Pugachev's Cobra... How Does It Work?

[superberkut]

Gee, I hope I'm not bombarding Ask GTPlanet! with too many questions, but I am suddenly full of them...

How does Pugachev's Cobra work? They say on Wikipedia that "the pilot disables the alpha limiter, pulls the plane up to an extreme angle of attack, then pulls it back down again, and resumes normal flight." Diagrams showed the plane, a Su-27 Flanker, execute all the said maneuvers while stationary in the sky, and yet a video showed a F22 Raptor doing so, but only by climbing by 2000 metres.

The Su-27 could indeed pull it off in motion and at one altitude, but it is said that only American canard AND thrust-vectoring aircraft could do the same trick, whilst the Su-27 has neither. That said, is there any technology behind this, or is it just the training of aircrews?

 

[Greycap]

I don't think it can be conducted stationary as the control surfaces need airflow to have any effect. Some airspeed is needed. To my understanding the plane has to be very manoeuvrable to build up that extreme angle before it actually begins turning, and after the angle has been built up it needs a truckload of thrust to keep it from falling off the sky. It's practically flying backwards at that point so the aerodynamics don't do much.

I've never heard that a propeller plane could do that as the plane is in a way superstalled in horizontal level and then pushed out of the stall by sheer power. The first problem is that the propeller planes can't be yanked to such an angle as they'll just turn sharply upwards and begin climbing, and even if that could be solved there would be the severe lack of power. Superstalling is more or less limited to delta winged planes.

 

[Duke]

The Cobra is when the pilot can generate enough pitch force to actually put the plane almost tail first while still maintaining motion in the direction the plane was already travelling. It's used to dump a huge amount of airspeed very quickly. This video is not terribly clear, but it does demonstrate the maneuver compared to a plane flying straight and level.



Thrust vectoring is NOT required, but if it's available (such as in the newer MiG 29), the pilot can balance the plane vertically on the engines for quite some time. Here's a MiG or Su doing it:



[edit] As Greycap says, you need a HUGE amount of control area and a highly maneuverable plane to pull this off.

 

[Leonidae]

That's Su-37 Super Flanker alright. but I never thought that Drakens could pull off that move >.>;

 

[Omnis]

It's safe to say the SU-37 is well beyond the F-22 in terms of maneuverability and stuff, right? I remember that being the case in Airforce Delta Strike, lol.

 

[Sting]

Yeah Drakan's can do it... although it just doesn't look as good as a Sukhoi doing it. It's an awesome move to watch.

Like this one. Has little diagrams:

 

[Keef]

I'm not sure if F-22s can do the maneuver or not. It is a air superiority fighter, but the Air Force would probably rely on long-range missiles as opposed to dog fighting. The plane really doesn't need to be maneuverable, so I'm curious about why they gave it thrust vectoring. I guess it's a showcase of technology.

 

[Perfect Balance]

I'm not sure if F-22s can do the maneuver or not. It is a air superiority fighter, but the Air Force would probably rely on long-range missiles as opposed to dog fighting. The plane really doesn't need to be maneuverable, so I'm curious about why they gave it thrust vectoring. I guess it's a showcase of technology.

The video is in russain, and they basically said the plane is so maneuverable so that the pilot doesn't have to worry about the plane's limits, and can focus all his concentration towards the target at hand.

 

[Wolfe]

The Cobra only works with planes that either aren't very stable, or are very maneuverable (Russian fighters tend to be both). Having an airframe that can withstand the forces involved helps, too.

What essentially happens is when the pilot yanks the stick, the tail pitches down with such force and speed that the aircraft is "broken free" from its lift, and put into a stall. After the plane tilts back, the pilot gets hard on the throttle and uses the forward momentum along with the airflow to bring the plane back to its original attitude, where it catches its lift again and begins accelerating.

There are some planes that are probably capable of doing the Cobra but wouldn't survive the maneuver because their airframes wouldn't take the abuse. I remember successfully performing the maneuver in X-Plane with an F-14 with invulnerability turned on.

 

[wfooshee]

The pull-up done by the Blue Angels solo "low transition" takeoff comes very close to the rotation needed for this, in an F-18.

(In this maneuver, the pilot raises the gear almost while the wheels are still touching, maintaining just a few feet of altitude. At the end of the runway he pulls back hard into a vertical climb. Every time I see it I wonder why the tail cones don't hit the runway.)

As for the stall, it wound't surprise me to find that not all of the surfaces are stalled. Main wings, sure, angle of attack goes to, maybe past, 90 degrees! But I'd bet the canards and tailplanes are still flying.

 

[Venom800tt]

The only US planes in service right now that can do the Cobra, or something close are the F-22 Raptor and F/A-18E/F Super Hornet. The F-22 not only can do the Cobra, but all sorts of crazy maneuvers too. The Super Hornet is also extremely agile, and technically could pull a cobra, although I don't know if anyone has tried to do a complete one.
http://www.youtube.com/watch?v=e_Q6Vb9xJM0 <- F-22 Raptor demo
http://youtube.com/watch?v=GW2Hvu_mUdU <- another F-22 demo
http://www.youtube.com/watch?v=FKPuGhNRmyE <- F/A-18F Super Hornet demo
Other than those two the F-14 could nearly perform the Cobra, but the plane is too stable to fully complete one if I recall. Various experimental aircraft could also do it such as the X-31 EFM, F-16 VISTA, and F/A-18 HARV.

 

[CDailey]

Those videos are sick 👍

 

[superberkut]

Following this thread, I want to thank you all for your answers at this moment. I now know more about Pugachev's Cobra than I know about aircraft!

That said, does anyone know if the MiG 1.42/1.44 pull off Pugachev's Cobra? It is still an experimental jet, but canards and thrust-vectoring are present. However, it is a rather large plane, raising questions on airframe durability.

P.S: To the person who gave the information on American fighters that can execute Pugachev's, does the F15S/MTD count? It was actually deployed for combat, but only for a short time. Or did you mean currently in the USAF's inventory? NASA has an example, refitted with swiveling conventional nozzles to become the F15 ACTIVE, as opposed to the flaps on the original, but that's it...