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reply to post by JuniorDisco
Please feel free to come up with just one example of a similar type aircraft exceeding an airspeed of 430kts/1.01M, even in an uncontrolled dive, which did not experience structural failure.
while the plane was cruising at 39,000 feet (11,887 m) and Mach 0.816, it began a sharp roll to the right. The roll continued despite the corrective measures taken by the autopilot and the human pilot. The aircraft went into a spiral dive, losing about 34,000 feet (10,363 m) in 63 seconds. During the course of the dive, the plane rolled through 360 degrees twice, and crossed the Mach limit for the 727 airframe. Control was regained at about 5,000 feet (1,524 m) after the first officer, with the captain in agreement, extended the landing gear in an attempt to slow the aircraft, and following the loss of the #7 slat from right wing. The plane suffered substantial structural damage, but made an emergency landing at Detroit Metropolitan Airport, Michigan, at 10:31 p. m. local time without further trouble.
As the plane descended through clouds, the captain's attention was drawn to the artificial horizon which displayed excessive bank and pitch. Because such an attitude is highly irregular, the crew incorrectly assumed the indicators to be faulty. Without any visual references (due to the clouds) and having rejected the information from the ADIs, the crew became spatially disoriented. The plane entered a steep dive at a high bank angle. Altitude decreased 10,000 ft (3,000 m) within only 20 seconds, a vertical descent averaging 30,000 feet per minute (150 m/s). The crew and passengers experienced g-forces reaching as much as 5g.
Learning there were injured people on board, an emergency was declared and they flew straight in to the airport and landed without further incident.
ULTIMATE STRUCTURAL LIMITS
These define the ultimate operating strength limits of the aircraft. Flight operations beyond the ultimate structural limits will result in structural failure of some component of the aircraft. It should be noted that the ultimate structural limits are outside the normal operating envelope of the aircraft. The usual aircraft design rule is for the ultimate structural limit to be 150% of the structural limit. However, this may not be strictly true since the structural limits may reflect aircraft lifetime concerns while the ultimate structural limits do not.
National Transportation Safety Board: China Airlines Boeing 747-SP Accident Report
"Although the captain said that the airplane exceeded Vmo twice and also decelerated below 100 KIAS during the dive, all three crew members said that they did not hear the overspeed warning and that the stall warning stickshaker did not activate. Examination of the reliable recorded airspeed data points showed that the Vmo limitation was not exceeded during the descent. However, the recorder data does show airspeeds at or below 100 KIAS. The Safety Board cannot explain why the stall warning stickshaker did not activate, or if it did activate, why it was not felt or heard by the flightcrew."
Re: 727-191 Vmo/Mmo
The following from Frontier Airlines 727-191 data:
MAXIMUM OPERATING SPEED – VMO/MMO
35,000’ - 310 KIAS .90 MACH
30,000’ - 345 KIAS .90 MACH
25,000’ - 383 KIAS .90 MACH
20,000’ - 409 KIAS
15,000’ - 403 KIAS
10,000’ - 398 KIAS
S.O, with all due respect, these precedents have already been covered in this thread,
reply to post by NewAgeMan
No one hates you its just been pointed out over and over your wrong and you refuse to see it. Here ill try another way so you can understand the difference between a dive and level flight.
I want you to watch a video used for training pilots on the P51 what they are doing is specifically taking the craft over its design limits to show the pilots how to solve the problems that occur. There is a dive at 16:50 if you dont want to watch the whole thing. But it is very neat film so its worth watching but more to the point they purposely exceed the limits of the aircraft and the pilot teaches them what to do.
Thanks for the important information.
Wow...I didn't realise the membership of P4T consisted of so many highly qualified and respectable professionals..
Who's opinion am I more likely to trust...a group of highly experienced aviation experts with collectively tens of thousands of hours of on-the-job first hand knowledge?...or a pack of wannabe debunker internet posters who add nothing to the discussion but mockery, derailment, and bullying?
Sec. 25.1505 Maximum operating limit speed.
The maximum operating limit speed (VMO/MMO airspeed or Mach Number, whichever is critical at a particular altitude) is a speed that may not be deliberately exceeded in any regime of flight (climb, cruise, or descent), unless a higher speed is authorized for flight test or pilot training operations. VMO/MMO must be established so that it is not greater than the design cruising speed VC and so that it is sufficiently below VD/MD or VDF/ MDF, to make it highly improbable that the latter speeds will be inadvertently exceeded in operations. The speed margin between VMO/MMO and VD/MD or VDFM/DF may not be less than that determined under Sec. 25.335(b) or found necessary during the flight tests conducted under Sec. 25.253.
[Amdt. 25-23, 35 FR 5680, Apr. 8, 1970]
Vd is another type of limit altogether... where they push the plane to the very edge of the flight envelope just before or right at the onset of flutter, which is the point where the airframe and wings start to wobble in strange ways and things start to rip off the airframe and the plane begins to experience structural failure.
The FAA establishes two kinds of load conditions:
Limit Loads are the maximum loads expected in service. FAR Part 25 (and most other regulations) specifies that there be no permanent deformation of the structure at limit load.
Ultimate loads are defined as the limit loads times a safety factor. In Part 25 the safety factor is specified as 1.5. For some research or military aircraft the safety factor is as low as 1.20, while composite sailplane manufacturers may use 1.75. The structure must be able to withstand the ultimate load for at least 3 seconds without failure.
reply to post by NewAgeMan
i read flutter is a function of TAS.. makes sense why an aircraft would be CAS limited at low altitudes and Mach limited at higher altitudes..
i cant confirm if its true though but is critical flutter speed roughly at a constant TAS for all altitudes?
So, dearest reader, consider that those who believe a standard, unmodified Boeing 767 can fly at 510 knots near sea level and remain stable/controllable, MUST also accept that the same airplane can fly in a controlled fashion, even in a dive,
- at 722 knots at 22,000 feet... or Mach 1.19, and 915 knots at 35,000 feet...or Mach 1.38 heading for 1.39 at 38,000 ft.