22. Terminal ballistics describes the characteristics and effects of the projectiles at the target. 23. Dispersion. If several projectiles are fired from the same weapon with the same settings in elevation and deflection, their points of impact will be scattered about the mean point of impact of the group of rounds. The degree of scatter (range and azimuth) of these rounds is called dispersion, and creates a cone of fire. The mean point of impact with respect to the target center, or intended air point, is an indication of the weapon's accuracy. Both dispersion and accuracy determine whether a particular weapon can hit an intended target; for machine guns, as range increases, dispersion increases and accuracy decreases. Dispersion is caused by errors inherent in firing projectiles. These errors are influenced, in part, by the factors discussed in the ballistics paragraphs. In addition, they may be influenced by the vibrations in the mount and condition of the sighting systems. The cone of fire striking the ground creates a pattern called a beaten zone.
24. Vibrations. Because mounts for weapons are fixed to the helicopter, vibrations in the helicopter transmit through the mounts. These vibrations affect azimuth and elevation. Because door guns are free to traverse and elevate within limits, and are in the gunner's hands, the gun barrel will never be pointed exactly the same for each round.
25. Sights. The condition of the sights (if used) and the accuracy of their alignment with the bore axis of the weapon cause a displacement of the dispersion pattern of the projectiles. Firing the door gun by instinctive pointing and correcting using tracer and strike further widens
dispersion.
26. Boresight. Proper boresighting of aircraft weapons is critical to accurate fires. Improper boresighting is a factor in dispersion differences between like aircraft.
27. Impact Factors. Several factors will influence the gunner's ability to effectively adjust fire and engage a target:
a. Tracer. Tracer ammunition does not generally begin burning brightly until about 100 metres and burns out at approximately 800 metres. It can also be difficult to see the tracer during daylight against a bright background such as snow or very light coloured sand. At target ranges beyond 800 metres, the burnout may be mistaken for impact, especially if there is no other strike indications;
b. Surface Conditions. Along with tracer, observation of bullet strike is important for adjusting fire. If the target is in an area where bullet strike may not be visible, such as heavy vegetation, and beyond tracer visibility, the following technique may be used. An area near to the target in which strike is visible is fired upon to adjust, then a further adjustment is made into the target; and
c. Angle of Impact. During plunging fire, bullets will bury themselves, but as the angle of incidence shallows, they will bounce and skip, depending on the surface. Generally, it is preferred to have bursts strike just short of the target, particularly if they will strike shallow, in order to allow easier viewing of strike and greater impact on the target.
28. These ballistic factors may seem to confuse the gunner’s ability to align the gun appropriately to bring fire on a target. However, knowledge of these factors combined with some experience firing in several flight regimes and the use of “burst on target” adjustment will allow the gunner to quickly bring effective fire on the desired target without complicated
sighting mechanisms. TARGET ACQUISITION
29. In order to ensure timely detection and location of targets in order to suppress them, door gunners, and pilots as well, need to be aware of why things are seen, visual search techniques, range estimation, and target indication methods.
30. The ability to observe effectively is an acquired skill. An understanding of the recognition factors is required in order to develop that skill. These factors are:
a. Shape. Experience teaches one to associate an object with its shape or outline. At a distance, the outline of an object can be recognized long before the details that make it up can be determined.
b. Shadow. Against a dark background the light surfaces of an object will be distinguishable while against a light background the dark or shadowed sides will show. In addition, an object may cast a shadow beside it, which may be visible although the object itself it is out of sight. Objects in a shadow may be missed because the eye tends to accept conspicuously dark or light areas as uniform, and does not seek out minor differences in darkness or lightness within them.
c. Silhouette. Anything silhouetted against a contrasting background is
conspicuous. Any smooth flat background, like water, a field or, most frequently, the sky will provide such a contrast. Any object may be silhouetted simply by being seen against a background of a different colour. Clothing and camouflage are chosen to match the background, if possible.
d. Movement. Although movement by itself seldom reveals the identity of an object, it is the most important factor for revealing existence. Even though the other recognition factors have been completely eliminated, an observer will be attracted to an area if movement is not controlled. The observer may be
concentrating on one area, but he will not fail to detect movement in another area through side vision.
e. Spacing. In nature, things are seldom regularly spaced. Regular spacing,
therefore, usually indicates man made objects, and attracts the eye of the observer. Examples are regularly spaced fire trenches or parked vehicles.
f. Position. An object is often identified by its position in relation to its
surroundings. A long object on a railroad track is assumed to be a train; similar objects on a river and parallel to its banks are assumed to be boats or barges. A large structure in a group of frame buildings might be a barn. Position is nothing more than the relationship in space of one object to another object or objects. g. Texture. Texture may be defined as the relative smoothness of a surface. A
rough surface, such as a field of grass, reflects little light and casts many shadows on itself. It appears very dark to the eye or on a photograph. A smooth surface, such as the roof of a building, reflects more light.
h. Colour. Colour is an aid to an observer when there is contrast between the colour of an object and its background. The greater the colour contrast, the more visible the object. While colour alone will not usually identify an object, it is often an aid in locating the object or confirming a tentative identification. A secondary
consideration is the tone of a colour. Usually, the darker shades of a given colour will be less likely to attract an observer’s attention than the lighter, more brilliant shades.
i. Scale. Objects that differ greatly in size from those around them will be more readily distinguishable than objects amongst others of approximately the same size.
j. Noise. Sudden noises contrast with the normal quiet of a battlefield. Loud noises such as the firing of artillery weapons or the running of generators can pinpoint locations. During the Korean conflict sound ranging equipment provided the initial location of 80 % of the enemy indirect fire weapons. In a helicopter, the report of a firing weapon on the ground will seldom be heard. However, explosions nearby, and strikes by projectiles or fragments on solid parts of the helicopter, will certainly be noticed, and may give some indication of the direction of the threat.
k. Shine. Flashes of light reflected off uncamouflaged materials such as glass and metal quickly attract the attention of ground and air observers.