Fighter Combat

FIGHTER WEAPONS \ \span of the enemy aircraft just extended over half the diameter of his sightring. The ring was also a useful tool in estimating the required lead angle.For a nonmaneuvering target of a given speed at a known range, the leadangle required is roughly related to the TAA. If the target was flyingdirectly toward or away from the shooter, only a small correction would berequired for gravity drop. However, if the attack was made from a positionoff the target's flight path, some lead would be required. The pilot wouldgenerally have a set of thumb rules, learned from the experiences of otherpilots in his squadron as well as his own, which related target positionwithin the sight ring to TAA at a given range. For instance, if the target fillsthe sight ring at a 90° TAA, the shooter might place the target's nosetangent to the bottom of the inner sight ring, about as shown in Figure 1-2.Of course, further corrections might be required for gravity drop andmaneuvering target or shooter aircraft, making "Kentucky windage" animportant factor.Shots that require great amounts of lead, generally as a result of largeangles off the nose or tail of the target, are called "high-deflection" shots,and the art of hitting targets under these conditions is known as deflectionshooting. Only the best marksmen mastered this art with fixed gunsights,and their scores generally reflected their proficiency.One of the factors which must be understood when shooting with asight such as the ring and bead is the effect of the pilot's head position. Ifthe pilot moves his head forward, closer to the sight, the ring will appearlarger and will cover a wider angular cone at a given range. This cone anglecan be measured in degrees or, more commonly, in mils (1° = 17.5 mils). Amil represents the span of an object 1 ft in length when viewed from adistance of 1,000 ft. A target with a 35-ft wingspan would appear to span 2°(35 mils) at a range of 1,000 ft, and 1° at 2,000 ft. Therefore, changes in theapparent span of the sight ring caused by pilot head position can result inlarge errors in both range and lead-angle estimation. Some installationsincluded headrests to assist the pilot in head positioning.This problem was normally addressed by the fixed optical sights, someresembling telescopic rifle sights, which largely replaced the ring-and-beadvariety between late World War I and early World War II. The optics of sucha sight required a certain pilot head position for a view of the entire sightpicture or a clear target image or some other inducement, and largelyeliminated this variable. The earlier designs were in tubular form, butthese were generally replaced before World War II by reflector sights. Thisoptical sight was usually in the form of a circle, or sometimes severalconcentric circles, of light projected onto a "combining glass" throughwhich the pilot sighted the target. The combining glass was transparent,but it still reflected the sight image so that the sight and target could beseen simultaneously. These sight images were normally focused nearinfinity so that both the target and the sight would be in sharp focus to thepilot. This also eliminated any apparent changes in the size of the sightring with head position.Once again, the angular span of the sight rings could be used for rangeand lead estimation. Some of these sights also had an adjustable feature,