[TheForge] Solar tracking (was: crackpottery)

[Bruce Freeman]

Well, hooking a cat up is an inspired idea, but it would fail in practice.  A cat you can't hook up to anything!

But there IS a lovely solar tracking idea out there.  This was intended for a dirt-cheap, high efficiency solar collector:

Bend a piece of shiny sheet metal into a parabola, with some end caps to  keep it that shape and to mount the pivot.  At the focal point of the parabola, run a water pipe (which can also serve as the rotational axis of the parabola).  Just outside either edge of the parabola, place a pipe ("control pipes"), one end of which is connected to a double-acting pneumatic cylinder which is rigged to rotate the parabola on its axis.  Charge the control pipes with a volatile liquid.  Orient the axis of the parabola (i.e., the water pipe) due north/south.

Here's the scenario:  At dawn, the parabola is pointing some arbitrary direction (probably streight up).  Sunlight hits the eastern control pipe, but the western one is shaded.  Eastern pipe warms up, pressure increases, pneumatic cylinder piston moves, rotating parabola toward sun.  Motion stops when both control pipes are equally warmed by the sun.

Bruce
NJ

>>> frosty at customcpu.com 12/12/2005 12:51:59 AM >>>
Okay, now we're talking!

I don't have any numbers, though Im sure they were posted before I read your 
post, but I'm pretty sure it doesn't take nearly as much solar focus as a 
person might think. I'd guess a few sq ft to a couple sq yds.

One of my projects if the opportunity arrises is foil or mylar lining a 
satellite dish to find out. Tracking the sun is simply a matter of hooking a 
cat up to it.

Frosty

Quoting Peter Fels And Phoebe Palmer <artgawk at thegrid.net>:

> 
> Well, if you are not going for natural methane as a fuel;
> How bout solar?
> How many square feet of reflective surface does it take to heat a 
> couple of cubic inches of iron to a healthy yellow?
> What's the junkyard tracking mechanism?
> All this talk of slacktubsicles leaves me cold.
> Pete F
> _______________________________________________



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