Basic fighter maneuvers
Encyclopedia
Basic fighter maneuvers (BFM) are tactical movements performed by fighter aircraft
during air combat maneuvering (also called ACM, or dogfight
ing), in order to gain a positional advantage over the opponent. BFM combines the fundamentals of aerodynamic flight and the geometry of pursuit with the physics of managing the aircraft's energy-to-weight ratio, called its specific energy. Maneuvers are used to gain a better angular position in relation to the opponent. They can be offensive, to help an attacker get behind an enemy, or defensive, to help the defender evade an attacker's weapons. They can also be neutral, where both opponents strive for an offensive position, or disengagement maneuvers, to help facilitate an escape.
ing. The development of BFM began with the first fighter aircraft, during World War I
.
Basic fighter maneuvers consist of tactical turns, rolls, and other actions to get behind or above an enemy, before the opponent can do the same. BFM are typically universal maneuvers which can be performed in most any fighter aircraft, and are usually considered to be training maneuvers. In actual air combat maneuvering, variations of these maneuvers may become necessary, depending on the different types of aircraft involved, the weapon systems each side is using, and the number of aircraft involved.
BFM are used in the three-dimensional arena of air combat, where maneuvers are not limited by simple two-dimensional turns, such as during a car chase. BFM not only relies on an aircraft's turn performance, but also on the pilot's ability to make trade-offs between airspeed (kinetic energy
) and altitude (potential energy
) to maintain an energy level that will allow the fighter to continue maneuvering efficiently. BFM also relies on the pilot's understanding of the geometry of pursuit within the three-dimensional arena, where different angles of approach can cause different rates of closure. The fighter pilot uses these angles not only to get within a range where weapons can be used, but also to avoid flying out in front of the opponent or crossing the enemy's flight path, called overshooting
.
The fighter pilot with the most advantageous position is usually above or behind the opponent, and is commonly called the attacker. Conversely, the pilot in the disadvantageous position is usually either below or ahead of the opponent, and is referred to as the defender. Most maneuvers are offensive, such as the "barrel roll attack," "high Yo-Yo," "low Yo-Yo," and "lag roll." Defensive maneuvers more often consist of turning very aggressively to avoid the attacker's guns, with maneuvers like the "break" and the "high Yo-Yo defense;" sometimes tightening the turn, sometimes relaxing it, and other times reversing the turn. The defender will usually maneuver to force an overshoot, or to extend the range enough to dive away and escape. However, other "last ditch" maneuvers are used by the defender when the attacker achieves a firing solution, or the defender's energy becomes depleted so that maximum turn performance cannot be maintained, such as "guns defense" or the "defensive spiral."
, and the "barrel roll
." However, the modern Immelmann differs from the original version, which is now called a "hammerhead turn." The original Immelmann was an effective maneuver in the early part of the war, but as aircraft technology advanced, and fighter engines became increasingly more powerful, it became a dangerous maneuver, because the opponent could climb and shoot the German fighters when they were almost motionless at the top of the turn." Development continued through each consecutive war, as aircraft and weapon systems became increasingly more advanced. Maneuvers such as the "combat spread" were first devised by pilots like Werner Molders
during the Spanish civil war
, while the energy-managing maneuvers called the "high and low Yo-Yos" were created by the Chinese pilot Yo-Yo Noritake, during World War II
. However, much of the modern energy-management techniques were only described scientifically after John R. Boyd developed his Energy-Maneuverability theory
during the Vietnam war
.
Primary maneuvers are those which are performed without respect to an enemy's position. These are often simple maneuvers, such as climbs, turns and rolls. Relative maneuvers are performed in relation to the motion of another aircraft. These are often more complex, including energy saving maneuvers, such as the high and low Yo-Yos, and repositioning maneuvers such as displacement rolls. It is easy to fall into the trap of considering BFM to be a series of set maneuvers providing a foolproof recipe for a dominant position. The reality is that BFM are a series of fluid and often improvised proactive and reactive actions, varying infinitely according to range, altitude, speed, aircraft type, weapons system type and any of an enormous range of other factors. An extremely successful tactic one day may yield unfortunate results if repeated the next day, and pilots often credit luck as a major factor.
BFM are normally considered to be individual maneuvers, where ACM is applied to the tactics behind dogfight
ing as a whole. In military training, BFM are often conducted against an adversary in the same type of aircraft. This allows the pilot to fly against a machine with known performance values and allows aircrew to build their awareness of important concepts such as sight picture, rates of closure and line of sight rates that are cues to being successful in the visual arena.
Dissimilar air combat maneuvers are advanced maneuvers performed by aircraft of two separate types (such as F-16 vs F/A-18). This training is valuable in that both pilots are not as aware of the performance capabilities and characteristics of the other aircraft and, therefore, must rely on the fundamental BFM principles and evaluation/decision making skills to maneuver to an advantageous position versus their opponent. Using BFM as the building blocks for multiple aircraft maneuvers, such as the finger four, loose deuce, and Thach weave
, pilots learn how to maneuver in situations involving one against one, one against two, or even one against many. This type of training, introduced during the last stages of flight school, is more like actual combat, and is the most beneficial for aircrew once basic BFM skills are mastered.
, and thrust-to-weight ratio
. Other limitations vary with speed and altitude, such as turn radius, turn rate, and the specific energy
of the aircraft. The fighter pilot uses BFM to turn these limitations into tactical advantages. A faster, heavier aircraft may not be able to evade a more maneuverable aircraft in a turning battle, but can often choose to break off the fight and escape by diving or using its thrust to provide a speed advantage. A lighter, more maneuverable aircraft can not usually choose to escape, but must use its smaller turning radius at higher speeds to evade the attacker's guns, and to try to circle around behind the attacker.
BFM are a constant series of trade-offs between these limitations to conserve the specific energy state of the aircraft. Even if there is no great difference between the energy states of combating aircraft, there will be as soon as the attacker accelerates to catch up with the defender. Instead of applying thrust, a pilot may use gravity to provide a sudden increase in kinetic energy
(speed), by diving, at a cost in the potential energy
that was stored in the form of altitude. Similarly, by climbing the pilot can use gravity to provide a decrease in speed, conserving the aircraft's kinetic energy by changing it into altitude. This can help an attacker to prevent an overshoot
, while keeping the energy available in case one does occur.
load, and varies with its structural design, weight, and thrust capabilities. It often falls in the area of 250 to 400 knots.
Instantaneous turn rate describes maximum g turns which cause a loss in energy, either in the form of speed or altitude. This loss may be compensated for, to a degree, by increasing thrust, known as "excess specific power." This usually occurs during hard turns or even harder breaks. Only by turning the aircraft at its best "sustained turn rate" can the aircraft maintain its specific energy. However, situations in combat may require a change in energy, and energy may also be increased by pulling less than the maximum sustained g-force.
as much as it does skill and stamina. Pilots must know their aircraft's corner speed, as well as optimum angles of bank (AOB) and angles of attack
(AOA), without consciously thinking about them. At the same time, pilots must remain conscious of the angle between the opponent's velocity vector and their own, called the angle off tail (AOT). A high AOT causes a high rate of closure, but makes achieving a suitable guns solution nearly impossible. Acquiring a low AOT, (getting on the enemies tail), can decrease or even reverse closure rate, and is usually the primary goal before an overshoot
occurs. However, an uncooperative defender may try to take advantage of the high closure rate by turning to increase AOT, forcing an overshoot.
The AOT is often estimated by the position of the attacking aircraft's nose in relation to the defender. AOT are generally grouped into three categories, called "pursuit curves." "Lead pursuit" occurs when the nose of the attacker points ahead of the defender, while "pure pursuit" happens when the attacker's nose points directly at the defender. If the attacker's nose points behind the defender the condition is known as "lag pursuit."
An attacker in lead pursuit is well within the defender's rear view. Unless the defender has enough of a speed advantage to escape by relaxing the turn and dropping into a shallow dive, the defender will likely turn sharply in an effort to increase the AOT, forcing the attacker to turn even harder, to overshoot, or to perform a maneuver out of the horizontal plane to compensate.
Lead pursuit is used during gun attacks, because the fast motion of combat requires that the aircraft's cannons be aimed at a point in space ahead of the defender, where the enemy will be when the bullets arrive. This is called "leading the target." Lead pursuit presents the attacker with difficulty in maintaining sight of the opponent, as the nose of the attacking aircraft becomes an obstruction to the pilot's view.
"Hot side" lag occurs when there is a large amount of forward separation between aircraft, showing the top side of the defending fighter. This puts the attacker in the defender's rear view, and the common defense is to tighten the turn. "Cold side" lag occurs when there is little separation, leaving the belly of the defending fighter in view. This puts the attacker in the defender's blind spot, and the common defense is to reverse the turn. Unless the defender is markedly more maneuverable, and lateral separation is just right, lag pursuit can not be maintained for long, causing the AOT to decrease until a suitable firing solution is presented.
An out-of-plane maneuver enhances this effect, by diverting the fighter into a new plane of travel. Increasing the pitch or slice can quickly provide a change in speed, which can just as quickly be reversed by returning to the original plane of travel. Out-of-plane maneuvers are not only used to provide a reduction in turn radius, but also causes the fighter to fly a longer path in relation to the direction of travel. A maneuver such as a high Yo-Yo is used to slow closure and to bring the fighter into lag pursuit, while a low Yo-Yo is used to increase closure and to bring the fighter into lead pursuit.
During an out-of-plane maneuver, the attacker's nose no longer points at the defender. Instead, the aircraft is rolled until its lift vector, (an imaginary line running vertically from the center of the aircraft, perpendicular to its wings), is aligned either ahead of, directly at, or behind the defender, using roll rate instead of turn rate to set the proper pursuit curve. The aircraft's velocity vector, (an imaginary line in the direction of motion) will be pulled in the direction of the lift vector.
s called displacement rolls, in order to shift the aircraft laterally from its projected flight path onto a new flight path. By controlling the roll rate the pilot can control the degree of displacement. An attacker following a more maneuverable opponent may become stuck in lag pursuit, (outside the defender's turn radius), unable to achieve a firing solution. By displacing the turn, the two aircraft's flight paths will eventually cross. The AOT will then decrease until the nose of the attacker's aircraft points momentarily at the defender, and then ahead of the defender. A displacement roll is a good tactic when ever a reduction in turn radius is needed, but a decrease in turn rate is allowed.
Once inside the defender's bubble, the attacker will be in lead pursuit and may have an opportunity for a lucky "snapshot" hit. If the attacker can maneuver onto the defender's flight path before an overshoot occurs, the attacker will be able to stop or reverse closure rate. The most desirable position is, following the defender's flight path, a distance equal to one turn radius behind the opponent. This position, from which the attacker will be able to safely maintain command of the fight, is termed the "control point."
One circle flow will result in another merge, unless an angular advantage can be obtained. During one circle flow, the fighter with the smaller turn radius will have the advantage. Pilots will often pitch-up out-of-plane while increasing thrust, to help minimize turn radius. Since turn rate is of little importance during one circle flow, it is often called a radius fight. An out-of-plane maneuver, such as a displacement roll, is a viable option for reducing turn radius.
Two circle flow will also result in another merge. Two circle flow is a turn rate fight, and the angular advantage usually goes to the aircraft with the higher turn rate at its corner speed. Pilots will often slice turn in order to maximize their turn rate. In both types of flow, the closest possible merge is desirable to keep the enemy at an angular disadvantage. Although circle flow is often described using neutral merges, the concept applies anytime two aircraft maneuver in relation to each other and the horizon.
consists of performing a roll and a loop, completing both at the same time. The result is a helical roll around a straight flight path. The barrel roll attack uses a much tighter loop than the roll, completing a full loop while only executing 3/4 of a roll. The result is a virtual 90 degree turn, using all three dimensions, in the direction opposite of the roll. Rolling away from the defender's break, the attacker completes the roll with the aircraft's nose pointed in the direction of the defender's travel.
back to a safe altitude, restoring the potential energy. This allows the attacker to set up another attack and dive again. Surprise is often a key element in this type of attack, and the attackers will often hide in the sun or clouds, stalking their opponents until a good opportunity is presented. A high-side guns pass is a very effective tactic against a more maneuverable opponent, where the turning battle of a dogfight is best avoided.
s intended to slow the relative forward motion of the aircraft in an attempt to either force a dangerous overshoot, on the part of the defender, or prevent a dangerous overshoot on the attacker's part. The defender's goal is to stay out of phase with the attacker, trying to prevent a guns solution, while the attacker tries to get in phase with the defender. The advantage usually goes to the more maneuverable aircraft. There are two types of scissor maneuvers, called flat scissors and rolling scissors.
over the top, forcing the attacker to attempt to follow. The advantage lies in the aircraft that can pull its nose through the top or bottom of the turn faster. In battles with aircraft that have a thrust-to-weight ratio
of less than one the aircraft will quickly lose altitude, and crashing into the ground becomes a possibility. According to author Mike Spick, "Disengagement from a vertical rolling scissors is best made with a split-s and a lot of hope."
Fighter aircraft
A fighter aircraft is a military aircraft designed primarily for air-to-air combat with other aircraft, as opposed to a bomber, which is designed primarily to attack ground targets...
during air combat maneuvering (also called ACM, or dogfight
Dogfight
A dogfight, or dog fight, is a form of aerial combat between fighter aircraft; in particular, combat of maneuver at short range, where each side is aware of the other's presence. Dogfighting first appeared during World War I, shortly after the invention of the airplane...
ing), in order to gain a positional advantage over the opponent. BFM combines the fundamentals of aerodynamic flight and the geometry of pursuit with the physics of managing the aircraft's energy-to-weight ratio, called its specific energy. Maneuvers are used to gain a better angular position in relation to the opponent. They can be offensive, to help an attacker get behind an enemy, or defensive, to help the defender evade an attacker's weapons. They can also be neutral, where both opponents strive for an offensive position, or disengagement maneuvers, to help facilitate an escape.
Introduction
Basic fighter maneuvers are actions that a fighter aircraft makes during air combat maneuvering or, historically known as, dogfightDogfight
A dogfight, or dog fight, is a form of aerial combat between fighter aircraft; in particular, combat of maneuver at short range, where each side is aware of the other's presence. Dogfighting first appeared during World War I, shortly after the invention of the airplane...
ing. The development of BFM began with the first fighter aircraft, during World War I
World War I
World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...
.
Basic fighter maneuvers consist of tactical turns, rolls, and other actions to get behind or above an enemy, before the opponent can do the same. BFM are typically universal maneuvers which can be performed in most any fighter aircraft, and are usually considered to be training maneuvers. In actual air combat maneuvering, variations of these maneuvers may become necessary, depending on the different types of aircraft involved, the weapon systems each side is using, and the number of aircraft involved.
BFM are used in the three-dimensional arena of air combat, where maneuvers are not limited by simple two-dimensional turns, such as during a car chase. BFM not only relies on an aircraft's turn performance, but also on the pilot's ability to make trade-offs between airspeed (kinetic energy
Kinetic energy
The kinetic energy of an object is the energy which it possesses due to its motion.It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its acceleration, the body maintains this kinetic energy unless its speed changes...
) and altitude (potential energy
Potential energy
In physics, potential energy is the energy stored in a body or in a system due to its position in a force field or due to its configuration. The SI unit of measure for energy and work is the Joule...
) to maintain an energy level that will allow the fighter to continue maneuvering efficiently. BFM also relies on the pilot's understanding of the geometry of pursuit within the three-dimensional arena, where different angles of approach can cause different rates of closure. The fighter pilot uses these angles not only to get within a range where weapons can be used, but also to avoid flying out in front of the opponent or crossing the enemy's flight path, called overshooting
Overshoot (aviation)
In aviation, an overshoot is an aborted landing. See: Go-around and Runway safety area.In air combat maneuvering, also called dogfighting, an overshoot can refer to three different situations. The first is referred to as a wingline overshoot...
.
The fighter pilot with the most advantageous position is usually above or behind the opponent, and is commonly called the attacker. Conversely, the pilot in the disadvantageous position is usually either below or ahead of the opponent, and is referred to as the defender. Most maneuvers are offensive, such as the "barrel roll attack," "high Yo-Yo," "low Yo-Yo," and "lag roll." Defensive maneuvers more often consist of turning very aggressively to avoid the attacker's guns, with maneuvers like the "break" and the "high Yo-Yo defense;" sometimes tightening the turn, sometimes relaxing it, and other times reversing the turn. The defender will usually maneuver to force an overshoot, or to extend the range enough to dive away and escape. However, other "last ditch" maneuvers are used by the defender when the attacker achieves a firing solution, or the defender's energy becomes depleted so that maximum turn performance cannot be maintained, such as "guns defense" or the "defensive spiral."
History
Basic fighter maneuver development began during World War I, with maneuvers such as the "Immelmann," named after German pilot Max ImmelmannMax Immelmann
Max Immelmann was the first German World War I flying ace. He was a great pioneer in fighter aviation and is often mistakenly credited with the first aerial victory using a synchronized gun...
, and the "barrel roll
Barrel roll
A barrel roll is an aerial maneuver in which an airplane makes a complete rotation on its longitudinal axis while following a helical path, approximately maintaining its original direction. It is sometimes described as "a combination of a loop and a roll"...
." However, the modern Immelmann differs from the original version, which is now called a "hammerhead turn." The original Immelmann was an effective maneuver in the early part of the war, but as aircraft technology advanced, and fighter engines became increasingly more powerful, it became a dangerous maneuver, because the opponent could climb and shoot the German fighters when they were almost motionless at the top of the turn." Development continued through each consecutive war, as aircraft and weapon systems became increasingly more advanced. Maneuvers such as the "combat spread" were first devised by pilots like Werner Molders
Werner Mölders
Werner Mölders was a World War II German Luftwaffe pilot and the leading German fighter ace in the Spanish Civil War. Mölders became the first pilot in aviation history to claim 100 aerial victories—that is, 100 aerial combat encounters resulting in the destruction of the enemy aircraft, and was...
during the Spanish civil war
Spanish Civil War
The Spanish Civil WarAlso known as The Crusade among Nationalists, the Fourth Carlist War among Carlists, and The Rebellion or Uprising among Republicans. was a major conflict fought in Spain from 17 July 1936 to 1 April 1939...
, while the energy-managing maneuvers called the "high and low Yo-Yos" were created by the Chinese pilot Yo-Yo Noritake, during World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
. However, much of the modern energy-management techniques were only described scientifically after John R. Boyd developed his Energy-Maneuverability theory
Energy-Maneuverability theory
Energy Maneuverability theory is a model of aircraft performance. It was promulgated by Col. John Boyd, and is useful in describing an aircraft's performance as the total of kinetic and potential energies or aircraft specific energy. It relates the thrust, weight, drag, wing area, and other flight...
during the Vietnam war
Vietnam War
The Vietnam War was a Cold War-era military conflict that occurred in Vietnam, Laos, and Cambodia from 1 November 1955 to the fall of Saigon on 30 April 1975. This war followed the First Indochina War and was fought between North Vietnam, supported by its communist allies, and the government of...
.
Training
Basic fighter maneuvers (BFM) are used by fighter pilots during a dogfight to gain a positional advantage over an opponent. Pilots must have keen knowledge of not only their own aircraft's performance characteristics, but also of the opponents, taking advantage of their own strengths while exploiting the enemy's weaknesses. Pilots need good eyesight, situational awareness, and the ability to maneuver against an opponent in three dimensions. BFM are generally grouped into two categories:- Primary BFM
- Relative BFM
Primary maneuvers are those which are performed without respect to an enemy's position. These are often simple maneuvers, such as climbs, turns and rolls. Relative maneuvers are performed in relation to the motion of another aircraft. These are often more complex, including energy saving maneuvers, such as the high and low Yo-Yos, and repositioning maneuvers such as displacement rolls. It is easy to fall into the trap of considering BFM to be a series of set maneuvers providing a foolproof recipe for a dominant position. The reality is that BFM are a series of fluid and often improvised proactive and reactive actions, varying infinitely according to range, altitude, speed, aircraft type, weapons system type and any of an enormous range of other factors. An extremely successful tactic one day may yield unfortunate results if repeated the next day, and pilots often credit luck as a major factor.
BFM are normally considered to be individual maneuvers, where ACM is applied to the tactics behind dogfight
Dogfight
A dogfight, or dog fight, is a form of aerial combat between fighter aircraft; in particular, combat of maneuver at short range, where each side is aware of the other's presence. Dogfighting first appeared during World War I, shortly after the invention of the airplane...
ing as a whole. In military training, BFM are often conducted against an adversary in the same type of aircraft. This allows the pilot to fly against a machine with known performance values and allows aircrew to build their awareness of important concepts such as sight picture, rates of closure and line of sight rates that are cues to being successful in the visual arena.
Dissimilar air combat maneuvers are advanced maneuvers performed by aircraft of two separate types (such as F-16 vs F/A-18). This training is valuable in that both pilots are not as aware of the performance capabilities and characteristics of the other aircraft and, therefore, must rely on the fundamental BFM principles and evaluation/decision making skills to maneuver to an advantageous position versus their opponent. Using BFM as the building blocks for multiple aircraft maneuvers, such as the finger four, loose deuce, and Thach weave
Thach Weave
The Thach Weave or Beam Defense Position is an aerial combat tactic developed by naval aviator John S. Thach of the United States Navy soon after the United States' entry into World War II....
, pilots learn how to maneuver in situations involving one against one, one against two, or even one against many. This type of training, introduced during the last stages of flight school, is more like actual combat, and is the most beneficial for aircrew once basic BFM skills are mastered.
Energy management
In combat, a pilot is faced with a variety of limiting factors. Some limitations are constant, such as gravity, dragDrag (physics)
In fluid dynamics, drag refers to forces which act on a solid object in the direction of the relative fluid flow velocity...
, and thrust-to-weight ratio
Thrust-to-weight ratio
Thrust-to-weight ratio is a ratio of thrust to weight of a rocket, jet engine, propeller engine, or a vehicle propelled by such an engine. It is a dimensionless quantity and is an indicator of the performance of the engine or vehicle....
. Other limitations vary with speed and altitude, such as turn radius, turn rate, and the specific energy
Specific energy
Specific energy is defined as the energy per unit mass. Common metric units are J/kg. It is an intensive property. Contrast this with energy, which is an extensive property. There are two main types of specific energy: potential energy and specific kinetic energy. Others are the gray and sievert,...
of the aircraft. The fighter pilot uses BFM to turn these limitations into tactical advantages. A faster, heavier aircraft may not be able to evade a more maneuverable aircraft in a turning battle, but can often choose to break off the fight and escape by diving or using its thrust to provide a speed advantage. A lighter, more maneuverable aircraft can not usually choose to escape, but must use its smaller turning radius at higher speeds to evade the attacker's guns, and to try to circle around behind the attacker.
BFM are a constant series of trade-offs between these limitations to conserve the specific energy state of the aircraft. Even if there is no great difference between the energy states of combating aircraft, there will be as soon as the attacker accelerates to catch up with the defender. Instead of applying thrust, a pilot may use gravity to provide a sudden increase in kinetic energy
Kinetic energy
The kinetic energy of an object is the energy which it possesses due to its motion.It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its acceleration, the body maintains this kinetic energy unless its speed changes...
(speed), by diving, at a cost in the potential energy
Potential energy
In physics, potential energy is the energy stored in a body or in a system due to its position in a force field or due to its configuration. The SI unit of measure for energy and work is the Joule...
that was stored in the form of altitude. Similarly, by climbing the pilot can use gravity to provide a decrease in speed, conserving the aircraft's kinetic energy by changing it into altitude. This can help an attacker to prevent an overshoot
Overshoot (aviation)
In aviation, an overshoot is an aborted landing. See: Go-around and Runway safety area.In air combat maneuvering, also called dogfighting, an overshoot can refer to three different situations. The first is referred to as a wingline overshoot...
, while keeping the energy available in case one does occur.
Turn performance
Both turn rate, (degrees per second), and turn radius, (diameter of the turn), increase with speed, until the "corner speed" is reached. At this point, the growing turn radius begins to decrease the turn rate, so the aircraft will reach its best turn performance at its particular corner speed. The corner speed of an aircraft is the minimum speed at which it can sustain the maximum g-forceG-force
The g-force associated with an object is its acceleration relative to free-fall. This acceleration experienced by an object is due to the vector sum of non-gravitational forces acting on an object free to move. The accelerations that are not produced by gravity are termed proper accelerations, and...
load, and varies with its structural design, weight, and thrust capabilities. It often falls in the area of 250 to 400 knots.
Instantaneous turn rate describes maximum g turns which cause a loss in energy, either in the form of speed or altitude. This loss may be compensated for, to a degree, by increasing thrust, known as "excess specific power." This usually occurs during hard turns or even harder breaks. Only by turning the aircraft at its best "sustained turn rate" can the aircraft maintain its specific energy. However, situations in combat may require a change in energy, and energy may also be increased by pulling less than the maximum sustained g-force.
Pursuit curves
Successful BFM requires geometryGeometry
Geometry arose as the field of knowledge dealing with spatial relationships. Geometry was one of the two fields of pre-modern mathematics, the other being the study of numbers ....
as much as it does skill and stamina. Pilots must know their aircraft's corner speed, as well as optimum angles of bank (AOB) and angles of attack
Angle of attack
Angle of attack is a term used in fluid dynamics to describe the angle between a reference line on a lifting body and the vector representing the relative motion between the lifting body and the fluid through which it is moving...
(AOA), without consciously thinking about them. At the same time, pilots must remain conscious of the angle between the opponent's velocity vector and their own, called the angle off tail (AOT). A high AOT causes a high rate of closure, but makes achieving a suitable guns solution nearly impossible. Acquiring a low AOT, (getting on the enemies tail), can decrease or even reverse closure rate, and is usually the primary goal before an overshoot
Overshoot (aviation)
In aviation, an overshoot is an aborted landing. See: Go-around and Runway safety area.In air combat maneuvering, also called dogfighting, an overshoot can refer to three different situations. The first is referred to as a wingline overshoot...
occurs. However, an uncooperative defender may try to take advantage of the high closure rate by turning to increase AOT, forcing an overshoot.
The AOT is often estimated by the position of the attacking aircraft's nose in relation to the defender. AOT are generally grouped into three categories, called "pursuit curves." "Lead pursuit" occurs when the nose of the attacker points ahead of the defender, while "pure pursuit" happens when the attacker's nose points directly at the defender. If the attacker's nose points behind the defender the condition is known as "lag pursuit."
Lead pursuit
The primary purpose for lead pursuit is to provide closure, even when chasing a faster opponent. The high AOT presented during lead pursuit allows the attacker to quickly decrease the separation between aircraft simply by traveling a shorter path. However, lead pursuit causes the AOT to increase at a rapid rate. This causes the closure rate to increase as well, and, in an attempt to prevent an overshoot, the attacker will have to pull an increasingly tighter turn upon nearing the defender.An attacker in lead pursuit is well within the defender's rear view. Unless the defender has enough of a speed advantage to escape by relaxing the turn and dropping into a shallow dive, the defender will likely turn sharply in an effort to increase the AOT, forcing the attacker to turn even harder, to overshoot, or to perform a maneuver out of the horizontal plane to compensate.
Lead pursuit is used during gun attacks, because the fast motion of combat requires that the aircraft's cannons be aimed at a point in space ahead of the defender, where the enemy will be when the bullets arrive. This is called "leading the target." Lead pursuit presents the attacker with difficulty in maintaining sight of the opponent, as the nose of the attacking aircraft becomes an obstruction to the pilot's view.
Pure pursuit
Like lead pursuit, pure pursuit is used to provide closure. However, closure is not as rapid, nor is the rate of increase in AOT. This is not as effective against a faster moving opponent, so the attacker may need to accelerate to maintain pure pursuit. Pure pursuit is used when acquiring a missile lock. It both places the attacker further aft of the defender and presents the defender with the smallest amount of surface area to see. This complicates evasive action, since only the front of the attacking aircraft is in view.Lag pursuit
Lag pursuit is used to stop or reverse closure rate and to decrease AOT, while allowing the attacker to maintain or increase forward separation. Following outside the defender's turn radius, the attacker can maintain or increase energy while forcing the defender to turn at an energy depleting rate."Hot side" lag occurs when there is a large amount of forward separation between aircraft, showing the top side of the defending fighter. This puts the attacker in the defender's rear view, and the common defense is to tighten the turn. "Cold side" lag occurs when there is little separation, leaving the belly of the defending fighter in view. This puts the attacker in the defender's blind spot, and the common defense is to reverse the turn. Unless the defender is markedly more maneuverable, and lateral separation is just right, lag pursuit can not be maintained for long, causing the AOT to decrease until a suitable firing solution is presented.
Out-of-plane maneuvers
Maneuvers are rarely performed in the strictly vertical or horizontal planes. Most turns contain some degree of "pitch" or "slice." During a turn in an oblique plane, a pitch turn occurs when the aircraft's nose points above the horizon, causing an increase in altitude. A slice turn happens when the nose points below the horizon, causing a decrease in altitude. The purpose is not only to make the aircraft harder for an enemy to track, but also to increase or decrease speed while maintaining energy.An out-of-plane maneuver enhances this effect, by diverting the fighter into a new plane of travel. Increasing the pitch or slice can quickly provide a change in speed, which can just as quickly be reversed by returning to the original plane of travel. Out-of-plane maneuvers are not only used to provide a reduction in turn radius, but also causes the fighter to fly a longer path in relation to the direction of travel. A maneuver such as a high Yo-Yo is used to slow closure and to bring the fighter into lag pursuit, while a low Yo-Yo is used to increase closure and to bring the fighter into lead pursuit.
During an out-of-plane maneuver, the attacker's nose no longer points at the defender. Instead, the aircraft is rolled until its lift vector, (an imaginary line running vertically from the center of the aircraft, perpendicular to its wings), is aligned either ahead of, directly at, or behind the defender, using roll rate instead of turn rate to set the proper pursuit curve. The aircraft's velocity vector, (an imaginary line in the direction of motion) will be pulled in the direction of the lift vector.
Displacement rolls
A useful type of out-of-plane maneuver employed to decrease AOT are various barrel rollBarrel roll
A barrel roll is an aerial maneuver in which an airplane makes a complete rotation on its longitudinal axis while following a helical path, approximately maintaining its original direction. It is sometimes described as "a combination of a loop and a roll"...
s called displacement rolls, in order to shift the aircraft laterally from its projected flight path onto a new flight path. By controlling the roll rate the pilot can control the degree of displacement. An attacker following a more maneuverable opponent may become stuck in lag pursuit, (outside the defender's turn radius), unable to achieve a firing solution. By displacing the turn, the two aircraft's flight paths will eventually cross. The AOT will then decrease until the nose of the attacker's aircraft points momentarily at the defender, and then ahead of the defender. A displacement roll is a good tactic when ever a reduction in turn radius is needed, but a decrease in turn rate is allowed.
Positioning
There are three basic situations in air combat maneuvering requiring BFM to convert to a favorable result, which are neutral, offensive, and defensive. Most relative maneuvers can be grouped into one of these three categories.Neutral
Neutral positions generally occur when both opponents spot each other at the same time. Neither the pilot nor the opponent have the advantage of surprise. Neither has the ability to point the nose of their aircraft at the opponent with sufficient range to employ forward firing ordnance (missiles/guns) prior to the opponent presenting a threat of a similar manner. Each is focused on converting to an offensive situation while forcing their opponent into a defensive.Offensive
An offensive position generally occurs when the pilot gets sight of the opponent first. With the advantage of surprise, the pilot can maneuver into a better position to attack the opponent, making it more difficult for the enemy to evade the attack. Common tactics include increasing altitude and attempting to place the fighter directly between the sun and the opponent. This helps put the pilot in a dominant position, primarily concerned with prosecuting their advantage for a kill. An offensive position is generally defined as the ability to get above or behind the enemy. The pilot is able to create an energy advantage, providing the ability to swoop down on the opponent and spray the area with bullets while using the speed to climb back to a safe altitude. The attacker also has an orientation-related advantage, being able to press the attack while avoiding the enemy's weapons.Defensive
A defensive position usually occurs when the pilot spots the attacker late. Usually below or ahead of the opponent, the pilot is in a weak position, primarily concerned with denying a shot to the opponent and converting to a neutral position. The secondary goal is either to escape or to achieve a dominant position. If the attacker is at an energy disadvantage, the defender will likely use the speed to disengage, but, if the attacker is moving much faster, the defender will usually maneuver in order to force a dangerous overshoot. A dangerous overshoot happens when an attacker flies out in front of the defender, causing their roles to be reversed.BFM concepts
Once an attacker gets behind a defender, there are three problems to solve in order to prosecute the kill. The attacker must be able to get into the same geometric plane as the defender, get in range without overshooting, and be able to lead the target. The defender will usually turn aggressively to spoil the attacker's solution.Turn circle
Aircraft turn in circular motions, following a circumference around a central point. The circumference is often referred to as the "bubble," while the central point is often called the "post." Any change in the g-force load on the aircraft causes a change in the bubble's size as well as a change in turn radius, moving the post in relation to the fighter. Because an aircraft turning at its maximum load cannot turn any tighter, any aircraft located between such a fighter and its post is momentarily safe from attack. It is in this area where an attacking fighter will usually try to position itself.Once inside the defender's bubble, the attacker will be in lead pursuit and may have an opportunity for a lucky "snapshot" hit. If the attacker can maneuver onto the defender's flight path before an overshoot occurs, the attacker will be able to stop or reverse closure rate. The most desirable position is, following the defender's flight path, a distance equal to one turn radius behind the opponent. This position, from which the attacker will be able to safely maintain command of the fight, is termed the "control point."
Circle flow
Aircraft can turn either towards or away from each other. How the opponent turns in relation to the other determines the flow of the fight. If two fighters meet head-on, they will usually make a very close, neutral pass, called a "merge." After the pass, both fighters may turn to engage. If the two fighters turn in the same direction, (i.e.: both turn to the north), they will be traveling towards each other along the same turn circle. This type of engagement is known as "one circle flow." If the aircraft turn in opposite directions, (i.e.: one turns north but the other turns south), they will move away from each other, flying around to engage each other on separate turn circles. This is called "two circle flow."One circle flow will result in another merge, unless an angular advantage can be obtained. During one circle flow, the fighter with the smaller turn radius will have the advantage. Pilots will often pitch-up out-of-plane while increasing thrust, to help minimize turn radius. Since turn rate is of little importance during one circle flow, it is often called a radius fight. An out-of-plane maneuver, such as a displacement roll, is a viable option for reducing turn radius.
Two circle flow will also result in another merge. Two circle flow is a turn rate fight, and the angular advantage usually goes to the aircraft with the higher turn rate at its corner speed. Pilots will often slice turn in order to maximize their turn rate. In both types of flow, the closest possible merge is desirable to keep the enemy at an angular disadvantage. Although circle flow is often described using neutral merges, the concept applies anytime two aircraft maneuver in relation to each other and the horizon.
Combat spread
The combat spread is the most basic of maneuvers used prior to engagement. A pair of attacking aircraft will separate, often by a distance of one mile horizontal by 1500 feet vertical. The fighter with the lower altitude becomes the defender, while the wingman flies above in "the perch" position. The defender will then attempt to lure their opponents into a good position to be attacked by the wingman.Defensive split
A pair of fighters encountering one or two attackers will often use a defensive split. The maneuver consists of both defenders making turns in opposite directions, forcing the attackers to follow only one aircraft. This allows the other defender to circle around, and maneuver behind the attackers.Break
Spotting an attacker approaching from behind, the defender will usually break. The maneuver consists of turning sharply across the attacker's flight path, to increase AOT (angle off tail). The defender is exposed to the attacker's guns for only a brief instant. The maneuver works well because the slower moving defender has a much smaller turn radius, and a target with a high crossing speed (where the bearing to the target is changing rapidly) is very difficult to shoot. This can also help to force the attacker to overshoot, which may not be true had the turn been made away from the attacker's flight path.Barrel roll attack
The counter to a break is often a displacement roll called a barrel roll attack. A barrel rollBarrel roll
A barrel roll is an aerial maneuver in which an airplane makes a complete rotation on its longitudinal axis while following a helical path, approximately maintaining its original direction. It is sometimes described as "a combination of a loop and a roll"...
consists of performing a roll and a loop, completing both at the same time. The result is a helical roll around a straight flight path. The barrel roll attack uses a much tighter loop than the roll, completing a full loop while only executing 3/4 of a roll. The result is a virtual 90 degree turn, using all three dimensions, in the direction opposite of the roll. Rolling away from the defender's break, the attacker completes the roll with the aircraft's nose pointed in the direction of the defender's travel.
High-side guns pass
If the attacker has a significant altitude advantage, a high-side guns pass is usually prudent. Sometimes called a "swoop," plus a variety of other names, it consists of a powered dive toward the rear quarter of a lower flying opponent. Shooting with the cannons in a single, high-speed pass, the attacker uses excess kinetic energy to disengage from the fight in a zoom climbZoom climb
A zoom climb is a climb where the rate of climb is greater than the maximum for a sustained climb, as determined from the thrust of the aircraft's engines. During a zoom climb, the aircraft accelerates to a high air speed at an altitude at which it can operate in sustained level flight. The pilot...
back to a safe altitude, restoring the potential energy. This allows the attacker to set up another attack and dive again. Surprise is often a key element in this type of attack, and the attackers will often hide in the sun or clouds, stalking their opponents until a good opportunity is presented. A high-side guns pass is a very effective tactic against a more maneuverable opponent, where the turning battle of a dogfight is best avoided.
Immelmann
An Immelmann trades airspeed for altitude during a 180 degree change in direction. The aircraft performs the first half of a loop, and when completely inverted, rolls to the upright position. The Immelmann is a good offensive maneuver for setting up a high-side guns pass against a lower altitude, slow moving opponent, going in an opposite direction. However, an Immelmann is a poor defensive maneuver, turning the defender into a slow moving target.Split-s
The opposite of an Immelmann is the Split-S. This maneuver consists of rolling inverted and pulling back on the stick, diving the aircraft into a half loop, which changes the aircraft's direction 180 degrees. The split-s is rarely a viable option in combat as it depletes kinetic energy in a turn and potential energy in a dive. It is most often used to set up a high-side guns pass against a lower but fast moving opponent that is traveling in the opposite direction. Also, the split-s is sometimes used as a disengagement tactic.Pitchback
A pitchback is an Immelmann that is executed in some plane other than the vertical. Basically just a pitch turn, the fighter will be at some angle of bank before performing the half loop and roll. Unlike the Immelmann, a pitchback depletes less kinetic energy and is harder for an adversary to track.Low Yo-Yo
The low Yo-Yo is one of the most useful maneuvers, which sacrifices altitude for an instantaneous increase in speed. This maneuver is accomplished by rolling with the nose low into the turn, and dropping into a steeper slice turn. By utilizing some energy that was stored in the vertical plane, the attacker can quickly decrease range and improve the angle of the attack, literally cutting the corner on the opponent's turn. The pilot then pulls back on the stick, climbing back to the defender's height. This helps slow the aircraft and prevents an overshoot, while placing the energy back into altitude. A defender spotting this maneuver may try to take advantage of the increase in AOT by tightening the turn in order to force an overshoot. The low Yo-Yo is often followed by a high Yo-Yo, to help prevent an overshoot, or several small low Yo-Yos can be used instead of one large maneuver.High Yo-Yo
The high Yo-Yo is a very effective maneuver, and very difficult to counter. The maneuver is used to slow the approach of a fast moving attacker while conserving the airspeed energy. The maneuver is performed by reducing the angle at which the aircraft is banking during a turn, and pulling back on the stick, bringing the fighter up into a new plane of travel. The attacker then rolls into a steeper pitch turn, climbing above the defender. The trade-off between airspeed and altitude provides the fighter with a burst of increased maneuverability. This allows the attacker to make a smaller turn, correcting an overshoot, and to pull in behind the defender. Then, by returning to the defenders plane, the attacker restores the lost speed while maintaining energy.Lag displacement roll
A lag displacement roll, also called a "lag roll", is a maneuver used to reduce the angle off tail by bringing the attacker from lead pursuit to pure, or even lag pursuit. The maneuver is performed by rolling up and away from the turn, then, when the aircraft's lift vector is aligned with the defender, pulling back on the stick, bringing the fighter back into the turn. This maneuver helps prevent an overshoot caused by the high AOT of lead pursuit, and can also be used to increase the distance between aircraft.High Yo-Yo defense
An attacker in lead pursuit may need to correct with an out-of-plane maneuver. If the AOT is excessively high, the attacker will probably use a displacement roll. However, if the AOT is low enough, the attacker will likely use a high Yo-Yo. The high Yo-Yo defense can be a good tactic in these situations. The maneuver is performed when the attacker rolls away from the turn to begin the correction. The defender will begin to relax the turn by easing off of the stick, called "unloading," which causes both turn radius and speed to increase, restoring the fighter's lost energy. If the defender maintains the same angle of bank, the subtle maneuver will be very difficult for the attacker to spot. When the attacker completes the out-of-plane maneuver, the defending fighter has regained some of its energy. This allows the defender to, once again, turn harder into the attack, regaining an angular advantage over the higher energy attacker. If the attacker is surprised by the maneuver, a high Yo-Yo defense might even cause an overshoot.Unloaded extension
An unloaded extension is a disengagement (bug out) maneuver often used by the pilot whenever there is enough energy and separation. The maneuver consists of slipping into a steep, straight dive and applying full thrust. Removing all g-force load from the aircraft causes it to accelerate at a very high rate, allowing the pilot to vastly increase range, or "extend," and possibly to escape. If a defender breaks suddenly, causing the attacker to overshoot, the defender may reverse the turn and move in behind the attacker. An unloaded extension is usually the attacker's best option, using the energy advantage to escape the slower moving defender. An unloaded extension is usually not recommended against a higher energy opponent. However, in many circumstances, such as when an attacker performs a high Yo-Yo too steeply, an unloaded extension is a viable option for the defender.Scissors
The scissors are a series of turn reversals and overshootOvershoot
Overshoot may refer to:* Overshoot , when a signal exceeds its steady state value* Overshoot , when a population exceeds the environment's carrying capacity* Overshoot , an aborted landing...
s intended to slow the relative forward motion of the aircraft in an attempt to either force a dangerous overshoot, on the part of the defender, or prevent a dangerous overshoot on the attacker's part. The defender's goal is to stay out of phase with the attacker, trying to prevent a guns solution, while the attacker tries to get in phase with the defender. The advantage usually goes to the more maneuverable aircraft. There are two types of scissor maneuvers, called flat scissors and rolling scissors.
Flat scissors
Flat scissors, also called horizontal scissors, usually occur after a low speed overshoot in a horizontal direction. The defender reverses the turn, attempting to force the attacker to fly out in front and to spoil aim. The attacker then reverses, trying to remain behind the defender, and the two aircraft begin a weaving flight pattern.Rolling scissors
Rolling scissors, also called vertical scissors, tend to happen after a high speed overshoot from above. The defender reverses into a vertical climb and into a barrel rollBarrel roll
A barrel roll is an aerial maneuver in which an airplane makes a complete rotation on its longitudinal axis while following a helical path, approximately maintaining its original direction. It is sometimes described as "a combination of a loop and a roll"...
over the top, forcing the attacker to attempt to follow. The advantage lies in the aircraft that can pull its nose through the top or bottom of the turn faster. In battles with aircraft that have a thrust-to-weight ratio
Thrust-to-weight ratio
Thrust-to-weight ratio is a ratio of thrust to weight of a rocket, jet engine, propeller engine, or a vehicle propelled by such an engine. It is a dimensionless quantity and is an indicator of the performance of the engine or vehicle....
of less than one the aircraft will quickly lose altitude, and crashing into the ground becomes a possibility. According to author Mike Spick, "Disengagement from a vertical rolling scissors is best made with a split-s and a lot of hope."
Guns defense
Guns defense maneuvering, or "guns-D," is the last resort for a defender that fails to out-maneuver the attacker. Guns-D is a series of random changes in the defenders flight path, intended to spoil the attacker's aim by presenting a constantly shifting target, and, hopefully, to maneuver out of the bullet stream. It consists of arbitrary speed changes, yaws, skids, pitch-ups, and rolls, often referred to as "jinking," and is very effective at preventing the attacker from achieving a suitable guns solution. However, guns-D maneuvering still leaves the defender susceptible to stray bullets and "lucky shot" hits, and does little to improve the relative positional situation. Thus, it is only employed as a last ditch defensive effort when nothing else works.High g barrel roll
A high g barrel roll is a last ditch defensive maneuver, performed when the attacker has achieved a suitable guns solution, in order to cause an overshoot. The high g barrel roll is performed much more aggressively than a normal barrel roll. Range is critical to the success of the roll, and the defender will usually turn very hard, or employ other measures to draw the opponent very close before performing the roll. This is an energy depleting maneuver that rarely causes the attacker to fly out in front, but usually will result in a flat scissors or, at the very least, will temporarily disrupt the attacker's aim.Defensive spiral
A defender that fails to out-maneuver the attacker can quickly become "out of energy and ideas." The defensive spiral is a maneuver used by the defender when the kinetic energy becomes depleted and other last ditch maneuvers can not successfully be implemented. The maneuver consists of dropping the nose low during the turn and going into a spiral dive, using gravity to supply the energy needed to continue evasive action. The defensive spiral becomes a rolling scissors performed straight down. The defender's goal is to stay out of phase with the attacker until the ground is dangerously close. The advantage usually goes to the aircraft that can decelerate quicker, and the defender will often cut the power and extend the speedbrakes in an effort to force an overshoot. If this attempt is unsuccessful, the defender will usually pull out of the dive at the last possible second, hoping to cause the attacker to crash into the ground.External links
- Basic Fighter Manoeuvring Terminology Overview of BFM terminology at F-16.net.