9/11: The Aircraft

Note:
This material is not intended to fit any theory.
Various pieces of information are merely brought together.

11/02/07: R. A. Herbst BAAE(1969); ME(1980) with 24 years of experience

As a Boeing flight controls and simulation engineer.

Flight_175_impossible_speed

Can a 767-200 fly at 500mph+ at 700ft altitude?

If you ask any member of "Pilots for 911 truth" they will verify that the "767-200 can fly at 500mph+ at 700ft altitude". They will also verify that the alleged flight 77 could have flown it's alleged trajectory. It is an entirely different matter at to wither they actually did.

In a letter to Joel Harel, a Scientific Panel Investigating Nine-Eleven (SPINE) member who published a paper The Impossibility of Flying Heavy Aircraft Without Training, a senior 757 captain noted: “Regarding your comments on flight simulators, several of my colleagues and I have tried to simulate the ‘hijacker’s’ final approach maneuvers into the towers on our company 767 simulator. We tried repeated tight, steeply banked 180 turns at 500 mph followed by a fast rollout and lineup with a tall building. More than two-thirds of those who attempted the maneuver failed to make a ‘hit’. How these rookies who couldn’t fly a trainer pulled this off is beyond comprehension.”

This says that pilots have attempted to fly this maneuver in full-up flight simulators, and although they failed, the simulator did not "crash" due to excessive speed. Simulation engineers have the job of assuring that the flight simulator is indistinguishable from the real aircraft in terms of performance. Still, the fidelity of simulations outside the usual flight envelope can be questioned.

If you do not believe "Pilots for 911 truth", or pilots who have tried these maneuvers in flight simulators, you can figure out the answer on your own:

Here is how you figure out how fast a 767 can go: link

The answer is: 493 knots = 567.334 267 876 mile/hour (mph) official max cruising speed

This is normally considered at high altitude. The velocity never to be exceeded (Vne) is typically at least 50 knots higher than Vmo, (see notes below) but few documented numbers are available. Vne at low altitude would normally be lower than at high altitude. Vne relates to the structural capabilities of the aircraft.

Here is how you figure out how fast a 767 can go at 700 ft (basically sea level) Link

We see that the "speed limit" is much lower at sea level than at 30k. 403 mph at sea level, and 581 mph at 30000 ft. But now the rubber to the road question is, how much beyond the "speed limit" can a Boeing 757 or 767 airplane be taken? To exceed Vmo/Mmo is not catastrophic. Boeing notes higher speeds can be authorized. To quote the Boeing Flight Ops review: "At speed in excess of Vmo/Mmo ... normal airplane handling characteristics are not assured." What they are saying is that an airplane can be taken somewhat beyond Vmo/Mmo by a skilled pilot. We would expect a safety factor of at least 10%, probably more like 20% or 30%, before structural damage may result.

How much beyond the "speed limit" can a Boeing 757 or 767 airplane be taken? Pilots For 9/11 Truth asked that question over a year ago, and still do not have an answer. It is fairly well established that Vmo is about 400 mph at sea level, but no solid numbers for Vne have been documented. While this question is still in the hopper, the assumption by Pilots For 9/11 Truth has been that all of the alleged maneuvers of the airplanes on 9/11 were within the scope of a skilled pilot and the Boeing aircraft.

The "flight 175 Impossible speed" Thrust-Drag Argument has been mentioned on the internet.

The argument is basically this: thrust must increase 134-fold to maintain the same 542 mph it had at 35,000' altitude down at 1,000' altitude. I believe this is definitely wrong. First, the quantity given for air density in this "thrust/drag argument " is incorrect: The air density quoted is for 35000 meters, or 114829 ft, not 35000 ft. At 114829 ft, not only would you not be able to breathe, but you would also explode, so it looks like someone got meters and feet mixed up in thier calculations.

The 757 or 767 has enough engine thrust to go about as fast at sea level as at 30000 ft. Here is why I believe that: Thrust increases by about the needed amount to compensate for the difference in air density between the higher and lower elevation.

At lower altitudes and denser air structural damage may occur due to vibration or flutter, while at higher altitudes and thinner air, structural damage due to shock waves may occur. That’s what the "speed Limits" are all about. The key question is, by how much can a 767 (or 757) exceed Vmo without incurring structural damage , and at this point, we just do not know.

Notes:

The first note shows that typically Vne is at least 50 knots higher than Vmo

Professional Pilots Rumor Network (PPRuNe) www.pprune.org/forums/showthread.php?t=282962
Kiwiguy (fom Australia)
type *** Vmo Mmo (kts)
B747-200 375 445
DC-8-73 352 406
DC-9-30 350 425
DC-10-30 356 400

"FAR Part 25 no longer requires demonstration of Vne"

"The B757-200 however has a Vmo below 10,000 ft of just 250 knots because the windshield isn't certified to withstand bird strike above 313 knots. Above 10000 ft the 757 Vmo is limited to 350 kts... The Vmo limit [of 250 kts] is a windscreen issue only"

******

The value of "velocity to never exceed" (Vne) is stated informally by several internet sources to be:
767: 514 kts. (Professional airline pilots discuss airliner approaches)
[www.abovetopsecret.com/forum/thread290046/pg2]

****** Recreational Aviation Australia notes that for smaller aircraft, a Vne of approximately 1.4 Vmo is typical

******

Different opinions:
One source says: "In the case of 757 and 767 their VMO is structurally limited to 313 knots... Vne is the limit at which control of an aircraft may" [www.abovetopsecret.com/forum/thread290046/pg1]

WTC attack air vehicles

11/17/08: Phil Tompson
(Note: click on each of these images to expand them twice)
Frames showing anomalous air vehicle during WTC attacks
Phil Tompson: Notes on frames

11/02/07: Ace Baker
Official video of Flight 175 entering WTC2.
(Why does the airplane appear to emmerse itself in the building before "exploding"?)

Pentagon attack air vehicle

2009: Phil Thompson
The issue of a missing tail number for Flight 77 is apparently resolved

3/23/08: R.A. Herbst
Flight77 Anomalies