why Northrop YF 23's diamond wing design has been quite a rare choice? Eventhough it may have quite an old background (1950s) like Northrop N-65 (guess Northrop had some long standing obsession with diamond wing designs
)..... and somehow reapearing in diffrent forms in some 6. gen ?? and does this diamomd wing fall under trapezoidal wings catagory which seems quite an inclusive & overarching catagory?
@Nilgiri @Yasar_TR
There are pros and cons to all (functional) wing designs. It depends on the main design drivers and compromises/balances of factors and issues.
It is easier to explain with diagram I made just now and using the extreme cases of backward and forward sweep at each end and then look at YF-23 vs F-22 in the gooey grey middle (they are quite close in the end, but YF-23 is a perfect diamond i.e a few %'s closer to a Forward Sweep):
i.e lets keep as much the same as possible and simplify a few things (wing areas, CofG being well forward so moment directions are always the same and produce stability with Angle of Attack aka AoA etc)
The taper (that makes the triangle/delta a trapezoid) pushes the center of lift line inwards to begin with (than if it was a triangle which already moved centroid to 1/3 of length than a rectangle wing with 1/2 etc). But this happens for all of them the exact same way.
A) What does change between them is the range of possible Center of Lift positions. The backward swept case will always have the most "stable" consequence (from increasing AoA) as the moments are always going to be larger than forward swept. Then diamonds/near diamonds are somewhere in the middle.
B) In contrast the forward swept case will (due to way spanwise flow works and flow separation at the wing tips and control surfaces there) have a greater possible AoA range to operate to begin with.
So these two matters (there are much more, but this is an example of compromises to adjudge) find more balance "in the middle" of the trapezoid spectrum.
Then the slight differences "in the middle" have their design and performance impacts (and how these are then prioritized by whomever selecting which one to go with).
So going with A), less of a moment range w.r.t CofG and (wing) CoL in the YF-23, means the horizontal stabilizer is tasked with more, the avionics is tasked with more (in high AoA regimens) and so on. Especially given it goes with V-tail there instead of dedicated horizontal stabilizer like F-22. So in the end it becomes a longer aircraft as sufficient larger moment (by distance) needed from the tail.
Advantage is its flatter overall than F-22 by this consequence too, but it has worse yaw efficiency etc. These all combine with dozens of other things to give differences in the overall performance (putting aside matter of any manufacturing , RCS and other issues between designs) and again what factors are weighted more in final selection analysis and testing.
