Why Not Use Empirical Adjustments for Solar Death Rays?

  • Thread starter Thread starter DaveC426913
  • Start date Start date
  • Tags Tags
    Death Ray
Click For Summary

Discussion Overview

The discussion revolves around the feasibility and effectiveness of using multiple mirrors to create a solar death ray, inspired by historical accounts and modern experiments. Participants explore various construction methods, empirical adjustments, and the efficiency of solar energy conversion, touching on both theoretical and practical aspects.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation
  • Experimental/applied

Main Points Raised

  • One participant suggests that instead of calculating mirror angles, an empirical approach could be used by adjusting mirrors manually to focus sunlight, proposing the use of flexible materials for easier adjustments.
  • Another participant agrees that using 300 individually controlled mirrors could potentially ignite a ship, but raises concerns about the distance from the mirrors to the target and the size of the mirrors.
  • A claim is made that the maximum achievable solar intensity is around 1.4 kW/m², which may decrease due to environmental factors, and that the effectiveness depends on the total area of mirrors and the material being ignited.
  • Some participants discuss the historical context, mentioning Archimedes and questioning the validity of modern experiments that claim to have "busted" the myth of the solar death ray.
  • One participant shares personal experience with a small-scale experiment using mirrors, which did not achieve ignition but did cause some damage to eyesight.
  • There are discussions about the efficiency of converting solar heat into electricity compared to other methods, with some skepticism about the feasibility of achieving high energy outputs consistently.
  • Another participant mentions the use of Stirling engines powered by solar energy, highlighting the challenges of mirror alignment without computerized systems.
  • Several participants express doubts about the practicality and efficiency of large solar concentrators, with one suggesting that the design is inefficient in terms of land use.

Areas of Agreement / Disagreement

Participants express a range of views on the effectiveness of using multiple mirrors for solar concentration, with some supporting the idea while others raise concerns about practical limitations. There is no consensus on the best approach or the feasibility of achieving ignition with the proposed methods.

Contextual Notes

Participants note various limitations, including the dependence on environmental conditions, the initial investment required for solar concentrators, and the challenges of energy storage. The discussion also highlights unresolved questions regarding the historical accuracy of the myth and the effectiveness of modern experiments.

  • #31
mr henry said:
now I'm no physicist, beyond my A-level, but maintain an interest, so feel free to laugh if required!
No laughing here...
mr henry said:
Wouldn't the size of focal area be dependent on the size of the mirrors and one's accuracy at lining them up? If they were, say, an inch square, and you had them perfectly lined up (a near impossible feat, i understand), would it not be only an inch square, rather than a cumulative total of the area?

Am going to try and build one myself, just to see if i can, so these little nuggets of info could prove useful and determine whether it works or not.
Yep. Three foot mirrors (the size of a soldier's shield) will make a three foot spot.

See http://www.solardeathray.com/about.html (as in the initial post) who did it with 3.5" mirrors.

Personally, I think he did it the hard way - he calcualted the angle of every mirror. Seems to me, all you need to do is set it one place, point a light at it (parallel), and move it until it reflects the light at the focus. Who cares what the numerical angle is.
 
Last edited by a moderator:
Engineering news on Phys.org
  • #32
aaaahhh, sorry, a simple misunderstanding. I imagined a comma ("3, foot round mirrors...") that blatantly wasn't there!

Thanks for the link, i stumbled across that site about a month ago, hence wanting to build one. Fancy the challenge of a longer range one (although my garden wouldn't quite accommodate 100'!) Clearly levels of observation and attention to detail will need to be improved if I am to stand a chance!
I do prefer the idea of doing the mirrors empirically though, the calculations seem a bit heath robinson, and more open to error.

Thanks
 
  • #33
mr henry said:
...the calculations seem a bit heath robinson

Ah, what??
 
  • #34
well, flat mirrors don't reflect 100% of sun energy, do they? Ordinary metalised mirror is lucky to reflect about 50% of visible light, but shoudn't they hunt for more like infrared side of spectrum?