It requires huge battery capacity and produces a big and heavy plane... here look at this: ruclips.net/video/8m4_NpTQn0E/видео.html This is 'Level 3' stuff...
Great work, indeed ! I built a 3,5 m solar plane (no buffer) during the 1990ies. Flew very well and is now on permanent display at "Flugwerft Schleissheim" (German Aerospace Museum).
I'm loving this series man, keep it up. Been watching since the first solar plane and loving the progress. Best of luck with the V4, but this V3 seems to be doing pretty well. 👍🏼
Long range FPV, you need directional antenna's, a lower frequency, looks like he is using 1.2Ghz band. 600mW+ transmitter, although you can get decent range by using decent antenna's. Bonus if you have a diversity receiver to utilize multiple antenna types. Tracking is even better. I can get 2KM with good signal on 5.8GHz with directional patch / helical antenna's and a 600mW transmitter with cloverleaf.
This airplane you made is so awesome. It has seemingly unlimited fly time and can fly itself and can go several thousand feet high. I need to learn how to make a plane like that myself some time!
Hey, thats exacly why do you need MPPT, in direct sunlight , at perfect angle on a sunny day you will get probably 95+% of your panels potential if you connect it directly to power system, but on a clouudy or smoky day, or even when you fly so just part of panels is exposed to sun, the MPPT can boost your power up a lot, and i mean really alot. Also your power meter is avaraging reading when it displays it so its n its not a good way to measure power. MPPTs work with usually with more than 10kHz control loop so its catching all the liitle power spikes and pushes most of it into the battery no matter how many cells it has . Keep up the good work, one of the most interesting series on YT right now. cheers!
Try adding a substantial electrolytic capacitor in parallel with the solar array. I can act like a super charger by defeating voltage lag. I've had good success with this method on stationary systems. I generally see a net boost of 30% or more under heavy loads.
Advice from a scientist in atmospheric physics: In case you will meet haze, etc. during future flights: Climb as fast fast you can, since these haze particles (aerosols) are confined in the so-called planetary boundary layer (not exceeding height of thermals). Just climb and climb and your plane will gain performance, once out of this hazy stuff. And get rid of this heavy Lipo. There are numerous RC planes around with PURE solar cell operation !
The real benefit of a charge controller or a standard buck/boost board is the ability to charge the battery even when the solar cells aren't above battery voltage. You were correct in finding they do have a penalty for peak power, but I think that it may more than outweigh it by allowing you to use power all the time. However if you're always above battery voltage it is a moot point. Awesome video! You got me into 100w led chips, and i'm loving it!
Nice video again Daniel, thanks. On my planes I'm using BLHeli ESC's and I have the props set to lock when the motors are shut down and have found noticeably better glide times, something you might want to try. I appreciate you sharing your info with us. Billy in Canada
Nice series. For a flight in summer I'd recommend attaching the solar cells to the bottom underneath the wings for cooling. This should improve the performance of the cells a few percent, depending on the temperature maintained inside the wings before. The backside of the cells should not be covered for the most part of it to improve cooling.
Usually when a plane tucks and speeds up in a dive, it's indicating that it's tail heavy (and is thus trimmed to provide positive lift with the horizontal stab, instead of more usual negative lift). For max efficiency you might want it little tail heavy, but have to be aware of that effect in a dive, or just avoid dives all together. Vector doesn't choose to descend at low amps. It's actually running the throttle at no less than cruise throttle position, but because it's descending it unloads the prop which causes the amps to drop below what you'd normally see for cruise. BTW, Vector will display watts. Just add it to the OSD.
That final analysis showing minimal power loss is hugely encouraging. I presume the current (pun intended) range of 'flexible' solar panels aren't the best when it comes to generating power. But once they are and are made available individually, then this type of project will be feasible for just about anyone. Myself included. ;¬)
With your weather conditions I was not surprised at a lack of thermals. Fishing and Flying - Watch the Birds!! Was a bit surprised with the Sink. Would be awesome to have Glide rate or Angle of attack but you have to have an accurate Ground Speed, too. I always look forward to your contributions. Perhaps a few tiny Wind Turbines could help the down-leg. When you are falling, you can bring them out like Flaps. A little Drag and a little Charging power? 2-Way to the Max.
Can't wait to see Solar Plane V.4! Hope you are able to get all the energy control features designed in. So you are also drawn to musing over the earlier approach to the horizon of the sun after you watched the moon pass in front of it. I have been watching the moon a lot too! Except missed the full moon during hurricane Irma, so tragic I was following wind speeds and precipitation radar. Hope this weekend's new moon brings you and your viewers luck!
Awesome, thanks for posting. Perhaps add a luminance meter during solar test, not trying to kill your data, just remember that solar isn’t a constant resource.
I'm not sure if this applies, but I used to make custom battery powered remote unattended data loggers. I would switch in a custom boost at the end of the discharge and gain a few more minutes of run time without it eating up more than it saved. I traded extra voltage by discharging the battery a little more than it normally would run my equipment. You have to test if it's worth the weight and a possibly shorter battery life for it. I really enjoy watching your engineering.
Those look like ~5.0Amp @ 0.6 volt cells, and most definitely need to have the sun Ray normal to the surface of the solar cell, to maximize power output of the cells.
Great project! I watch your progress since first video, really. If you want better efficiency you need to place solar cells directly to the sun, I mean foil covering wings reflect about 30% of light.
The windmilling prop is really a problem for gliding. A motor brake with the fixed prop would already help but folding props could be the even better solution for this project.
i know the charge rate in watts is important. but if you charge without voltage protection the max voltage of the cells must be the max charging voltage. another thing is if the solar voltage is lower as you battery you wont charge. ok this is obvious but what i wil say is, your mttp charger might be able to boost charge so it could use a lower voltage as input to get a higher voltage output so you get still power. unfortunaly most mttp are buck converter type charger and they go in a pwm mode if the input voltage is to low and stops about 2v difference. what you need is a boost-buck converter with mttp tracking
For what it's worth, I have one of those cheap CMP12 PWM charge controllers on my boat (a very bare bones boat with 2 x 20W panels) and it's more efficient than any MPPT controller I've tried so far over the course of a day, with the sun and boat moving around. I plan to test a few more, but it's by no means a certainty that MPPT is best. It's certainly not super important for my application.
I would support you just for some sanity. Too much YT for me recently while researching and I can relax while you do your video content. Must look into the V3
You might consider switching to a dragon link dipole for your 1.3 video along with a yagi on the ground. Very little wind resistance and tiny profile plus I've had great results with this setup out to 50 miles thus far. Awesome project though!!
At 13:08 the right wing looks like its rotating around the wing spar, look at the trailing edge near the fuselage. At 13:10 the wing moves back in to place after the dive is stopped.
Daniel, just had a thought... Wondering if you could use the length of the body tube ... Build an old school idea and run a rubber band through it's length run an "excapement - generator" that can be remotely started when you need it ... You possibly could do similar ones in the wings if they could preload the span to add to a semimonocock preload to make the wings stiffer ... Each could be geard to run slow and spin up a generator that can be started individually when needed... Just a thought ... Ed in Phoenix writes
What if you put a small battery in it, and a bigger one, then after climbing high enough, make the bigger one go down with a parachute. Then glide with solar assist for as long as you can. Maybe the weight difference would help to sustain a flight with the voltage not dropping at all :?
The way you were trying to measure efficiency at about 9:00 in the video is sorta problematic. You've got to measure both input and output. In other words, with the MPPT in the circuit, you need a power meter between the panels and MPPT, and another power meter between the MPPT and the battery. You would calculate efficiency as: output divided by input. For example: 100 watts coming out of the panels vs 93 watts coming out of the MPPT = 93% efficiency. You would then repeat that measurement for each different kind of controller (the two MMPTs and the PWM). That's the only way you're ever going to figure out which charger is the most efficient. Hope that helps, awesome vid.
MPPT's have their place in terrestrial solar power systems but they aren't the best solution here. They're useful when you have arbitrarily selected panel and battery voltages but for a custom system the elements can be selected to match so the controller is just extra weight on top of the small losses to thermal systems inside the electronics.
not enterly true. since the efficiency of the solar panals varry with both the amount of light and the resistance of the load (*spectrum of the light also matters). So the most efficient setting depends on these 2 variables. the amount of sunlight wont always be the same due too many obvious reasons. but the load resistance also varies. *eg: how full is the battery charged, what is the discarge rate, overall temperature potential out of spec solar panel. so aslong the efficiency/consistency gained from the controler is more that the power needed to lift the weight one should use it. wsc112782 for efficiency you indeed always NEED to mesure input and out put. otherwise you're just measuring raw power with unknown variables/changes. have said that. since thats said rctestflight might want to invest in a cheap LUX meter to make setup comparisons more easy and fair.
It’s so great what you’ve been able to do with solar tech, I wonder if you could do a toned down version on a hexactoper (with really long arms but lightweight enough to hold a lot of panels
You should have maybe a seperate two cell and bec That powers all the servos and the fc, that way if the main battery dies or disconnect you got a good battery powering the tech
There likely isn't a folding prop that will compare to the efficiency of the props he is running. He is running fairly low RPM with big props and low air speeds to get high efficiency. Typical folding props are designed to run at higher RPM and higher airspeed.
Superb test good job! each test will definitely contribute design improvements. What if you test your plane in DIY wind tunnel with High CRI LED lightings. Simulations brings lot of dynamic information for design improvement. With wind tunnel you can test the flight under smooth and bad wind condition. High CRI LED lights to simulate solar radiation. With that i hope i can help..Keep it up dude!
Avoid using a charge controller, it reduces efficiency and adds weight. Even if the generated solar voltage is much higher than the battery, the internal resistance of the battery will prevent the voltage from rising higher than the current state of charge. As long as you don't exceed the max charge rate or charge over 4.2V per cell, the direct connection will be your most efficient. If you are using a diode to block voltage, consider Schottky diodes to reduce drop. If you can find a small FOC based motor drive, it should also gain efficiency.
Next goal is to make it climbing during the day and charge and at night descent and keep flying until sunrise. 24h unlimited flight...
It requires huge battery capacity and produces a big and heavy plane... here look at this: ruclips.net/video/8m4_NpTQn0E/видео.html This is 'Level 3' stuff...
What @Simon L said + you are assuming the night + day is going to be peaceful and sunny. One rainy day and the flight is pretty much over.
@@1stKillZone fly above cloud coverage
At least a vision fir durability and endurance
Kill Zone go into stratosphere bud, and maybe use some other system to help it get up initially. Can do for months until equipment failure maybe.
Great work, indeed !
I built a 3,5 m solar plane (no buffer) during the 1990ies. Flew very well and is now on permanent display at "Flugwerft Schleissheim" (German Aerospace Museum).
Cool!
DUDE I SAW IT!!!!
Mhmmmmmm
@@KiraOTS where is that?
@@Silver-xd1ge ?
You donate $5, "your name is now flying over salt". Such an achievement in life
frill necked lizard lmfao
Sounds so salty about it too.
frill necked lizard money well spent
People can get conned pretty easily
One less thing on the bucket list LOL
I'm loving this series man, keep it up. Been watching since the first solar plane and loving the progress. Best of luck with the V4, but this V3 seems to be doing pretty well. 👍🏼
Aussie RC Playground if
Aussie RC Playground you are trash
i feel like this channel is so under rated
You should live stream a flight
Yup!
Yup
Cell tower,...ah no!
Yes
This series is pretty awesome; and you're like an rc enthusiast Napoleon Dynamite, I dig it
Got some sweet air that time
1. Nunchuck skills
2. RC plane skills
Daniel can you please make a video that explains the required electronics for long range FPV?
I don’t know how it works sooo
Check out Stone Blue Airlines channel. They have a great series on exactly what you need for LR FPV.
.
Long range FPV, you need directional antenna's, a lower frequency, looks like he is using 1.2Ghz band. 600mW+ transmitter, although you can get decent range by using decent antenna's. Bonus if you have a diversity receiver to utilize multiple antenna types. Tracking is even better. I can get 2KM with good signal on 5.8GHz with directional patch / helical antenna's and a 600mW transmitter with cloverleaf.
By using a 4G module and an appropriate data plan you can fly as far away as you want as long as you have cell reception...
Made it to a altitude of 2100 meters! That's great!
I love cracking open a nice IPA and watching these videos
This airplane you made is so awesome. It has seemingly unlimited fly time and can fly itself and can go several thousand feet high. I need to learn how to make a plane like that myself some time!
Loving that "the end"
Hey, thats exacly why do you need MPPT, in direct sunlight , at perfect angle on a sunny day you will get probably 95+% of your panels potential if you connect it directly to power system, but on a clouudy or smoky day, or even when you fly so just part of panels is exposed to sun, the MPPT can boost your power up a lot, and i mean really alot. Also your power meter is avaraging reading when it displays it so its n its not a good way to measure power. MPPTs work with usually with more than 10kHz control loop so its catching all the liitle power spikes and pushes most of it into the battery no matter how many cells it has .
Keep up the good work, one of the most interesting series on YT right now.
cheers!
*not an easy feat* _young grasshopper is rapidly becoming a Jedi master_
Try adding a substantial electrolytic capacitor in parallel with the solar array. I can act like a super charger by defeating voltage lag. I've had good success with this method on stationary systems. I generally see a net boost of 30% or more under heavy loads.
This is one of my favorite projects on RUclips.
Advice from a scientist in atmospheric physics: In case you will meet haze, etc. during future flights: Climb as fast fast you can, since these haze particles (aerosols) are confined in the so-called planetary boundary layer (not exceeding height of thermals).
Just climb and climb and your plane will gain performance, once out of this hazy stuff.
And get rid of this heavy Lipo. There are numerous RC planes around with PURE solar cell operation !
The real benefit of a charge controller or a standard buck/boost board is the ability to charge the battery even when the solar cells aren't above battery voltage. You were correct in finding they do have a penalty for peak power, but I think that it may more than outweigh it by allowing you to use power all the time. However if you're always above battery voltage it is a moot point. Awesome video! You got me into 100w led chips, and i'm loving it!
I love how you catch your plane.
I'm ever impressed with this project. Next test can be an entire sunny day in RTH. I have a feeling it can do it.
How are you able to fly that high without the threat of FAA regulation?
One of many excellent details is that you can land it into your hand. 👍🏼🥂🤠
Nice video again Daniel, thanks. On my planes I'm using BLHeli ESC's and I have the props set to lock when the motors are shut down and have found noticeably better glide times, something you might want to try. I appreciate you sharing your info with us. Billy in Canada
It's BEAUTIFUL!!! Especially the HD footage and views of the plane in the sky from the ground. AWESOME!
You are awesome - you’ve come a long way and done some amazing things. Nice.
Nice series. For a flight in summer I'd recommend attaching the solar cells to the bottom underneath the wings for cooling. This should improve the performance of the cells a few percent, depending on the temperature maintained inside the wings before. The backside of the cells should not be covered for the most part of it to improve cooling.
Usually when a plane tucks and speeds up in a dive, it's indicating that it's tail heavy (and is thus trimmed to provide
positive lift with the horizontal stab, instead of more usual negative lift). For max efficiency you might want it little tail heavy, but have to be aware of that effect in a dive, or just avoid dives all together.
Vector doesn't choose to descend at low amps. It's actually running the throttle at no less than cruise throttle position, but because it's descending it unloads the prop which causes the amps to drop below what you'd normally see for cruise.
BTW, Vector will display watts. Just add it to the OSD.
That final analysis showing minimal power loss is hugely encouraging. I presume the current (pun intended) range of 'flexible' solar panels aren't the best when it comes to generating power. But once they are and are made available individually, then this type of project will be feasible for just about anyone. Myself included. ;¬)
With your weather conditions I was not surprised at a lack of thermals. Fishing and Flying - Watch the Birds!! Was a bit surprised with the Sink. Would be awesome to have Glide rate or Angle of attack but you have to have an accurate Ground Speed, too.
I always look forward to your contributions. Perhaps a few tiny Wind Turbines could help the down-leg. When you are falling, you can bring them out like Flaps. A little Drag and a little Charging power? 2-Way to the Max.
Can't wait to see Solar Plane V.4! Hope you are able to get all the energy control features designed in.
So you are also drawn to musing over the earlier approach to the horizon of the sun after you watched the moon pass in front of it. I have been watching the moon a lot too! Except missed the full moon during hurricane Irma, so tragic I was following wind speeds and precipitation radar. Hope this weekend's new moon brings you and your viewers luck!
That's a pretty nice machine, i'd love to see it fly with your latest improvments!
Awesome, thanks for posting.
Perhaps add a luminance meter during solar test, not trying to kill your data, just remember that solar isn’t a constant resource.
I would love it if you got back to flying the solar plane, Daniel.
Excellent video. Keep them coming.
You might want to look into a can antenna to focus the rf energy downwards which could improve control and video range, as long as you only go up!
Thanks for the info on the charge controller. I'll have to try it myself.
I'm not sure if this applies, but I used to make custom battery powered remote unattended data loggers. I would switch in a custom boost at the end of the discharge and gain a few more minutes of run time without it eating up more than it saved. I traded extra voltage by discharging the battery a little more than it normally would run my equipment. You have to test if it's worth the weight and a possibly shorter battery life for it. I really enjoy watching your engineering.
Great video series ... love your experimental nature. And those awesome CATCHES ... !
Keep it up.
watched so many of your videos , searched for solar plane alot , and yet after a year i find this video. YT algorythm sucks
am I the only one that clicks on a new rctestflight video and instantaneously click like?
Good production values and editing, I really dig that data stream and heads-up
display
When a plane noses down with an increase in speed (dives steeper on it's own) that plane is in a tail heavy condition.
You've got like mad RC skills, gahhhhhhh.
Didn't know logic was into RC stuff
Yes I was really hoping an altitude test would be done!
The part from 12:07 on sounded cool!
i love these videos but do you completely ignore the altitude rules from the FAA
I have a special account just for this channel --- it's THAT awesome!
On either side of the I-80 corridor East of Wendover is restricted military airspace. Check out a sectional chart.
Yeah, I was wondering when it would be stated there was clearance for this flight. Guessing the answer can be inferred...
Great work young grasshopper
10:15 That glow is Opposition Surge. The camera is looking down its own shadow and light is reflecting back to the camera.
Today's a good day to see how high I can get.
Those look like ~5.0Amp @ 0.6 volt cells, and most definitely need to have the sun Ray normal to the surface of the solar cell, to maximize power output of the cells.
That's really a beautiful plane!
Great project! I watch your progress since first video, really. If you want better efficiency you need to place solar cells directly to the sun, I mean foil covering wings reflect about 30% of light.
this guy low-key looks like logic, like the cap and just everything, it just makes him look like logic
Randomz Does 😆 surprised I’ve never seen a comment like this before now. I thought the same the first time I watched one of his videos!
Glad you finally put the MPPT issue to rest.
Awww I wish I could've donated!!
Sending a donation now!
Was a success
The windmilling prop is really a problem for gliding.
A motor brake with the fixed prop would already help but folding props could be the even better solution for this project.
man i learn so much on this channel. one of the best ever. keep it up buddy, inspired me a lot
Truly Awesome Flight Unbelievable (( 7 Thousand Meters )) Unfortunately in My Country Australia it's go too Jail Directly too and Don't PASS GO !!
he should have gone highter.
i know the charge rate in watts is important. but if you charge without voltage protection the max voltage of the cells must be the max charging voltage. another thing is if the solar voltage is lower as you battery you wont charge. ok this is obvious but what i wil say is, your mttp charger might be able to boost charge so it could use a lower voltage as input to get a higher voltage output so you get still power. unfortunaly most mttp are buck converter type charger and they go in a pwm mode if the input voltage is to low and stops about 2v difference. what you need is a boost-buck converter with mttp tracking
For what it's worth, I have one of those cheap CMP12 PWM charge controllers on my boat (a very bare bones boat with 2 x 20W panels) and it's more efficient than any MPPT controller I've tried so far over the course of a day, with the sun and boat moving around. I plan to test a few more, but it's by no means a certainty that MPPT is best. It's certainly not super important for my application.
launch one on a balloon. also put some solar on the body and tail.. gps it full stick forwards. gopro it. would be fun to see where it lands
Andrew Jay fly it as high as possible and just let it glide and follow it with a car and a gps tracker or something and see where it will land
Very Nice ;: really Nice plane.
Great job man.
I would support you just for some sanity. Too much YT for me recently while researching and I can relax while you do your video content. Must look into the V3
Very good video
You might consider switching to a dragon link dipole for your 1.3 video along with a yagi on the ground. Very little wind resistance and tiny profile plus I've had great results with this setup out to 50 miles thus far. Awesome project though!!
Amazing achievement! keep those updates coming
So freaking cool! Thanks for all the awesome videos bro!
Dude! when you can sustain flight next step will be to put a 4g(GSM) controller and then you can go places without worrying about your antenna :D
At 13:08 the right wing looks like its rotating around the wing spar, look at the trailing edge near the fuselage. At 13:10 the wing moves back in to place after the dive is stopped.
"Your names are now flying over salt."
Daniel, just had a thought... Wondering if you could use the length of the body tube ... Build an old school idea and run a rubber band through it's length run an "excapement - generator" that can be remotely started when you need it ... You possibly could do similar ones in the wings if they could preload the span to add to a semimonocock preload to make the wings stiffer ... Each could be geard to run slow and spin up a generator that can be started individually when needed... Just a thought ... Ed in Phoenix writes
Nice video
What if you put a small battery in it, and a bigger one, then after climbing high enough, make the bigger one go down with a parachute. Then glide with solar assist for as long as you can. Maybe the weight difference would help to sustain a flight with the voltage not dropping at all :?
Very nice. Add a Daemon Relay to it next! :-)
I will like to meet with you, so I can learn some few things from you. I love adventures like this.
The way you were trying to measure efficiency at about 9:00 in the video is sorta problematic. You've got to measure both input and output. In other words, with the MPPT in the circuit, you need a power meter between the panels and MPPT, and another power meter between the MPPT and the battery. You would calculate efficiency as: output divided by input. For example: 100 watts coming out of the panels vs 93 watts coming out of the MPPT = 93% efficiency. You would then repeat that measurement for each different kind of controller (the two MMPTs and the PWM). That's the only way you're ever going to figure out which charger is the most efficient. Hope that helps, awesome vid.
MPPT's have their place in terrestrial solar power systems but they aren't the best solution here. They're useful when you have arbitrarily selected panel and battery voltages but for a custom system the elements can be selected to match so the controller is just extra weight on top of the small losses to thermal systems inside the electronics.
not enterly true. since the efficiency of the solar panals varry with both the amount of light and the resistance of the load (*spectrum of the light also matters). So the most efficient setting depends on these 2 variables. the amount of sunlight wont always be the same due too many obvious reasons. but the load resistance also varies. *eg: how full is the battery charged, what is the discarge rate, overall temperature potential out of spec solar panel.
so aslong the efficiency/consistency gained from the controler is more that the power needed to lift the weight one should use it.
wsc112782 for efficiency you indeed always NEED to mesure input and out put. otherwise you're just measuring raw power with unknown variables/changes.
have said that. since thats said rctestflight might want to invest in a cheap LUX meter to make setup comparisons more easy and fair.
So...your reward to your Patrons is some sentimental bullshit!? I love it 🙏💕✌🏼 Well done comrade ✊🏼😢
It’s so great what you’ve been able to do with solar tech, I wonder if you could do a toned down version on a hexactoper (with really long arms but lightweight enough to hold a lot of panels
You should have maybe a seperate two cell and bec That powers all the servos and the fc, that way if the main battery dies or disconnect you got a good battery powering the tech
Dude, I love the work you do with these and I would LOVE to have one of those planes to mess with. You do great work, keep it up! :-)
the foot steps sounded like minecraft lol
As challange would be awesum to get a big plane running, day and night, will need very slow climb, huge wings and lots of batteries
Bravo. Super work.
Always like to watch your videos! Always interesting. Thanks.
Why don't you use a folding propeller to reduce drag when you throttle back
There likely isn't a folding prop that will compare to the efficiency of the props he is running. He is running fairly low RPM with big props and low air speeds to get high efficiency. Typical folding props are designed to run at higher RPM and higher airspeed.
I guess there would have been less haze up high. Will be interesting to see how you combat low sun angles with the new design.
Very cool!!!
Superb test good job! each test will definitely contribute design improvements.
What if you test your plane in DIY wind tunnel with High CRI LED lightings. Simulations brings lot of dynamic information for design improvement.
With wind tunnel you can test the flight under smooth and bad wind condition. High CRI LED lights to simulate solar radiation.
With that i hope i can help..Keep it up dude!
Very interesting information on the solar charging. Too bad it was so hazy for your flight.
Awesome project! Thumbs up!
Awesome video. Regenerative braking on the motor would be cool to test. Think about how much you could recharge on the descent...
Man this is such a good channel keep up the good work 👌🏻👌🏻 i hope you get paid for these videos cuz its a lot of work.
Nice work man!
Avoid using a charge controller, it reduces efficiency and adds weight. Even if the generated solar voltage is much higher than the battery, the internal resistance of the battery will prevent the voltage from rising higher than the current state of charge. As long as you don't exceed the max charge rate or charge over 4.2V per cell, the direct connection will be your most efficient. If you are using a diode to block voltage, consider Schottky diodes to reduce drop. If you can find a small FOC based motor drive, it should also gain efficiency.
Thats really cool. thumb up brotha
I would suggest a flying wing configuration. More efficient flight high payload and more surface area for solar panels.