by Enver Masud
[Watch, read author's rebuttal of The 9/11 Commission Report.]
A simple formula, familiar to high school students, may debunk the official account of American Airlines Flight 77 that is alleged to have struck the Pentagon on September 11, 2001.
That formula is: Force = Mass X Velocity Squared / Radius.
This formula gives the additional force that would be exerted on a moving object when it transitions from its downward path to level flight in a circular arc.
The official account is that Flight 77 struck the Pentagon at "530 miles per hour" (The 9/11 Commission Report, p10) with "the top of the fuselage of the aircraft no more than 20 ft above the ground" (Pentagon Building Performance Report, p14).
So the velocity input to the preceding formula is given as 530 miles per hour. Next we determine the mass.
Flight 77, a Boeing 757, had taken off from Washington Dulles International airport, and was bound for Los Angeles. Assuming its fuel tanks were full, and ignoring the weight of the 64 passengers, and cargo (which should be available if one wants to include them), the weight of the plane would be about 255,000 pounds (Boeing Technical Specifications).
For our calculation we'll assume that weight and mass are equal, i.e. 255,000 pounds.
To calculate the radius, we need the slope of the flight path before Flight 77 levels off. We then draw a circle for which this slope and a horizontal line are tangents -- a simple problem in geometry.
We can calculate the slope from the following description of its final moments from The 9/11 Commission Report (p9): Flight 77 was "5 miles west-southwest of the Pentagon" when it "began a 330-degree turn. At the end of turn, it was descending through 2,200 feet".
Alternatively, we calculate the slope from the Flight Data Recorder data.
Pilots for 9/11 Truth obtained the Flight Data Recorder data following a Freedom of Information Act request filed with the National Transportation Safety Board.
Leaving aside the discrepancies between the official account of Flight 77, and the Flight Data Recorder, Pilots for 9/11 Truth calculated a radius equal to about 579 feet.
From this they calculated the force on the Boeing 757 at 34 Gs, i.e. 34 times the force due to gravity.
There has been some criticism of the calculations performed by Pilots for 9/11 Truth, and they have answered their critics.
With mass, velocity, and radius equal to 255,000 lbs, 530 mph, and 579 feet respectively, the preceding formula yields force equal to 8,276,850 lbs, i.e. the Boeing 757 would act as if it weighed 8,276,850, or more than 32 times its normal weight.
With a force of this magnitude, the Boeing 757 would have disintegrated in front of the Pentagon. There is no evidence that this is what occurred.
This fact alone is sufficient to debunk the official account of Flight 77.
If you disagree, figure out the mass, velocity, and radius, and plug them into the formula to calculate the force. If you have a better formula, use it. Could a Boeing 757 survive the calculated force?
Given the scientific, and other evidence, we stand by the conclusion we reached four years ago: Flight 77 did not strike the Pentagon.
Enver Masud, "What Really Happened on September 11 at the Pentagon," The Wisdom Fund, March 7, 2005
Enver Masud, 9/11 Unveiled," The Wisdom Fund (September 11, 2008)
Enver Masud, "When Did Fort Meyer Fire Department Engine 331 and Foam Unit 161 Arrive at the Pentagon on September 11, 2001?," The Wisdom Fund, January 1, 2009