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Aug 20, 2007, 10:07 PM
Your ruler, in part...
Angry_Monk's Avatar
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2.23g Solar Plane

A while back i bought a bunch of small solar cells from Spectrolab. each cell could generate about 2.1v @ 30mA in good sun. After seeing Ralph B's solar planes i thought it time to build one myself. i knew i wanted to go light but i didn't want to go so light as to make the plane a pain to build. i wanted this plane to be more of a test bed or stepping stone for even lighter R/C solar planes.

Having already built a square 5.5 i decided to use that plane as the base for the solar electronics. the main reason i chose this design was because the motor and prop combo is ever powerful and draws little current, ideal for these solar cells. i did, however, make the plane a mono wing because i will be flying it outside and i want to minimize the wind's affect on the plane.

I'm using 4 solar cells mounted above the wing to give me about 4.5v @ 60mA max in good sun. i'm also using the plantraco butterfly rx because it seemed like a good rx to use for a outdoor plane like this (and i had one around already). actuator is 50AWG wire and is about 170 ohms if i recall correctly, and the fuse stick is reinforced with a .009" CF rod in case of a bad crash into the grass.

i haven't had a successful flight with this plane yet but i see no reason why it wont fly. the only day i could test it was the morning i was leaving for a trip, i got in some glide tests and a couple powered flights. glide tests were good but the powered tests showed that there was lack of thrust because the prop pitch was too little. i have since fixed the problem and now i'm waiting for another cloudless sunny day with no wind to fly it again.... ... i can see this taking a while. i'll let everyone know when i get a good flight. comments are welcome.


WS: 5.5"
AUW: 2.23g
Motor: 4mm 28ohm, 6:1 gear reduction
Act: 170ohm 50AWG
Power: 4 solar cells, 4.5V @ 60mA max

(i'll try to get some better pictures tomorrow)
Last edited by Angry_Monk; Aug 21, 2007 at 12:04 PM.
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Aug 21, 2007, 03:07 AM
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boss's Avatar
Wow, I was wondering how it could ever be that light, as most plantraco planes are heavier.

Sat down for a while and thought: Aah, there is no battery! Silly me.

But even then it is a nice piece of work! What do the solar cells weigh? How expensive are they? It really is a shame that when you go outdoors to the sun, there is almost always wind! But I reckon with the fast devellopment for 'green energy' there will be some very nice MAV solar cells in the near future.

Please post some more pics and maybe a vid of the maiden.

Good luck!

Aug 21, 2007, 07:52 AM
Registered User
Dave Wulff's Avatar
Congrats on your accomplishment, Ralph is a tough act to follow. Bright sunshine and no wind is a tough combination to wait for.

Aug 21, 2007, 10:44 AM
Your ruler, in part...
Angry_Monk's Avatar
Thread OP
I figure there are a grad total of 3 days out of the year when i can fly this plane! im hoping to get the last one sometime in the next couple weeks.

the 4 cells come to about 1g total with the framework holding them together. you can buy 100 from spectrolab for $250. but i still have some around that i sell for $3.5 each plus shipping.
Aug 21, 2007, 10:52 AM
Absolutely stunning work. Kudos.

Just curious, why did you opt for balsa versus CF rod?

Also, in the event of cloud cover, what to do (brownout?)

A small cap perhaps to keep her afloat?

Cheers, again, beautiful work.

Aug 21, 2007, 11:47 AM
Registered User
Cobra command,

in case of a cloud the motor stops and the model glides to ground. At this weight you cant carry an additional capacitor to overcome a cloud.

Angry Monk,

there are definitely more days in a year to fly the model. But I know it's hard to wait for the maiden flight. Take your time and dont risk to much.

Last edited by Helmut-Schweig; Aug 21, 2007 at 11:51 AM. Reason: Additional text
Aug 21, 2007, 12:02 PM
Your ruler, in part...
Angry_Monk's Avatar
Thread OP

the plans for the airframe called for balsa, so i used balsa. only later did i realize that this plane might take harder landings that it would if it was indoors. so i added a CF rod under the balsa to add some strength. and as Helmut said, a cap would add too much weight. also i try to fly on a cloudless day and in the event of clouds i will time the flight to occur between clouds. i wouldn't be flying this plane high or far away, so if it does brown out it will just glide to the ground.
Aug 21, 2007, 12:26 PM
Inciting Riots
village_idiot's Avatar
I would be really cool if cell technology advances far enough that you could fly it indoors! I'm sure it is just a matter of time.
Aug 21, 2007, 01:13 PM
is it supposed to smoke??
3dFlyer88's Avatar
now that is an amazing plane wow nice work monk
Aug 21, 2007, 06:05 PM
Your ruler, in part...
Angry_Monk's Avatar
Thread OP
More pictures:
Aug 21, 2007, 08:05 PM
Mach 2 with hair on fire!
TeraHurtz's Avatar
Dude, you rock!
Aug 21, 2007, 08:08 PM
is it supposed to smoke??
3dFlyer88's Avatar
ahh yes i supose a block out of the sun could really hurt. did you wind that coil yourself? man 50 awg i make mine from 47awg and i just mastered that but 50 man thats insane lol
Aug 21, 2007, 10:17 PM
Time wounds all heels.

probably not a short term product, but this could be like those strange 'silver sugar packet' batteries I got a Korean company to send me to play with back in 2000. I sure wish I had been smart enough and in a position to set myself up to be the US importer for those...whew...(or that I hadnt gotten discouraged by all the haters back then, who thought my idea of a 10oz ducted fan Flying Styro A7 to fly in the park was the equivalent of violating the laws of physics, how does that crow taste fellas?) Mount a few of these on that new paper cell as a covering and you have a plane with storage capacity for high current applications like takeoff and climbing, and a charging circuit and virtually unlimited duration during the day. Now I need a solar cell for my Tx. =P
Aug 21, 2007, 10:30 PM
Your ruler, in part...
Angry_Monk's Avatar
Thread OP

thanks, i like to think i do...


yeah, when i started winding acts i always broke the wire. but then i stopped pulling the wire and started pushing it around when working with it. i dont really know how to explain it but ever since then i haven't broken a single coil, and thats before i started working with 48, 50 and 52+ AWG wire! all i can really say is that you just have to let the wire do what it wants to do, dont pull it or bend it, just push it around when you need to solder the ends or move the wires. but regardless, any wire above 45 AWG is hard to work with!


thats a nice find! it says that the efficiency was improved about 60% in the UV range, so i wonder how that compares to the whole spectrum in which solar cells generate electricity. its amazing how fast technology advances, in a couple years solar cells could be double there current efficiency (~60%) which means solar planes could be smaller or more powerful!
Aug 21, 2007, 10:33 PM
RIP Sheba :(
Robster's Avatar
Awesome accomplishment!

Just wondering if bright indoor standard white light incandescent bulbs would juice it up enough to fly indoors. Probably not justifyable from an electricity cost standpoint. Just posing the question.


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