RC Solar Plane Flight Duration Test

this video is sponsored by simplisafe more on them later so it's a beautiful morning out here at the test field i've got the solar plane v4 here with me now the last time i flew this plane was last winter pretty close to the winter solstice and i think back then it flew for about two and a half hours or so i don't remember the exact time but it was quite a while and uh now it's july 25th i think the sun's gonna be a lot higher in the sky so i'm expecting this thing to be able to fly all day but that's what i'm out here to find out i'm gonna get it in the air now to start racking up the flight hours and i'll talk more about the details later [Music] [Applause] so it's now 8 20 am the plane is in the air circling just in rth mode right now or return to home mode you might notice a fuzzy thing right here on the side of the frame that's a a big wind sock on my microphone and i put it there because it's already getting pretty breezy which is uh surprising for this early in the morning and a bit concerning because this plane will not handle very much wind so hopefully it's just a few rogue thermal cycles rolling through and the real strong winds don't pick up until later in the day i didn't want to launch the plane too early in the morning because then it wouldn't get enough solar power to sustain flight while the sun was low and the battery would end up dying if i timed it just right i would be able to have the battery get super low right before it started charging back up again assuming it actually is able to charge i think i ended up launching a bit later than i potentially could have but that's all right so it's about 11am now and the voltage has actually gone up quite a bit so that goes to show we're charging and it's going to be a long flight so there are a lot of things wrong with this plane i really should just put a whole new autopilot setup in it because i've been having some problems with the power modules i thought it was a reference voltage issue but i fixed that and it's still very wacky the measurements that i do trust are the battery current and battery voltage on power module 1. this is the power module that is placed right in front of the esc so it's measuring the current draw of the motor the second power module is in between the solar cells and the mppt controller its readings are all over the place and not to be trusted my compass is wacky and i'm unable to get a good calibration with it might be because the power wires are too close or something i'm not sure but luckily that doesn't really matter because the autopilot can derive the heading from the gps direction as for the airframe it's not very optimized for efficiency at all you might remember from my first video of this plane but it actually crashed last year so there's a lot of extra hot glue and tape holding things together many of the solar cells are still scuffed up from the crash too to make things worse i glued an fpv system on the front so that's even more drag the only reason i'm even bothering to fly it in this condition is because it was working so well last year that i'm confident it will still be able to fly all day even with all these inefficiencies so it's high noon now and the battery is just about full at least i think it's full i'm not actually sure because the power module is not calibrated properly i spent like six hours trying to calibrate them and they change all the time there's something going on with the power system but i'm pretty sure the battery's full because the voltage has climbed and it's not climbing any further so it was a bit breezy this morning but luckily the wind has not picked up any more since then the solar plane is definitely kind of weaving a little bit on its circular path but it hasn't deviated too much so it seems to be handling the little bit of wind just fine it also seems like there's some thermals because it's kind of bumping around i can tell especially when i was chasing it with the with the mavic and my nazgul i could tell that that it was moving up and down a lot flying through the lift the turbulent air pockets but yeah so far all as well i'm getting hungry now gonna have to uh break out the george foreman do some solar powered grilling so it's about noon and the battery voltage is going up which means we have a surplus of power when the sun is high in the sky that's fantastic by now we've confirmed the solar plane v4 is able to sustain flight purely on solar power which was my goal with the solar plane project from the beginning so now let's talk about why it works now i'm no aerospace engineer so all of what i'm about to say is just my theory and it might not actually be true i'll start off by acknowledging there's a big difference between this type of solar plane and a solar plane that would be capable of flying indefinitely like a pseudo satellite now one of those has to be extremely efficient so that it not only has enough solar power to sustain flight but it also needs to be able to fully charge the battery every day and use that power to stay up all night it's much harder to build one of these because in order to stay up all night on battery power alone you need an extremely efficient airframe not only does it need to be super smooth and sleek for low parasitic drag but it also needs to have an efficient wing for low induced drag and the way to get the lowest induced drag is to make your wings long and thin like a glider the problem with this is that you can't fit as many solar cells on there so there's definitely a sweet spot in the wing aspect ratio planes with long thin wings are also much more difficult to build because they require more structure and stiffness and thus end up heavier too now the solar plane v4 is on the other end of the spectrum it definitely would not be able to survive the night on battery power but it does have some advantages like it's easier and simpler to build and it might even be better for climbing to high altitudes more quickly because of its excess power and lower weight so the concept here is basically just to forget about high efficiency wings with low drag and just to make a thick slow flying wing that you can fit a bunch of solar cells on the extra power that you gain from a thicker wing cord with more solar cells is greater than the efficiency you lose from making that wing aerodynamically less efficient by making it fatter now this only works at low speeds and here's why if we look at a graph that shows the total drag of an aircraft we can see that parasitic drag increases the faster you go and the lift induced drag decreases the faster you go the solar plane v4 flies really slow so parasitic drag has less of an effect and induced drag has more of an effect this is a good thing because by making our wings nice and fat like a park flyer we significantly increase our parasitic drag but we did not increase our induced drag at all assuming the weight stays the same even though we have significantly more parasitic drag the parasitic drag doesn't matter as much because we are going super slow and the induced drag makes up the majority of the total drag of the aircraft now i don't really think this fatwing concept would work with a larger aircraft but it makes sense for smaller solar powered planes if i ever want to build one that survives the night i'll probably have to use a higher aspect ratio wing because loading up a fat aspect ratio wing with a lot of batteries creates much more induced drag and you end up flying faster so the parasitic drag matters more if we do a direct comparison looking at airframes with the same number of solar cells i still think the skinny wing version would probably perform better but from a practical perspective it would take a more complex wing structure and just end up being inconveniently large so i'm not claiming that this fat wing more power concept really makes for a better solar plane all around but i do think it makes for a better and more practical hobbyist grade solar plane rc solar planes are definitely not very popular yet but i think this fat wing concept could change that since they are really pretty simple to build again not sure if any of that is actually true but it's my speculation big thanks to simplisafe for sponsoring this video when it comes to home security the subaru with outback is usually a pretty good guard dog but my roommates and i felt like we needed something a little better since we live in a slightly sketchy area simply put simply safe is a network of sensors that you install throughout your house and they all connect to wi-fi so you can monitor and control everything from a smartphone or computer the sensors include entry motion glass break water panic smoke carbon monoxide video doorbell camera smart lock key fob control panel and the ever so aesthetic base station they also include a multi-purpose burglar engagement harpoon axe that can be used to tactically neutralize any threats that tried to enter your home it also doubles as a yard sign now all this tech probably sounds pretty tough to install huh turns out it's actually as simple as connecting the base station to your wi-fi and following the simple step-by-step instructions to connect to each one of the sensors they even use adhesive pads to attach to the walls so installation is quick and easy all the sensors are monitored 24 7 so if any of them are triggered a trained professional will evaluate the situation and call the police if necessary click on the link in the description to get your own simply safe home security system now back to the video we got the rover over there driving around also on solar power i've got some vegetables grilling the wind is kind of picking up though so hopefully it doesn't crash the plane while i'm caught off guard here cooking this is gourmet powering it all with the ef delta 1300 there also charging the computers and that's charging off of the solar panel out there chef daniel does it again how elegant so i put it into auto mode so that it'll fly the waypoint mission that's uploaded and it's not doing a very good job at following the path it's probably a mix of poor tuning and having a super lightweight airframe in the wind the wind speed has picked up quite a bit so i think i'll put it back into return to home mode so it just circles around the field that seems a bit safer so the voltage telemetry is showing upwards of 20 volts sometimes which is definitely not true if that were true the battery would be exploded once i land i'll have to figure out the exact offset that's what we're battling now seems to be doing fairly well though [Music] so what happened next is pretty wild i decided to put the plane in fbwa mode and manually fly it around for a little while with fpv while doing this it seems like something got messed up with the altitude estimation because when i descended back down it was reading falsely high altitudes also right here there were strong winds and the plane thought it was flying backwards since the compass wasn't working anyways the altitude inconsistency must have triggered an ekf error or something like that because i was unable to put the plane back into auto or return to home mode because of this i decided to land super quickly arm and disarm the flight controller and hopefully reset the ekf error and take off again a few seconds later i also thought this would be a good time to check the true battery voltage so i could calculate the offset based on what mission planner was telling me i thought it must have been reading 3 volts high or something like that and i would just be able to subtract that offset from whatever mission planner was saying and know the true battery voltage turns out it was a good thing i checked jesus christ holy crap this is a bomb i have to get it out of the airplane before it blows up this is why you need a bms holy cow it's hot uh this is very dangerous very very dangerous 4.6 volts on one of the cells so maybe that uh ultra high voltage reading i'm gonna get rid of that thing so maybe that super high voltage reading on the telemetry wasn't false after all that is sketchy now let's talk about why this plane almost turned into a fireball in the sky so the solar panel makes around 24 volts that goes directly into the genuson gv5 mppt charge controller its job is to calculate the optimal amount of current to pull from the solar panel so that it operates at its maximum efficiency it's also supposed to stop charging the battery when it gets too full and it seems in this case it failed to do that in most solar power systems with lithium batteries a bms is used a bms job is to keep the battery cells balanced and prevent overcharging and over discharging for the solar plane i haven't really needed a bms because the battery isn't being cycled enough times to allow it to get out of balance i just stick a freshly balanced charged battery into the solar plane fly it for a few hours and then take it out assuming the overcharge protection on the gv5 charge controller actually worked as expected i still wouldn't need a bms and all would be well i emailed genasun asking why their charge controller overcharged my 4s lipo to 20 volts and their reply was this i believe what you observed is the controller's ability to charge a battery even when the minimum battery power for normal operation is not available if the minimum amount of power is not available from the battery the controller will act similarly to a diode attempting to connect the solar panel directly to the battery now i'm still not sure why the gv5 went into this mode because the battery voltage never got that low but this definitely goes to show that the gv5 really relies on the battery having a bms with over charge protection so i will either need to get a bms or find a new mppt charge controller the show must go on so i'm going to take some of these little uh race quad batteries these are dead i've already flown these they're pretty much totally dead okay so two batteries are in there only one is plugged in the other one is just to help get the center of gravity right okay this thing says we're at 14.9 volts and the telemetry is reading 14.97 so it's basically accurate i thought it was i thought there was a huge offset the whole time but it was actually just overcharging that battery that's laying out there now okay let's get this thing back up in the air so we are back up in the air with a small 1300 milliamp hour 4 cell and the plane is back in return to home mode circling above as you can see it's not doing a very good job at circling this plane flies poorly to say the least it's not an aerodynamically stable aircraft at all it's just flying because the flight controller can control it well enough i also had a really close call when i was launching it there um with the small battery i almost hit the blackberry bushes over there i couldn't turn the right direction for a second because my airspeed was too low and then the plane started circling around the trailer as the home position which is too close to these big tall trees over there so i had to try and scramble and fly the plane while at the same time updating the home position in mission planner 2 out in the middle of the field and it was going all over the place and it was just a mess the sun is pretty high in the sky but it's definitely not directly overhead so it will be pretty impressive if it's able to charge the battery also to cope with the extra wind i bumped the cruise throttle up by a few percentage points so it might not be as efficient now so the idea behind flying with this smaller battery is just to see how the plane would be doing solar power wise if i wouldn't have had to land [Music] i started discharging this since the cells were super high and i'm gonna have to transport it home and then it started making strange noises wow that's so sketchy blow up already so i've been flying for quite a while with this new smaller battery and the voltage is remaining pretty consistent weird the cells are at 3.8 volts each which is pretty normal i wonder why it started puffing up i discharged it by plugging it into the ef delta 1300 here because it has an xt60 connector right there for a solar charging so i figured i'd just drain that thing into this every time i look up i don't see the plane and it scares me for a second so the winds have calmed down quite a bit it's actually pretty nice now but the voltage is dropping down quite a bit it's kind of getting into the 14 volt range and i'm pretty over this to be honest so i'm gonna land it now the eagle has landed it's been a long day for the solar plane v4 it's a bummer we couldn't do one continuous flight but we still stayed up for hours and hours i'm not exactly sure how long but it's been a long time let's see what this battery is at here's my cell checker so the lowest cell is 3.77 the highest cell is 3.78 and that was at 28 so i landed probably about the right time well it's been an interesting day maybe a little more exciting than i would have preferred i'm glad we're finally on the ground i'll be glad if i never have to fly a plane for nine hours straight ever again it's not a great use of your time but anyways it was cool to see that this thing is capable of that and i'll have to think of something else that's cool to do with it since it's still in one piece anyways that's all for this video thanks for watching bye

Channel: rctestflight

Views: 613,324

Rating: 4.929039 out of 5

Keywords: solar, drone, fpv, UAV, rc, plane, airplane, long range, powered, electric, rctestflight

Id: 1OGrDvInUAY

Length: 16min 48sec (1008 seconds)

Published: Sat Aug 22 2020

Reddit Comments

[u/cat-and-or-dog-food]

Nice. I'm pretty sure that in terms of a relevant load carrying capacity that batteries say minimum five times heavier than whatever equivalent in fuel/ice (which currently the FAA limits to 5 gallons or ~150 kWh) and scales even worse

And - a solar sail smaller than a few tens of square meters?

edit: lets assume we could get twenty sq meter solar sail in under 8 stone which could provide half of the load carrying capacity - of the whole getup plus of maybe a person and a suitcase - at solar noon