Sukhoi Su-27/30/33/35/37 Flanker series & Su-34 Fullback - History, Design, Performance & Dissection

The structural lifespan of those aircraft is inherently high, and they don’t need reinforcement to avoid additional routine maintenance costs.

As someone who has had contact with the Su-27 in the air force and airshows, that’s the only information I can provide. My words may not hold value for you, but it also doesn’t prove that the Su-27 can perform the Cobra maneuver at high speeds.

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Out of their way?
Of course, they go out of their way to not provide their adversaries the intelligence of their combat systems full capability.

Countries do not publicly disclose full capabilities in writing or in public demonstration for in service fighters, neither does the exports client states. There is reason for this militarily, contractual and geopolitical.

The reason I believe GJs initial full real control flight model because it coincides with my own research and GJ is known to hire consultants in the form of ex pilots to speak about aircraft and has publicly made that known prior.

The 800km-900km is a very specific regime and they didn’t not just randomly pick it. It’s not even the edge of transonic. I am not saying it’s the speed you can do a cobra. I am saying it’s a speed at which high alpha and dynamic attainment aka supermaneuvrability can be initiated.

Ok, I have heard some say that the acceleration the Wanker has in-game is a bit too high from real life, which might be part of the reason loses so much speed in turns (to match theturning curves). So I decided to test it out. Bear in mind, I have never done these kinds of tests before, so scrutiny to my method is welcome.

The test: acceleration at sea level (~200 m) in level flight (n_y = 1) on low fuel (8:10 min).

Source: https://www.mycity-military.com/uploads2/154453_865801817_Cy27_F15.pdf
That paper compares the flight performance of the Su-27 to the F-15 / F-16 / Tornado. The flight curves given for the Su-27 are from its technical manual “Руководство по технической эксплуатации N 10 книга 1”

Conditions of the test (from the paper):

  • The weight of the aircraft is not directly provided by the paper, but the wing loading is, 305\ kg/m^2. By using the wing area we can find the weight of the aircraft 305 \times 65 = 18910\ kg.
  • The load out is given as 2 \times R-27 and 2 \times R-73
  • Flight is done at 200 m altitude with n_y = 1 at full afterburner.
  • The speed in the curves is given as TAS

Conditions of the test (in the game):

  • The weight is set to 18910 with the use of http://localhost:8111/editor/fm_commands.html
  • The load out is as 2 \times R-27 and 2 \times R-73
  • The flight was done at about 250 m altitude at full afterburner and level.
  • Speed was measured using TAS from the in-game HUD

About the units: The paper uses a parameter called V^*_y = \frac{\Delta H_e}{\Delta t}, where H_e = H + \frac{V^2}{2g}. The logic behind is that using energy the usual way of adding the potential and the kinetic together we don’t get a useful metric, since the speed and altitude of the aircraft are more important than the actual energy (an Il-76 could be flying much slower and at a lower altitude and still have more energy than a faster and higher fighter, but that does not mean what we usually mean by “higher energy”). The units of V^*_y is m/s.
To calculate that value from the in-game measurements for a speed v', a precise time stamp is taken at t_0 with the speed of v_0 = v' - 20\ km/h and at t_1 with the speed of v_1 = v' + \ 20 km/h. The time stamps are taken using Davinci Resolve

Spoiler

image

Since the altitude is constant, all we need to do is to convert v_0 and v_1 to m/s to get

{\displaystyle V^*_y = \frac{H_1 - H_0}{\Delta t} = \frac{\displaystyle \frac{v_1^2}{2g} - \frac{v_0^2}{2g}}{t_1 - t_0}}

The graph:

Results from the test:
The video: https://youtu.be/wWgUpUJdmDY

The data:

Spoiler

image

Conclusions:

  • At speeds around 350 - 730 km/h there is a small but significant overperformance in acceleration in-game.
  • At speeds around 770 - 1030 km/h there is a small but significant underperformance in acceleration in-game.
  • At speeds above 1050 km/h there is a big overperformance in acceleration, which becomes massive above 1250 km/h.
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Note: there are also curves for n_y = 3 and n_y = 5, but I don’t know if I can do them, as it would require to fly at the say altitude while keeping the same g load.

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Why did you call it the Wanker though?

Your word has value to me, bro. I am not saying you got no word now completely henceforth.
However, the reinforced airshow airframe claim is a tough one for me to swallow. Thats all I am saying.

So, essentially every Flanker and Fulcrum we have seen perform on YouTube is actually a reinforced special variant and the actual combat performance and airframe of the in-service fighters are less capable?

Yeah, that is why it’s a discussion and I am here to stimulate research in which I clarified earlier as follows:

Based on my knowledge, airshow aircraft are often finely tuned, and part of that tuning is described as “structural adjustments.” Of course, I cannot assert that every aircraft is tuned in this way, and I am sure that the Cobra maneuver is a maneuver that significantly reduces the structural lifespan.

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I get that, but a structural reinforcement is not “fine tuning” like removing a gun etc.

Everything within any given fighters’ wings such as the wiring, the fuel tank placements, the fuel pumps and hydraulics that power the flaps, leading edges are crammed together and specially placed.

To reinforce an airframe requires quite a bit of reengineering and replacement of these systems. That is why a totally new variant would have to be redesigned and made at Sukhoi/Mikoyan OKB.

Also keep in mind Soviet aircraft are built much more tougher than Western fighters. @BBCRF has more knowledge on how many Gs these aircraft can withstand.

No one among us knows the details of those changes, so… well, there’s no reason to speculate.

Are you making a bug report?

Just looking at it from a engineering perspective makes no sense.

it’s not technically possible for anyone other than Mikoyan or Sukhoi take an old airframe and “reinforce it”. Additionally, it’s not even a technically logical for them to do so either to an existing airframe.

It’s easier to develop a new variant instead of taking an old airframe and repositioning the countless mechanical parts, nuts and bolts a few degrees all just to reinforce the airframe for airshows.

I do not believe the Su-27s you see at airshows are specially modified airframes that are reinforced to cobra and perform high alpha maneuvers. Additionally, since the Russians have done it freely at airshows for years without any worry about the degrading the longevity of the airframe as well as the fact that that no nation demonstrates full combat capability publicly of any in-service fighter.

It is safe to say the Flanker is much more capable when pushed to the limits in actual combat than publicly known.

Flyght manual

???

No need to write nonsense. There is exactly the same aircraft as the combat one

here is an ordinary combat aircraft

In the video you posted, it doesn’t show any extreme G-forces being applied to the airframe, there is no cobra in it either. Sure it does pull some nice turns but nothing that’s stressing the airframe as much as a cobra maneuver. It also appears to be going extremely slow for most of the high AoA maneuvers.

I am not saying that there ARE reinforced planes but the video you linked doesn’t prove that there aren’t any either.

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This is an ordinary combat aircraft. No special training.

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Does Malaysia also have special planes for the airshow?
And Su-27SMK

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Russian aerobatics teams are part of VKS and use same aircrafts as others and can play same role in combat as others VKS aircrafts.
image

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Also keep in mind the flanker is known to be one of the most aerodynamically perfected designs ever. By western aviation scholars.

Though the wings are quite broad, the special placement allowed for airflow pass over the top at high angles of attack. The the elongated front fuselage that blends into the wing assist with diffusing airflow that would otherwise place enormous stress on the wings.

I meant to say you know more about how structurally resilient soviet 4th generation fighters are in high g maneuvers.