>From my friend Ken offlist:
Note that an effect similar to that achieved with the floating system 
that I mentioned could be obtained by having a frame that tilted on x 
and y axes with expanding bags outside the receiver area that were 
heated by off centre radiation. If a phase change was acheived the 
travel and force available could be substantial, but even with just 
heating air an adequate system could probably be achieved.


        RM

_________________________________________


From: "Ken Mardle"
Russell,

Passive solar trackers using an aluminium frame filled with a volatile 
fluid
have been commonplace for years.  I forget the details of how they 
work but
I have some promotional info at home somewhere.

You may also recall some work I did some years back on solar tracking 
using
a dumb constant-motion yaw-drive combined with couple of manual 
adjustments
through the year for azimuth.  This strongly suggested that such a 
system
would provide a total energy output which was within a few percent of 
active
trackers.  If you took into account the much higher energy demands of 
an
active solar tracker it would very likely be well ahead (and it's a 
lot
cheaper).  This assumes a flat panel collector  - you do need 
something
better for a focussed collector.

Regards,

Ken Mardle
Applied Digital Research Ltd.

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