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Old Oct 26, 2004, 09:30 AM
chelsearules is offline
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Singapore Seletar, Singapore
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Solar Powered RC Plane Project

Hi to one and all,

Thanks alot for all your help and suggestions for the previous enquiry. We're back again. We are a bunch of polytechnic students from Singapore and are currently trying to build a Solar powered RC aircraft as part of our final year project. We failed miserably with our previous attempt to convert a Cherub 2 Electric glider to a solar powered one.

We crashed the glider while trying to fly it using battery power (testing purposes). While working with the glider we realised that it had too small a wing area to mount a sufficient solar panels and another big problem that we faced was not knowing the exact power comsumption of the aircraft.

We obviously need these values to decide on the number of panels needed to be mounted on the aircraft. It seemed, however, as though that the amount of power needed for this particular aircraft was going to be something big (Arnd 7.2V @ 3A!). We weren't very sure of such factors and were rather rash in purchasing the glider.

Ok so here's our current situation. We have no aircraft and no solar panels. We wouldnt want to waste our project budget and are weighing up our options carefully before going ahead with the next aircraft.

We do however have a futaba controller and receiver. What we need from you guys are some suggestions on some good models to convert to solar.

We would like the aircraft to have some power consumtion values to work with and also one that requires the least amount of power, has a large wingspan and is easy to fly for beginners like us. We look forward to your kind help.

Thanks guys!
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Old Oct 26, 2004, 09:43 AM
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Sailplanes powered by efficient brushless motors require as little 25-30W/lb to maintain level flight in dead air.
Assuming a total weight : solar panel weight ratio of 10:1 (i.e. panels are no more than 1/10th of total airframe weight), find a solar panel of any size that can produce 10x the 25-30W/lb ratio (i.e. if the panels weigh a total of 8oz, they should be capable of putting out (.5 x 30W x 10)=150W). If you accept a 5:1 airframeanel ratio (20%), then an 8oz panel should put out 75W.. etc.
..a
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Old Nov 04, 2004, 09:39 AM
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Singapore Seletar, Singapore
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Searching for best plane (Need help from anyone)

Hello everyone,

I'm currently doing a project in school and the aim is to power an rc plane using solar panels.

I'll be mounting thin flexible solar cell sheets onto the wing of the plane and because of this I need a plane that is able to take off and land safely with as little impact as possible.

I'm an rc beginner, so i'm looking for anyone who can offer me some advice on how to choose a suitable plane and maybe name some models that are currently available in the market.

The plane definetly must have the following:
1) long wingspan (for solar panel mounting)
2) light weight.
3) landing gears

I would also like to know the rating of the plane (Amount of amps, volts and watts it requires to be powered)

If u have any models to recommend. Pls post them together with the RATING of the plane. I really need to know the amount of power it requires.

Thanks!

Regards,
Jeremy
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Old Nov 04, 2004, 12:25 PM
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I don't know why you're ignoring Andy's reply, it has everything you need in it. I'll throw in my own 2 cents worth even though Andy pretty much covered the idea.

Under your parameters, a powered sailplane is absolutely the only way to go. They're easy to fly and require the least amount of power to weight ratio to stay aloft. The reason for this is their extremely light wing loading. Wing loading is a description of how hard each square inch of the wing is having to work to keep the plane flying. For model airplanes in the U.S. this is usually expressed as ounces per square foot (oz/sq.ft.). To get this figure convert your planes weight into ounces and it's wing area into square feet, then divide the weight by the area. For example:

All up weight 3 pounds
3 pounds X 16 ounces = 48 ounces

Wing Span 78 inches
Chord 10 inches
WS X Ch = 780 square inches
780/144 = 5.42 square feet

48/5.42 = 8.86 ounces per square foot

This sailplane would be acceptable for a sport flyer. However, for competition or your project the wing loading is much too heavy. I'd try to keep the wing loading as light as possible and at least under 6 oz/sq.ft.

If you're looking for a specific plane and money is no object, I suggest a bubble dancer. That sailplane was designed by Mark Drela and has very efficient airfoils. It also has a ridiculously low wing loading, like 3 oz/sq.ft or something. To get the wingloading that light, it's built with very expensive composite materials and is not an easy build. I think somebody overseas was selling an ARF for around a $1000 based closely on the bubble dancer if you don't want to build. I'm fairly sure the wing span is well over 2 meters, so you should have plenty of surface area for solar cells. Mark has been seen handlaunching his bubble dancer and then taking it to speck height on many occasions. You'll probably raise that wing loading by adding a motor, esc, and the cells, but it will still be the lightest wing loading possible that I can think of with plenty of surface area for power generation.

If you're interested in this plane, find out what it's total flying weight is as a pure sailplane. Now add the weight of your solar cells, motor, and electronic speed control. Be sure to buy the best brushless motor there is for your application. Efficiency is everything here. You need a motor in the 90 percentile or better. Probably a plettenberg or a hacker with a ceramic planetary gearbox. After adding your component weight to the weight of the sailplane, use Andy's formula to find how many watts you'll need. If you can keep the wingloading to 4 oz/sq.ft. or less, you might even be able to get away with as little as 20 watts/pound. I'm not sure how many volts you can get out of solar cells, but high voltage and low amps to get to your watts per pound goal would be more efficient.

Jim
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Old Nov 04, 2004, 01:00 PM
Lorddrek is offline
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I don't know much about this but I wanted to make a solar assisted sailplane recently and found a bunch of info on it here. Do a search here and sift thru the posts for a couple of nice links if you have not already.

From what I found I think if you want to make it with no battery assist you won't have the power for takeoff. So no need for landing gear. A glider is your best bet anyways. Find a kit or plan with a low wing loading then use that to figure out how many solar cells you can mount. Then when you know how much power you will have you can find the proper motor for it. When you figure that out that check out your thrust figures and you will have a better idea of what you got.

My findings were while it could work the power seemed too low to justify the hundreds of dollars those thin film solar cells cost. Maybe a powered indoor micro would be the way to go for your project? Play with the numbers when you have them and you should have no suprises when you try to fly. Good luck on your project!

Lorddrek
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Old Nov 04, 2004, 02:22 PM
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ok, maybe it is a toy
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Hello.

I agree with dreck on the landing gear...loose it. It will save considerable weight, so just belly land. I would use a high-efficiency geared brushless, like a Hacker. A glider/sailplane will provide "free" lift from thermals on a calm sunny day that is also perfect for max. solar radiation.

You may want to consider getting an experienced Pilot to help you fly it...as most of us know, building our first masterpiece didn't qualify us to fly it.

All the best. Look forward to hearing about your progress.
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Old Nov 04, 2004, 05:14 PM
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I think I said this last time, but buy something cheap to learn on first (like a slowstick or easystar), so you won't be worrying about how to fly when you've got the expensive gear on board.
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Old Nov 05, 2004, 12:04 PM
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Europe - Slovakia
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Hallo "chelsearules",

you can look my solar-powered glider RIVAL-8 here:
http://www.rivamodels.sk/image_gal/1215.jpg
or in the "PIC chronicle" in the same site (www.rivamodels.sk).

Model have 20 solar cells from Graupner (50x100 mm one cell).
Max. voltage 10V, max.current 1,1-1,3 A
Power unit: 360/240 (14,5/9,5") propeller, gear 6:1 (home made), Speed 400/7V motor
ESC: Graupner Solar-mos-18 electronic speed controller
Buffer accus: 6-cells Robbe 700 mAh
Receiver: Graupner 6-chanels
Servos: 2x MINI (approx. 18 g).

Power consumption: approx. 3 A for climb, appr. 1,3 A for horizontal flight
Best flight: approx. 3 hours and 50 minutes (then come big rain and I must sit down).

This model I build in end of 1992 and fly 1992/1993.
Today you can build similar model as my RIVAL-8 but you can use better
solar cells, better motor (likely small brushless), smalest NiMH buffer accus, low weight servos....

If you need some help from me, send me message here: info@rivamodels.sk

Palo

P.S.: big sorry for my "childrenīs english"
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Old Nov 05, 2004, 12:25 PM
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Hallo Jeremy one more time... my solar-plane from 1992 is here



Palo
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Old Nov 18, 2004, 06:14 PM
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Might find some useful info here. Fyi, the plane is still flying well.

http://www.rcgroups.com/forums/showthread.php?t=88868
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Old Nov 18, 2004, 07:15 PM
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Singapore
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Jeremy,
All the information you need is on this forum but some of the parts to buy and the techniques to build may be difficult to learn in a short time through the net. If you need to contact Singapore modellers, go to the forum at

http://forum.starhub.net.sg/cgi-bin/...gi?act=SF;f=83

or you can PM to me.

Shane
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Old Oct 05, 2008, 02:39 AM
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Whitstable, UK
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What about getting a cheap palm-z plane and putting some solar panels on the wings? You'ld only need to split open the body,, cut out the battery and connect the solar panels to it. That's going to be my next project.
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Old Oct 05, 2008, 03:48 AM
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http://www.dienlin.de/sieghard/Model...ergalerie.html

http://sky-sailor.epfl.ch/docs/Histo...oth%202008.pdf

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Old Feb 12, 2016, 09:06 AM
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Thank you for using the Search feature.
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