Solar-powered model planes

Anything you like!
Martin
Posts: 744
Joined: 16 Feb 2018, 14:11
Location: Warwickshire

Re: Solar-powered model planes

Post by Martin »

I flew mine today in a relatively strong breeze - we measured it at 12 mph with gusts to over 15 mph. There were people at the strip with large glow powered models who said they didn't want to fly because it was a bit windy for their liking. It was tricky to hold the solar flyer for launch but once away it flew well and penetrated into the wind easily.
Ralkbirdy
Posts: 44
Joined: 25 Feb 2018, 13:10

Re: Solar-powered model planes

Post by Ralkbirdy »

Solar cells in place, then tin the cells and joiner.
Solar cells in place, then tin the cells and joiner.
Cells soldered together.
Cells soldered together.
I got some cells from Martin, solder 6 together, +'ve marked red.
Ralkbirdy
Posts: 44
Joined: 25 Feb 2018, 13:10

Re: Solar-powered model planes

Post by Ralkbirdy »

Cut a 25mm strip of glasscloth
Cut a 25mm strip of glasscloth
The cells are put in place, the rear resting on some balsa/Depron to get the front resting on the LE. Then held down with an aluminium bar.
The cells are put in place, the rear resting on some balsa/Depron to get the front resting on the LE. Then held down with an aluminium bar.
The glass cloth is fixed with acrylic varnish, about 10mm on the cells, 15mm on the Depron LE. Make sure none sticks the bar to the cells.
The glass cloth is fixed with acrylic varnish, about 10mm on the cells, 15mm on the Depron LE. Make sure none sticks the bar to the cells.
Ralkbirdy
Posts: 44
Joined: 25 Feb 2018, 13:10

Re: Solar-powered model planes

Post by Ralkbirdy »

Bar holds the rear of the solar cells down to fix trailing edge glass cloth fixing.
Bar holds the rear of the solar cells down to fix trailing edge glass cloth fixing.
Finally glass cloth covers the rest of the cells and slightly overlaps the other glass cloth.
Finally glass cloth covers the rest of the cells and slightly overlaps the other glass cloth.
This side is now completed, there is a connecting 20swg 0.9mm copper wire going from tip to tip, I have used enamelled wire but copper earth or similar is fine. Next task is to do the other side.

All the work is done on this flat board, old table top that my eldest daughter did her school work on in the late 1990's. This ensures that these long wings end up without warps. Once the solar cells are fixed it adds to the torsional strength.
Ralkbirdy
Posts: 44
Joined: 25 Feb 2018, 13:10

Re: Solar-powered model planes

Post by Ralkbirdy »

The other wing has had the solar cells soldered together, fitted to the wing carefully get them the right way around, only to find they were turned around. So had to alter the wiring. I am using 2 old Graupner servos which remain excellent and work fine with this low voltage.

The servo connection I use is a 1.5mm ply horn, 30mm long, 20swg pushed and then connected to a clevis with a short piece of brass tube 2mm diaameter threaded for 2mm. Fixed with Loctite.
20180702_214732.jpg

The fuselage seemed a bit fragile so have added 1.5mm ply doubled and covered in glass cloth.
20180702_214807.jpg
Ralkbirdy
Posts: 44
Joined: 25 Feb 2018, 13:10

Re: Solar-powered model planes

Post by Ralkbirdy »

Set up the Clovis, set servo to neutral on the radio, apiece of balsa to set the elevon level with the lower wing, then add glue to the slot and horn and stick with elevon in the correct alignment.
Set up the Clovis, set servo to neutral on the radio, apiece of balsa to set the elevon level with the lower wing, then add glue to the slot and horn and stick with elevon in the correct alignment.
I paint strips on the underside, the fins being positioned underneath makes the wing look odd and as if you are inverted until you become accustomed to it.
I paint strips on the underside, the fins being positioned underneath makes the wing look odd and as if you are inverted until you become accustomed to it.
I aim to change it to a 100kv motor later and a 8 or 9" prop.
I aim to change it to a 100kv motor later and a 8 or 9" prop.
The plane is now completed ready for testing on Thursday if the weather is good. I am getting about 28W of power, between 4A and 4.6A with direct sun, dropping to 3A when at an angle, but looking good. Weighs 410g, the motor position was a reasonable guess with more cells and a larger motor the CoG has come out a litte bit infront on my estimate, i wll see how it seems when flying.

Tip fins were stuck on with Por. On my previous models they were just painted, this time to make them more durable wither increased weight, they have been covered each side with glass cloth before fitting.

The wing servos have a tight hole cut in the top Depron sheet, this time I put an edge of glass cloth around the hole, then when ready they just have 2 strips of Sellotape Clear to hold them.
Ralkbirdy
Posts: 44
Joined: 25 Feb 2018, 13:10

Re: Solar-powered model planes

Post by Ralkbirdy »

Had the test flight, no video today. The first flight needed full up trim and the controls were sluggish. Landed altered the sub trim and moved the aileron link to the outer hole in the servo. There is a better power then the 8c model but not as manoeuvrable, also on a dive test it recovers easily, so the CoG can go backwards.

At home I have now tried a 2812 but I did not get enough power on an 8" prop, and I'm so not t,think a smaller faster revving motor will improve things, so back to the 2822 1400kv motor, wait until the 1000kv motor arrives and then try some different props. I may then shorten the nose to move the CoG backwards.

Motor and prop selection is far more critical than with battery planes, it just needs to be adjusted to the power V and A available. The motors are easiest fitted it you can find short hexagonal bolts, and use a long handled driver, unfortunately I have some from he'll maintenance.

So a successful first day, had flights of about 20 minutes before deciding to land. On bright blue sky days then it really is just keep flying for as long as you want to. When clouds come I expect chasing after the clear sky and missing the clouds will become important and another task.
Martin
Posts: 744
Joined: 16 Feb 2018, 14:11
Location: Warwickshire

Re: Solar-powered model planes

Post by Martin »

I was there for the first test flight (in fact I launched it :D ) but I'd arranged to dash off to another flying field so I didn't have the time to shoot any video. Hopefully we can do that on Sunday, weather permitting. I can confirm that Mike's new solar model flew great from the first flight, and I'm sure after a little more adjustment to the c.g. position and some motor/propeller experiments, it will be the best performing one yet.

I was going to the different flying field to meet someone about arranging a venue for test flying my jet (hopefully that will now happen on Monday).
Martin
Posts: 744
Joined: 16 Feb 2018, 14:11
Location: Warwickshire

Re: Solar-powered model planes

Post by Martin »

Here's a short video of Mike flying his 12-cell solar model (the one detailed in the build log in this thread) this morning.

At the moment it doesn't seem to be climbing any better than the 10-cell model, despite the extra power available. This may be due to the heavier weight (spruce spar versus balsa on the smaller models) but the wing loading is about the same so more likely it's just that the optimum motor / propeller combination to suit the 12 cells is still to be found.

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RON
Site Admin
Posts: 613
Joined: 12 Jun 2017, 15:09
Location: Stokesley North Yorkshire

Re: Solar-powered model planes

Post by RON »

Nice job there

In some of the video there it actually looks like a bird of prey, think it’s the black on the wings.
Looks great fun

Ron.
G0MBV Class A Radio Amateur, North Yorkshire
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