Heliostats as death-rays

Ronald Reagan was not the first person to think about directed-energy weapons.

A potential application for heliostats

I've been putting some thought into how I might sell my system of cheap plastic heliostats and it occurred to me that the back pages of comic books might be the best place to advertise.

Do you remember when you were a kid that every Marvel Comics comic book had a few pages advertising of novelty gadgets? Exploding cigarettes, pepper gum, x-ray glasses, and hypnosis coins are classic examples. It's a pretty sure bet that a genuine death-ray system would appeal to the kind of person who reads those ads. And it wouldn't even be a hoax: as long as you can convince your victim to stand on the top of a ladder for a couple of minutes... :-)

I don't consider seriously exploiting this market, but it is still amusing to consider. I even got an e-mail from Doug Wood at Sunflower that hinted at what one could actually do. The photos and the e-mail below tell the story.

field of propped-up mirrors burning tree-tops concentrator made from a TV dish

Erik Rossen wrote:
> Sunflower wrote:
> >
> > I thought you might like to see these 100 mirrors (40 by 80 cm) tilted
> > up with sticks to burn the tops of too tall trees to the south.  Slight
> > sag from gravity made things hot.
> >
> > Also included a 4 meter TV satellite dish with glass mirrors tightened
> > down to the curve.
> >
> > Doug.
> >
> >     ---------------------------------------------------------------
> >  [Image]  [Image]  [Image]
> You were right: I DID find those pictures interesting!
> May I ask why you did that experiment with the 100 mirrors?  Did you
> really
> mean to burn that tree? 

Yes I did mean to burn those trees.  There were about 12 trees that were
causing problems at our concentrator site and they needed to be topped. 
It was not an experiment, just an application.  I did this alone, it was
easy.  after the mirrors were tilted up the image moved from tree to
tree  day after day burning mostly foliage off green wet winter
evergreens.  They did catch on fire.  The trees were green and wet so
the solar fires were self extinguishing.

> It makes me wonder if I shouldn't market my
> mini-heliostats as a "death-ray" system and advertise on the backs of
> comic books! :-)

The book "A Golden Thread" by Butti and Perlin, has a good historical
section on burning mirrors used as weapons.  "Legend has it that in 212
BC Archimedes used burning mirrors to destroy the ships of invading
Romans at Syracuse, but this story appears to be no more than a myth. 
None of the reliable historians of the period - Polybius, Livy or
Plutarch - mentioned that Archimedes used burning mirrors."  "...Roger
Bacon, a Franciscan monk, who taught at Oxford and the U of Paris during
the thirteenth century ... doomsday weapon that might be wielded by the
Anti-Chirst - the Moslems whom the Crusaders were battling in the Holy
Land.  Bacon advised Pope Clement IV that - 'We are to believe that the
Anti-Christ will use these mirrors to burn up cities, camps and

The idea of transforming mild sun rays into a fierce weapon of fire was
now condemned as the work of the devil, and Bacon was thrown into the
dungeon as a heretic ... "

Solar energy is best used as an instrument of peace.

> If you haven't posted them anywhere else, I'd like
> your permission to put those pictures on my website.

These pictures and the story about them (on Fox Island WA USA) has never
been told and yes you can post the pictures on your web site. Let me
know when you post these pictures so I can stop mailing them and
reference your web site instead.

> I don't understand your comment about the gravity.
The mirrors flexed slightly compressing the image 2:1 from gravity sag. 
100 mirrors had the temperature equivalent of 200 stiff mirrors. 
Because they tilt between the sun and the target a rectangle images a
square.  You may want to make your heliostats longer than the width.

> The dish is pretty, but I imagine that it was fairly expensive to
> construct?  

This dish cost a contributed TV dish frame, left over mirror, and a new
$150 US tracking arm plus one week of my labor.

The dish is an economic experiment. See...

Our big dishes are at...

Information about me can be found at...

> Are you interested in making heliostats as well?
> Erik Rossen.

Yes I like heliostats as well.  

I am hot on 1000:1 concentrator pv and I am designing a small square
dish using glass mirror strips curved against parallel joists. The  dish
is 243 by 243 cm square with a 243 cm focal length.  The mirror strips
will be 2.43 cm wide and 243/2 cm long. The cr may actually be about
2000:1.  This will be free technology for the world to use.

We are non-profit and offer free consulting when requested from solar
tech developers (for environmental motivations.)

Happy to be a service


Erik Rossen <rossen@rossen.ch>
OpenPGP key: 2935D0B9
Tel: +41 78 617 72 83
Home URL: http://www.rossen.ch

Copyright © 2000 until the heat-death of the Universe (thanks, Mickey!), by Erik Rossen
Last modified: 2016-02-07T12:43:23+0100