voltage but power and the power from solar cells gets really low if the current is too high. This happens when the battery voltage drops, e.g. when there is voltage sag when more motor power is needed. It may be worth testing your charging setup with the actual solar cells and changing lighting conditions and motor power. Also, with a plane that valuable it is always a good idea to provide a small extra battery for the receiver and servos so the plane can be landed as a glider if push comes to shove.
@@Gosuminer maybe a small parachute system instead?
@@JojitBuenaventuraJr A parachute with failsafe release system would weigh a lot more than a tiny battery. Plus it is better to land the plane than to have it come down uncontrolledly, maybe into a tree or water.
Charging a lithium pack with a voltage regulator is a recipe for disaster, and also fails to properly load the solar panels for maximum efficiency. Put the mppt back in the loop, but power the motor directly from the pack.
I'd personally run the receiver and servos using a separate pack that is either wired up with a passive failover circuit (custom) or continually charged from the motor battery using a small liion charger rated for the average draw of the receiver +servos
Use carbon and glass fiber laminates to form the wings. No additional reinforcements are needed, probably gives you the lightest fuselage.
Composite materials also make it easier to produce more aerodynamic joints. For your solar powered plane, efficiency matters
There's a company called PowerFilm that makes super thin and flexible solar panels. I don't know if they are as efficient as the ones you are using, but they could possibly be placed over a frame or even just wrapped around foam or something.
Not a bad idea...
Your design, as I see it, has several things working against it:
1. That aluminum spar is probably more than the wing actually needs in terms of stiffening. You'd probably have better luck with a less-substantial aluminum or carbon-fiber reinforcement, or you could build a torsion box out of balsa. The challenge isn't making the wing strong enough, it's making it just barely strong enough. If it didn't break in the first test flight, chances are good that a very minute amount of reinforcement would be enough to stand up to most turbulence. Your wing probably only really needed any real reinforcement towards the root.
2. Swept wings inherently have poor lift properties at low speeds. Your wing is actually swept well into jet airliner wing territory - unless you're in the mood to start adding high lift devices, you're kinda working against yourself.
3. There's no reason why the chord of the wing inboard of the elevons shouldn't be extended to match the chord at the elevons. Sure, the overall aspect ratio of the wing would decrease, but I doubt it'd create enough drag or weight to offset the lift benefit, especially since I'd wager increasing the chord at the tips is adding to induced drag...
4. You're going to have to optimize the powerplant for efficiency with respect to thrust... a ducted fan of the same diameter as your propeller is probably the best approach. While the duct imposes a drag penalty at high speeds, you're low and slow.
I don't think a delta wing is going to solve your problem - in fact I think it might make it worse. Delta wings are low aspect ratio by nature, so you're going to be sacrificing a lot of efficiency to no real benefit since your airplane isn't meant to fly at supersonic speeds. You're designing a low-speed airplane. High aspect ratio straight wings are the way to go.
God, I was thinking the same thing about the wings, like every solar plane created has had straight wings for a reason.
Rctestflight made it work. Though he was following quite a different design with much wider wings
More wing = less efficiency
However
More panels = more power
A hollow tubular spar would give better strength for the weight. Also, the spar doesn't need to extend the entire length of the wing. Some wing flex is perfectly fine. You just need enough strength to prevent catastrophic failure.
I assume you made the wings swept because of the center of gravity. Otherwise, straight wings would be better for the low speeds.
The electronics are not only a fire hazard, but also not ideal. First of all the purpose of an MPPT controller is to squeeze out as much juice as you can from the solar cells, something that seems vital in your case. Secondly, lithium batteries degrade rapidly without a proper charging curve, and could even explode. Source: am an aerospace Electrical Engineer.
How would a lithium battery explode if the voltage that it's being charged at is lower than the threshold needed to trigger thermal runaway? If you have a battery whose nominal voltage is 14.4 volts and you supply it with 14.4 volts, how would the battery ever get a voltage above 14.4 volts? Especially if it's connected in parallel with a motor?
Your source isn't good enough. It is a logical fallacy called the argument from authority, you may well be knowledgeable but there is always more to learn and mistakes like human error are common place.
Nobody asked
What exactly do you mean, that li-ion batteries degrade w/o proper charging curve? I am not criticising in any way but I am trying to learn from someone with practical experience.
Let's divide my question into three simpler ones.
1. Can li-ion or li-poly work in buffer regime at constant voltage, say 4.1v/cell, given they remain there most of the time and they are occasionally discharged and finally charged in cccv mode?
2.Do the batteries NEED regular charge/discharge for longer lifetime?
3.Should someone keep some state-of-charge (e.g. charge in amper*hours) constant instead of voltage?
@@WhoIsTheEdman In nominal operation, the cheap chinese DC/DC module they are using might not be a problem. But it is your single point of failure regarding battery safety. Who is to say that its output is temperature compensated ?
You could try to mount the solar cells inside the wings with a transparent cover. This should reduce air drag and help (somewhat) to protect the cells in case of a crash. (Yes, this will slightly reduce the efficiency of the cells).
I tried to charge my phone with a solar panel on the inside of the windscreen in my car covering the entire window, I got about 30% of the charge on the inside compared to when I put it on the outside of the window...
I can't see up close, so I'm not sure, but I think the propeller is facing the wrong way. Since you are using the motor as a pusher, the propeller should be facing the other way. This could lead to a significant loss of power. This might be one of your biggest problems. I believe this design should be able to fly comfortably at lower powers. Congratulations, you're doing great!
The simple solution would be connecting battery and ESC to the same terminals on the MPPT. Skip the "Load" terminals as they have a cutoff.
Ideally you can find an MPPT controller for 4s lipo. The one in the video has a slightly lower voltage limit,so wont start charging until voltage drops a bit, but should work just fine after that.
That voltage regulator has no MPPT, this reduces panel efficiency, likely by a significant amount. you could use MPPT + regulator, but this adds weight and extra losses.
Her magical hair almost distracted me from the epic mission undertaken. This is wildly ambitious, and bro just keeps on smashing it, video after video.
4:52 - Some lovely cars in the background here. Can we get a workshop tour?
I have no answers or help, but i'm really enjoying the natural progress of this video series.
Hey buddie, i am working with composite materials and CAD prototyping. That being said, reach out and we can do some carbon-fiber or aramid shenanigans😊 also, i would not have made the motor mount stronger because now more force will be applied to the plane body and the rotor. I would just print 5 of these and just use them as a "failure point"😊
you should try a delta wing and canard plane, like the eurofighter, it would be harder but have much better control
I agree with the top comment here. I have been living totally off-grid for over six years now on a solar setup, and none of my loads are connected to my MPPT; all the loads are connected directly to my batteries. I would still use the MPPT as it has an inbuilt battery charging profile and will reduce the charge voltage if the battery is getting full and avoid you cooking it. The voltage regulator will just keep pumping in power which could be catastrophic.
The motor mount, the fillet helps, but mutch better is some ribs in the other plane/force direction.
📐is stronger than L
Printing it with the "L" shaped side touching the print bed would also make it much stronger, to prevent it from snapping along the layer lines
Couldnt you take those aluminum L brackets and maybe cut triangles out of them to maintain rigidity while reducing the mass of the brackets significantly?
DIY Perks, yeeeeah! What an awesome collab
Oh yes baby, ive been looking forward to see this project again.
Im hooked to this channel, keep it up! You will get it flying!
Brilliant work, James and team! Really well done! 😃
Stay safe there with your family! 🖖😊
I would really like to see you building a rocket-launched glider. launch it 250m into the air and glide it down.
Same
😊
Yeah, electrical systems are something I know nothing about. It's very interesting to see your problems as well as your solutions. Bravo!
For motor mount, you need some ribs. And also print orientation is crucial. You snapped mount along layer lines, just print your mount on the side and you'll be fine.
we use solidworks in school in DT which is my favourire subject!
At least the plain landed flat on the ground better than a nose dive . I agree the delta wing design should be more stable and carrie the load better can't wait to more on the future project keep up the great work 😊
I would love a video entirely focusing on the solar+battery setup
I also have a solar charge controller that protects my batteries by shutting off. The thing is, I really *really* must keep my navigation lights on at night, or risk being run down (and killed) by a ship. So I have an override switch that bypasses the controller. It might damage my battery, but on the other hand, I'm a lot less likely to die. When your plan fell out of the sky, I was 90% sure I knew why!
As others have noted, carbon fiber rods would likely be a better choice than aluminum L-channel. You can also attach them to one another with a custom printed 3D bracket to extend rigidity across the entire wingspan (though you might consider reinforcing that with a layer of fiberglass).
Burt Rutan's design!!!
It went around the world none-stop!!
Now it would be interesting if you made a plane with aerogel ❤
I like the idea of the 'ready made' twin conversion, I think you should also explore other aircraft types as well before settling on the next iteration of your project
Here's what I would do for your electronics:
- Keep/reintroduce the mppt as its way more efficient in harvesting power from the solar cells. Also add a small BMS for battery safety.
- Group your systems into different levels of criticality. Your power will eventually run out, so what you wanna do about it? You need to know what systems need to run till the absolute end even if it kills your battery (these are likely radio + flight controls). At the moment you just keep discharging your battery, which wil likely kill it - thats what the disconnect precents after all.
- Set the disconnect to the lowest safe voltage for the battery if possible.
- cut off the motor if power is lost, effectively turning your plane into a glider.
- manually or automatically switch on a little reserve battery for flight controlls so you can land safely.
Yes I was waiting for this one !
Thank you for taking the time of making such high quality videos
This is actually crazy. I know how hard building planes can be. I can only imagine how hard it can be if you’re the one designing it too.😮
The width of the plane's wing should keep them from wobbling front to back too much which means you don't have to use L-shaped aluminium profiles, use flat profiles and mount them vertically in the wing. This will provide up-down stability while cutting the weight of the reinforcement in half
Why don't you use pre-tensioned kevlar string to prevent wing flexing? Of course, string will cause some little air drag but it weights about to nothing and does significant stabilisation efficiency as a triangular element. Just tight it in between winglet tips and the center of the wing.
You are doing a great job with the channel! Keep it up! Also I feel like a delta wing is the way to go. Good luck! Can’t wait to see what you come up with.
The two of you need to come to California for your next experiment. We have a lot of beautiful deserts where the sun always shines and the wind is minimal
Why are you using a swept wing? Arent those for efficiency at high speeds?
Yeah I wonder if it provides some advantage I'm not aware of. Because it's usually not used for long range stuff
My guess is to avoid having the extra drag of tail surfaces. That's the main benefit of flying wing designs, reduced drag. But it requires a fair bit of wing sweep to get sufficient moment arm for the elevator control surfaces.
Really a video that deals with an interesting topic, that of solar powered aircraft, a much discussed topic in recent years. Well done and congratulations for bringing this very current content to TH-cam
Was expecting a part 2 and here you are
In before 5 minutes of release - nice
Good to see part 2 on this project :D
Maybe make the wing spars carbon fiber?
Moding the gliders is a flippen good idea!!!
I think it’s time you consider moving to the western U.S., loads of flyable days a year, plus we’d love to have your entrepreneurial spirit here
0:28 💥KABOOM
Saw you two at project air on the bbc today so glad everythings going well on the channel and and glad me and all the followers are part of your journey 👍
Part orientation while 3D printing would make the motor mount stronger, print so it's less likely to snap along the print lines. great job!
Lengthen the nose a bit more. Make a sharper front nosecone and place angled canards on the front to bring down the stall speed. Move the verticals to mid wing, and add small wingtips to the end of the wings to add efficiency.
I remember a few years ago seeing somebody created a solar hovercraft, but the technology has advanced quite a bit in the last couple of decades, so it might be worth you exploring it a bit.
That would've been RCtestflight you saw, his plane was quite impressive
Looking forward to part 3😅🙏
Knowing the wing load of first version and final version of the aircraft would be nice. I always keep track of my R/C aircraft g/dm². For roughly 1m wingspan planes, I had 10g/dm² as the target for slow planes, 20g/dm² for faster trainers and +30g/dm² for really fast and heavy planes.
FINALLY PT 2 I HAVE BEEN WAITING FOR SO LONG
I'd rethink a few things:
Flying wing is not as efficient or stable as a conventional tail setup.
Pusher prop is not as efficient, quiet, or safe as a tractor.
MPPT is more efficient than a charge controller, just hook load up to battery. MPPT should prevent overcharge, and ESC should prevent undercharge.
I'd love to see those RTF glider wings attached to a wide lifting body for extra cell space.
drill lots of holes in the aluminum to reduce weight and maintain rigidity
Since the plane is painted like the German ICE train, it will inevitably break down for no reason. And arrive very late.
That was a classic 'spiral dive' manoeuvre - I think the recovery method is level wings, wait for flying speed then pull up and roll out
Love your Mini!!
If you aren't flying at high subsonic speeds, I'm confused why you're using a swept wing design. perhaps consider a slight dihedral as well for stability.
I would personally bring back the mppt cobtroller just as a battery charger maybe even add more than one. Basically my idea is section the wing in such a way as to minimize the drop of performance during partial shading of series panels. For example using a separate mppt controller for each wing or maybe something like the external parts of both wings go to one controller while the internal ones to another. The mppt charge controllers shouldn't have any issues charging the same battery. Also ardupilot have a cool looking charge controller on their wiki that can talk directly over can and provide a ton of useful information.
Idea:
-Use thinner but wider wings to increase lift without increasing drag.
-Take one or both fuselage parts from the gliders and reinforce the wings with 2-3 thin carbon or aluminum tubes.
-Theoretically, you could also cover the gliders fuselage in a thin but stable layer of fiberglass and then dissolve the Styrofoam with acetone so that a hollow ultra-light shell remains
These are just ideas and I would love to be able to implement something like this
Keep it up. Properly invested in this now and even if we have to wait until next June for the maximum sunlight it’s worth persevering with. Finally taking it way north for 24 hours of sun and a whole day of flight
really enjoying these videos
Using a battery balancer would be a good idea. There are standalone breakout boards that you can hook up to the battery for that. As just using a voltage regulator is not really ideal for battery charging. Using proper charge circuitry would be better for safety and battery health. But balancing the cells would make it at least less bad.
Really Looking forward to the twin gliders tho!
Balancing isn't really necessary for this. The battery will stay balanced for the most part
Use carbon fibre SHS for your wing stiffener and print the motor mount on its side to increase its strength, you can also coat the printed parts with super glue, this will increase strength and reduce wind drag.
Wing structure can be made lighter and stronger by having thinner support beams in wing tip and and tail and bottom and top centre instead of one thick beam in the centre. Wing skin can be made of mylar foil glued to airfoil rib structure of the wing to massively reduce the weight
You should try these wing that have the shape of a staircase, apperently they help reduce drag at low speed, I think this would be perfect for your plane
This is an awesome project! Love to see how you progress!
For one I really like the foam board design.. but you also could mold the solarcels in a glass fiber composite wing (under vacuum).
"Simply": 1. build a negative wing mold. 2. lay a thin layer of glasfiber 3. Lay in the rest of the lamiate. 4. Close up the wing with its underside and internals.
The vacuum pressure should hold the solar cells in place and you can build a structurally more sound wing, while keeping the turbulence from the solar cells to a minimum. Obviously it is more expensive, more complex, more waste full, if you damage one cell the entire wing is trash, the efficiency goes down by a bit (I wonder how much though). But the wing, could be overall lighter/larger, and the reduced drag could eventually made up for the loss in solar efficiency.
(Therfore a negative mold, where the vacuum pushes the cells into the curvature, rather than on to it, like it would be if you mold it over a positive or a wing directly.)
And at last, I know it is your channel but I think you really should start to say "we" instead of "I" when you also state that Hannah worked on the project as well.
I See forward to your next project and the continuation of the solar plane.
Why not cutting some rectangles in the aluminium bars to make it a lot lighter and still durable and resistant. You should try first cutting small amount and try cutting more till the resistance is too low then you get new bars and cut them to the desired measure. Also you should let the batteries be in recharge only up to like 90% to not encounter fire/explosive hazards and similar and start recharging at like 70% or so. I would lastly suggest using at least 2 batteries to be safer in case one shutdowns or worse (could happen with lithium batteries). Source: I’m a student of Physics engineering at the Politecnico di Milano in Italy.
Wow, amazing video as always!! Keep going!
Try a front elevators to counter the nosedive
Nice mini I’ve spent all day picking parts for the old minis
build it like a normal glider. Take one of the ASW-17 you have and just add more wing span, you don't need it to be fast, just add lift until it can handle the weight. also mostly use the rudder to turn so you don't bank away from the sun. I guess you could even mix it to bank a little in straight flight to maximize solar input 😉
If you look at real life flying wings, their rear tends to be more of a W shape instead if a V. Maybe having a longer wing root and having actual elevators on it would help. The increased wing area also makes space for more panels and inherently increase rigidity.
Option 1: perforate the aluminum to lose some weight.
Option 2: use carbon fiber arrow shafts (splice them together) to stiffen the wings.
I just saw bro has about 500,000 subscribers and honestly I'm shocked
He deserves 10 mil easily
I would stick to the MPPT for solar, as it is much more efficient in suboptimal conditions and just have a small backup battery just for telemtetry and avionics, so when there's not enough charge left to power the motor, you can atleast bring it down safely.
To reduce weight, you can punch holes into the aluminum L bracket, retaining the edge for rigidity. And also remove amy unneccesary plastic covering the controllers.
Probably makes sense to try carbon fiber rods instead of the heavy aluminium. Kite shops have them in all shapes and sizes for pretty cheap and the beefier ones are strong enough to withstand heavy winds (and the resulting crashes) on large wingspan kites.
You didn't fail, you learned something new.
If you gave up, then you have failed
A few tips:
Use distributed propulsion, twin, or 3 or 4 or more motors, low KV, and high pitch props.
Ditch the aluminum L extrusions. They are heavy and offer very little torsional resistance. Use carbon tubes instead, 1mm wall thickness, and as large diameter as are practical.
for a tech demonstrator, you can use direct charging, if you get the ratio of solar cells to lithium cells about right, it will work well. use a simple electronic switch to disconnect in case you succeed in charging more than you use, and for use on the ground when not flying, to avoid over-charging the battery.
use a moderately high aspect ratio wing with a real airfoil. about 12 percent thick would be good. you may have to make your own airfoil or modify one that already exists. for instance start with a SD7034 or something like that and thicken it. something with a deep drag bucket in polars, and that can still conform solar cells is about ideal. use open frame construction, and place cells under the covering material.
use a design with a lifting stabilizer, a triangular fuselage, and place solar cells on the rear fuse, and also the horizontal stab.
Glider wings are usually too thin, and are not optimal for endurance, as they are optimized for L/D instead, which is the equivalent of a distance optimization.
of all the gliders, the super light weight thermal ships would be the closest.
Consider using tensgrity inside the wing to keep it stable. Sometimes just pulling without being able to push is advantageous.
From devastating crashes come breakthrough ideas and success. Cheers!
If you find you need to drop more weight but worry about a 'wobble', I wonder if using something like Ultem line to pre-stress the wing might help provide some additional stiffness.