26-02-2011, 02:26 AM
(This post was last modified: 26-02-2011, 03:05 AM by Jeffrey Orling.)
Jack,
I am not an expert in photo analysis. But I do have some question about the spire photos - column 501 turning to dust.
The most recent analysis of core column 501 was that it was 78 stories tall. This makes it 936' tall made from 26 segments. It was attached lower down to column 601 at the 63rd floor at elevation +756'. This means it extended for 180' or 15 stories.
In the frames pictured we can calculate the rate of descent if we know the frame rate. From full height of 936' it drops in the second frame about half way to the the 756' elevation... let's call that 90' The water tank eclipses the bottom of the column at about another 15 stories. So we are able to see 45 stories of core column 501 from that camera position from the north and east of the Spire.
Frame 1 - we see all 45 stories (can't see the bottom 33 which are eclipsed by the water tank)
Frame 2 - we see column 501 drop 15 stories and the 15 stories where it was joined to column 601 has dropped and is eclipsed by the water tank. One frame drops 180'
Frame 3 - we see column 501 drop another 15 stories or MORE. It is not dropped and it is totally eclipsed by the water tank. We can see that the wind that day was from the north west as the dust has been displaced (blown) by the wind east and southward and is clearly dispersing in frame 3
You can also use the top of the water tank to observe that as the column was dropping it was moving or tipping south and east. Note how close the column in Frame 1 is to the top of the water tank and how it has moved to the east in Frame 3. Since it was shown tipping to the south and east it is logical that if it fell down it would appear to "intersect" the water tank further and further to the east as it descended.
Now if we know the frame rate we can produce the average speed from frame 1 to frame 2. And we might guess at what the rate of acceleration was since it started at 0m/s in frame 1.
The dust has displaced quite a distance between frame 2 and 3. This distance can be determined and knowing the prevailing wind speed the time different between images can be estimated.
There is something else odd about the frames. They seem to jump up and down. Obviously there is some cropping going on.
I think there is a lot of useful information in these frames. But it requires some detailed analysis. I believe you can determine the speed the column is dropping. We can probably find another view to cross reference this and sharpen the calculations and reduce the error.
My hunch is that it dropped at free fall.
The water tank appears to be on the roof of 90 Duane Street. Now you can do some math and calculate the distances etc.
I am not an expert in photo analysis. But I do have some question about the spire photos - column 501 turning to dust.
The most recent analysis of core column 501 was that it was 78 stories tall. This makes it 936' tall made from 26 segments. It was attached lower down to column 601 at the 63rd floor at elevation +756'. This means it extended for 180' or 15 stories.
In the frames pictured we can calculate the rate of descent if we know the frame rate. From full height of 936' it drops in the second frame about half way to the the 756' elevation... let's call that 90' The water tank eclipses the bottom of the column at about another 15 stories. So we are able to see 45 stories of core column 501 from that camera position from the north and east of the Spire.
Frame 1 - we see all 45 stories (can't see the bottom 33 which are eclipsed by the water tank)
Frame 2 - we see column 501 drop 15 stories and the 15 stories where it was joined to column 601 has dropped and is eclipsed by the water tank. One frame drops 180'
Frame 3 - we see column 501 drop another 15 stories or MORE. It is not dropped and it is totally eclipsed by the water tank. We can see that the wind that day was from the north west as the dust has been displaced (blown) by the wind east and southward and is clearly dispersing in frame 3
You can also use the top of the water tank to observe that as the column was dropping it was moving or tipping south and east. Note how close the column in Frame 1 is to the top of the water tank and how it has moved to the east in Frame 3. Since it was shown tipping to the south and east it is logical that if it fell down it would appear to "intersect" the water tank further and further to the east as it descended.
Now if we know the frame rate we can produce the average speed from frame 1 to frame 2. And we might guess at what the rate of acceleration was since it started at 0m/s in frame 1.
The dust has displaced quite a distance between frame 2 and 3. This distance can be determined and knowing the prevailing wind speed the time different between images can be estimated.
There is something else odd about the frames. They seem to jump up and down. Obviously there is some cropping going on.
I think there is a lot of useful information in these frames. But it requires some detailed analysis. I believe you can determine the speed the column is dropping. We can probably find another view to cross reference this and sharpen the calculations and reduce the error.
My hunch is that it dropped at free fall.
The water tank appears to be on the roof of 90 Duane Street. Now you can do some math and calculate the distances etc.