You still don't understand, do you? You do not require a seal to produce vacuum or, my suggestion, under pressure.
The WTC7 demolition went fast. No time to set up a seal. Use your brains, if you have any.
Since you're asking others to be polite, the final clause would seem a little inconsistent.
Your argument here is complete rubbish. A seal of some sort is required to produce a significant amount of vacuum for a reasonable time. If there was no time to set up a seal, then there can't have been a significant amount of vacuum for a reasonable time. Your argument seems to be that a vacuum was known to exist, that there wasn't time to set up a seal, therefore it follows that a vacuum can exist without a seal. Your first premise is unproven.
Vacuum device? What's wrong with under pressure and no device?
OK, so you're backing off on the vacuum claim? Fine. In that case, you require a device that produces a significant overpressure in the open air above the roof of WTC7. We'll quietly ignore the massive hole known to exist in the roof, over the time period in which the facade's fall was fitted to a 1g acceleration, arising from the prior collapse of the mechanical penthouses; let's assume that the roof was able to resist this overpressure and transmit the resulting force to the collapse zone. What could have caused this overpressure, without producing any visible effects, or indeed being at all visible itself?
In my opinion you have to remove most columns below floor 11 to start the show. It takes two seconds. How is this done? I will tell you later. You have to be patient.
As some columns are still there providing resistance, you need under pressure below floor 11 to suck down the structural assembly above floor 11 at free fall. Gravity alone cannot produce free fall, when there are columns below providing resistance, you see. This part of the show takes 2.5 seconds.
And now you've decided to argue for a partial vacuum again, persisting for 2.5 seconds with no possibility of a seal around it. Let's see what we can deduce about the collapse initiation mechanism assuming your hypothesis has any merit to it.
Firstly, at most your downward acceleration due to vacuum is about 0.5-0.6g (as I said earlier, I made a stupid mistake last week; you're right on this point). If we take your oft-repeated figure of 3 for the safety factor, that means that a hard vacuum alone could not initiate collapse below about the 30th-35th floor, as the increase in downward force has to be at least twice the weight above the collapse initiation zone for columns to fail. Therefore, we need to invoke some other means of severing columns for a collapse at the 11th floor. Let's assume, further, that your handwaved imaginary silent mechanism for doing this exists. How many do we need to cut?
The columns at floor 11 are capable of supporting 3 x 36/47 times the full weight of the building, or about 2.3 building weights. The vacuum exerts 0.6 building weights, and the building from the 12th floor upwards exerts 0.76 building weights. The excess strength of the columns is therefore 0.94 building weights, so this amount of strength must be removed before collapse. This requires the removal of over 40% of the columns at floor 11.
OK, now suppose you're the conspirator planning to demolish WTC7. You have at your disposal two super-secret demolition devices. One of these can sever columns silently and invisibly, causing a building to collapse with very similar features to a controlled demolition, but which can easily be explained away by claiming that columns failed due to fire, and that the gross features of collapse would be expected to resemble those of a controlled demolition. The other can create a vacuum inside a building, causing its collapse to accelerate too rapidly to be explained by any similarity to a controlled demolition, and in fact creating a physically observable feature of collapse that can't be explained satisfactorily.
Can you explain why you would want to use the second device, rather than simply severing 67% of the columns undetectably with the first one?
It can't be to ensure a rapid and symmetrical collapse of WTC7, by the way. Since one of the aims of the operation was to kill thousands of innocent bystanders, limiting collateral damage at this late stage seems a little counter-productive.
Dave
