Variable Factors - P-8210199

BASIC FIGHTER MANEUVERING (BFM) THEORY

CHAPTER NINE

Structural Limitations

Structural limitations include both the maximum lift that can be supported by an airframe and the

maximum-g capability (varies with fuel and ordnance load). The aircraft's maximum airspeed

may also be a limiting factor during an engagement. An aircraft's VN diagram is the "picture" of

these limitations. The T-2C VN diagram may be found in NATOPS.

Thrust-to-Weight Ratio

The thrust-to-weight ratio of an aircraft is computed by dividing thrust by combat weight. This

ratio is an excellent indicator of an aircraft's performance capability going into a BFM

engagement. The higher the ratio for the aircraft, the better the energy addition rate will be. The

T-2C has a thrust-to-weight ratio less than one. Crews flying aircraft with thrust-to-weight ratios

greater than one, will use different tactics than crews flying aircraft with ratios less than one.

Wing Loading

Wing loading is computed by dividing the combat weight of an aircraft by the wing area. For

two aircraft at the same airspeed, the aircraft with the higher wing loading will have a larger turn

radius and a faster turn rate.

In VT-86, students will be fighting other T-2Cs. For this reason, fixed factors become less

crucial as both aircraft have the same limitations. Therefore variable factors and tactics become

the deciding factors when fighting against the same model aircraft.

915. VARIABLE FACTORS

Numerous factors will constantly vary during each engagement in the BFM arena to include a

fighter's altitude, airspeed, angle of attack (AOA), and G. At any given "snapshot" in time these

variable factors present the fighter with a set of parameters requiring instantaneous analysis in

order to achieve the relative positional advantage desired. Turn radius and turn rate are two

additional variable factors that define the aircraft's turning performance.

Turn Radius

The distance from the center point to the arc of the circle an aircraft scribes through the air

during a turn is its turn radius. Turn radius (TAS2/G) is a function of airspeed and G. At a given

G-load, an aircraft's turn radius will increase as airspeed increases. The ability to have a small

turn radius and "turn inside" the bogey can often be used to gain a positional advantage.

Turn Rate

Turn rate is the rate at which an aircraft turns (in degrees per second) and is approximated by the

simplified formula (G/TAS). Simply, an aircraft that can pull more g at a given airspeed will

have a faster turn rate than another aircraft. This gives the faster-turn-rate aircraft the ability to

get his nose on the bogey first, which can be used to gain a positional advantage.

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BASIC FIGHTER MANEUVERING (BFM) THEORY