It seems that trapezoid wings are used by all fifth generation fighters (although the wing of J20 looks quite like delta wing), but why? What made a trapezoid wing so attractive? Why don't they use other forms, like the swept wing on SU27?
Trapezoidal wings have advantages and disadvantages:
- Better performance than delta wings at transonic speed
- Good stealth performances
- Flaps can be easily used.
- drag reducing
- better Lift/Drag ratio than delta wings
The problem is that they stall at much lower angles of attack than delta wings.
Edit:this problem is overcome using leading edge,LERX,and/or canards
$\begingroup$ I’ve edited your question a bit. If I accidentally removed something important, feel free to edit or revert to the original. $\endgroup$– dalearnMar 24, 2020 at 14:22
$\begingroup$ Thanks for your answer! But can you compare the trapezoid wing with the swept wing(like ones on SU27) ? $\endgroup$– zyxMar 24, 2020 at 15:01
$\begingroup$ what is biscus drag? $\endgroup$– zyxMar 25, 2020 at 0:07
1$\begingroup$ drag caused by layers of the fluid sticking to the object.More surface area means more of the object is in contact with the fluid, which means more drag $\endgroup$ Mar 25, 2020 at 10:05
1$\begingroup$ possible typo in above comments -- the word is "viscous" $\endgroup$ Mar 25, 2020 at 11:29