J-20 5th Gen Fighter Thread V

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Deino

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I hope your heart can sustain a fair amount of these near heart attacks ;)


Me to ... but I will take a longer break from tomorrow evening on when we leave for the summer-holydays in France (close to Nantes and Les Sables-d’Olonne on the Atlantic for one week and the two more at Perpignan at the Mediterranean) ... so nearly three weeks without the PS (I promised my wife) and a lot of time to relax.

As such I need You all my friend to save each and every single new image ....
Deino
 

delft

Brigadier
Me to ... but I will take a longer break from tomorrow evening on when we leave for the summer-holydays in France (close to Nantes and Les Sables-d’Olonne on the Atlantic for one week and the two more at Perpignan at the Mediterranean) ... so nearly three weeks without the PS (I promised my wife) and a lot of time to relax.

As such I need You all my friend to save each and every single new image ....
Deino
Have a nice holiday and we will look for 2016.
 

Deino

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Due to being most likely NOT a J-20 or J-31 and even more being most likely a Flanker only ... I moved all posts to the Flanker tread.

Deino
 

JayBird

Junior Member
A short article translation from ifeng. There is a video with the linked post.
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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. :p

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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.
 

kriss

Junior Member
Registered Member
Interesting, it's the first time I know the term of this. This is the major cause of most of my crash when I started to play lock on. During landing or in flight, sometimes even during taking off.
 

delft

Brigadier
A short article translation from ifeng. There is a video with the linked post.
Please, Log in or Register to view URLs content!


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. :p

Please, Log in or Register to view URLs content!
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. :p

Please, Log in or Register to view URLs content!


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.
As the wiki implies this first appeared about half a century ago in the lifting body tests. At that time the connection of the pilot to the control surfaces was still mostly mechanical and correcting it was pretty difficult. With modern flying control systems it is a matter of accurately modelling the flow around the aircraft dynamically, i.e. how will the flow change as control surfaces are being deflected and then combine a software program between the pilot and the flight simulator to see under what circumstances trouble ensues and adapting the software. This is mostly successful but sometimes ...
 
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