Originally Posted by
pontifex
Static and dynamic sidslips are different breeds of the same animal; one can be quantified and measures taken to limit it, the other one cannot be quantified and, thus, cannot be protected against. Having said that I recon it is not beyond some clever software engineer to devise a means of doing so on a fully FBW aircraft.
Originally Posted by
arcniz
With a couple or three accelerometers and a teensy bit of power, a sensor unit the size of a cigarette package in the tail area could provide all the measuring needed, and a similar-size box up forward with access to an airspeed data signal would be able to provide numeric data for the logs and an actuation signal for panel or EFIS display advising caution or emergency status re dynamic sideslip. Log data from same would be useful for assessing cumulative airframe & tail stress history. Cheap (in aviation terms), easy enough to make and retrofit. No FBW and no rocket science required. How many would you like?
If what you’re describing is something akin to FDR information – you bet! However, and again, without meaning to sound overly critical, I’m not sure that putting additional displays “…advising caution or emergency status regarding dynamic sideslip…” is something that would be valuable to the crew. You can see, from the animation provided, it was a maximum of 9 seconds between the first indication of the last turbulence encounter to the point where something major occurred – causing loss of some or all of the data feed – like the loss of the vertical tail. Nine seconds! Even if the data sensors read, computed, and displayed whatever data might be appropriate in less than a second, such a system would still require some data-trace history on which to base its computations (and the technical folks would have to tell us what that time requirement would be), the crew would have to notice, read, interpret, and respond (and respond correctly) to that notification in something considerably less than 8 seconds. Also, I would think there would have to be a pretty standard control application strategy developed (and likely practiced) that could be applied in such a circumstance or it is likely that the “interpret/respond” portion of that strategy would be significantly longer. And with any delay, the likelihood of experiencing a similar structural failure would go up at an alarmingly quick rate.
I recognize that the A-300 has a particularly different rudder and rudder pedal deflection relationship from other, large transport category airplanes. Is this what needs to be examined? I think that a simple reading of the aircraft certification requirements in a ground school class would be most enlightening as well. Also, examining aerodynamic controls during initial flight training and revisiting this area during recurrent flight training is important in
all airplanes; and I keep coming back to the reason that a controllable rudder is on the airplane in the first place – that being to keep the airplane in a “coordinated” flight condition. Roll control spoilers have been around for a long time … perhaps to the extent that newer (read, “younger”) pilots have not had the opportunity to fly the airplanes they fly without that particular addition – which, as most of you know, handsomely reduces the necessity for pilot application of rudder to maintain that “coordinated” flight condition under
most circumstances. When you get into a lateral/directional PIO – which isn’t taught in very many (if any) airline training programs – I believe the existence of roll control spoilers may well
complicate the understanding of what is happening and what should be done to escape from that PIO. Knowing the problem and knowing what to do about either eliminating the problem or extracting oneself from having encountered the problem are not necessarily the same things.