Solar-powered model planes
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- Location: Warwickshire
Solar-powered model planes
Not really retro so it's in the general chitchat section. I suppose there are some vintage designs that might lend themselves to solar conversion: that would be no worse than converting an old i.c. design to electric battery operation - something that most of us accept nowadays.
Mike (Ralkbirdy) came up with this present design - prototypes really - but they fly really well.
I assisted with the on-board power controller. This is just an Arduino that takes the motor output from the receiver and passes it on to the speed controller.
The Arduino monitors the available voltage from the solar cells and throttles the motor back quickly if the voltage begins to fall below the ideal level. So if you do a loop and the solar cells are facing down, or the sun suddenly disappears behind a cloud, then the motor is automatically slowed down, or even stopped, so as to always keep enough power back to run the radio and servos. You can hold the plane upside down a few inches off the ground when it's cloudy - and there is still enough power to operate the radio and servos, so there's no need to worry about losing radio control.
The solar cells used are about five inches square. Each one makes about 0.6 volts, so with ten in series you have 6 volts to work with. The no load voltage varies hardly at all from cloudy to full sun, but the brighter the light falling on the cells, the more current can be drawn from them - up to about 4 amps in direct sunshine. Maximum power occurs when you draw enough current to pull the voltage down to about 85% of the no load value - so about 5.1 volts with a ten-cell setup. If you shop around you can get the cells for about a pound each if you're prepared to buy about thirty of them. AliExpress is one source. The Sunpower C60 cells are nice and a little more rugged than some other cells (slightly bendable but still eggshell thin and fragile). If you're buying, look for cells that are advertised as 'tough' or similar.
Mike is now working on a twelve cell design and I'm sure he'll be happy to share the details if anyone is interested in building a similar model.
Mike (Ralkbirdy) came up with this present design - prototypes really - but they fly really well.
I assisted with the on-board power controller. This is just an Arduino that takes the motor output from the receiver and passes it on to the speed controller.
The Arduino monitors the available voltage from the solar cells and throttles the motor back quickly if the voltage begins to fall below the ideal level. So if you do a loop and the solar cells are facing down, or the sun suddenly disappears behind a cloud, then the motor is automatically slowed down, or even stopped, so as to always keep enough power back to run the radio and servos. You can hold the plane upside down a few inches off the ground when it's cloudy - and there is still enough power to operate the radio and servos, so there's no need to worry about losing radio control.
The solar cells used are about five inches square. Each one makes about 0.6 volts, so with ten in series you have 6 volts to work with. The no load voltage varies hardly at all from cloudy to full sun, but the brighter the light falling on the cells, the more current can be drawn from them - up to about 4 amps in direct sunshine. Maximum power occurs when you draw enough current to pull the voltage down to about 85% of the no load value - so about 5.1 volts with a ten-cell setup. If you shop around you can get the cells for about a pound each if you're prepared to buy about thirty of them. AliExpress is one source. The Sunpower C60 cells are nice and a little more rugged than some other cells (slightly bendable but still eggshell thin and fragile). If you're buying, look for cells that are advertised as 'tough' or similar.
Mike is now working on a twelve cell design and I'm sure he'll be happy to share the details if anyone is interested in building a similar model.
- Attachments
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- solarRegulator.zip
- 2018-Aug-12 Added feature to only sample solar voltage for first 10 secs.
- (3.6 KiB) Downloaded 196 times
Last edited by Martin on 12 Aug 2018, 17:44, edited 3 times in total.
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- Posts: 44
- Joined: 25 Feb 2018, 13:10
Re: Solar-powered model planes
Clwyd Queen is a 1956 free flight glider/if power plane, it is essentially a typical flying wing. These planes are an evolution of this, putting the motor at the front, building with Depron and adding solar cells for power. Should interest Shaun with his knowledge of Depron and Phil as it has an Arduino based electronics.
https://outerzone.co.uk/plan_details.asp?ID=1877
https://outerzone.co.uk/plan_details.asp?ID=1877
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- Joined: 25 Feb 2018, 13:10
Re: Solar-powered model planes
Having repaired the Panasonic microwave door switch, time to do some building for my Solar Clwyd Queen.
I use 3mm AeroDepron, it comes in sheets 1250mm long, trim to 900mm. Then cut 2 sheets of 900x360mm, then divide to give 200mm root and 160mm tip. These 4 wing blanks then need to have the tips cut to 15 deg.
I used to use PVA but the AeroDepron is not gluing well, I found that Superphatic was best, so first time building a complete plane this way. The spar is 7mm spruce from a diy store, the leading edge is 3mm balsa strip, about 8mm. Weigh down and wait a while.
I use 3mm AeroDepron, it comes in sheets 1250mm long, trim to 900mm. Then cut 2 sheets of 900x360mm, then divide to give 200mm root and 160mm tip. These 4 wing blanks then need to have the tips cut to 15 deg.
I used to use PVA but the AeroDepron is not gluing well, I found that Superphatic was best, so first time building a complete plane this way. The spar is 7mm spruce from a diy store, the leading edge is 3mm balsa strip, about 8mm. Weigh down and wait a while.
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- Joined: 25 Feb 2018, 13:10
Re: Solar-powered model planes
http://www.hobbytronics.co.uk/d24v5f3-3 ... -regulator
https://www.banggood.com/Racerstar-Tatt ... rehouse=CN
The motor and prop are quite specific, you need to identify what voltage you are working at, 12 panels about 7.2v with about 4A, so 28W. The motor / prop combination needs to get this current at this voltage, for 10 panels a 2208 motor with 1800kv and a 6x4 prop should work well. I am going to try out some larger motors for my 12c model.
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- Joined: 25 Feb 2018, 17:59
Re: Solar-powered model planes
Thank you for sharing the details and techniques of your construction process, they are invaluable for a beginner like myself.
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- Joined: 25 Feb 2018, 13:10
Re: Solar-powered model planes
Simple box fuselage, holding the motor to the wing and covering up the Rx, ESC, and arduino controller.
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- Joined: 25 Feb 2018, 13:10
Re: Solar-powered model planes
https://www.ebay.co.uk/itm/SOLAR-CELLS- ... eTa9i4PNbA
https://www.ebay.co.uk/itm/SOLAR-CELLS- ... eTa9i4PNbA
I have ordered 25, so will now wait a week to fit the cells.
- Mike_K
- Posts: 677
- Joined: 16 Feb 2018, 06:35
- Location: Hertfordshire
Re: Solar-powered model planes
What a great project and thanks for sharing it with us.
Having seen Mike's flying wing at Ponty and having now seen the video of the flying wings in action, I've been inspired to order all the bits you've listed to have a go myself. I'm certain I'll be asking you a few questions in the next few weeks! Solar powered fly-in next?
Thanks
Mike
Having seen Mike's flying wing at Ponty and having now seen the video of the flying wings in action, I've been inspired to order all the bits you've listed to have a go myself. I'm certain I'll be asking you a few questions in the next few weeks! Solar powered fly-in next?
Thanks
Mike
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- Posts: 44
- Joined: 25 Feb 2018, 13:10
Re: Solar-powered model planes
It is really pleasant flying in the sun without any concern about how long you have been going for, no battery to go flat or to charge, just pick up and fly away. They are quite light weight so will have to see how they cope with more wind. This 12 cell plane should have much greater flexibility. I tried the 1800kv motor and a 6x4 prop gave about 4A so should be fine. I have had a number of 2212 1,000kv motors but they seem to have disappeared, so have ordered some more 1,000kv and 1,400kv motors coming. I am looking to use an 8x4.5 Graupner CAM folding prop.