Shenyang FC-31 / J-31 Fighter Demonstrator

wtlh

wtlh

Junior Member
Air Force Brat said:
I had never noticed that, it is odd that we never see the brakes deployed, on the J-20 nor the J-31, if you watch F-15s they will be deployed on almost every approach??? I would imagine that on most applications you might possibly pick up an "aerodynamic rumble" or burble on deployment. Its obvious that the "drag chute " is "way Kooler", but can only be deployed after touchdown, while the speed brake deployed on approach, gives you the option of "spooling up" the engines and carrying a little more power. So the question is, do they just not like to use the brake and prefer the chute, or does the brake induce some type of aerodynamic pitch oscillation or some other unpleasant side effect? (always possible when you deploy a large surface that it may have some negative affect?)

On the F-15 the brake seemed to stabilize and help manage the approach, so I have wondered, particularly with the J-20 why it wasn't deployed as a matter of course??? On of the supposed advantages of placement behind the cockpit was some very productive drag on approach without significant trim changes?

I have usually limited my flap deployment on the Cessna 150 and 172 to 10-20 degrees on the approaches and landings that I fly these days as the 30-40 degree positions do cause a most unpleasant rumble as they disrupt airflow over the horizontal stabilizer and elevator, and they greatly increase the amount of aft stick necessary for a "clean flare" as you arrest your decent and can create problems in a crosswind landing or even a go around, as you must get the flaps up to 20 degrees to get a decent climb rate on a go around. In fact Cessna limited flap travel on the 152 a redesign of the 150 to 30 degrees for the reasons listed.
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I think that J-20 breaks with the tail fin? And if so, it would be difficult to notice just from the photos.

Also I think the most pictures we see are that from takeoff or when the chute has already being deployed.
 
wtlh

wtlh

Junior Member
Air Force Brat said:
take a chill pill janjak, reading this gave me a headache dude???? WHUT R U talkin about man??? and then rewrite your sentence in a clear, concise statement, remember, its called "communication" meaning we both need to understand what your saying???? and yes, I am a teacher!
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Probably copy and pasted from some automatic translator like google translate?

I don't have much clue either, but I guess from the various words, he is meaning that:

"it is better to have separate and parallel developments and complete commercial-esk competitions (cf LM vs Boeing) than the current all-under-one-roof, share project, technology and personal model."

???
 
Deino

Deino

Lieutenant General
Staff member
Super Moderator
Registered Member
:eek: :eek: :eek: :eek:
 

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Deino

Deino

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... two more ... :p:p
 

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plawolf

plawolf

Lieutenant General
I think the big air brake on the J20 got deleted after the first blk of prototypes.

I wonder if they will do the same for the J31?

The reason we seldomly saw the air break used on the J20 and J31 is probably FBW software related, as you would not want that thing popping up much if at all in war mode or else it will ruin your stealth. That is probably why the J20 ditched its airbreak.
 
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