I have never read any literature about the antenna fairing on the side wall of the air inlet providing lift and control gain at high AOA. Is it convenient to provide literature?
In fact, regarding the horizontal tail at high angles of attack, it should be remembered that its angle of attack is always smaller than the main wing. The control problems at high angles of attack are more from the ailerons (such as the roll reversal that often occurs in the F-14, which manifests as weak aileron control effect on fighters such as the MiG-29 and F-15). These problems can be alleviated by flaperon design, horizontal tail roll control and rudder roll control, which is also the solution used on aircraft such as the Su-27 and F/A-18.
2 Likes
Interestingly, the Chinese Su-27 variants did not remove them until the J-16. The J-11B and J-15 still use these antennas as the RWR’s goniometric antennas.
1 Like
Because they’re using their own RWR system. And decided to keep such antennas placement.
3 Likes
I do not want to use another video game.
It’s not obvious. Its rather silly when actually carefully reading the Su-27SK flight manual & carefully understanding the technology involved and the history of it.
The radar dish does not move. There is a single reflector plate enclosed inside the radar that pivots. it is reliant directing reflection of a plate at the front of the radar that is fixed & back to the main plate that moves at outward in a limited range of motion. That is why the Mig-23, Mig-29 & Su27 are severely limited in ability to scan.
These radars do not have any ability to follow the line of sight of a human being. All actual sources state that only IR missiles are utilized with the sighting rings of the HMS.
You must point the radars nose at the target so that it may be captured by the radar. There is no high off boresight radar missile capability. I am so sorry that was not a thing for the Soviet Union. It’s made up.
If you have radar weapons selected. The radars will switch on & stand-by until the target enters its FoV. All the OEPS does, if communicates the direction or angular position of the target so that the moment it crosses its view, it will track it. Then you must look at your HUD for verification & further aiming. There no frequency growl or tone like IR missiles or flashing light in the sight rings for radar missiles.
You cannot use radar weapons as if they IR missiles with the HMS. The HMS does not communicate with any radar weapons.
Because they rely entirely on the radar for guidance. Not the opto-electronic pointing station
They do not provide lift bro.
all they do besides be an antenna is provide wingtip vortices which are caught along the fuselage through the middle and right where they are caught by the elevator. They are the same fan like shape of the Yak-141. I am trying to find which other designs had them too. I will let you know.
These destabilized, energized airflows will stick to the surface of the aircraft, elevators & maintain the boundary layer allowing the elevators to continue to provide pitch at angles of attack beyond lift. This is one of many reasons the Flanker can be controlled in situations where most aircraft will deep stall & become unrecoverable.
The Su-27 & Mig-29 have numerous technologies throughout that when added together make it supermaneuverable. Of course, the Mig-29 is not the Su-27 (only because the Mig-29 did not get the same digital design treatment). But it is still the only other aircraft in the world considered supermaneuverable without the use of thrust vectoring.
It’s a fascinating aircraft. Literally nothing like the Su27 in the world.
For example the 9-15 utilized different vortex generators for its elevators. these are dogtooth extensions. The F-15 uses them too.
As for the Su-27 they are called intake strakes which are found on other aircraft such as the Mirage 2000.
Here’s some literature on the use and placement of strakes
Aircraft Vortex Generators - The Nacelle Strakes - GridPro Blog
These application are for commercial but of course gives you an idea how they apply in conbat aviation. I will bring up some more specific to the Flanker when I get the chance.
1 Like
The vortex generators of the Mirage 2000 are located above the main wing, overlapping with the main wing in projection, which can effectively delay the airflow separation on the upper surface of the main wing when flying at a high angle of attack. On the Su-27 and MiG-29, this task is completed by the wing strips.
In fact, the later Su-27 and MiG-29 families also adopted some unique ways to increase the lift at a high angle of attack to slow down the stall, such as the spoilers used by the MiG-29K and MiG-35. However, the pair of antennas of the Su-27 are too far away from the horizontal tail and their installation position is lower than the horizontal tail, so it is difficult to have much actual impact on the horizontal tail.
In my limited communication with real VKS pilots, I believe that thanks to its substantial increase in thrust and slight increase in weight, the Su-27SM/SM3 equipped with AL-31F series42 is one of the most difficult Su-27s to defeat in BFM. Perhaps only the Su-35 with greater thrust and vector thrust function has the conditions to surpass them in hardware. In Akhtubinsk, the Su-27SM piloted by experienced “Blue Army” instructors was responsible for imitating the imaginary enemy of the NATO Air Force, and conducting BFM training with more advanced fighters such as Su-30SM and Su-35. Almost no one could detect the impact of the missing antenna on the flight (of course, at least in my limited communication, they told me so). Of course, we all know that there are some problems with the gaijin’s Su-27 FM. But this is not the main point we are going to discuss.
2 Likes
The paraboloid transreflector is fixed. The twist reflector moves without feed horn. The Mech radar does not need the paraboloid transreflector to move when choosing the direction of its radiation, so it is displayed as a “hood”. In practice, it achieves this function by rotating the twist reflector on a universal joint.
In addition, in the Su-27 tactical manuals of the VVS and the PLAAF, “tactical lapel” (the action of a two-plane formation turning 45-60 degrees to the opposite side to keep the enemy aircraft on the edge of the radar STT tracking after launching SAR missiles at the enemy aircraft) is a standard tactical operation.
In addition, the Mirage 2000C’s RDM/RDI radar is an inverted Cassegrain antenna like the N001/N019. In terms of antenna composition, they have similar features. This technology is not exclusive to Soviet fighters, and the Mirage 2000 is no better (or worse) than them - one of the few things worth discussing is the Mirage 2000’s ground mapping function, which the N001 series upgraded in VP/VEP (equipped with Su-30MKK/MKK2/M2). There are reports that the Su-33’s radar has basic sea mapping capabilities, but I have no information to confirm it.
3 Likes
Smarter already is the antenna of the RWR.SPO-15
1 Like
blah-blah-blah
Just giving a pointless presentation lol so how do you track beyond ±25 degrees?
Afaik, The radar is like a floodlight that illuminates a large area at a time. It does not scan a small area and get rapidly directed left/right up/down like a typical Western radar of this type.
To my understanding,
The radar iluminates a 50 degree by 10 degree (±25 degrees horizontally, ±5 degrees vertically)
This is the scan zone of the antenna/dish and can be interpreted a very wide field of view.
The radar dish can then tilt ±35 degrees horizontally (35 + 25 = 60), and +55 degrees/-45 degrees vertically.
The radar system does a lot of deterministic calculations and signal processing to understand where the radar target is located once locked.
I see no reason why the FCS would not be able to use inputs from the hms to attempt an ACM lock in a certain orientation at any point up to the scan/gimbal limits of the radar nose.
I would imagine that it is not a precise function, or very accurate, but is more easily done with the technology constraints because of the wider FOV.
In principal, the radars are very basic and are “obsolete” compared to western radars of the same type, but they are used in very clever ways that still makes them very effective.
They are still extremely susceptible to all types of jamming, large bursts of chaff and any really struggle when dealing with stealth technology.
Phased array antenna much much more versatile, accurate and reliable than
1 Like
A radar beam is a floodlight, just not that wide. The N001 should have a beam width of about 2.5^\circ
wide. To scan the sky for targets it then sweeps the dish (and so the beam) over the sky and periodically listens for returns.
This is what it looks like on the N019 (N001 is also very similar to this)
Spoiler
1 Like
What does that highlighted square I marked in red mean ? Is it the AoA manual limit ? I remind everyone that Su 27SK has a limit of 24 AoA, here it looks like about 28 AoA.
I quote McAir engineer :
During this time, the Structural Dynamics engineers in St. Louis had discovered a horizontal tail flutter
problem during wind tunnel testing of a dynamically scaled model (flexible model with structural dynamics which mimic the real airplane). To solve this problem, the inboard portion of the horizontal tail (stabilator) leading edge was removed. Although the effects on the aerodynamics were minor, the impact on the structural oscillation
modes was dramatic. A quick fix to the real airplane stabilator was fabricated, and that modification known as a “snag” was successfully evaluated in flight.
1 Like
Do any of the Russian Flankers have MAWS?
1 Like
Su-35S
1 Like
область нормальных режимов=Normal mode zone
область неустойчивых режимов=Unstable mode zone
2 Likes
I measured with a ruler (:-D) and it’s about 24 AoA, which corresponds to the SK version, which says 24 is the recommended AoA limit. The picture shows that up to this AoA Su 27 is stable and above it is not. If implemented in a WT game, how many people would fall into a spin… it would be a crying session… :D
That’s not to say that the real Su 27 is exactly dangerous above 24AoA, but it’s not for the average Su 27 pilot of the 80s and 90s. Flying above the AoA limit is for the better pilot.
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.
2 Likes
Just a few notes for the bigger picture.
Ventral Fin was standard on the F-15 and was chosen for overall greater aircraft stability (AoA and Mach) but their contribution to F-15 stability was found to be problematic and inadequate, so F-15 designers increased the area of the vertical tail surfaces and the stability problem was solved.
The MiG 29 had ventral fin very early on, perhaps from the beginning, it was later removed, on the other hand, the Su 27 did not have ventral fin from the beginning it was added later for better stability, probably to solve the stability problem.
1 Like
I don’t think the RWR covers on the sides of the intake ducts on the Su 27 had much effect on vortex formation, so they were soon removed. But I don’t know for sure. I won’t argue, I’ve never read about the benefit of these covers to the aerodynamics of the Su 27.
3 Likes