Posted by dvgibson in Uncategorized.
I watched a Nova last night on the Filippo Brunelleschi who built the dome on the Cathedral of Florence. He was a most impressive guy. Not even trained as an architect or a builder but did not let that keep him from competing against those who were and then built the largest masonry dome ever built to this day, and he did it 600 years ago. But unlike Leonardo, he made no notes. The program was focused on modern architects and builders who are uncovering how he did it. The cathedral had been under construction for 80 years when the competition was opened for the dome.
Brunelleschi claimed he know how, but would not tell the committee what he proposed to do. He said he would show them when they gave him the job. They did a prelimary contract with them and he showed them how to get tons of materials 17 stories up, and back down using a lift that had never been used before. So they let him go for the dome. His trick was very clever, to use a herringbone brick pattern that helped lock the bricks together and transfer the load laterally so that the dome would not fail along the circumferential mortar lines.
I liked the idea that flying buttresses were forbidden by the committee. Yeah, to an engineer they are cool, but do you really want to look out through them? So much stuff in the view. And the dome was way to high to use centering, temporary supports that are removed after the mortar sets. And my thought is that centering allows you some imperfection. Once you get the last brick in place and the mortar sets, then some misalignment will be compensated for. For a while anyway. I heard that in about 50% of the cases it didn’t. Many cathedrals were built more than once.
We know that masons use rope lines to check their progress but exactly how he did this would not be known if one of his very vocal detractors made drawings of the construction to prove that it would fail. Those drawings survive and know we know that the rope lines came off not a circle in the center but an eight sided flower like design, that gave each side and inverted arch to transfer weight diagonally down, not just straight down. So its good to have people who think you are full of crap checking your work.
He managed to get this done in 16 years!
But I wonder about something they did not mention. What kept the base together? were the crossings acting a buttresses. Most of the weight is transferred down, but some weight is transferred out, right?
I don’t see how the curve was maintained. Is the curve a section of a circle? So not only the rope lines provided angle, but distance from the pattern line in the floor? No, I think not. They were very long and there is a lot of stretch.
Posted by dvgibson in Uncategorized.
I heard two stories on NPR yesterday morning that both grabbed my attention and I linked in my head. I wonder if anyone else will? One was on tracking illegal fishing. Its very difficult to do. Fish that are illegal to take in one area are not in others and once the fish is off the boat that caught it you loose track. So John Amos who runs Sky Truth in West Virginia uses the automatic identification system (AIS) that ships to avoid collision to do just this. AIS uses VHF radio to communicate location, vessel information and other data one to another, and to satellites that then gather that information and make it available on the internet. I just took a look at our area on http://www.marinetraffic.com/. Its pretty fascinating. Radar has been the primary collision avoidance for boat for a long while but there are times it does not work so well. Over horizons, in bad weather of if you are a very low boat, like our sailboat and a large ship which is headed your way and cannot turn to avoid a close encounter. Amos uses this to plot movement of boats on the other side of the world and coordinate with officials when they think that a boat is involved in illegal fishing so they can intercept it before it leaves the area or transfers the catch to another boat. Pretty clever use of existing technology I think. See:
http://www.npr.org/blogs/thesalt/2015/02/05/383562379/gotcha-satellites-help-strip-seafood-pirates-of-their-booty
Then I heard another story on an U.N. agency that is holding a conferece on how we can track airliners during their flights. Our current tracking is very limited so once a plane is way out there we just have to hope it is going to come back into view again. They want to have a system where the plane transmits its position heading and other vital information every 15 minutes. Sounds like they just need to go over to West Marine and pick up some AIS enabled radios. Get them for about $300. OK I know, its not anywhere near that simple. And you would want the air traffic on a different frequency. Either that or with different encoding. But the technology has already been tested and is in use world wide.
http://www.npr.org/blogs/thetwo-way/2015/02/05/383963482/new-standards-for-tracking-aircraft-in-flight
Deep Ocean to Deep Space 