A short article translation from ifeng. There is a video with the linked post.
Chengdu Aircraft Institute flight control system expert Li Jianping revealed for the first time that one of the prototype J-20's wing tip slightly grazed the ground during landing process. (he didn't say when or which J-20 airframe specifically) He says it was a little scary but the jet landed successfully. The cause was due to a relatively rare phenomenon called pilot-induced oscillation or aircraft-pilot coupling, and they've since came up with several new innovative optimization measures to greatly eliminates the risk of future flights.( Is that the reason why we don't see 2016?
)
The article also mention the other Chinese stealth fighter(J-31) had some problem with landing takeoff and resulting in missed opportunities to demonstrate in front of the top leader of the People's Liberation Army. And military experts noted that pilot-induced oscillation is the invisible killer for modern aircraft and the main reason for the landing accidents other than mechanical malfunctions. Both prototype of JAS-39 and F-22 crash were due to pilot-induced oscillation.
I don't know what is the meaning of Pilot induced oscillation. So, I lookup wikipedia.
Chengdu Aircraft Institute flight control system expert Li Jianping revealed for the first time that one of the prototype J-20's wing tip slightly grazed the ground during landing process. (he didn't say when or which J-20 airframe specifically) He says it was a little scary but the jet landed successfully. The cause was due to a relatively rare phenomenon called pilot-induced oscillation or aircraft-pilot coupling, and they've since came up with several new innovative optimization measures to greatly eliminates the risk of future flights.( Is that the reason why we don't see 2016?
)
The article also mention the other Chinese stealth fighter(J-31) had some problem with landing takeoff and resulting in missed opportunities to demonstrate in front of the top leader of the People's Liberation Army. And military experts noted that pilot-induced oscillation is the invisible killer for modern aircraft and the main reason for the landing accidents other than mechanical malfunctions. Both prototype of JAS-39 and F-22 crash were due to pilot-induced oscillation.
I don't know what is the meaning of Pilot induced oscillation. So, I lookup wikipedia.
Pilot-induced oscillations, as defined by MIL-HDBK-1797A,[1] are sustained or uncontrollable oscillations resulting from efforts of the pilot to control the aircraft and occurs when the pilot of an aircraft inadvertently commands an often increasing series of corrections in opposite directions, each an attempt to cover the aircraft's reaction to the previous input with an overcorrection in the opposite direction. An aircraft in such a condition can appear to be "porpoising" switching between upward and downward directions. As such it is a coupling of the frequency of the pilot's inputs and the aircraft's own frequency.
duced_oscillation[/URL]
Pilot-induced oscillations, as defined by MIL-HDBK-1797A,[1] are sustained or uncontrollable oscillations resulting from efforts of the pilot to control the aircraft and occurs when the pilot of an aircraft inadvertently commands an often increasing series of corrections in opposite directions, each an attempt to cover the aircraft's reaction to the previous input with an overcorrection in the opposite direction. An aircraft in such a condition can appear to be "porpoising" switching between upward and downward directions. As such it is a coupling of the frequency of the pilot's inputs and the aircraft's own frequency.
