unmodified

It's an impossible airspeed for an unmodified commercial Boeing passenger jet



i] Zaphod58

You have to prove that it couldn't have dove down and reached that speed. Which you haven't, and can't. If a plane can dive down, and remain under perfect control and reach Mach 1, there is absolutely no reason why 175 couldn't have done it.



Zaphod58

They climbed to 52,000 feet , where they put it (the DC-8) into a half G pushover (a dive no steeper than 175 performed, and possible not as steep), at 45,000 feet , while in perfect control, the aircraft reached Mach 1.01 for 16 seconds. They were able to recover at 35,000 feet , with no damage to the aircraft.



The dive speed (Vd) is the absolute maximum speed above which the aircraft must not fly. Typically, to achieve this speed, the aircraft must enter a dive (steep descent), as the engines cannot produce sufficient thrust to overcome aerodynamic drag in level flight. At the dive speed, excessive aircraft vibrations develop which put the aircraft structural integrity at stake.



theflyingengineer.com...

In that video, for the Airbus380 flutter test, they descended in a steady dive from 38,000 feet aiming for a Vd of Mach .96 (it's a big plane with lots of surface area) which to certify required some major modifications.



The south tower plane, according to you, would be able to exceed Mach 1.39 to Mach 1.4 when descending from the same height of 38,000 feet.. for an EAS of 510 knots, at sea level.



Vd is 420 knots for the Boeing 767 as set by the manufacturer based on wind tunnel and flight testing.



Here are those limitations, from Boeing...

(pfd) rgl.faa.gov...$FILE/A1NM%20Rev%2026.pdf





Vd explained

theflyingengineer.com...



At EAS (Sea Level), over test Vd - let's take a look at the range, beyond Vd for the Boeing 767, and we'll do it in full 5 knot increments , which is fair, since we're already at and beginning to exceed the threshold limit for structural failure, Vd limit, and even the smallest increments at that point can have grave effects, as the flight testers experienced with the Airbus A320 in the video contained in that link above i.



420 (Vd limit, by stress/flutter testing)

425 (which is .99 - Mach 1.0 equivalent airspeed and pressure at higher altitude of 22,000 feet - which is about the threshold from all those examples of near or just over Mach flight, while surviving, and this is very conservative, because such dives are mostly done from much higher altitudes as per your DC-8 ref cited above in which case an EAS of 425 represents an even higher Mach # up around 35,000 - 52,000 ft, well exceeding Mach 1.0 ++)



430, 435, 440, 445, 450, 455, 460, 465, 470, 475, 480, 485, 490, 495, 500, 505, 510 knots + (including windspeed, 515)

edit on 10-1-2014 by SkepticOverlord because: modified opening post when moving to the hoax forum



edit on 10-1-2014 by SkepticOverlord because: (no reason given)



ADMIN NOTICE:It has been confirmed in this post on page 27 of the thread , that a critical data point used for the premise in the opening post has been falsified by whomever created the material (not necessarily the fault of the thread author). As a result, due to what clearly appears to be intentional deception, the thread is now in the hoax forum.The South Tower PlaneFlight 175, a Boeing 767-222, registration number N612UA.The following is physical evidence, that the south tower plane was not and could not possibly have been the originating flight 175, anUnited Airlines Boeing 767-222, simply because it was seen and recorded as flying, and maneuvering deftly, at a speed of 510 knots at 700 ft. altitude (sea level), which represents an over-Mach EAS (equivalent airspeed) at high altitude where the air is thinner and less dense by about 2/3rds at 30,000 ft. - let alone under the control of a pilot no better by comparison than the likes of Hani Hanjour who allegedly piloted the Pentagon airplane whom the 9/11 Commission considered the most trained and "skilled" of the would-be Boeing pilots, in this case without any actual flight time in the real macoy.It too, like the building's destruction, would violate the laws of physics if the offifical story is to be believed and accepted, which cannot be believed in light of the simple truth that it was and must have been based on all observable phnomenon, an elaborate, highly sophistacated and complex HOAX, which cannot be believed in the face of a rational and objective, scientific scrutiny, of the events themselves as they actually occurred in reality. Physical evidence. Irrefutable, and incontrovertible facts in evidence, which cannot be denied nor overlooked.-------------------------------I've already proven it. And we'll do a comparison yet between your DC-8,16 second Mach dive at high altitude example, both in relation to it's Vd limit, and as it compares to the STP (south tower plane), as well as numerous other precedents of near Mach flight by 767's and similar aircraft, but they're all at high altitude, often much higher than 22,000 feet, which is a relatively low and conservative point comparison considering that most if not all the examples are at altitude - and what they PROVE is that such aircraft are not made to exceed the sound barrier, which carries with it it's own transonic effects still further placing any such airplane when it reaches or exceedes the Mach 1.0 threshold in grave jeapardy. Again, all those examples of near Mach 1 filght are at altitude, often exceeding 22,000 feet.Therefore any equivalent airspeed, where the air it 2/3rd's thicker than at 30,000 feet, which represents a corresponding airspeed exceeding Mach 1.0, at altititude reveals that within the margin by which the plane exceeded this threshold, I've proven the case, because it's too great, the margin, too far beyond the established Vd or max structural speed, beyond which, by only five knots, and we're at an equivalent airspeed at the Mach .99 - 1.0 threshold, already, at 425 knots EAS at sea level.To put this into perspective in regards to the airspeed magnitude by which the south tower plane is/was observed exceeding the Vd limit as set by first wind tunnel then flight testing, just like with the Airbus380..EAS:EAS is sea level airspeed. As a factoral expression of the equivalent dynamic pressures on an airframe at low vs. high altitude, because the air is so much thicker at sea level, there is an airspeed appropriately titled "Equivalent Airspeed" or EAS.The air is thinner at higher altitudes so the aircraft will need to go faster to match the amount of air hitting the airframe at low altitudes, in thick air.EAS is defined as:EAS is the airspeed at sea level which produces the same dynamic pressure acting on the airframe as a True Airspeed at higher altitudes. It is used for determining aircraft performance, structural integrity.. .etc. The Vd limit is expressed in an EAS. In other words, to be more specific, 510 knots at sea level (EAS) would produce the same dynamic pressure as 722 knots True Airspeed (TAS) at 22,000 feet.