Fighter Combat - Tactics and Maneuvering

FIGHTER WEAPONS 49
the radar track, rather than just detect, the target. Automatic radar tracking
is possible using electronic methods that vary with the design of the
particular radar system. The transition from radar detection to automatic
track is called the "acquisition" or "lock-up" process. Depending on the
sophistication of the radar, this too may be an automatic procedure requiring
very little time or aircrew effort, or it may be a manual process of
designating the target LOS and range or closing velocity so that the radar
can determine which return is the desired target. Manual methods are
generally adequate at longer ranges, when LOS rates are low, but once a
fighter is engaged in a close-range swirling "dogfight" some automatic
means of target acquisition is almost a necessity. The ability of Doppler
radars to distinguish between moving airborne targets and ground clutter
makes automatic acquisition systems more practical.
In some cases, however, a radar lock may not be available. If the missile
(a heat seeker, for instance) does not require a host-aircraft radar lock for
guidance information, then some other means of envelope recognition is
necessary. Generally it is achieved by reducing the many envelopes to a
very few, relatively simple "rules of thumb" which describe optimum
firing zones for the missile under expected combat conditions of altitude,
speed, target turn rate, etc. Pilots then must memorize these thumb rules,
along with any special operating restrictions for the missile, such as
requirements for look-up, acceptable load factor at launch, etc. In essence
these rules of thumb provide the pilot with very simplified envelopes that
give him a "ballpark idea" of his missile's capabilities. Of necessity, such
simplifications will underestimate the weapon's true performance under
some circumstances and be overly optimistic in others.
Once the envelope is known, recognition of the critical parameters
becomes the problem. Often range and target aspect must be estimated
visually, based on the apparent size and presented view of the target.
Stadiametric ranging, the method by which gunsight mil dimensions are
compared to the apparent size of a target of known size, was discussed in
relation to air-to-air gun employment. This method may also be used with
missiles, but because of the typically longer ranges of AAMs, where slight
variations in apparent target size may equate to very great differences in
distance, it is generally useful only at short range. A more widely used
method involves the ability to discern various features of the target aircraft
and equate this ability to approximate target range. For instance, at some
range the target will appear to change from a mere black dot to something
recognizable as an aircraft. A little closer, depending on aspect, its type
may be apparent, then the canopy may become visible, followed by its
markings and color scheme. Mastering such methods requires a great
amount of practice, and at best this method results in rough approximations.
In tests of experienced fighter pilots estimating the range of familiar
aircraft, it has been found that errors of 50 to 200 percent can be expected.
The results will be even worse against unfamiliar target aircraft.
We always underestimated our range.
Air Vice-Marshal J. E. "Johnnie" Johnson, RAF
Target aspect estimation presents a similar problem, with ± 30° accu-