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View Diary: Politics ahead of national security (128 comments)

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  •  Okay... (none)
    Okay, I'll take it step by step:

    Teterboro
    Speed
    The plane that rolled into the warehouse in Teterboro, NJ was a Canadair CL-600, which has a V<sub>r</sub> of 140kts (takeoff speed in nominal conditions). Now, due to the fact that there is evidence that the pilots had locked up the brakes 1,000 feet before the end of the runway and engaged the thrust reversers, the plane was not traveling that fast when it impacted the warehouse, after running off the airport property and across a highway (assume at least 4,000-5,000 feet traveled since takeoff was aborted).

    The 757-200 that flew into the side of the Pentagon was traveling at somewhere between 450-500kts when it impacted the E-ring of wedge 1.

    Mass
    CL-600 Challenger 600 maximum takeoff weight (MTOW): 40,000lbs
    757-200 MTOW: 225,000lbs

    Impact Structure
    The CL-600 impacted a traditional unreinforced brick-and-mortar wall, with results similar to what you'd expect if a car impacted at about 45mph. Theoretically, the structure would have failed sequentially, spreading the impact force out along a short period of time (tenths of a second).

    The 757 impacted a heavily-reinforced stone, steel and concrete structure designed to withstand a moderate bomb blast. Functionally, except in portions of the aircraft of extreme density (engines, landing gear, APUs) the deccelerative force of the impact would have occurred instantaneously  (millionths of seconds, at most).


    Now, I'm not going to do the math, but bear in mind that F=M(A) and that while the forces on the Pentagon and the aircraft were equal, the 757 had a significantly more fragile structure and less mass than the stone building. (Also bear in mind that other than the obvious damage - the collapse of the E-ring, the fire and the holes - the structural damage to the Pentagon was so significant that the entirety of wedge 1 was demolished and rebuilt.)


    Other points
    A) I'm not sure what you'd expect to see attached to an airliner, but no, all I saw was a Boeing 757 painted in American Airlines colors, zoom at extremely low altitude over Washington Boulevard (VA-27) and impact the side of the Pentagon;

    B) I'm an aviation buff -- there are only three Boeing jets with long fuselages and twin engines (757, 767, 777). If it wasn't a 757, then it was one of their larger jetliners. (And yes, you can differentiate a Boeing from a twinjet Airbus, mainly by the shape of the nose and the outline of the vertical tail.)

    C) No, I don't think there were any conventional explosives used. It wasn't a massive explosion -- it was a fireball. Yes, there's a difference. The impact resulted in immediate ignition of the jet fuel that had been turned into a vapor by the disintegration of the aircraft. Though it might have looked spectacularly powerful, there was relatively little concussive force associated with it. (The E-ring collapse occurred later in the day, due to the ensuing fires that burned until September 14th.)

    D) Had the 757 been "shot down" it wouldn't have flown horizontally into the Pentagon. Furthermore, the two F-16's from Langley AFB didn't arrive until about 10 minutes after the impact (trust me, I remember that -- the sound of another pair of jet engines being throttled all the way up made everyone freeze in their tracks in terror until we saw that it was two USAF fighters.)

    The lack of debris on the "lawn" was mainly due to the fact that the plane impacted the building and not the ground in front of it. The Pentagon is much bigger than it appears -- the windows are deceptively large -- keep in mind that the building is 921ft on a side and nearly 80ft tall. It's a much easier target to hit than one would suspect, especially given the fact that pre-9/11, it was largely surrounded by flat, open spaces.

    A voice of objective reason in the partisan sea of the U.S. National Security community.

    by mustang dvs on Thu Feb 10, 2005 at 11:28:35 AM PST

    [ Parent ]

    •  thanks (none)
      for your comments. All good points. Was not aware you were an aviation buff from your original post, and it's clear you've thought about this before, which is good. I am not being snarky here, so one last question: have you also looked into the other issues around 9/11, particularly the WTC collapse? Just curious. I really am one of those people who has no agenda on this, but am open to learning more. Your post has dissuaded me from many of the Pentagon things I've read, but then again I'm not an expert. But thanks for this.
      •  No problem... (none)
        Gnat -- I've never made a point of detailing a whole lot of my personal life on the web. It's more or less an attempt to keep my personal political opinions separate from my professional life, in effect making harder for anyone to allege that my professional judgments are in any way influenced by my personal views (they're not, but people will stop at practically nothing to discredit you, even if you're right, if you happen to take a stance that opposes their interests).

        As for the WTC collapse -- I'm not quite sure what you're referring to. I've seen the engineering recreations on the Discovery Channel/TLC and PBS' Nova, as well as the extensive reports in The New York Times.  All of the data seemed pretty kosher to me -- the heat from the fires causing the trusses to bow, shifting the weight of the upper floors disproportionately to the outer walls, which were already bearing more than their design load due to the damaged sections. Once one or two of the floors above the damage gave way, the entire structure pancaked rapidly, collapsing first on the outside and then the center core. (Basically, the design revolution that made the WTC possible: a load-bearing outer structure was its Achilles heel when it was damaged and on fire.)

        A voice of objective reason in the partisan sea of the U.S. National Security community.

        by mustang dvs on Thu Feb 10, 2005 at 02:20:13 PM PST

        [ Parent ]

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