J-20 5th Gen Fighter Thread IV (Closed to posting)
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That's the most likely scenario, 2003 as a test mule for weapons, as it likely is the first aircraft with all the systems basically in place, it is typical for early prototypes to be airframe and power-plant centric. That renumbering theory is non-sense, I'm sure that has been done in Soviet Russia, Possibly in China before, but its only purpose would be to inflate your actual capability to fool your own populace, as your potential adversaries are not likely to be fooled, it would only serve to make you look foolish and delusional, something that would be likely in NK??? brat
Well we know they'll still change the engines of the aircraft, but a big question mark still sits over the matter of ventral fins.
And weapons testing wouldn't necessarily entail anything regarding the structure of the rest of the aircraft...
Engineer
Major
The ventral fins will most likely stay. They are an integral part of the aircraft's aerodynamics.
TerraN_EmpirE
Tyrant King
You don't make those kinda change's this late in the program. If the Chinese wanted a tailless fighter j20 or 21 would have been rolled out that way. More likely changes may be avionics based, electo optics, radar changes to radar and the like if there are major changes planed like when YF22 became F22 you would see those in a new bird.
MiG-29
Banned Idiot
The area of vertical stabilators either ventral or dorsal fins is fixed, ventral fins are fit to reduce the size of dorsal vertical fins, you delete the ventral fins, then you need to increase the size of the dorsal vertical fins, only way to reduce them is with redesign of the aircraft it self aerodynamically or fit TVC nozzles.
(the advantage of ventral fins is they experience less turbulence at high AoA by not being blanketed by the forward fuselage)
Other solution is reduce the performance in terms of speed and AoA, something which is unlikely
The aircraft is just testing internal stuff.
The MiG-29 had ventral fins these were deleted but but Mikoyan added extensions to the dorsal vertical fins, Sukhoi in T-10 added ventral fins in T-10S aka Series Su-27 they were added to increase AoA, MiG-25 also increased vertical tail area from the first prototypes but deleted the wintip vertical stabilators.
Tu-160 even uses the wing to make additional vertical tail area when the wing is fully swept.
So those aerodynamic changes are not as easy to delete as people think
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The ventral fins of the J-20 were added to increase directional stability and eliminate roll-off at high angles of attack, the same reason they were added to the Su-27, they increase directional stability by virtue of "flying in relatively clean, high pressure airflow". The disadvantage of Lev-cons, vortex generators etc is that they increase turbulence in the low pressure area on top of the wing/fuselage, increasing buffeting and reducing directional stability. brat
Maggern
Junior Member
Mobile surfer, ey
? Well, for those of us that are using a computer, here is non-mobile version:
MiG-29
Banned Idiot
Is not that exactly, if you remove the canards on J-20, you will still have flow separation by virtue of high AoA, the fore body will still generate vortices and the wing it self will have flow separation, the problem is the flow stops flowing parallel to the flight path thus it creates turbulence and you can see that on a Mirage III or F-106, here is where LEVCONs and even canards and LERX help by re-attaching the flow to the wing.
Where the vortices burst can generate buffeting but having two dorsal fins add stability by symmetric vortex burst, F-18 was prone to have structural failure due to buffeting however LEVCONs are a step ahead of LERX by adding control to the vortex and increasing lift and as such moving the vortex burst farther back.
Drag and structural strength play another part in ventral fins, you can see it on the SR-71 that basically flies straight at low AoA but uses ventral fins to reduce drag or structural strength on ERJ-145 AWACS and A-50 AWACS (Indian and Chinese versions ) both added ventral fins without increasing vertical tail area on their original designs.
Wing rock or any roll instability also is dealt with flattening the nose radome as in X-31 or S-37 Berkut.
J-20 uses chines which will help for lateral stability
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