TWCobra
Senior Member.
The Video-
The claim: That hobby level Flight Simulation software; Microsoft Flight Simulator X (10) can be used to scientifically discredit the NTSB reports on the speeds that were evidently achieved by AA Flight 11 and UA Flight 175 during the September 11 attacks.
Background: The video in question features an attempt to disprove the NTSB reports by utilizing the "crash logic" of FSX. This is done, for some reason using a 737 (?), by flying towards a Manhattan scene first with the crash logic off and then with the crash logic of the simulator turned on.
The video is strange for a number of reasons, not the least being that is appears to hang its argument on whether or not FSX accurately models flight structures beyond normal operating limits. The video also ignores the certification requirements of a real Part 25 airliner which requires extension of the flight envelope to Design Dive Speed (VD) and +2.5G, and once those inconsistencies are taken into account, paradoxically refutes one of the principle arguments of P4T, that a 767 would be uncontrollable at the speeds attained.
The question of whether or not FSX accurately models structural damage beyond VMO (Velocity Max Operating) is quickly answered.
It doesn't.
Either Robert Balsamo is developing a contempt for the people he is trying to deceive or he is just getting sloppy. Numerous dialogues with Balsamo reveal that he is well aware of the flight envelope on a Part 25 airliner and the speed and G limits at the boundary, so it seems to require a lot of "front" to publish a video that claims a 737 will fatally overstress at VMO+42 (382 kts) and 1.2G as seen in this part of the video.
VD for a 737-800 is 380 KEAS and the aircraft was certified safe to that airspeed at 2.5G during its test phase. As mentioned elsewhere on this forum, 737s have been known to survive large excursions past VD and survive without any structural damage. An Adam Air 737-400 went to 495 KCAS knots and 3.5 G before breaking up
Therefore the crash logic of FSX is way out and really renders the rest of the video moot. Why Balsamo used a 737 makes this particular exercise even more baffling.. there are many 767 add-ons available for the program.
Balsamo also shows a demonstration of the terminal dive with the crash logic off. The early speeds shown on the demonstration are in error, as it shows the aircraft maintaining approx 510-520 KCAS during the entire descent. The aircraft never approached those speeds until approximately 10 seconds before impact as can be interpolated from the official radar speed analysis.
In another thread I did and approximation of the speeds required from 10,000, reproduced here;
In the demonstration Balsamo is flying the terminal groundspeed as the indicated airspeed all the way down, instead of the indicated airspeeds needed to maintain the recorded groundspeeds. The IAS's required to fly the correct speed profile are substantially less at higher altitudes.
Having said that, Balsamo manages to fly the aircraft quite easily into the target tower, even allowing for the large TAS errors caused by using the wrong (too high) IAS for most of the descent. TAS (and G forces) is the major determinant of the radius of a turning circle at any given altitude so flying too fast would make the lining up of a target substantially more difficult. Yet Balsamo accomplishes the feat with little difficulty.
So what does that say about his use of FSX to make his supposed points? The crash logic is not real world as evidenced by the numerous aircraft that have made forays past VD without crashing. P4T has made much of the supposed difficulty of flying an airliner at such speeds and the problems that may cause for controllability. Yet in this simulator it doesn't appear to be an issue, as also seen in X-Plane, a far more advanced FAA approved piece of Flight Sim software.
I leave that for other to decide.
Sufficient to say that the legitimacy of using FSX to "prove" structural failure at speeds much lower than that seen on 9/11 and during other real world over-speed incidents is - Debunked
The claim: That hobby level Flight Simulation software; Microsoft Flight Simulator X (10) can be used to scientifically discredit the NTSB reports on the speeds that were evidently achieved by AA Flight 11 and UA Flight 175 during the September 11 attacks.
Background: The video in question features an attempt to disprove the NTSB reports by utilizing the "crash logic" of FSX. This is done, for some reason using a 737 (?), by flying towards a Manhattan scene first with the crash logic off and then with the crash logic of the simulator turned on.
The video is strange for a number of reasons, not the least being that is appears to hang its argument on whether or not FSX accurately models flight structures beyond normal operating limits. The video also ignores the certification requirements of a real Part 25 airliner which requires extension of the flight envelope to Design Dive Speed (VD) and +2.5G, and once those inconsistencies are taken into account, paradoxically refutes one of the principle arguments of P4T, that a 767 would be uncontrollable at the speeds attained.
The question of whether or not FSX accurately models structural damage beyond VMO (Velocity Max Operating) is quickly answered.
It doesn't.
Either Robert Balsamo is developing a contempt for the people he is trying to deceive or he is just getting sloppy. Numerous dialogues with Balsamo reveal that he is well aware of the flight envelope on a Part 25 airliner and the speed and G limits at the boundary, so it seems to require a lot of "front" to publish a video that claims a 737 will fatally overstress at VMO+42 (382 kts) and 1.2G as seen in this part of the video.
VD for a 737-800 is 380 KEAS and the aircraft was certified safe to that airspeed at 2.5G during its test phase. As mentioned elsewhere on this forum, 737s have been known to survive large excursions past VD and survive without any structural damage. An Adam Air 737-400 went to 495 KCAS knots and 3.5 G before breaking up
Therefore the crash logic of FSX is way out and really renders the rest of the video moot. Why Balsamo used a 737 makes this particular exercise even more baffling.. there are many 767 add-ons available for the program.
Balsamo also shows a demonstration of the terminal dive with the crash logic off. The early speeds shown on the demonstration are in error, as it shows the aircraft maintaining approx 510-520 KCAS during the entire descent. The aircraft never approached those speeds until approximately 10 seconds before impact as can be interpolated from the official radar speed analysis.
In another thread I did and approximation of the speeds required from 10,000, reproduced here;
In the demonstration Balsamo is flying the terminal groundspeed as the indicated airspeed all the way down, instead of the indicated airspeeds needed to maintain the recorded groundspeeds. The IAS's required to fly the correct speed profile are substantially less at higher altitudes.
Having said that, Balsamo manages to fly the aircraft quite easily into the target tower, even allowing for the large TAS errors caused by using the wrong (too high) IAS for most of the descent. TAS (and G forces) is the major determinant of the radius of a turning circle at any given altitude so flying too fast would make the lining up of a target substantially more difficult. Yet Balsamo accomplishes the feat with little difficulty.
So what does that say about his use of FSX to make his supposed points? The crash logic is not real world as evidenced by the numerous aircraft that have made forays past VD without crashing. P4T has made much of the supposed difficulty of flying an airliner at such speeds and the problems that may cause for controllability. Yet in this simulator it doesn't appear to be an issue, as also seen in X-Plane, a far more advanced FAA approved piece of Flight Sim software.
I leave that for other to decide.
Sufficient to say that the legitimacy of using FSX to "prove" structural failure at speeds much lower than that seen on 9/11 and during other real world over-speed incidents is - Debunked
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