If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|
|
Thread Tools | Display Modes |
#11
|
|||
|
|||
David Kinsell wrote:
Sometimes the current rating given is into a short circuit, so you get substantially less in practice. I'm sure these particular ratings are for the panel laid flat, pointing directly into the sun, with no cloud cover. Wrapped on a fuselage, frequently pointing away from the sun, the average will be a whole lot less. These panels are rated at the "maximum power" point; the short circuit current is higher, of course. In any case, the average will be as you point out. So, $120 would buy me 4 panels, which would give me 200 ma at 15+ volts, almost enough keep up with my panel (including the transponder) over a full day. By "full day", I'm including the time it's tied out, as it would be at a soaring camp or on a safari, and a five hour flight. A full panel these days (with an active transponder) easily draws over 2 amps. My panel is not so full, apparently, with a radio, 302 vario/recorder, Aero 1530 PDA, Becker transponder, as it draws about 650 ma while flying (radio on, but not receiving or transmitting; transponder on mode C). This will go up next year if I switch to an Ipaq PDA. The current you'll actually get out of the solar panel would not make a significant difference. The $/ma was good enough, that trying a 200 ma set would give me a good idea of their value, and more could be easily added. The engine doors would hold over an amp's worth. You'd be more likely to notice the additional drag due to the turbulence than you would notice a benefit in the electricals. At 0.008" thick (slightly thicker than wing tape), and placed on the engine doors, I wouldn't expect any extra drag. If 36 AH of batteries (with a generator on your engine) isn't enough, you've got other problems. It's enough for probably 3 typical flights (5-6 hours) with new batteries. The generator doesn't charge at a very high rate, and for the typical 6-8 minute launch, does little more than replace the starting draw. I would go longer if a charge was needed, but it's much more pleasant with the engine off! -- ----- Replace "SPAM" with "charter" to email me directly Eric Greenwell Washington State USA |
#12
|
|||
|
|||
Keith W wrote:
But more seriously, would the material of the canopy absorb the frequencies used by the solar panel - if not, would there be a problem with mounting the panel inside the 'glass'. I don't think it is significant, but these particular panels don't have any specifications that would let you know. The Strobl panels the German factories supply on their gliders seem to have the similar ratings when used under a canopy. Even mounted outside, I suspect that the joint around the canopy would cause sufficient turbulent layer that the extra 'roughness' would not be noticeable, if the panel were to be mounted behind the canopy. These panels are attractive in part because they are very thin (0.008 inches), about the same as wing tape. I"d put them on the engine doors where the boundary layer is quite thick, but even behind the canopy might be in a thick enough layer. The further back from the canopy, the less drag. -- ----- Replace "SPAM" with "charter" to email me directly Eric Greenwell Washington State USA |
|
Thread Tools | |
Display Modes | |
|
|