Archimedes Death Ray in San Francisco

Monkey-Man2000 writes "Following the recent demonstration by MIT students that Archimedes' death ray could have been used to burn Roman ships, the producers of the Discovery Channel's Myth Busters invited the MIT team to San Francisco to try their death ray on an 80-year old fishing boat. This time, even with perfect weather, they were unable to set the boat afire. From the article, "Peter Rees, executive producer of "Myth Busters," said the experiment at the Hunters Point Shipyard showed that Archimedes' death ray was most likely a myth.""

Comments

So tell me

[elmegil]

Why are they trying to burn the wood, when it seems like the rigging should be easier to torch and just as debilitating?

The sail

[DigiShaman]

Couldn't they have just burned the sail and let it burn down the rest of the ship? As I know, cloth burns much better then wood ;)

Re:The sail

[Deadstick]

I imagine it certainly could be possible to actually, permanently BLIND the people on the boats,

Yul Brynner did that trick in Solomon and Sheba (1959), having his troops polish their shields before an expected sunrise attack. The enemy weren't blinded, just dazzled, but he had positioned his men behind a convenient chasm...

rj

flammability differences

[G4from128k]

I wonder if Roman ships may have been innately more flammable than that 80 year old boat. The use of tar or pitch to seal rough-hewn planks on the sides of the Roman ships would have made them more susceptible to fire. Any oiled cloth would also have made these ancient boats more flammable.

300 SQFT??

[jackb_guppy]

They where using 300 sq ft of mirrors to set fire to a boat. They actually set fire boat at 75ft, so I call it a PASS. At 150ft they got smoke.

Now we know that SQ of distance effects the power so at 75ft there was 4 times more light/heat hitting a sq in of boat.

So that would suggest that 1200 sq ft would be needed for a fire at 150ft. Or use a different mirror that can cause a tighter beam.

Roman navies.

[Savage-Rabbit]

Early Roman navys were often temporary entities although there were also permanent squadrons even during the later empire. By then it seems their main function was to combat pirates and smugglers since the Romans had by then eliminated all serious naval challengers. A large standing navy only reappeared during the very late imperial and Byzantine period when various barbarian and large moslem naval forces reappered as the Western and then the Eastern Roman Empire collapsed. The temporary fleets, built on campaign or to deal with some sudden maratime threat, were often built of unseasoned or low quality wood and intended to last no more than a few of campaigning seasons before they were either scrapped as unseaworthty or had been lost to bad weather. While it is probably possible to torch a Roman war galley at ancor on a calm cloudless day using some sort of mirror array I don't think such a weapon would have scored more than a couple of sucesses at best and it would have been practically useless against a fast moving and maneuvering target. It would have been most useful against relatively immobile targets such as floating siege towers or catapults that would have been mounted on platforms made by lashing several galleys together. If anything the psychological effect of this 'death ray' would have been far greater than the practical destructive effect, sort of like the effect that rockets had the first time Chinese armies deployed them in combat. At first they probably scared the hell out of the barbarians but after a short while barbarians got wise to the fact that unless they were really big and carried exploding warheads Chinese rockets were not terribly destructive and made sure their forces knew it and that the horses were acclimatized to the alien noises the rockets made. I would not expect a force that achieved the very high degree of professionalism the Roman army did to have been impressed by this sort of a weapon for very long even if the weapon worked under ideal conditions.

Re:I'm shocked, shocked

[irc.goatse.cx troll]

My first thought back when watching the originalepisode was pretty simple: Hold something (preferably colored glass) infront of your mirror. Your bright dot will be the colored one. Bonus points for a unique stained glass design you can use so multiple people can aim at once, but once you start coloring them you can fix your aim and move on to the next guy within 30seconds.

Re:I'm shocked, shocked

[Harbinjer]

The thing I don't know if they took into account is global dimming. Because of all the airliners and other pollution, we now get over 20% less sunlight than we did in the 50's. Now consider how much less air pollution there was in Roman times. If we take that into account, maybe this would've worked just fine.

Don't believe me? Google 'global dimming' and you'll see.

Somebody has confirmed it in another experiment

[thanasakis]

Looks like a similar experiment was successfull

ARCHIMEDES: CRANES, CATAPULTS, MIRRORS

Archimedes played a major part in defending his natal city of Syracuse against a protracted Roman siege, as the designer of a host of weapons and machines to repulse the attackers. These fall into three main categories: a) cranes (or 'claws') that lifted enemy ships out of the water and dashed them against the rocks, b) catapults of every size and description that hurled bolts and stones varying distances, and c) the mirrors that focused sunlight on the ships and set them alight. This latter invention has become legendary, and much has been written about whether such a thing could in fact have been possible in the time of Archimedes. Most experts, and particularly foreign experts, were persuaded that the construction of such a system was a myth, despite the weight of literary evidence supporting the story, until engineer Ioannis Sakkas succeeded in demonstrating that it was indeed possible. Sakkas used 70 copper-plated glass lenses, with diameters ranging from 1.70 to 0.70 metres, and his experiment was carried out at the Palaska Training Centre on the island of Salamina on November 6, 1973. Sakkas placed his 70 lenses in a circle, and succeeded in focusing the sun's rays on a small boat, built in the same way as Roman craft and equipped with the same sort of materials, lying 55 metres away. In less than three minutes the boat was ablaze. Sakkas' experiment was reported around the world, and caused quite a stir. Three previous tests had also produced satisfactory results, and together they confirmed that Archimedes did indeed set fire to Roman ships. While we do not know the full effect of this conflagration, the psychological impact on the enemy must have been terrible. That, of course, is why his feat acquired the status of a legend and is still talked about to this day.

And, really, we are talking about Archimedes here. If there was one guy in the whole Ancient world who could successfully pull something like this, it would be him. I for one believe that he actually did it.

Re:What a Scientific Conclusion!

[mattcasters]

So what you're saying is that in the case of bronze (inefficient) mirrors you would need more mirrors to get the same amount of sunlight on the target.
The problem is that alledgedly they had five thousand mirrors, not one hundred.
Also, they had thousands of soldiers pointing the mirros, not a few students to do all the work.

So let's say the mirros where half as effective as we know them today, that means the reflected sunlight was still ( 5000*50% ) / 100 = 25 times as great as in the experiment. That's not even counting for the better accuracy when having 5000 soldiers doing the targetting.

IMHO, I think it's still a bit early to call this a "bullshit myth".

Why didn't they figure out a way of measuring the disposed energy?
You could target a large steel barrel of water and see how many degrees it heated... or something ;-)

Just a few thoughts...

Cheers,

Matt