Shenyang next gen combat aircraft thread

taxiya

Brigadier
Registered Member
Regarding the groove at the central line of fuselage bottom. I guess may be because the air inlet is thin sidewise thus it has to be longer from top to bottom. And the bottom of the air inlet is lower than the (central fuselage) thus the groove. This is prominent on the Flankers but not on J20 and J36, probably due to the size of air inlet of J20 and J36.

As to why they don't design all flat bottom fuselage, my guess is a fully flat bottom for J-XD(S) may produce more drag, and may be less stealth on front view?

Just my two cent. Feel free to comment.

Below diagram of F-18E/F is just for illustration only.
View attachment 150313View attachment 150314
I have a very strong feeling that it is due to aerodynamic reasons especially related to the intake being "two inlets with single bump" and demand of inlet tip covering the bump at a specific distance. Also the groove would have great impact to the deeper groove between engines.

Remember the tiny change of LERX from J-20 200x to 201x? It was so tiny in size but so big to the vertox on the wings. A tiny groove may be shallow in depth but may have a great impact in aerodynamic performance.
 
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