Can an F-16 perform Pugachev's Cobra?

Question

I know that the F-16 VISTA tech demonstrator incorporated 2D thrust vectoring and could perform this maneuver. I also know that military variants of the F-16 are prevented from intentionally entering such extreme angles of attack via their flight limiters.

However, I also know one more thing; there is a switch just in front of the throttle that allows "manual pitch override". This disables the pitch-plane limiter of the FLCC to allow the pilot to recover from certain types of deep stalls when normally the flight limiters would freeze the control surfaces due to the detected extreme AOA.

The question is, can U.S. military-variant F-16s, with MPO enabled, perform a "Cobra" maneuver like Pugachev's Cobra?

Answer 1

No.

This would require a docile pitch behavior of the airframe up to approx. 110° angle of attack. The design of both the Su-27 and the MiG-29 is based on a geometry that has been carefully optimized by TsAGI to behave nicely over its full AoA range, a care that has not been spent by General Dynamics while designing the F-16. The specifications did not call for it, because the idea was to create a low-cost lightweight fighter to complement the heavy F-15.

However, even the F-15 is AoA limited because less care was spent on its aerodynamic refinement. At higher angles of attack, both the F-16 and the F-15 show a nasty pitch-up which cannot be controlled with the aerodynamic control surfaces - only thrust vectoring can manage this. Contrast this which the Su-27, which shows balanced and slightly negative (nose down) pitch moments over the full AoA range, so the limited control authority coupled with the aircraft's dynamics can make the Cobra maneuver possible.

Answer 2

It's a no - simply because of the AoA limiter.

Basically the MPO switch is only for getting out of a Deep Stall condition (the switch was added around Block 5).

For the F-16MATV program they removed the AoA limiter and tested it (including A-A) in the early 90s. It could do all the high Alpha stuff the YF-22 could do simple as really.

So yes it was Multi Axis Thrust Vectoring (MATV) not 2D - it had to be - the TV is basically providing the Yaw directional stability the tail cannot provide at high Alpha (not unique affects most single tail jets).

TV was going to be fitted to the entire fleet - the MATV had a GE engine but P&W had also started on one - but they decided it wasn't required.

Answer 3

In reality no. But in theory if no FLCS is present, according to the pitching moment coefficient (Cm) curve, then yes.

Please refer to the Cm curve from the NASA F-16 wind tunnel data in NASA TP-1538.

The nose-up moment (Cm > 0) below 65 deg AOA, typical to a relaxed static stability fighter aircraft, can provide considerable pitch rate. Owing to the kinetic energy of rotation, the attainable angles of attack exceeds the trim angles of attack (Cm = 0). The higher pitch rate by the nose-up moment, the greater is the dynamically attainable max angle of attack. Then the nose-down moment above 65 deg AOA enables the pitch motion to be stopped naturally.

Likewisely, the Cm curve of Su-27, F-18, Jas-39 and aft cg F-35B.

Su-27, by TsAGI at AIAA-1993:

F-18C:

Jas-39 by SAAB official document:

F-35B by AIAA-2019:

There's also a plot of F-15 Cm-CL chart, but as noted it's not a Cm-alpha chart. As you can see the F-15 is statically stable in a ranges of CL.

Answer 4

No, due, primarily, to the fact that the "cobra" maneuver is entirely useless in ACM/BFM. There is no need for the flight software to support such a maneuver. Any fighter pilot who left himself in a zero energy state after a purely defensive maneuver like the so-called "cobra" will find himself with a much-deserved missile up his tailpipe.

Pugachev's Cobra is an airshow maneuver, nothing more.