Pure Pursuit:

Pure Pursuit is exactly what it sounds like. You keep your nose on the target and fly straight at him. A Pure Pursuit path all the way to the bandit will lead to an over shoot. This is reason enough not to fly in Pure Pursuit and put your nose on the target until you are ready to shoot him. Use Pure Pursuit for missile shots.

Lead Pursuit is the "short cut" to the target. You fly Lead Pursuit to close on the target and get into weapons parameters. This is also the most commonly used pursuit for Guns shots. You must be careful not to establish Lead Pursuit to early or you will over shoot the bandit when you get in close, unless you have a much higher turn rate than the bandit. When flying against an aircraft with similar abilities (F-16 vs. MIG-29 etc.), you will not be able to maintain a Lead Pursuit for very long, and may be forced into an overshoot situation. It is critical to pick when you go into Lead Pursuit to close the gap to set up in Guns parameters.

I have been forced to go Lag to Lead to Lag to Lead, several times over in some dogfights. This is not desirable. You want to pull your nose on the bandit and shoot him, get it over and done with. This sort of maneuvering also bleeds speed at a higher rate, this is just not a good idea. If you find yourself very evenly matched, you may have no choice but to "dance" for a while to line up a good kill shot.

Determining the Pursuit Course:

There are two positions that the bandit can be in, "In Plane" and "Out of Plane". Figure 5 shows both "In Plane" and "Out of Plane" examples.

"In Plane" is where the attacker and the defender are both in the same plane of motion. If the bandit is "In Plane" with your aircraft, the HUD Velocity Vector will determine the pursuit course you are taking.

For ease of explanation, the Velocity Vector is the nose of the aircraft. It represents the direction of travel of your aircraft. The Flight Path Marker on your HUD will indicate your Velocity Vector.

If the defender and attacker are not in the same plane of motion, then you are "Out of Plane". To determine the pursuit course during "Out of Plane" maneuvers, use your "Lift Vector". Figure 7 demonstrates "Lift Vector".

Click to continue . . .

"Lift Vector" is simply a vector, or the direction, that sticks out the top of the aircraft. This is the direction the aircraft moves at high G’s. You position your Lift Vector by rolling the jet so that the Lift Vector points in the direction you want to go, the nose of the aircraft will track towards the Lift Vector.

When an attacker pulls "Out Of Plane", he is technically flying "Lag Pursuit". As he pulls back into the bandit, he may be flying Lead, Pure or Lag pursuit, depending on the maneuver. Remember, when you are attacking, where you position the nose of your aircraft is VERY important.

The Weapons Envelope:

The Weapons Envelope is often overlooked as a fundamental and listed in other areas of BFM instruction. But if you do not know and understand the Weapons Envelope and how it affects your choice of maneuvers, you will not be able to make good choices for the next move you should make.

The Weapons Envelope is the area in which a particular weapon is effective. It takes into account the weapons maximum and minimum range, weapons capabilities, Aspect Angle, Speed, Angle Off, Relative Headings .... what I am I missing? Basically, the Weapons Envelope is determined by every possible variable imaginable.

The basic shape of a weapons envelope is that of an egg shaped doughnut that you impose over the BANDIT. See Figure 8.

RMAX is the maximum effective range and RMIN is the minimum effective range of a particular weapon. Figure 8 is an example of a weapons envelope of an All Aspect missile. A Rear Aspect missile would not have the front lobe of the "egg". As you can see, the effective operating range to the front of the bandit is much larger than the rear area. Obviously, if you are shooting the bandit in the face, he is moving towards you as your weapon moves towards him ... he is doing half the work for you, whereas a rear aspect shot forces the weapon to "chase down" the target.

If you shoot too soon, the missile will burn out it’s motor before even coming close to the target (remember this when we get to Defensive BFM). Figure 8 is a "perfect world" example of a Weapons Envelope, the bandit flying straight and level. The shape of the Weapons Envelope will change as the target starts to maneuver and pull G’s. The Weapons Envelope will deform and may grow in one area while almost completely disappearing in another. It should go without saying, the target will attempt to put the less effective portion of the Weapons Envelope towards you (remember this as well for Defensive BFM, what works for them will work for you too.).

Most missiles will have similar Weapons Envelopes, RMIN and RMAX figures being the primary difference. As I said before, Rear Aspect Only missiles would not have the forward portion of this diagram. Guns are the other exception. You are close enough to minimize the effect of the bandits movement for RMAX range, so the "egg" becomes more rounded. There is no minimum range on a bullet. You can have your nose half way up the targets tailpipe and still shoot guns. The problem here is that you may end up killing yourself as pieces of your opponent start coming off and smacking your aircraft. Most recently released sims as well as some on the way, have begun to model this aspect of air combat. So beware just how close you get before you take the shot.

This covers the basic fundamentals of BFM. The next lesson will cover OFFENSIVE BFM. We will learn how to apply these fundamentals to get into weapons range and shoot your opponent.

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