Questions about the aircraft used on 9/11/01

I didn't watch the video, as I try to avoid conspiracy type theory stuff. However aircraft are built with substantial margin of safety over their published limits. This is particularly true when you are only talking about one time flights. The aircraft would be designed to withstand loads 1.5 times greater than its design limits. In addition beyond that the design is still very conservative as it has to account for an entire fleet of aircraft and the inherent scatter in assembly, tolerances, materials and such that go along with that. Beyond that many parts will have substantially more capability due to the difficulty of analyzing everything perfectly. Finally the loads experienced under VMO are unlikely to be the design driver for most components. All this adds a huge amount of capability to the planes beyond what they are designed for and is one of the reasons why flying is extremely safe.

 

I honestly don't know how fast they were going, but flying above Vmo is not going to cause structural failure. In fact, as part of certification they are required to go, I think, 10% past Vmo and nothing bad should happen. Now, banking and pulling Gs at those speeds can cause issues, but just going too fast shouldn't cause a big problem. And even going way too fast is likely to result only in the loss of gear doors, or some fairings, or something like that, and I can't imagine those guys were too worried about it.

EDIT: I did a quick bit of google research, and in flight test they actually go substantially beyond 10% past Vmo.

 

Is that John Lear on the video? I'm not planning on watching it either.

 

That claim has been thoroughly debunked, which you can find if you do a reasonable internet search.

 

What would you expect to happen at that speed if going in a straight line like it did? It's not like it was doing barrel rolls and turning like a fighter....

 

Stuff probably did fall off! So what?

Flying faster than Vmo doesn't require Chuck Yeager skills... you need to be careful not to over-stress the airplane by pulling too many Gs, although if you don't really care about keeping it in one piece, even that isn't all that important.

 

Warning:
Tread lightly and try to stay on topic, threads like these can easily devolve into political barking, so let's try not to wake up the ban hammer, alright?

As for the video and topic at hand, I find it very interesting. I will take my speculative statements to P&R tho

 

The PAA 707 Gander incident illustrated the "failure cushion" in the airframe structure when the airplane was pulled out of a 24,000 ft descent that exceeded Mach 1. The wings reached the yield point and they were permanently "bent" from the pullout. I think that I remember 1 deg of additional dihedral. Amazingly, there were no fuel leaks but the wing to body fairings were compressed to the point where they failed and departed the airplane. Many small access panels blew off. The horizontal stabilizer had to be replaced and when everything else had been inspected and repaired, the airplane was put back into service.

 

Flew for another 25+ years, for several carriers.

Did they fix the dihedral? Ha...

 

Boeing builds a tuff airplane. Image Unavailable, Please Login

 

I saw those two aileron rolls that day and if you place a straightedge along the leading edge in the photo you can detect a slight curvature that indicates a positive load. Just like the Bob Hoover thing of pouring a cup of tea while inverted. The -80 flight engineer said that if your eyes were closed, you would have never known that you were in a roll. 1G all the way around.