Max Test flight Mach Number for the 737NG!
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Actually, an A320 can fly easily at M0.84-0.85, it still won't be very dangerous
Some airlines will conduct their own "test flights" and test some features of the flight control laws.
Here is how someone can know if a speed is acceptable.
Here is how someone can know if a speed is acceptable.
China airlines B747 did a barrel role and yet everyone survived it doesn't mean it can easily be done.
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If I recall correctly, that airplane was repaired and returned to service. I'm pretty sure it wasn't cheap to repair the extensive structural damage done during the high speed dive and pullout. A 5 gee pull in a 747 is impressive indeed, even if it did cause the loss of nearly half of the HS and elevator surface. Don't try this at home kids!
Last edited by vilas; 28th Oct 2016 at 16:43.
A 5 gee pull in a 747 is impressive indeed, even if it did cause the loss of nearly half of the HS and elevator surface.
Vilas, my memory is the same as westhawk - it returned to service. According to Wiki:
After repairs were made to the plane, it returned to service on April 25, 1985. It continued in service for nearly 12 years until it was leased to China Airlines' sister company, Mandarin Airlines, on January 1, 1997, and was in daily service for the remainder of that year.[citation needed] Mandarin then sent it to McCarran International Airport for storage.[citation needed] From April 2002 it was owned and operated by a religious organization known as Gospel to the Unreached Millions (GUM), headed by K. A. Paul, and was christened 'Global Peace One'. On July 17, 2005 the FAA suspended its operating certificate due to insufficient maintenance.[citation needed] As of May 20, 2010[update], the aircraft is kept in a large hangar at General Abelardo L. Rodríguez International Airport in Tijuana, Baja California, and is reported to be in very poor condition.
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More to loads than just speed
When an airplane is certified to a particular speed it is not only tested by going that fast in a calm air, 1 g maneuver. Demonstrations for Vmo also include maneuvering to limit load factor of 2.5 g pull-up and -1g push over when at those speeds. As you would imagine, the loads associated with these maneuvers are significantly higher than those for 1g flight at slightly higher speeds.
On the topic of the China Air 747, it was the 5 g pullout that bent the airplane. A well executed barrel role by itself will not take an airplane beyond its design load capability as load factor should not exceed 2.5g.
Commercial airplane flight tests are so heavily instrumented with data being recorded all the time that it is hard to imagine a test pilot getting away with an unauthorized barrel role today. In the past, however, I have heard rumors that pilots have performed barrel rolls with most models some time during flight testing. Tex Johnson in the 707 over Lake Washington during SeaFair was a little more public than most!
On the topic of the China Air 747, it was the 5 g pullout that bent the airplane. A well executed barrel role by itself will not take an airplane beyond its design load capability as load factor should not exceed 2.5g.
Commercial airplane flight tests are so heavily instrumented with data being recorded all the time that it is hard to imagine a test pilot getting away with an unauthorized barrel role today. In the past, however, I have heard rumors that pilots have performed barrel rolls with most models some time during flight testing. Tex Johnson in the 707 over Lake Washington during SeaFair was a little more public than most!
the debris from the gear doors is what damaged the tail.
In the NTSB accident report it's also noted that the wings had a permanent "set" of 2 or 3 inches upward at the tips following the incident, still within Boeing tolerances for the type. And the APU broke loose from it's mounts. Any way you look at it, it's an amazing testament to the structural engineering of the 747 that it was able to tolerate such abuse without failing catastrophically.
It was calculated that the indicated airspeed of one of the 767's that hit
the WTC was over 460 Knots, the old girl stayed together as long as she could..
the WTC was over 460 Knots, the old girl stayed together as long as she could..
The maximum demonstrated dive speed will be less than the speed at which any of these effects become excessive. All on an airplane which has not yet been subjected to the rigorous daily abuse associated with years of line flying and the minimal maintenance attention many airliners have to live with in the real world.
Just as a thought experiment, I wonder how a typical certification test pilot would react to the idea of being assigned to dive test a typical 737 with 20,000 typical airline cycles on it.
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Most if not all of the damage to the horizontal tail was not due to aerodynamic forces. The landing gear uplocks failed and the gear deployed through the landing gear doors during the pullout - the debris from the gear doors is what damaged the tail.
Vilas, my memory is the same as westhawk - it returned to service. According to Wiki:
Vilas, my memory is the same as westhawk - it returned to service. According to Wiki:
I'm sure there are exceptions, but as a general rule (at least for subsonic aircraft) max airspeed is limited by dynamic pressure, while max Mach is limited by controllability issues primarily related to supersonic flow over the control surfaces.
