J-20... The New Generation Fighter III

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AssassinsMace

AssassinsMace

Lieutenant General
This PS would be an interesting look.

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P

paintgun

Senior Member
^J-20's sexiest angle so far

can someone explain if the upper body surface right beside the canards and above the intakes generates lift? part of the overall lift or itself a lift device?
 
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D

delft

Brigadier
paintgun said:
^J-20's sexiest angle so far

can someone explain if the upper body surface right beside the canards and above the intakes generates lift? part of the overall lift or itself a lift device?
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Body lift is important to this aircraft. Subsonic aircraft have less induced drag with a wide wing span. Look at the wings of airliners. Supersonic aircraft reduce their wave drag if the lift is generated over a greater length of the aircraft. The whole of the upper and lower surfaces of the fuselage contribute to the lift. Induced drag is of much less importance.
 
Engineer

Engineer

Major
Quickie said:
If the FBW were to actually counteract the undulating movement, instead of letting it be, the aerodynamic drag would be increased considerably.
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The FBW isn't actually counteracting movement caused by the uneven runway. It is counteracting what it thinks is aerodynamic distrubance in flight.

Quickie said:
I saw the wild flipping of the control surfaces in only one of the many videos of J-20 taking off and I presumed it was part of the scheduled testings in the particular flight test.
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If you are referring to the movement of control surfaces while the aircraft is stationary on the tarmac, then yes, those are likely scheduled testings.
 
Quickie

Quickie

Colonel
Engineer said:
The FBW isn't actually counteracting movement caused by the uneven runway. It is counteracting what it thinks is aerodynamic distrubance in flight.
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The FBW has to know that the aircraft is taking off so that the lift of the aircraft can be maintained at the optimum value for take off, irrespective of the other forces caused by the undulating surface. The undulating forces will be gone by itself once the aircraft starts to leave the ground.

Engineer said:
If you are referring to the movement of control surfaces while the aircraft is stationary on the tarmac, then yes, those are likely scheduled testings.
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That was during takeoff for a number of seconds from the start position. I seem to remember all the control surfaces, excluding the canards, was moving at that moment. It could also be due to a particular takeoff condition on that day e.g. sudden cross wind, but this is inconsistent with the stabilizers moving intoe and outtoe repeatedly which I seem to remember. Can't remember where I saw that video.
 
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