Cobra maneuver

The cobra maneuver requires more than just pilot input and aircraft maneuverability to be performed. Since the maneuver requires the aircraft to not lose or gain substantial altitude during the maneuver, the change of alpha during the vertical pitchup has to be fast enough to break the airflow of the wings, as to not make the aircraft climb. To be able to perform this rapid vertical pitchup the aircraft needs an "aerodynamic instability" in its core aerodynamics which will make the aircraft rapidly pitch up by itself once the elevator of the aircraft is pitched to the point where it breaks the airflow during a pitch up; but also post-stall control and stability to not enter an uncontrollable stall at the peak of the pitch; which then allows the aircraft to center the elevator and using the torque from the elevators added drag to pitch forward and make an aerodynamic recovery to horizontal flying again.[1]

Only specific aircraft feature this "instability" and thus the maneuver can only be performed by a small number of aircraft models. This is because conventional aircraft are designed to lack this instability for safety reasons, and can thus not execute the maneuver by conventional means.

Simply put, the cobra relies more on the core aerodynamics of the aircraft than its control surfaces and avionics and can thus only be performed by specific aircraft featuring aerodynamics allowing for the maneuver.

Cobra maneuver schematic of the Su-27. It is one of the tests of supermaneuverability for the Su-27.

In the case of the Su-27, to execute the maneuver the pilot initially disengages the angle of attack limiter of the plane, normally set at 26°.[3] This action also disengages the g limiter. After that, the pilot pulls back hard on the stick. The aircraft reaches an angle of attack of 90–120° with a slight gain of altitude and a significant loss of speed. When the elevator is centered, the drag at the rear of the plane causes a torque that makes the aircraft pitch forward. At the same time, the pilot adds power to compensate for the reduced lift.

If pursued by an enemy fighter in a dogfight, by executing the cobra, a sufficiently closely pursued aircraft may suddenly slow itself down to the point that the pursuer overshoots it, allowing the previously pursued aircraft to complete the cobra behind the other. This may allow the now-pursuing aircraft an opportunity for firing its weapons, particularly if a proper pointing aspect (facing toward the former pursuer) can be maintained. Due to the speed loss when performing a cobra, maintaining weapons on target may require the use of thrust vectoring and/or canard control surfaces. Otherwise, the maneuver may also allow the pursued plane to flee as the overshooting attacker may lose track of the target.

The maneuver is also potentially a defense against radar, as the sudden change in velocity can often cause Doppler radars to lose their lock on the target.[11] Doppler radars often ignore any objects with a near-zero velocity to reduce ground clutter. The cobra maneuver's sudden change to near-zero velocity often results in the target being momentarily filtered off as ground clutter, making it difficult for the radar to lock onto the target, or breaking the target lock if already established. However, there is no available documentation of this being tested beyond theory.

While the cobra maneuver may appear to be a useful force of the overshoot, the tactic would almost never be employed in any active threat scenario for a variety of reasons. The most obvious of these is the extreme loss of speed. Assuming the defending aircraft successfully forces the aggressor to overshoot the attack, the defender often does not have enough energy to counter-attack. The second more prevalent reason for avoiding the use of the maneuver is taught in most fighter pilot training. When attacking an aircraft, the pilot must be mindful of the closure-rate between both aircraft. If the closure rate is too high, the defender can change direction rapidly, which denies the attacker a shot opportunity, and thereby decreases the Probability of kill. However, if the attacker manages their speed and rate of closure properly, a cobra maneuver would just present the attacker with a larger target to shoot. (Due to the increased presented surface area when the defender is oriented vertically)

The cobra maneuver has been used in mock dogfights but there is little to no known documentation of it being used in actual combat. One primary described mock dogfight was fought between a Saab 35 Draken and a Saab 37 Viggen in Swedish service, where the latter pursued the former, when the former suddenly performed a Cobra and got the latter to overshoot. Existing material of this mock dogfight does not cover the elements of the engagement before and after the maneuver in detail, which would be useful in assessing its usefulness in modern combat. Reflective discussions from the pilots does however say that the maneuver was a useful combat move if performed correctly, with the caveat that it was only really effective as a last ditch maneuver due to the loss of speed when performed.[2]

Swedish Saab 35 Draken (J 35A, a/f 35076) during camouflage tests in the early 1960s.

During the early 1960s, the maneuver was developed and performed by Swedish pilots flying the Saab 35 fighter jet.[12] It was invented during training for recovery from super stalls (also known as deep stalls) to which the double delta tailless design of the Saab 35 is susceptible.[13] A super stall is an uncontrollable stall which is much harder to recover from than a standard stall. Super stall plagued the early years of Saab 35 service, causing several deaths, which led the Swedish air staff to implement extra training on how to counteract and recover from them.[12] The result was the cobra maneuver. The Swedes named the maneuver "kort parad" (short parry) after a fencing maneuver of the same name, known as "beat parry" in English. When pulling high alpha, the pilot would have noticed that he was entering super stall, and would then have pulled negative alpha to recover. The dramatic effect of this maneuver on aircraft speed was noticed and pilots started to purposely use it to drop speed.[12] The Swedish test pilots who discovered the cobra were Bengt Olow and Ceylon Utterborn, who developed the technique around 1961–1963.[14]

Saab 35 Draken

The Swedish pilots soon considered how to use this move in combat to get a pursuing aircraft to overshoot, putting it in a perfect position for a riposte, and it was not long until it was proven viable during mock dogfights.[12][2] In real combat, depending on the situation and the execution of the maneuver, it could be used to confuse the enemy by making it lose the target or to overshoot, which would allow the pursued pilot the opportunity to either flee from combat or re-engage. However, the maneuver was very difficult and dangerous to use as anything more than a last-ditch effort, as without precise execution the aircraft's slow speed after the maneuver would make it an easy target.[15]

The maneuver originated with the Bråvalla Wing, the first one to receive the Saab 35 fighter plane. As the fighter was adopted by other wings over time, so was the maneuver. The Scania Wing apparently called the maneuver "Wacka", which has no real meaning in Swedish.[2]

Sweden effectively shared borders with the Soviet Union over the Baltic Sea, so both sides regularly flew into the international space between the two. In the event, the Saab 35s regularly intercepted and escorted Soviet planes away from Swedish airspace. Sometimes these encounters would result in non-combat dogfights, which were either playful or threatening in nature.[12] Apparently, the cobra maneuver was used during some of these engagements, surprising the Soviets.[8] Late in the Saab 35's service life, the maneuver was used as a 'secret weapon' by Saab-35 pilots in mock dogfights facing the more advanced Saab 37 fighter. The Saab 37 was unable to safely enter super stalls, and therefore its pilots did not receive any major training against its use. The cobra maneuver was therefore unknown to many Saab 37 pilots prior to facing it in competition.[2] Due to the appeal of the tactic, some Saab 37 pilots attempted it, but to their dismay were unable to effectively perform it above speeds of 350 km/h (220 mph) as the Saab 37 couldn't safely handle the necessary gs, rendering it effectively useless in combat.[2]

When the Saab 35 was retired, so was the maneuver, as the next generations of Swedish warplanes, the Saab 37 and the Saab 39, couldn't effectively perform it. Due to the secrecy of the Cold War era and other factors, the Swedish cobra was largely unknown to the world until some former Saab 35 and 37 pilots wrote about it years later in books[2][12] and articles,[8][15] long after the Soviets had been credited with its discovery.

As Sweden exported the Saab 35 Draken, so was the cobra maneuver. Fighter variants of the Saab 35 was exported to both the Finnish Air Force and the Austrian Air Force.

In an interview, former Finnish Air Force pilot Ari Saarinen recalled performing the maneuver in a Draken while intercepting a Royal Air Force Hawker Siddeley Nimrod over the Baltic Sea; the Nimrod pilot reduced power in order to get the Finns to overshoot, but the Finnish Drakens performed the maneuver to slow down, which according to Saarinen drew praise over the radio from the British Nimrod crew.[9]

According to a video uploaded by the Scania Wing comrade association (Swedish: F10 Kamratförening), the Swedish cobra was taught to Austrian pilots training on the Saab 35 in Sweden.[16] It is unknown whether the Austrians used this as a combat maneuver or just as training against super stall.

Beyond Sweden, Syria also discovered the maneuver prior to the Soviets.

In 1961 when Syria left the United Arab Republic, they were left with a very weak air force. The Syrians had to order new combat aircraft, and procured the Mig-21F-13 in June 1962.[17] Once the aircraft had arrived and been integrated into the fleet, a problem became apparent. All of the unit commanders had been selected based on their political associations and loyalty to superiors, instead of knowledge of air combat. The new commanders were over-reliant on advice from about 30 Soviet advisors assigned to the Syrian Air Force to help with training on the Migs, but were generally ineffective. In this era of power over knowledge, however, a handful of pilots with powerful connections were able to disregard their Soviet advisors and orders from their commanders.[17]

One of these pilots, Mohammad Mansour, then a novice MiG-21-pilot fresh from a conversion course in the USSR, had an older brother, Fayez Mansour, with deep connections high in the chain of command in Damascus. Those connections enabled him to challenge Soviet advisors and demand greater operational flexibility for himself and other pilots of his unit.[17]

During Mohammed's first clashes with the Israeli Air Force, he realized that there was a need for an effective defensive maneuver in close combat that forced a pursuer to overshoot. His initial solution based on Soviet manuals consisted of rapid descending turns followed by a sudden activation of the afterburner and a climb. However, during a test flight in early 1967, Mohammad inadvertently pitched the nose of his MiG-21 too hard, so that the forward movement of his aircraft nearly stopped. In reaction, he engaged the afterburner of his MiG, and ended with the plane standing vertically on the verge of stalling out of control. Mohammad managed to recover the plane from that state, just in time to prevent a crash. Intrigued, he decided to try to replicate the maneuver in a controlled manner, this time by engaging the afterburner beforehand, as the Tumansky R-11 engine of the MiG-21 had to spool for full effect. After successful replication of the maneuver, it became clear that this was the close combat defensive maneuver that he sought.[17]

The Syrians named the cobra the "zero-speed maneuver" (Arabic: مناورة السرعة صفر "munawarat alsureat sifr"). Mohammad soon saw combat again with the Israeli Air Force but never got to use the maneuver.[17] The cobra quickly became a standard part of defensive tactics for Syrian Mig-21s.

Egyptian MiG-21

With time, as their air forces were stationed in Syria, the maneuver spread to both the Pakistan and Egyptian air force, who also began using it as a standard defensive maneuver for their MiG-21s.[17]

The cobra maneuver may have been performed in combat by an Egyptian pilot during the Yom Kippur War, but the theory is based on a quote from an Israeli pilot that only mentions an Egyptian MiG-21 apparently standing on its tail while trying to evade an attack.[17]

Research and developments on supermaneuverability started in USSR in the early 1980s by Central Aerohydrodynamic Institute, Gromov Flight Research Institute, Sukhoi and Mikoyan.[18]

In flight testing the Su-27 test pilot Igor Volk was the first to perform the maneuver in that aircraft in practice. Viktor Pugachev was the first who publicly demonstrated the maneuver in the Su-27 aerobatics display at the Le Bourget airshow of 1989.[18]

Soviet Sukhoi Su-27

The cobra maneuver came to public attention when Soviet test pilot Viktor Pugachev performed it at the Le Bourget Paris air show in 1989 using a Sukhoi Su-27.[3] The tactic was previously unknown to the public and it was quickly named after Pugachev.[19]

• F10 Kamratförening – Tisoe, Johan Röds Sista
• Aviation Technology Space Channel – SU 27 - Cobra
• NTPS national test pilots school — Saab Draken SK-35 Erect SuperStall (tail cam)
• NTPS national test pilots school — Inverted Super Stall
• NTPS national test pilots school — Erect Superstall, Abrupt Entry