Pugachev's Cobra in a MiG-29?

[zerO_crash]

On 5/10/2024 at 12:28 AM, DummyCatz said:

Not exclusive to T-shaped tail aircraft, but happens on F-16 and F-35 as well (especially the SVTOL version that has the smallest horizontal tail). It is due to Cm/AOA characteristics, not CL/AOA. Let me refer to the Cm (pitching moment coefficient) of F-16, Su-27 and F-35 to illustrate different requirements to enter a deep stall and a cobra.

From https://ntrs.nasa.gov/api/citations/19800005879/downloads/19800005879.pdf

 

As you can see with only an insignificant stab deflection, combined with the instability due to reduced static margin and loss of pitch-down control effectiveness, the aircraft can enter the deep stall region and be stuck in it. Because the nose-down control even creates positive Cm. And the positive static margin region of AOA greater than 55° allows pitch oscillation to be reduced, stranding the aircraft into a specific deep stall trim point.

Similar in F-35, from https://arc.aiaa.org/doi/abs/10.2514/6.2019-3227

 

Eventually the F-16 developed a technique called pitch rocking to increase pitch oscillation, in order to get out of the trim point. The F-35 even have an automatic pitch rocker for this. It wouldn’t require a cobra for deep stall recovery, as the pitch rate is too significant on recovery too, that it can go over the deep stall area rather quickly.

 

But cobra is really about how many pitch-up moment the aircraft can generate, and is particularly refering to the upper most Cm curve. Now here’s such Cm of Su-27, from TsAGI paper https://arc.aiaa.org/doi/10.2514/6.1993-4737

The pitch rate culminates at around 70° AoA, as all the positive Cm accumulates to form pitch-rate. After that the pitch-rate decreases to 0 at 100° AoA due to the pitch-down moment by the airframe.

So they’re not completely related. The Su-27 doesn’t exhibit a deep stall, at least not in negative AoA.

 

Your extrapolations are correct, but you mess it up with the wording in certain cases (I see that English is not your native language). In some instances when you write "pitch rate", you actually mean "pitch angle". The whole definition of "Pugachev's Cobra", is that you have to have an aircraft, which with its aerodynamic and technical properties (thrust), allows to pull a pitch rate (rate of change) high enough to attain 90* - 120* pitch angle with minimal increase in altitude (hence why cm is important, not CL, in the equation). The specific maneuver was coined by Pugachev and Sukhoi. Any other aicraft mimicking this maneuver, has typically not been able to attain a pitch rate high enough (so as to reach at least 90* AOA), or enentered superstall resulting in severe gain in altitude throughout the maneuver. You are otherwise correct in your analysis. For the record, aircraft with thrust vectoring might replicate this maneuver, while not having the required aerodynamic properties, resulting in a impression of similar build (not aerodynamics - supermaneuverability assumes flight regimes outside of maximum lift).

 

On 5/10/2024 at 1:53 AM, 303_Kermit said:

2. I find extremely uncertain any aerodynamic data of F35. They can't be verified, since you support your revelations with article with limited access. Also I don't see a point  in it. We are talking about J35 and Cobra maneuver. 

3. Same case is for Data quote for Su-27 - dokument has limited access. Your revelations can't be verified. Do you have any public accessible source? The data I saw about MiG-29 come from Aerodynamic Institute in Warsaw. Where they're available to see for every visitor.

It occurs to me that you shouldn't be engaging in any deeper level of discussion, if you have a problem with verifying the authenticity and reliability of a document. It becomes even more clear that you are above your knowledge, if you don't understand why @DummyCatz mentioned the F-35. Obviously, he's making a comparison with multiple airframes that don't have a T-tail, which you stated are the exclusive empennage with regards to deep stall. Rightfully so, not only T-shaped tails enter deep stall. The sources that he lists to build his argument, are credible and relevant. I can attest to that. 
 

Here is a 101 for you to wonder who you are actually being skeptical to (F-35 document as example):

 

 

On 5/10/2024 at 1:53 AM, 303_Kermit said:

Whole post is very interesting, unfortunately unverifiable, and... not quite about the discussed subject. Changes nothing. Cobra maneuver exists since early 60, and was first performed by Swedish pilots. Aerodynamical difficulties of J35 makes their inventors even more respect worthy. 

No, Cobra does not exist since 60s. Read the specifics of Cobra-requirements, and check whether J35 was able to attain all the metrics (it was not!).

Edited May 24, 2024 by zerO_crash

[zerO_crash]

As to MiG-29, this is about the closest to Pugachev's Cobra that you will see it perform:

(2:20 ->)

 

MiG-29 is not as unstable as a Su-27, hence why it doesn't need FBW. For this particular maneuver, it won't likely reach 90* AOA, unless equipped with TV (MiG-29OVT). 

Edited May 24, 2024 by zerO_crash

[DummyCatz]

17 hours ago, zerO_crash said:

Your extrapolations are correct, but you mess it up with the wording in certain cases (I see that English is not your native language). In some instances when you write "pitch rate", you actually mean "pitch angle". The whole definition of "Pugachev's cobra", is that you have to have an aircraft, which with its aerodynamic and technical properties (thrust), allows to pull a pitch rate (rate of change) high enough to attain 90* - 120* pitch angle with minimal increase in altitude (hence why cm is important, not CL, in the equation). The specific maneuver was coined by Pugachev and Sukhoi. Any other aicraft mimicking this maneuver, has typically not been able to attain a pitch rate high enough (so as to reach at least 90* AOA), or enentered superstall resulting in severe gain in altitude throughout the maneuver. You are otherwise correct in your analysis. For the record, aircraft with thrust vectoring might replicate this maneuver, while not having the required aerodynamic properties, resulting in a impression of similar build (not aerodynamics - supermaneuverability assumes flight regimes outside of maximum lift).

 

To clean up misunderstandings, I never referred to 'pitch angle' in any of my posts. Instead, it is exactly pitch-rate (denoted as q in flight dynamics) that contributes to the max attainable AoA, while Cm contributes to pitch-rate. It's all about Cm, pitch-rate and AoA, but not pitch angle.

When I said 'the pitch rate culminates at around 70° AoA, as all the positive Cm accumulates to form pitch-rate', what I mean is that maximum pitch-rate (q-max) is achieved at Cm=0 in the Cm curve from the TsAGI paper, and pitch-rate can be indicated by the shaded area of positive Cm, or accumulated Cm.

The TsAGI paper explained everything related to the Cobra.

Edited May 22, 2024 by DummyCatz

[zerO_crash]

On 5/22/2024 at 7:21 AM, DummyCatz said:

To clean up misunderstandings, I never referred to 'pitch angle' in any of my posts. Instead, it is exactly pitch-rate (denoted as q in flight dynamics) that contributes to the max attainable AoA, while Cm contributes to pitch-rate. It's all about Cm, pitch-rate and AoA, but not pitch angle.

No, I stated that pitch angle has to find its way into that explanation. Pitch angle is essential, for considering whether an aircraft is actually capable of pulling a Pugachev's Cobra (90* - 120* AOA), or simply mimicking it (similar, but not attaining the metrics). That's what I corrected you on. It was however a linguistic correction (in message, if you will), as obviously I see that you understand it.

 

Yeah I know, but then that TsAGI table shows a relationship between Cm and AOA. Naturally, it will only indicate pitch rate (really showing at what points the pitch rate (q) is highest - preferrable to perform the maneuver). Don't worry, it's all correct

Edited May 24, 2024 by zerO_crash

[draconus]

On 5/22/2024 at 2:25 PM, zerO_crash said:

Pitch angle is essential

Only in one special case when you start the maneuver from straight and level flight. Theoretically you can do a cobra starting from any attitude so pitch angle is useless then since it's a measure of nose pitch from level flight.

Edited May 24, 2024 by draconus

[Rifter]

As a side note: The German Mig-29s often had to demonstrate the cobra manoeuvre because the NATO partners wanted to see it. Officially it was not allowed, it was prohibited in the flight manual. The pilots considered the cobra as a stunt and not as a meaningful combat manoeuvre. Also for the german Mig-29s it was not possible to get the nose higher than about 70 degrees pitch angle. At that time only the Mikoyan demonstrators with radar equipment and gun removed were able to show 90 degrees because of the COG being more aft.

 

[zerO_crash]

3 hours ago, draconus said:

Only in one special case when you start the maneuver from straight and level flight. Theoretically you can do a cobra starting from any attitude so pitch angle is useless then since it's a measure of nose pitch from level flight.

 

Any maneuver, is closely defined with entry-/exit- points, and typically speeds and other mertrics. 
 

"Only in one special case..." - Have you ever seen a Pugachev's Cobra performed from anything other than level flight? There is very little "special" about a maneuver, which is always performed in a given way. "Specific", however, is probably what you meant. Still, if initial metrics deviate much, you won't adhere to the full maneuver, which means that you haven't in fact performed a Pugachev's Cobra, but rather, a derivative.

 

People don't understand that maneuvers are not as loosely defined, as a appeoximation of a geometric figure. It's more specific than thay, with relative turn lengths and a total. If you perform a Cuban Eight, albeit horizontally, then you are not performing a Cuban Eight at all.

Edited May 24, 2024 by zerO_crash

[zerO_crash]

On 5/24/2024 at 9:28 AM, Rifter said:

As a side note: The German Mig-29s often had to demonstrate the cobra manoeuvre because the NATO partners wanted to see it. Officially it was not allowed, it was prohibited in the flight manual. The pilots considered the cobra as a stunt and not as a meaningful combat manoeuvre. Also for the german Mig-29s it was not possible to get the nose higher than about 70 degrees pitch angle. At that time only the Mikoyan demonstrators with radar equipment and gun removed were able to show 90 degrees because of the COG being more aft.

 

Correct, albeit Germans weren't actually pulling Pugachev's Cobra, but a similar maneuver. The pitch never entered the territory bar minimum of 90* AOA.

 

As to the usefullness of a Cobra maneuver, that is something that imagination and situation dictates. Any real pilot will tell you that a prolonged dogfight (scenario), will result in a ever lower airspeed. That is not a question, it is a fact. That is dictated by whichever opponent pulls the fight slower (in fhe attempt to lower the turn radius). If the contender then, doesn't follow and rather extends, the one doing a tighter, albeit slower turn, will place himself right at the opponents back and have a window for atleast a missile. A cobra, can ultimately cut down the length of the initial engagement, and finish off the target faster. Performing a Cobra, or a derivative, amplifies the AOA for a short while, giving the pilot more opportunities. Being able to pull more AOA, has always been a desired metric in fighter aircraft, whether sustained or instantaneous.

 

If the scenario is, however, comprised of more than 1 vs. 1, then the maneuver will potentially expose you more, by eating all your airspeed. Tactically, it is a stupid choice to use it in this case. There are better tactics involved. 
 

The problem is most people don't have rhe capability to think for themselves. They listen to a pilot speak, and parrot whatever they heard. Pilots being good sources, you still have to evaluate the context. Pilot train most often in 1 vs. 1 with guns. IRL, you'd more often than not, have a heatseeker, otherwise avoid engagement. The times of chivalry are long gone, and no pilot is taught to enter a fight in a gentleman-type of way, greeting his opponent. That up until WWI-stuff, and it stayed there. The point being, you might question whether a Cobra-derivative allows for enough aircraft control to use a gun in that window effectively, but IRL, that is enough to pop off a IR-missile or two! Talking about the real aspect of warfare, not a synthetic one, any maneuver closing the loop, is a advantagous one. Whether one uses it or not, is up to the pilot and situation. That's all there is to it!

 

I have never heard a F-18 pilot complain about the Hornets AOA-capabilities (that, understanding that Hornet can pull way more AOA than what its thrust will allow it to hold). Not once, have I heard a pilot criticize it. I haven't either heard a F-22 pilot complain about their 2D thrust vectoring. Sadly, what pilots (just as most humans) are often subject to, is national pride. Until western pilots can perform Pugachev's Cobra, or better, they will muddy the water with their scepticism (based on pride and jealousy). Have you noticed how Eurofighter and basically any other delta-wing configuration has become famous in the modern 4th/5th generation era? A delta configuration, by design, projects high instantaneous turn, at the expense of speed (huge airbrake). That's not enough, to get even more turn, they add canards! If you pull maximum deflection on the control column of the Eurofighter/Rafale, you don't get a Cobra, rather something similar, but the speed will get eaten too. 
 

One important point; having capability, doesn't mean that you neccessarily have to use it. It can be a emergency one, depending on what tactics one trains. However, if maneuverability wasn't desired, than all those canards, thrust vectoring nozzles, and much more, is just dead weight. F-22 shouldn't have been chosen, but rather YF-23 with its (supposed) longer range and better speed characteristics - that, where every engagement is a mach 4+ in closure. Nope, I don't think so.

Edited May 25, 2024 by zerO_crash

[Dragon1-1]

One thing about the Cobra, rarely noted but explained by GS in one of his videos, is the effect it has on the control zone in a guns-only fight. Basically, it shifts the control zone further behind the aircraft that can perform the maneuver, because if you get too close, a Cobra can make you overshoot, so you have to hang out further back. Why does it matter? Because landing a gunshot from that zone is much more tricky. In that way, the capability to do a Cobra already protects you to some extent, even if you never actually do it. Of course, that's assuming heaters are not in play.

In general, like other high AoA maneuvers, it's a great tool for turning your opponent's excessive closure into an overshoot. Tactically, it has to be weighed against other options, but if he's bearing down on you and closing for guns, the possibility of exposing yourself to his wingman later is offset by averting the near certainty of eating cannon rounds right now. It can be a replacement for guns-D in some situations, too, but you have to make it messy and gain altitude during it. This will result in great loss of forward speed combined with upwards movement that's very hard to follow, unless you misjudged the distance, in which case it just makes you a huge target. You don't really need the capability to do a full Cobra for this, a Hornet can also "stand on its tail" to pull one over an opponent who can't go as slow, but Cobra gets you there faster.

[Allesmor Obranna]

Cobra maneuver at 1992 Farnborough, MiG-29M 9.15 with Valery Menitsky, the chief test pilot of the MiG-29M 9.15 program:

 

[MA_VMF]

https://youtu.be/9T3VHa_DyE8?si=1qdJbKDn_o0pDsK2

[Hog_driver]

I know I'm a bit late to the party, and frankly I don't care about the MiG-29 too much, but in early 90s (the Polish Air Force acquired their Fulcrums in 1989), people talked a lot about its supposed 'supermaneuverability' and the maneuver called "kolokol" (bell, or Kvochur's bell). Just my 2 cents, maybe it was mentioned earlier.

[F-2]

4 hours ago, Allesmor Obranna said:

Cobra maneuver at 1992 Farnborough, MiG-29M 9.15 with Valery Menitsky, the chief test pilot of the MiG-29M 9.15 program:

 

Sadly the only 9.15 demo I could find

[Seaeagle]

20 hours ago, F-2 said:

Sadly the only 9.15 demo I could find

Well there is the one in the post by MA_VMF just below the one you quoted.

[F-2]

31 minutes ago, Seaeagle said:

Well there is the one in the post by MA_VMF just below the one you quoted.

M2 isn’t 9.15 though? It’s much heavier and twin seat.

[Seaeagle]

8 hours ago, F-2 said:

M2 isn’t 9.15 though?

Yes it is  . The  "M2" in the video is the fourth 9.15 airframe(no 154), which was used as prototype for the tandem seat design and later also became the prototype MiG-35.

8 hours ago, F-2 said:

It’s much heavier and twin seat.

Well the extra seat will obviously add some weight, but apart from the modified forward fuselage/cockpit, its essentially the same airframe

[Seaeagle]

Another video with the MiG-29M2 and MiG-29K (9.31 no 312) flight displays - cobra in both  .

 

[MA_VMF]

https://www.youtube.com/watch?v=t4FZNAIO6nw

1:37,1:56

Edited January 10 by MA_VMF

[Raven King]

On 5/9/2024 at 2:27 AM, AeriaGloria said:

While I don’t completely trust wiki and the same page claims MiG-21 can cobra, I understand the mentions of it being used in the memoirs of Draken pilots. 

But I wonder what the limitations are, I had heard it needed roll to enter and you can sort of see this in the video. 

 

On 5/2/2024 at 6:16 PM, 303_Kermit said:

You have to turn off momentarly battery while in flight, and turn it on again. CAS failure appears and Cobra is possible.

PS. It's not "Pugachev's cobra" - First plane who performed it was actually J35 Draaken , and swedish pilots performed it first. over 20 years before MiG-29. Pugachev probably was by that time small child - in best case.

 

As a matter of fact, what we know as a "Cobra" is no more than the extreme version of a Controlled Stall. That means virtually any airplane with sufficient nose authority and engine power can in fact execute the maneuver, including the Fishbed.

We will never know for sure "who did it first" because as far back as WWII, pilots used stalls to decelerate abruptly and make an opponent overshoot. Technically, "Cobrettes".

It is called "Pugachev's Cobra" because Viktor Pugachev performed it at Le Bourget in 1989. The first time Soviet fighters were allowed to participate. The occasion was so memorable that the name stucked. The first Soviet pilot to do cobras was Cosmonaut Igor Volk.  

[okopanja]

This is becoming one of those Pluto-is-not-a-planet discussions.

Its like "Hey I did it first but forgot to file patent application".

We all know who did it first in front of the public and at such low altitude.

[draconus]

11 hours ago, Raven King said:

engine power

Not needed, just pure elevator work, unstable design and inertia.

[AeriaGloria]

On 1/20/2025 at 4:19 PM, Raven King said:

 

As a matter of fact, what we know as a "Cobra" is no more than the extreme version of a Controlled Stall. That means virtually any airplane with sufficient nose authority and engine power can in fact execute the maneuver, including the Fishbed.

We will never know for sure "who did it first" because as far back as WWII, pilots used stalls to decelerate abruptly and make an opponent overshoot. Technically, "Cobrettes".

It is called "Pugachev's Cobra" because Viktor Pugachev performed it at Le Bourget in 1989. The first time Soviet fighters were allowed to participate. The occasion was so memorable that the name stucked. The first Soviet pilot to do cobras was Cosmonaut Igor Volk.  

Is any controlled post stall a cobra them? 
 

I was always under the belief that what makes Cobra unique, is that is achieved 90 degrees or more of AOA. A MiG-21 will never do that unless it’s some sort of sub 100 kmh tail slide