Figure 9-2 Lift Vector

BASIC FIGHTER MANEUVERING (BFM) THEORY

CHAPTER NINE

your airplane, the characteristics of the air-to-air arena, and finally, the bogey. First, we will take

a look at the basic component of "lift vector" and its affect on maneuvering.

909. LIFT VECTOR

The lift vector is an imaginary line extending outward from the canopy and perpendicular to the

aircraft's wingspan (Figure 9-2). This line is simply a tool used to describe the plane in which

an aircraft is turning. During an engagement, the tactical placement of the aircraft's lift vector is

essential to achieving an advantageous position on the bogey. When a maneuvering fighter is

unable (due to position, energy state, or nose authority) to gain a positional advantage with

aircraft nose placement, the lift vector may be utilized. A defensive, neutral, or offensive fighter

can lead or lag a bogey with its lift vector. The lift vector can be manipulated to gain an

offensive (or improve a defensive) position. Once offensive, the fighter will need to transition to

pulling lead with the nose to obtain a valid guns solution.

Figure 9-2 Lift Vector

910. HORIZONTAL MANEUVERING

The most basic of all aerodynamic principles state that in order for an aircraft to maintain straight

and level flight, it must generate exactly 1"G" to overcome the effects of gravity. Because the

amount of lift required to maintain 1"G" flight is based on the weight of the aircraft (excluding

the effects of drag), the vector representing gravity remains constant as long as the weight of the

aircraft remains constant.

An aircraft in a turn at any angle of bank (AOB) must generate an additional load factor in order

to have the same effective lift. The required load factor increases because your lift vector is

moved out of the pure vertical. If we assume that the effective lift of the aircraft opposes gravity

(which is a constant force), the load factor will vary according to how tightly you want to turn

the aircraft. As you can see in Figure 9-3, both aircraft A and B are in level turns at a constant

true airspeed (TAS). Aircraft A is in an 80 AOB and aircraft B is in a 60 AOB. Because

aircraft A is turning at 80 degree AOB, his load factor is greater than aircraft B turning at a 60

AOB. Notice that because gravity and the effective lift remain constant, the resultant vector,

9-5

BASIC FIGHTER MANEUVERING (BFM) THEORY