Fighter Combat - Tactics and Maneuvering

14 FIGHTER WEAPONS
This system has several advantages over the predictor method. One of
these is that the only calculations involved are based on the most accurate
information: bullet ballistics and the shooter aircraft's attitude and maneuvers.
Another is that the information displayed by the pipper is realtime,
and so is not dependent on future target maneuvers.
With a historical sight, the pilot must remember to open fire at least one
TOP before the pipper appears to touch the target on the sight unit in order
to get the maximum number of hits. Tracking can also be somewhat more
difficult, since there is a lag of one TOP between movement of the shooter
aircraft and a change in the pipper indication. The pilot has little immediate
control of the pipper (just as he can't control the flight path of bullets
after they are fired) for fine tracking corrections. Even with these shortcomings,
however, sights based on this real-time technique generally
show better results against maneuvering targets than do director sights.
Many variations of these two basic methods have been tried with some
success. Often the differences are only in display formats, and sometimes
combinations of the two computational techniques are used. Several
clever prediction and estimation tricks that are often employed result in a
need for much less computer sophistication than the full historical sight
requires.
Undoubtedly the quest will continue for the "perfect" air-to-air gunsight,
but there are practical limits to the attainable accuracy, in large
measure because of manufacturing variations in ammunition which cause
slight ballistics changes. Barrel vibrations during fire and other factors also
have an effect. The practical accuracy of air-to-air guns at present, discounting
sight errors, seems to be about 5 mils.
1OOO FT
PIPPER MOVING
RANGE BAR
NOTE: MOVABLE RANGE BAR INDICATES TARGET RANGE
(IN THIS CASE ABOUT 27OO FT)
2000 FT
RANGE
INDICES
Figure 1-3. Typical Radar Lead-Computing Gunsight
Display