Perhaps some of you old timers can tell me if my thinking is correct in this regard. I have a picture in my mind of the old time design and manufacturing process. It had its limitations and one of these in the matter of stress and strain was estimates.
The old boys built em good! There was always a little bit more than required in each part and collectively those additions made for a very strong airframe. My company operated the BAC-111 until the 90's. We had DC-9's until 2002 and they were all designed "hell for stout" and stood up very well but they were very heavy airframes. The old joke was if you drove an tug into a parked BAC-111, you broke the tug. The old Douglas Direct Cable and Airplane Company came in a close second.
By way of an example, TWA Flight 841,On April 4, 1979, at or around 9:48 p.m. Eastern Standard Time (01:48 UTC), while flying over
Saginaw,
Michigan, the
Boeing 727-31 airliner began a sharp, uncommanded
roll to the right, and subsequently went into a
spiral dive. Pilots were able to regain control of the aircraft and made a successful emergency landing at
Detroit Metropolitan Airpor Despite the best efforts of the flight crew, the aircraft spiraled out of control, diving about 34,000 feet (10,000 m) in just 63 seconds.
[1]:2 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 (1,500 m) after the pilots extended the
landing gear in an attempt to slow the aircraft
[3][4] The plane suffered substantial structural damage, but made an emergency landing at
Detroit Metropolitan Airport in Michigan at 10:31 p. m.
EST without further trouble. No fatalities occurred among the 82 passengers and seven crew members. Eight passengers reported minor injuries related to high
G forces. https://en.wikipedia.org/wiki/TWA_Flight_841_(1979)
Considering that CAD/CAM now makes airframes much lighter and that computer aided design makes limits a better known quantity, would an A320 hold up as well in the above scenario? Is there as much buffer in the newer airframes.