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Kulbit

The Kulbit (Russian: Кульбит, meaning "somersault") is an advanced aerobatic maneuver developed by Russian pilots, in which a supermaneuverable fighter aircraft executes an extremely tight vertical loop—often no wider than the length of the aircraft itself—resulting in a full 360-degree rotation that reverses the plane's heading while maintaining positive pitch throughout.^[1] This high-angle-of-attack supermaneuver demands precise thrust vectoring and exceptional aircraft stability to avoid stalls, typically entered at low speeds around 350 km/h with the nose pitching up sharply to vertical before completing the somersault.^[1] It is classified as a post-stall maneuver, building on earlier tactics like Pugachev's Cobra but with a continuous, higher pitch rate that enables the full loop without deceleration-induced loss of control.^[2] Originating in the 1990s during testing of thrust-vectoring prototypes, the Kulbit was first publicly demonstrated by the Sukhoi Su-37 "Super Flanker" at the 1996 Farnborough Airshow, where it showcased the potential of 3D thrust vector control for enhanced agility in dogfights.^[1] The name "Frolov's Chakra" alternatively honors Russian test pilot Yevgeni Frolov, who first performed the maneuver, reflecting its roots in Soviet-era supermaneuverability research aimed at outturning Western fighters like the F-16.^[3] Subsequent demonstrations by aircraft such as the Su-30MKI and Su-35 have highlighted its tactical value, as the rapid directional reversal can force a pursuing enemy to overshoot, positioning the performer for a tail-chase advantage.^[4] The Kulbit requires specialized avionics and engines with thrust vectoring nozzles, limiting it to a select group of modern fighters including Russia's Su-30, Su-35, and Su-57, as well as the F-22 Raptor.^[5] While primarily a showcase for airshows and flight demonstrations—such as those by the Indian Air Force's Su-30MKI squadron or Russia's Knights aerobatic team up to 2025—it underscores advancements in fly-by-wire systems and aerodynamic control that push the boundaries of post-stall flight without compromising pilot safety.^[6] Risks include high G-forces, mitigated by automated flight controls in capable airframes.^[7]

Description

Definition

The Kulbit is an extremely tight, closed-loop aerobatic maneuver performed by advanced fighter aircraft, in which the aircraft rapidly pitches up to a near-vertical attitude, enters a stall, and executes a full 360-degree rotation around its tail while maintaining a turning radius often comparable to the aircraft's own length.^[1]^[8] This post-stall supermaneuver involves minimal forward progress and altitude gain, relying on thrust vectoring to sustain control beyond conventional aerodynamic limits.^[7] The name "Kulbit" derives from the Russian word kulbit, meaning somersault, reflecting the maneuver's backward-flipping motion.^[9] It is also referred to as the "Frolov chakra," a term evoking a circular rotation akin to a wheel.^[1] From a visual perspective, the Kulbit presents the aircraft as if it is tumbling end-over-end in a compact loop, with the nose tracing a tight vertical circle while the tail acts as the pivot point, all under controlled post-stall conditions.^[7] This distinguishes it as a more extreme variation of the Pugachev's Cobra, extending the partial pitch-up into a complete 360-degree loop.^[7]

Key Characteristics

The Kulbit maneuver is characterized by its exceptionally tight loop diameter, often described as extremely small relative to the aircraft's size, enabling a full 360-degree rotation in a compact vertical plane that distinguishes it from conventional aerobatic loops.^[10]^[7] This tight radius, typically on the order of the aircraft's length, results from controlled post-stall dynamics where the aircraft inverts and recovers while maintaining directional control.^[7] A defining attribute is the drastic speed reduction during execution, transitioning from low subsonic entry speeds of around 350–400 km/h (Mach ≈0.3) to near-stall conditions, with airspeeds dropping significantly, sometimes below 50 knots in the loop phase, before relying on thrust for reacceleration.^[1]^[7] This deceleration, approximately 0.1 Mach loss in post-stall regimes, places the aircraft in a low-energy state, emphasizing the maneuver's reliance on initial momentum for completion.^[7] The Kulbit involves extreme angles of attack, with peaks reaching 90 degrees and sustained high-alpha conditions up to 70 degrees, enabling a continuous 360-degree pitch rotation to complete the loop.^[7] G-forces during the pitch-up and recovery phases typically peak at 5-7g, with longitudinal loads around 4 Gx and intermittent negative Gz, subjecting the airframe and pilot to intense but brief accelerations.^[7] Entry and exit occur at full stall, where aerodynamic control diminishes, and recovery depends on thrust vectoring to manage the unstable energy state.^[7]

History

Origins

The Kulbit maneuver emerged in the late 1980s and early 1990s as part of Soviet and Russian efforts to advance supermaneuverability in fighter aircraft, driven by thrust-vectoring experiments aimed at improving dogfight performance. These developments were rooted in the need to enhance close-combat capabilities for Soviet designs, allowing pilots to execute post-stall maneuvers that could evade or outposition adversaries in simulated engagements. Research began as early as 1983 when the Sukhoi Design Bureau initiated work on thrust vectoring under a Soviet government directive for the Su-27M program, focusing on nozzle technologies to redirect engine exhaust for greater control at low speeds and high angles of attack.^[11]^[12] Building directly on earlier post-stall techniques, the Kulbit extended the principles demonstrated in the Pugachev's Cobra maneuver, first performed in 1989 on Su-27 prototypes. While the Cobra—a variant of the Herbst turn—involved a sudden pitch-up to stall followed by a quick recovery, the Kulbit pushed this further into a complete 360-degree loop at near-stall conditions, leveraging advanced thrust vectoring for stability and control. This evolution was tested extensively on Su-27 variants during the early 1990s, as part of broader aerodynamic studies to refine supermaneuverable flight envelopes.^[13]^[5] The Sukhoi design bureau led the Kulbit's development, motivated by simulations showing Western fighters like the F-15 Eagle and F-16 Fighting Falcon dominating beyond-visual-range engagements, prompting a focus on within-visual-range superiority through radical maneuvers. Conceptual work intensified around 1990-1992, aligning with the maturation of the Su-37 prototype program, which integrated 2D thrust-vectoring nozzles to enable such feats. These efforts reflected a strategic push to counter perceived U.S. advantages in air superiority tactics.^[14]^[12] The maneuver received its public debut in 1995 at the Paris Le Bourget Air Show, performed by test pilot Evgeny Frolov on the Su-37 prototype.^[15]

Notable Demonstrations

The Kulbit maneuver gained international attention through its debut public performance at the 1995 Le Bourget Air Show in Paris, where Russian test pilot Evgeny Frolov executed it in the Sukhoi Su-37, showcasing the revolutionary capabilities of thrust-vectoring technology for the first time to a global audience.^[16] This demonstration highlighted the maneuver's potential for extreme post-stall aerobatics, drawing widespread acclaim and marking a pivotal moment in aviation displays. Following its introduction, the Kulbit became a staple in subsequent air shows, including a striking presentation at the 1996 Farnborough International Airshow, where the Su-37 again performed the tight loop under Frolov's control, emphasizing its 360-degree pitch-up and brief tail-first hover.^[17] The maneuver featured regularly at the MAKS Air Shows in Moscow from 1995 onward, evolving into a signature element of Russian aviation exhibitions with aircraft like the Su-35 executing it in high-profile routines, such as the intense display at MAKS 2017 that included the full somersault at near-stall speeds.^[18] In the 2000s, the Indian Air Force demonstrated the Su-30MKI variant's proficiency in the Kulbit during joint exercises and air displays, underscoring its adoption beyond prototype testing and integration into operational fleets.^[19] The maneuver has been reportedly incorporated into Russian Air Force pilot training curricula since the early 2000s for enhanced maneuverability skills. By the 2010s, demonstrations advanced to include multiple Kulbits in Su-35 routines at international events, pushing the limits of sequential post-stall loops and further illustrating the maneuver's maturation.^[20] Western aircraft have simulated Kulbit-like high-alpha maneuvers in public settings, with the F-22 Raptor demonstrating advanced post-stall capabilities at airshows including Aviation Nation.^[21] As of 2025, the Kulbit continues to be performed by advanced Russian aircraft such as the Su-57 at international airshows and by aerobatic teams like the Russian Knights.^[22] These showcases collectively elevated the Kulbit from an experimental feat to a benchmark of supermaneuverability in modern fighter aviation.

Mechanics

Aerodynamic Principles

The Kulbit maneuver relies on post-stall aerodynamics, where the aircraft operates beyond its critical angle of attack, typically 16–20 degrees, entering a regime of separated airflow that conventional control surfaces alone cannot manage. In this high-alpha environment, control is maintained through thrust vectoring and vortex-dominated flows, allowing sustained flight despite the loss of attached airflow over the wings.^[23] Lift generation shifts from primary reliance on wing camber to forebody and leading-edge vortices, which form at angles of attack exceeding 20–45 degrees and provide nonlinear lift augmentation. These vortices create low-pressure regions over the fuselage and wings, compensating for the drop in conventional lift coefficient (C_L) post-stall. Concurrently, drag coefficients spike dramatically due to flow separation and the high presented area, inducing rapid deceleration essential for achieving the tight turning radius characteristic of the Kulbit—often as small as 10–20 meters (comparable to half the aircraft's length). This drag-induced slowdown reduces forward momentum, enabling the aircraft to pivot around its center of gravity with minimal forward travel.^[5]^[21] The maneuver adheres to conservation of momentum principles, wherein initial kinetic energy is converted to rotational and potential energy during the aggressive pitch-up phase. As the aircraft decelerates, thrust vectoring redirects engine exhaust to counter stall inertia, providing the necessary torque for rotation while preventing uncontrolled departure. Recovery from the near-vertical attitude then reverses this process, with vectored thrust overcoming residual drag to reaccelerate and restore forward flight.^[24] Mathematically, the fundamental lift equation, L = \frac{1}{2} \rho V^2 S C_L, underscores these dynamics: here, air density \rho, velocity V, and wing area S contribute to force, but post-stall, C_L peaks near the critical angle before declining sharply, necessitating vortex lift and thrust augmentation to sustain positive lift. Thrust vectoring effectively modifies the net force vector, enhancing normal acceleration for the loop.^[23]

Execution Steps

To execute the Kulbit maneuver, the pilot must follow a precise sequence of inputs, relying on the aircraft's post-stall high-alpha aerodynamics for stability during the rotation. The process begins with an entry phase where the aircraft approaches at a speed of approximately 400-500 km/h (216-270 knots) with the nose pitched up 20-30 degrees. Full throttle is applied, and the pilot pulls back on the stick to initiate a controlled stall by rapidly increasing the angle of attack, reducing forward momentum while maintaining control authority. Thrust vectoring assists from entry to sustain the pitch rate, integrated with aerodynamic controls.^[2]^[25] In the subsequent pitch phase, the pilot applies rapid full elevator deflection to pitch the nose up 90-120 degrees, entering a post-stall attitude. Simultaneously, a coordinated roll input aligns the aircraft's longitudinal axis with the plane of the impending loop, ensuring the rotation remains tight and contained. This phase demands precise timing to avoid excessive sideslip.^[2]^[26] As the aircraft reaches the apex near vertical orientation, thrust vectoring nozzles are deflected downward to generate a rotational moment, flipping the tail over the nose and completing the 360-degree loop. The pilot maintains a steady pull of approximately 5g to sustain the positive pitch rate through the somersault.^[21]^[5] Recovery follows immediately as the nose passes through the horizon, with the pilot easing elevator input to level the wings at the original altitude. Afterburner is engaged to rapidly regain airspeed and energy, concluding the maneuver in 2-4 seconds total.^[21]

Requirements

Thrust Vectoring

Thrust vectoring, also known as thrust vector control, enables an aircraft's engine nozzles to redirect the exhaust flow away from the longitudinal axis, typically by up to ±15 degrees in pitch and yaw for 3D systems, to enhance control in pitch, yaw, and roll beyond what aerodynamic surfaces can achieve alone. This technology is pivotal for supermaneuverable fighters, allowing precise attitude adjustments at low speeds or high angles of attack where conventional controls lose effectiveness.^[27] In the Kulbit maneuver, thrust vectoring serves as the primary enabler by directing engine thrust rearward and upward during the post-stall phase, generating the torque required for the aircraft's tight 360-degree rotation while minimizing forward travel. The system compensates for the loss of lift and control authority in stalled flight, using coordinated nozzle deflection to initiate and sustain the loop. Thrust vectoring systems in supermaneuverable fighters integrate with the flight control system for rapid response.^[28] The development of thrust vectoring in Sukhoi designs progressed from 2D pitch-only capability in early Su-30 variants, powered by the AL-31FP engine with ±15-degree deflection, to advanced 3D systems in the Su-35, utilizing AL-41F1S engines that allow multi-axis control for superior post-stall performance. These evolutions prioritize hydraulic or electromechanical actuation for reliability under high-thrust conditions, with operations demanding at least 100% military power—often full afterburner—to maintain sufficient exhaust momentum during the maneuver.^[28] A key limitation is the dependence on engines equipped for vectoring, such as the AL-31F series with afterburner and specialized nozzles; without this, aircraft lack the thrust redirection needed to execute and recover from the Kulbit, as non-vectoring designs rely solely on aerodynamics that fail in deep stall.^[28]

Aircraft Specifications

To perform the Kulbit maneuver safely, an aircraft must possess a thrust-to-weight ratio exceeding 1.0, enabling sustained vertical climbs and rapid energy recovery during high-angle-of-attack operations.^[7]^[29] This ratio is achieved through powerful low-bypass turbofan engines equipped with afterburners, typically delivering 110-140 kN of thrust per engine in representative twin-engine configurations, such as the Saturn AL-31FP series used in Su-30 variants.^[29] These engines provide the necessary axial thrust for post-stall pointing and tight turning radii without excessive airframe stress.^[7] Structural integrity is paramount, with the airframe rated for load factors of at least +9g positive and -3g to -4g negative to withstand the torque and stall-induced loads during the maneuver.^[29] Reinforced tail sections and wings are essential to handle the asymmetric forces from thrust deflection and high-alpha flight, preventing flutter or deformation at angles of attack up to 70 degrees.^[7] These limits ensure the aircraft can endure the rapid transitions between positive and negative g-forces inherent in supermaneuvers.^[29] Control systems must incorporate fly-by-wire (FBW) architecture with specialized high-alpha software to maintain stability and authority in post-stall regimes.^[7] Relaxed static stability, managed through digital flight control laws like linear quadratic regulator (LQR) scheduling, allows for precise nose pointing via integrated thrust vectoring, which serves as a core component for executing the Kulbit.^[29] This setup provides pitch rates up to 30 degrees per second and enables carefree handling without pilot-induced oscillations.^[7] Aircraft size and weight optimizations favor lightweight fighters with empty weights under 20 tons to facilitate tighter turn radii and reduced inertia.^[29] Low wing loading, typically in the range of 300-400 kg/m², enhances lift at low speeds and high angles of attack, contributing to the maneuver's feasibility by minimizing stall speed and improving responsiveness.^[29] These attributes collectively lower the energy barriers for entering and recovering from the Kulbit.^[7]

Capable Aircraft

Russian Designs

The Sukhoi Su-37 served as the pioneering demonstrator for the Kulbit maneuver, featuring advanced 3D thrust vectoring with AL-37FU engines that enabled unprecedented post-stall aerobatics. Developed from the Su-35 prototype, it first flew in April 1996 and publicly debuted the Kulbit at the Farnborough International Airshow later that year, where test pilot Evgeny Frolov executed the tight 360-degree somersault at an entry speed of 350 km/h, pausing inverted before completing the loop and exiting at 60 km/h with a 30-degree nose-down attitude.^[1] The Sukhoi Su-30 series, entering operational service in the late 1990s, incorporates thrust vectoring in variants such as the Su-30MK, enhancing supermaneuverability for post-stall maneuvers like the Kulbit. Russian Su-30s and export models, including the Indian Air Force's Su-30MKI with its AL-31FP engines and canards, have routinely demonstrated the Kulbit in airshows since the early 2000s, showcasing the platform's agility in controlled high-alpha environments.^[30] Building on Flanker lineage advancements, the Sukhoi Su-35 integrates sophisticated 3D thrust vectoring via AL-41F1S engines, allowing for seamless execution of complex aerobatics including the Kulbit and its variants. This fourth-generation+ fighter has performed single and double Kulbits as standard elements in airshow routines, such as those at the MAKS International Aviation and Space Salon, highlighting its superior angular rates and stability at extreme attitudes.^[31] The Sukhoi Su-57, Russia's fifth-generation stealth fighter, features 3D thrust vectoring with AL-41F1 engines (upgraded to Izdeliye 30 in later variants), enabling advanced supermaneuverability including the Kulbit. Demonstrated in airshows such as the 2021 MAKS and international exhibitions, the Su-57 performs tight loops and post-stall tactics, emphasizing its role in modern aerial combat.^[32] Variants of the Mikoyan MiG-29, notably the MiG-29OVT demonstrator, achieve limited Kulbit capability through retrofitted RD-33OVT engines with full 3D thrust vectoring nozzles, providing omnidirectional control independent of angle of attack. Tested extensively since the early 2000s, including an eight-minute display at the 2005 MAKS airshow featuring tail-standing and other novel supermaneuvers, the MiG-29OVT emphasizes enhanced low-speed handling but has seen less emphasis on full Kulbit routines compared to Sukhoi designs.^[33]

Western and Experimental Aircraft

The Lockheed Martin F-22 Raptor, a U.S. Air Force stealth fighter equipped with 2D pitch-axis thrust vectoring nozzles on its Pratt & Whitney F119 engines, enables high-angle-of-attack maneuvers that include the Kulbit.^[34] With ±20 degrees of vectoring authority, the F-22 can perform post-stall loops such as the Kulbit, alongside the Herbst J-Turn and Pugachev's Cobra, as demonstrated in NASA propulsion research linking these capabilities to the aircraft's engine integration.^[10] While videos and simulations from airshows and flight testing in the 2000s depict Kulbit-like tight loops, official U.S. military confirmation of operational Kulbit execution remains unverified due to classified performance details.^[35] In the experimental domain, NASA's X-31 Enhanced Fighter Maneuverability demonstrator from the 1990s achieved post-stall tight turns comparable to aspects of the Kulbit through its innovative canard configuration, vane control surfaces, and 3D thrust vectoring paddles on modified GE F404 engines.^[36] On April 29, 1993, the X-31 executed a minimum-radius 180-degree turn at over 70 degrees angle of attack, exceeding conventional aerodynamic limits and validating post-stall technology for future fighters under the Department of Defense's Advanced Research Projects Agency program.^[36] This aircraft's 580 research flights at NASA's Dryden Flight Research Center highlighted the potential for Kulbit-similar supermaneuverability without full reliance on traditional control surfaces.^[37] Among other Western platforms, the Eurofighter Typhoon has undergone limited post-stall testing, leveraging its canard-delta wing design and fly-by-wire controls for high-angle-of-attack recovery, though it lacks production thrust vectoring.^[38] Ground tests of 3D thrust-vectoring nozzles for the EJ200 engine were conducted in the early 2000s, but integration into the airframe was not pursued for standard variants, restricting extreme maneuvers like the Kulbit to experimental evaluations.^[39] Similarly, the Lockheed Martin F-35 Lightning II exhibits potential for enhanced post-stall handling through software updates to its flight control laws, as explored in high-angle-of-attack wind tunnel and flight tests, but it does not feature thrust vectoring and is not configured for Kulbit as a standard capability.^[40] Western aircraft designs, including the F-22 and F-35, emphasize sustained supercruise, stealth integration, and sensor fusion over extreme post-stall agility, which diminishes focus on maneuvers like the Kulbit compared to vectored-thrust priorities in some international programs.^[34] This approach aligns with U.S. doctrine favoring beyond-visual-range engagements, where high subsonic maneuverability at 9g limits suffices without routine reliance on full-stall loops.^[41]

Applications

Airshow Performances

The Kulbit maneuver serves a prominent role in aerobatic displays, primarily to highlight the supermaneuverability of advanced fighter aircraft equipped with thrust vectoring, thereby demonstrating technological superiority to international audiences and potential export customers.^[5] As a crowd-pleasing element, it underscores the precision and control achievable at extreme angles of attack, often integrated into the standard routines of the Russian Aerospace Forces' aerobatic teams like the Russian Knights.^[21] In notable performances, the Kulbit is frequently combined with complementary post-stall maneuvers such as Pugachev's Cobra and tailslides to create dynamic sequences that emphasize the aircraft's agility. For instance, aerobatic teams have executed such routines with Su-35S and similar aircraft at international airshows, showcasing seamless transitions between high-alpha pitches and rolls that captivate spectators. These displays, performed in formation or solo, exemplify how the Kulbit enhances the overall narrative of a routine by building tension through tight, circular loops. Over time, airshow executions of the Kulbit have evolved from isolated single maneuvers to more complex iterations, including multiple consecutive Kulbits, allowing pilots to push the boundaries of visual spectacle while maintaining safety margins. This progression is evident in demonstrations by aircraft like the MiG-29OVT, which has performed double Kulbits at international events, reflecting advancements in pilot training and aircraft handling.^[33] The maneuver has also appeared in non-Russian routines, such as those by Su-30 variants at events like the Singapore Airshow during the 2010s, broadening its global appeal in aerobatic competitions. To enhance visibility and dramatic effect, Kulbit performances are commonly augmented with colored smoke trails, which trace the aircraft's path and make the tight loop more discernible from the ground, symbolizing the pinnacle of modern flight control technology. This visual emphasis not only amplifies audience impact but also reinforces the maneuver's status as an icon of aviation prowess. The Kulbit was first publicly demonstrated in 1996 at the Farnborough Airshow by test pilot Evgeny Frolov in a Su-37.^[1]

Tactical Uses

The Kulbit maneuver provides a key evasion capability in close-range aerial combat by enabling a rapid 180-degree reversal of direction, which can cause a pursuing aircraft to overshoot due to the sudden deceleration and tight loop. This tactic leverages the aircraft's supermaneuverability to disrupt the attacker's alignment, particularly effective at distances under 1 km where visual identification and gun or short-range missile engagements dominate.^[21] In dogfighting scenarios, the Kulbit allows pilots to swiftly reorient the aircraft—completing the full loop in mere seconds—to position weapons against the former pursuer, turning a defensive situation offensive. Russian forces have incorporated such supermaneuverable tactics into training exercises to simulate engagements against agile opponents like the MiG-29, emphasizing thrust vectoring for positional dominance.^[42] However, the maneuver's practical limitations stem from substantial energy loss during the high-angle-of-attack loop, which reduces airspeed and altitude, constraining immediate follow-on actions and increasing vulnerability to counterattacks. It proves most viable against less agile threats, such as legacy surface-to-air missile systems lacking advanced tracking, rather than in sustained or beyond-visual-range fights.^[43]

Risks

Physiological Effects

Performing the Kulbit maneuver imposes significant physiological stresses on pilots due to rapid changes in acceleration and orientation. During the tight 360-degree loop, pilots encounter longitudinal accelerations of approximately 4 Gx accompanied by some negative Gz, as simulated in dynamic environment centrifuges. These forces, combined with thrust vectoring, result in short-duration positive Gz peaks up to +9 Gz in comparable push-pull profiles, with onset rates as high as 15 G per second.^[44] Sustained exposure to +6 Gz or higher causes blood to pool in the lower body, reducing cerebral blood flow and potentially leading to gray-out (loss of peripheral vision) or blackout without the use of anti-G suits.^[45]^[46] The maneuver's extreme pitch rates (up to 25 degrees per second) and roll (30-50 degrees per second) in a post-stall regime induce spatial disorientation, as the rapid decoupling of the aircraft's attitude from its velocity vector overwhelms vestibular and visual cues. Pilots must rely on instruments rather than external references to maintain orientation, increasing cognitive workload and the risk of vertigo, particularly in poor visibility conditions.^[44] No G-induced loss of consciousness occurs if peaks remain below +9 Gz for under one second, thanks to cerebral oxygen reserves, but prolonged exposure heightens this danger.^[44] To tolerate these demands, pilots undergo centrifuge-based training to simulate G-onset and practice anti-G straining maneuvers (AGSM), which involve muscle tensing to maintain blood flow to the brain. Russian pilots, drawing from cosmonaut programs, demonstrate enhanced G-tolerance, enduring peaks of 8-9 Gz through rigorous preparation that includes multidirectional acceleration exposure.^[46]^[47]^[48] Health risks include acute neck strain from head movements under high Gz, with pilots experiencing significant neck loads, equivalent to 100-250 pounds or more on the cervical spine during high-G maneuvers with rapid head movements.^[45]^[44]^[49] Repeated exposure contributes to chronic neck and back pain, degenerative disc disease, and reduced mobility, though advanced anti-G suits like the Libelle prototype mitigate arm fatigue and visual impairments during short bursts. At +4 Gz, pilots may notice shifts in visual perception, such as loss of blue hues, while speech remains intelligible up to +9 Gz.^[44] Despite these risks, no known pilot injuries have been publicly reported from performing the Kulbit in operational or demonstration flights as of November 2025.

Structural Demands

The Kulbit maneuver places extraordinary demands on the aircraft's airframe due to the extreme angles of attack exceeding 60 degrees and rapid angular accelerations, resulting in multi-axis load factors that challenge structural integrity. During the maneuver, the aircraft experiences peak longitudinal accelerations up to 4 Gx accompanied by negative Gz loads, contributing to torsional stresses on the tail and empennage.^[7] In broader post-stall contexts, these loads can escalate to transient peaks of +15 Gz and -10 Gz, with onset rates reaching 15 G/s, though design limits typically cap sustained loads at 9 G to prevent overload.^[7] The wings must accommodate significant flexing to mitigate aeroelastic flutter at high alpha, while the overall structure endures uneven load distribution from thrust vectoring inputs. Material selection for Kulbit-capable aircraft emphasizes fatigue-resistant alloys and composites to withstand repeated high-stress cycles. Titanium alloys are extensively used in critical areas for their high strength-to-weight ratio and corrosion resistance, particularly in engine nacelles and high-heat zones, while advanced composites form portions of the skin and control surfaces to reduce weight without compromising durability.^[50] For the Su-35, the airframe incorporates these materials to achieve a service life of approximately 6,000 flight hours, reflecting rigorous testing for supermaneuverable operations.^[51] Key failure modes during the Kulbit include potential structural exceedance from G-transients and control surface departure at post-stall angles of attack, which can lead to loss of authority or spin entry.^[7] These risks are mitigated through redundant hydraulic systems for flight controls and carefree handling qualities designed into the airframe, ensuring recovery without pilot overload. Engine surge from wake ingestion at high alpha is another concern, addressed by robust inlet designs and thrust vectoring that maintains airflow stability. Post-maneuver maintenance protocols mandate detailed inspections for fatigue cracks and stress concentrations, particularly in the empennage and vectoring nozzles, to maintain airframe longevity.^[7] No structural failures from the Kulbit have been reported as of November 2025.

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Vectored Thrust | Glenn Research Center - NASA
Jul 2, 2025 · The ability to change the angle of the thrust is called thrust vectoring, or vectored thrust. Vector Quantities. Forces are vector quantities ...
[24]
AL-31F turbofan engine - GlobalSecurity.org
Sep 13, 2021 · The AL-31FP version incorporates a thrust vectoring nozzle. Modernization of the engine included the installation of a FADEC-type digital ...
[25]
[PDF] NASA Aeronautics Book Series - Flying Beyond the Stall: The X-31 ...
The X-31 had a 40 percent higher thrust-to-weight ratio, a 35 per- cent lower wing loading, a 30 percent higher maximum g-limit, and twice the thrust-vectoring ...
[26]
Su-30
### Summary of Sukhoi Su-30 Thrust Vectoring and Supermaneuvers
[27]
New Russian Su-35S Super-Maneuverability Display Wows MAKS ...
Jul 21, 2017 · Video of Sukhoi's Su-35 super-maneuverable aircraft flying an impressive new demonstration routine at the MAKS airshow in Russia this week has gone viral on ...Missing: Kulbit | Show results with:Kulbit
[28]
MiG-29OVT FULCRUM - GlobalSecurity.org
Sep 7, 2011 · "Three-dimensional thrust vectoring will make MiG-29M/M2 control more precise and confident, practically independent from the angle of attack, ...
[29]
F-22 Raptor > Air Force > Fact Sheet Display - AF.mil
The sophisticated F-22 aerodesign, advanced flight controls, thrust vectoring, and high thrust-to-weight ratio provide the capability to outmaneuver all ...
[30]
F-22 Raptor - Lockheed Martin
Discover the F-22 Raptor, the ultimate military plane with unmatched air dominance capabilities. Learn more about this fighter jet at Lockheed Martin.
[31]
X-31 Enhanced Fighter Maneuverability Demonstrator - NASA
On April 29, 1993, the second X-31 successfully executed a minimum radius, 180-degree turn using a post-stall maneuver, flying well beyond the aerodynamic ...
[32]
X-31 - NASA
Feb 15, 2016 · With nose strakes added to increase stability, the aircraft exhibited remarkable “post-stall” maneuverability, such as a 180° turn at an ...
[33]
Eurojet pushes thrust-vectoring technology for Typhoon - FlightGlobal
Oct 18, 2009 · The proposal is to integrate a thrust vectoring capability with the twin-engined Typhoon's digital flight-control system so that it effectively functions as an ...
[34]
Thrust vectoring for eurofighter - the first steps - ResearchGate
Aug 6, 2025 · Thrust vector control (TVC) might be used to control aircraft at large altitudes and in post-stall conditions when aerodynamic control surfaces ...
[35]
F-35A High Angle of Attack Testing - AIAA ARC
Modern fighters have the ability to maneuver in the post stall region, giving these planes a significant advantage in air-to-air combat.Missing: Lightning II capability
[36]
F-35A Lightning II > Air Force > Fact Sheet Display - AF.mil
The F-35A is an agile, versatile, high-performance, 9g capable multirole fighter that combines stealth, sensor fusion and unprecedented situational awareness.Missing: stall | Show results with:stall
[37]
МиГ-29ОВТ MIG-29OVT DOUBLE KULBIT MANEUVER ... - YouTube
Nov 3, 2017 · This content isn't available. МиГ-29ОВТ MIG-29OVT DOUBLE KULBIT MANEUVER (FROLOV CHAKRA). 27K views · 8 years ago ...more. KNIGHT FLIGHT VIDEO.
[38]
Sukhoi Su-30 MKM Fighter Shows Off Thrust Vectoring Maneuvers ...
Mar 10, 2016 · At the recent Singapore Airshow, we had the rare chance to see an example of thrust-vectoring maneuverability at its best with the Russian-built Sukhoi Su-30 ...Missing: Kulbit | Show results with:Kulbit
[39]
The Agile Threat : Su(khoi)Superagility
Two AL-31F afterburning bypass turbojet engines, each having a maximum thrust of 12,500 kgf, provide the plane with an excellent thrust-to-weight ratio and ...
[40]
Tactical maneuvering and engagement in modern air combat
Jun 30, 2025 · Air combat is based on simple geometric principles: relative position, speed, altitude, and angle of attack. These are the basics of what ...
[41]
None
Below is a merged summary of the Kulbit maneuver information extracted from RTO-TR-015, consolidating all details from the provided segments into a comprehensive response. To maximize density and clarity, I’ve organized key information into tables where appropriate, supplemented by narrative text for context and additional details. The response retains all mentioned information, including page references, G-forces, physiological effects, human factors, and URLs.
[42]
Aerospace Physical Effects - StatPearls - NCBI Bookshelf
High G force subjects the spinal column to significant stress. Pilots exposed to high G forces have an increased incidence of chronic neck and back pain ...
[43]
[PDF] Acceleration in Aviation: G-Force
Another technique for dealing with G forces is the anti -G straining maneuver. This is a physical technique where the aviator pushes air out of the lungs ...
[44]
Centrifuge training - Vegitel | Aerospace tours in Russia
Centrifuge training simulates G-loads for cosmonauts, using the TsF-18 to simulate space flight conditions, including g-load and microgravity.
[45]
Russia Working on New-Generation g-force Pilot Protection Gear
"The gear will protect the pilot from dynamic multidirectional g-forces during combat maneuvering. These forces pose danger of loss of consciousness, spine ...<|control11|><|separator|>
[46]
Aluminum Alloys for Aerospace Industry: Development & Applications
The lower wing and body skin of an aircraft are mainly subject to tension and are mostly made of 2xxx series Al alloys. The lower wing is made of 2324–T39 or ...
[47]
World's Best Dogfighters – F-15 & Su-35 Fighters - EurAsian Times
Jun 22, 2024 · The Su-35, however, shows improvements in this area, with an expected service life of six thousand flight hours. In comparison, the F-15C ...