As I understand it, like the 707 roll in the 50s (that footage does kick ass, BTW) Any plane is capable of the barrel roll if done correctly.
IIRC another 707 crashed when a pilot attempted a barrel roll during a test flight - hence the reason they're generally not encouraged. I have read this accident report but am not sure where to locate it now (probably somewhere around here: http://amelia.db.erau.edu/ec/ntsbaar.htm#67
") - apparently there was not enough evidence to definitively point to a barrel roll but it was obvious reading the report that that was what the investigators believed.
I'll keep searching for this report and if I find it I'll post a direct link...
However, on modern planes w/ computerized flight controls, doesn't the software prevent excessive angles of bank, etc, which would make the roll impossible, not for the airframe, but the operator?
On some modern planes, yeah. Depends on what you mean by "modern", though, too - some airplanes have bank angle warnings but no bank limiter. You won't find a bank limiter in a DC-9-50 flying with Northwest today, for example.
Airliners are designed to be inherently stable, though, which means if you invert one it will pitch down (or up, depending on your perspective) pretty rapidly and in some cases uncontrollably. This has happened many times in accidents where the equivalent of a barrel roll was performed in an uncommanded manner - the airplane may have been saved if only there was more altitude to play with, but it's nearly impossible to come out of a barrel roll at anywhere close to the same altitude you went into it with in almost any airliner I could think of. So generally once you get beyond a 90 degree bank angle it becomes practically impossible to either keep the nose up or even maintain altitude if you do - "flying upside down" is futile because the wings aren't shaped to generate lift in that orientation.
The stress of a barrel roll itself wouldn't kill an airframe but the stress of the airspeed you'd gain in the resulting dive, combined with the stress on the control surfaces required to keep a positive attitude would probably at least do some significant damage. The few examples I can think of where airplanes have entered rolls uncommanded and lived to tell about it (China Air off the California coast a while back, for example) have all resulted in major damage to the airplane.
In other words, airlines can
roll, but it's not really something you want to do in any modern plane
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