Because it’s a Delta wing. The strakes would logically be placed on top. That is where airflow separation occurs at angles of attack beyond lift… Why would they be placed at the bottom??
The Mirage 2000 was only mentioned because it has vortex generators at the intakes. it is the same technological concept..
The Su-27s fuselage & elevators are located below the wing. That is why the strake was placed there.
The strake is situated in the optimal position so when the aircraft pitches up only then do the strake begin to produce vortices that travel along the fuselage that is specifically designed to channel airflow into two paths. The Elevators & aft fuselage. Between these two channels is another strake only few who actually appreciate the Flanker’s aerodynamic traits & know why it is special.
Vortices/energized air flow is represented in orange. NOTE: Vortices stay attached to the surfaces of aircraft, that is why they vorticity is utilized in alpha flight technology.
Regarding additional strake. This strake is called a Ventral Strake (belly) or Ventral fin.
You most likely understand it as simply as stabilizer. For NATO aircraft, yes. However ventral fins can be designed for both. Stability & vortex generation. This is something the Flanker has that the Mig-29 does not. This is also why the Fulcrum can only cobra Its elevators cannot pitch the aircraft in to the same degree or speed of the Flanker. Even though it has a much higher thrust to weight & substantially lighter.
The ventral fins traditionally serve as a vertical stabilization substitute when an aircraft is operating at angles of attack where the vertical stabilizer is shielded from sufficient airflow by the aircraft’s fuselage & wings the aircraft will begin to yaw uncontrollably. They are added in specifically on the center fuselage of aircraft like the F-16 to prevent unintentional yaw@ higher angles of attack.
The Su-27 does not have this problem, nor does it need any yaw stability. It has the tallest foreword positioned vertical stabilizer, rudders & LERX. They are massive for this exact reason & they can very well still yaw at angles of attack beyond 90 degrees.
The ventral strakes of the Su-27 are unique. They are primarily vortex generators. They are the largest & is the only design in which the elevators are actually attached to it. All vortices generated are immediately caught in the elevators.
The Su-27 ventral strakes directly fed by constant airflow of the Su-27s fuselage channels shown above. The ventral strake produces very little vortices in pitch alone. That is why the RWR receiver was fashioned into the aerodynamic shape & pattern of standard vortex generating stakes. a Nacelle strakes. The RuF likely easily decided that it was not necessary once the RWR was upgraded. It would be a such a small variation in performance in an exclusive flight regime that the Flanker is already the best in. Additionally, the plan to implement modern Flankers with TVC further this a non-issue.
Vortex Generators Can Also Delay A High-Speed Stall
When airflow across an airfoil reaches transonic or supersonic speeds, a shock wave forms. Eventually, these shock waves will form at the leading edge of the airfoil, plus at the trailing edge and at any control surface hinge points.
As air moves across the shock wave, it suddenly loses energy. In fact, the energy loss may be so great that the airflow separates from the airfoil behind the shock wave - just like it does in a low-speed stall. If an aileron or elevator lies behind the shock wave, the separated airflow makes the control surface ineffective, and it may make the aircraft impossible to control.
In this high-speed situation, vortex generators can pull in high energy air from outside the boundary layer, mix it with air inside the boundary layer, and prevent separation. They can also disrupt the shock wave, reducing the amount of energy lost as air travels through the wave.
You just named a technology on the Su-27 as a “Wing Strip” I do not believe you are equipped to determine what technology has an impact on the Su-27 or not accurately.
What is too far away?
Look, there is a reason the Flanker’s aerodynamics are still studied to this day. Do not be surprised if there are little things you had no idea existed in the aircraft prior that not found anywhere in open source.
What the hell is a Wing Strip???
Whatever you are referring to as “Wing strips” is wrong and is entirely made-up name for technologies.
The only technology on the Su-27 wings besides basic flight control surfaces is the droop flaps. Leading Edge Droop flaps simply drop down when the aircraft is in alpha flight to allow airflow to easily pass over the top of the wing. They are not vortex generators & the airflow that passes is just regular airflow that is not energized.
They are called droop flaps because they do not extend out like traditional leading-edge slats. They also do not expose any space between such as leading-edge flaps. Droop flaps are technologically superior to the mentioned types. Because not only do they allow airflow to pass over the wings in high angles of attack, they can increase the camber of the wings to produces higher lift.
They are found on aircraft such as Su-27, Mig-29, F-16. As well as aircraft like the F-22 & Su-57
So, what are you referring to on the wing??? Again, they do not produce energized airflow. They also have zero effect on the elevator’s ability to operate. They do increase lift & delay the stall alone. But there is no one single technology that makes an aircraft supermaneuverable. It’s a combination of several technologies & specifications.
