Factors Affecting Trajectory

CHAPTER EIGHT

DIVISION AIR TO GROUND TACTICS AND PROCEDURES

This angle decreases to zero (ideally) as the aircraft accelerates to release airspeed, so flight path

and armament datum line are the same at release airspeed.

Sight Angle. The angle between the ADL and the line of sight, sometimes called "sight

depression angle". With a sight angle of zero, the line of sight is parallel to the ADL. With any

depressed sight angle, the line of sight will be below the ADL.

Mil. An angular measure defined as 1/6400 of a circle. Sight angle is measured in mils. A mil

is a convenient unit of measurement because a mil subtends approximately one unit at one

thousand units. That is, if two lines spread apart with an angle of one mil, they will be one foot

apart after 1000 feet, two feet apart after 2000 feet, and so on out.

Time of Fall. The length of time between release of a weapon and its impact with the ground.

This is the time, during which gravity acts on the weapon to bend its trajectory below the

aircraft's line of flight.

808. FACTORS AFFECTING TRAJECTORY

In the fleet, each type of weapons run will have a corresponding "mil setting", which will

compensate for the extent to which a weapon will drop below your aircraft's flight path. Each

mil setting is calculated such that if a weapon is released at the proper altitude, with correct

airspeed, dive angle, and G with wings level, zero yaw, and the "pipper" on the target, the

weapon will hit the target, assuming no wind. A change in any of these parameters will affect

the trajectory and therefore accuracy of the weapon. The effect of each of the above parameters

will now be considered:

Release Altitude. Releasing high will increase the time of fall of the weapon, and therefore will

increase the time during which gravity can act to bend its trajectory. You are also releasing a

greater distance from the target. Therefore, if you release high, with all other parameters correct,

the weapon will hit short. Conversely, if you release low, the hit will be long.

Release Airspeed. Any deviation from planned release airspeed will cause a false sight picture.

For example, a fast release will decrease your AOA and bring the pipper short of the impact

point causing a long hit. A slow release will show the pipper long and cause a short hit.

Airspeed also has an effect on the weapon's time of fall.

Dive Angle. Deviations from planned dive angle will also cause a false sight picture. A steep

dive will cause a long hit and a shallow dive a short one. Changing the dive angle will change

the extent to which gravity will bend the weapon's trajectory below the line of flight. Suppose

you release a weapon at a dive angle of 90 degrees. Since gravity works straight down, there

will be no effect on the trajectory.

You can see that a steeper angle requires a smaller mil setting; if you release steep, your mil

setting is too large and the bomb will strike beyond the target. If you are shallow, you need a

greater mil setting, just as you do for a shallow pattern, and your hit will be short.

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DIVISION AIR TO GROUND TACTICS AND PROCEDURESS