Chapter 2 - Fighter Maneuvers -- Procedures for the Defensive Turn
Defensive Turn
The purpose of the defensive turn is to prevent an opponent from achieving a launch or firing position. As stated earlier, the objective of this maneuver is to rotate our angular velocity cone away from the attacker. The best way to achieve this is to turn into the plane of the attack. This means that in an overhead attack, we will pull up into the attack; in an underside attack, we will dive into the attack; and if the attack is from six-o’clock, we will turn in whichever direction provides the greatest tactical advantage. Assuming that an attacker armed with an IR missile is approaching our angular velocity cone from six-o’clock, how would we defend against this attack? First, perform a hard turn with a slight dive. This turn should not be a break or maximum performance maneuver. If so, we will experience high speed-decay and loss of maneuvering potential, eventually diminishing our angular velocity. As a result we will probably successfully defend against the missile attack, but our attacker will be in position for a follow-up gun attack. If we employ the hard turn and the slight dive, we generate enough angular velocity to preclude a missile launch at long range, and at the same time we retain future maneuvering potential. As range diminishes, the attacker will be looking for an opportunity to launch a missile; however, since he is in a pursuit curve attack, his rate of turn is a function of target speed, angle-off and range. At long range the rate of turn required for the attacker to track is considerably less than ours. Consequently, the attacker’s angle-off and rate of closure will increase. The increase in angle-off demands a further reduction in range before the attacker can successfully launch without exceeding the lambda limitation. This forces the attacker to get closer and, since he is on a curve of pursuit, his angle-off is continuing to increase as his range decreases.
The rate of turn formula
indicates that rate of turn will increase if angle-off increases (Sinθ) and range decreases on an attack against a maneuvering target. Both of these conditions occur. This means that the attacker generates a rapid buildup in his rate of turn, and by the time he reaches the point at which he can launch without exceeding lambda limit, he exceeds the 2G launch limitation. With a .9-Mach co-speed attack at 35,000 feet, this will occur at a range of about 7,000 feet from the target. If the attacker gets closer, he must forego a missile attack and attempt to set up a 20mm cannon attack. This is necessary because when attacking a maneuvering target, once the G-limit is exceeded, G cannot be reduced – it will continue to build up as range diminishes.
As a defender, we are now forced to nullify our opponent’s subsequent gun attack. To accomplish this, let us once again analyze our relative positions: The attacker, noting that he has lost the opportunity to deliver a missile, will attempt to reduce his angle-off and slide into our six-o’clock position. To prevent this, we must increase G and rotate our angular velocity cone away from our opponent. Our concern now is to acquire a smaller turn radius than the attacker. This will force him outside our turn and prevent him from achieving a tracking solution. To accomplish this objective, we must play the turn in respect to the attacker. The moment we notice his attempt to diminish angle-off, we increase our G, to prevent him from diminishing his angle-off and sliding toward our six-o’clock position. If he continues to press the attack, tighten the turn to prevent him from staying on the inside of the turn. In effect, we are trying to place him on the other side of our angular velocity cone. If we play this maneuver correctly, he will be unable to match our turn radius. The formula for turn radius:
Where
R = Turn radius in feet
Vf = Fighter velocity in feet/second
N = Number of radial G
Indicates that the fighter with the lower velocity and/or greater G has a smaller turn radius. In this situation, the attacker’s speed and G are directly dependent upon the defender’s action and if we pull a certain number of G, the attacker cannot pull the same amount. If he does, his rate of turn will equal ours, and, at the end of a 180° turn, the attacker becomes the defender and we the attacker. Of course this will not occur, because the attacker will be forced to play his turn in respect to our position. This means that his G will be less, and as a result, his speed decay will not be as rapid as ours. As is shown by the above formula, the attacker will have a greater turn radius for two reasons: (1) higher speed, and (2) lower G. As a result if the attacker continues to press the attack in the plane of our turn, he must overshoot. This provides the attacker little opportunity to track the target and places him, geometrically, on the other side of our flight path. Of course, this presupposes that we, as the defender, are turning near or at maximum rate. If not, the attacker would be able to slide toward 6-o’clock, pull a higher G, diminish airspeed and avoid an overshoot. As we will see later, the lateral separation provided by this overshoot is a “must” for the defender’s subsequent actions.
Chapter 2 - Fighter Maneuvers -- Procedures for the Defensive Turn