Mr. Deets,
Part of this issue pertains to who has the burden of proof. If a flutter engineer cited Flt 175 as evidence an airplane can fly 100 knots over its dive speed, and I were a senior manager higher up in the chain, I would send this engineer back for more background information. I would ask for any precedents where such a thing had happened previously. I would ask for an engineering analysis, in this case involving predicted flutter modes as a function of equivalent airspeed or Mach no. offering some explanation.
In this post, I'll address only the question of "was this plane Flight 175?"
I am not an aerodynamicist. I am a mechanical engineer & a low time (~400 hours) pilot.
As I understand flutter, its causes & remedies, there are three alternative strategies for dealing with it.
1. Redesign some aspect of the airframe such that the aerodynamic forces don't develop in the first place.
2a. [Viable brute-force approach] Beef up the affected surfaces such that they can resist the oscillating driving aerodynamic forces that cause the flutter in the first place.
2b. [Unviable brute-force approach. Included for completeness.] Beef up the affected surface, but all from under the skin such that no modifications are visible from external examination of the plane.
3. If the flutter is due to some feedback in the control system, change its frequency response to stabilize the control system's response at the problematic frequencies.
In the case of Flight 175, we can eliminate option #1 & 2a immediately. By all inspection of the size & shape of all parts of that airplane & its control surfaces in the video, it is, unquestionably, a 767-222. Just like Flight 175. Given resolution limits of the videos, the probability that it was externally modified is < 1 in 1000.
Similarly, I believe options 2b & 3 to be untenable. The scale of any development program to achieve either requires a large, highly skilled aerodynamics engineering staff, a huge project & enormous funding. All begging for discovery during or after the event.
Yet, any aerodynamics professional would immediately identify this incredibly dangerous, massive, expensive, certain-to-be-discovered project as rendered utterly unnecessary by the simple act of keeping the plane's airspeed within acceptable limits.
Any scenario for a modified 767 requires this large group of oxymoronic "incredibly competent / brain-dead stupid" evil geniuses. And is therefore dismissed as the stuff of very poor fiction. With a probability of < 1 in 1,000,000. (Essentially zero. Lost in the noise level of the other probabilities.)
There is no viable scenario, that I can see, that this was a modified 767-222. And so I am left with the probability that this was a stock, unmodified 767 as > 999 out of 1000.
I invite you to show any weakness in this argument and to produce any reasonable alternative.
It seems highly likely (>90%) that the people who committed this act would have (correctly) concluded that any domestic passenger jet would serve their purposes. Domestic route planes were chosen to eliminate frequent, risky customs clearances if their surveillance flights had been international.
Given this, Flight 175 was as likely a choice as any domestic passenger jet flying out of their chosen cities that morning.
Given that it was a stock 767, given all the radar tracking data & phone conversations from the plane, given the absence of the plane & passengers, given the complete lack of any viable alternative, the probability that this was NOT Flight 175 is indistinguishable from zero.
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The next steps are so short, we might as well take them now.
Controllability:
It is patently obvious from the video that the plane that hit the tower WAS controllable at its terminal speed. The plane began drifting to the right of the building and to compensate, the pilot rolled left, and pulled back on the yoke. Thereby successfully hitting his target.
Controllability is thereby proven to a certainty.
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Speed of the plane:
Several independent groups of analysts examined the many videos & photographs of the plane's approach to the south tower.
They came up with different, mostly overlapping, speeds (with error bounds). But like all engineering analyses, poor estimates or assumptions in early reports are improved & corrected over time. And a consensus of the best conclusion & error is achieved in the engineering / science community.
The probability that the velocity of whatever plane hit the tower is wrong (within the stated error bounds) is miniscule. Less than 1 in 1000.
The fact that one 767 successfully flew this fast does not mean that any one of them can, of course. But that isn't what we are looking to prove or disprove. We are looking for the probability that it was a 767 that managed to hit that tower on that day.
Combining these two probabilities, we now have a demonstration that the probability that at least one stock 767 did fly this fast, controllably, is very high. By these calculations, around 999,999 out of 1,000,000.
And that probability is not altered in the slightest by limiting the plane to Flight 175.
The inverse probability, that the videos & photos of that day did NOT show Flight 175 flying into the side of that building, at the speeds calculated by several independent groups, while maintaining controllability, is estimated to be around 1 in 1,000,000.
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All of the above has not leveraged the previous experience of other commercial jets that also exceeded their performance envelopes. Some did so by larger margins than Flight 175. With none of them suffering catastrophic break up in flight (with the exception of the irrelevant-to-this-discussion thrust reverser deployment).
This data only serves to strengthen the case for the plane being Flight 175.
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In making your case, your offerings are paltry at best.
The single counter argument for mid-air break up that you've offered is the questionable & self-serving Egyptian government's suggestion that "perhaps an elevator broke off on Flight 990."
And you've brought your personal doubts.
And you've brought your dissatisfaction with the amount & timeliness with which the FBI has released information to the public.
And you've brought your estimates of the probabilities (1 in 1000 that it was a 767 flown by a low time pilot). Which, as far as I can see, is based on no data whatsoever.
If I were the senior person making judgments in an engineering review board, and you brought your case, and a competent engineer brought the opposite case, then I can assure you that the verdict would be swift.
And it would not go in your favor.
flow