Little Fighter Plane: The Story of the de Havilland Mosquito

A light fighter or lightweight fighter is a fighter aircraft towards the low end of the practical range of weight, cost, and complexity over which fighters are fielded.[1][2] The light or lightweight fighter retains carefully selected competitive features, in order to provide cost-effective design and performance.[3][4]

Little Fighter Plane

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A well-designed lightweight fighter is able to match or better a heavier type plane-for-plane in many missions,[5][failed verification][6][7][8] and for lower cost.[9] The lightweight class can therefore be strategically valuable.[10]

A key design goal of light/lightweight fighter design is to satisfy standard air-to-air fighter effectiveness requirements at minimum cost. These criteria, in order of importance, are the ability to benefit from the element of surprise, to have numerical superiority in the air, to have superior maneuverability, and to possess adequate weapon systems effectiveness.[12][13][14][15][16] Light fighters typically achieve a surprise advantage over larger aircraft due to smaller visual and radar signatures, which is important since in the majority of air-to-air kills, the element of surprise is dominant.[17][18][19] Their comparative lower cost and higher reliability also allows for greater numbers per budget.[20] Finally, while a single engine light fighter would typically only carry about half the weapons load of a heavy twin engine fighter, its surprise and maneuverability advantages often allow it to gain positional advantage to make better use of those weapons.

Small fighters like the F-5 with a planform area of about 300 square feet (28 m2) or the F-16 at about 400 square feet (37 m2), compared to about 1,050 square feet (98 m2) for the F-15,[24] have a much lower visual profile. The small fighter is typically invisible to opposing pilots beyond about 4 miles (6.4 km), whereas a larger fighter such as the F-15 is visible to about 7 miles (11 km).[25] This is a non-linear advantage to the light fighter opposing a heavy fighter. Additionally, smaller targets take longer to visually acquire even if they are visible.[26] These two factors together give the light fighter pilot much better statistical odds of seeing the heavy fighter first and setting up a decisive first shot.[27] Once the small fighter sees and turns towards the opponent its very small frontal area reduces maximum visual detection range to about 2 to 2.5 miles (3.2 to 4.0 km).[18][28]

Given similar technology, smaller fighters typically have about two thirds the radar range against the same target as heavy fighters.[a] However, this cannot be counted upon to give the large fighter a winning advantage, as larger fighters with typical radar cross sectional area of about 10 square metres (110 sq ft) are detectable by a given radar at about 50% farther range than the 2 to 3 square metres (22 to 32 sq ft) cross section of the light fighter.[29] This approximately balances these trade-offs, and can sometimes favor the lightweight fighter. For example, from the front the F-15 actually presents about 20 square metres (220 sq ft) radar cross sectional area,[30] and has been typically defeated by opposing F-16 forces not only in close dogfighting combat, but also in extensive Beyond Visual Range (BVR) trials.[6][31] Also, airborne fighter radars are limited: their coverage is only to the front, and are far from perfect in detecting enemy aircraft. Although radar was extensively used by the United States in the Vietnam War, only 18% of North Vietnamese fighters were first detected by radar, and only 3% by radar on fighter aircraft.[32] The other 82% were visually acquired.[33]

2. Numerical superiority in the air, which implies the need for lower procurement cost, lower maintenance cost, and higher reliability. Not even taking into account the sometimes superior combat capability of lighter aircraft based on surprise and maneuverability, the pure numbers issue of lower cost and higher reliability (higher sortie rates) also tends to favor light fighters. It is a basic outcome of Lanchester's laws, or the salvo combat model, that a larger number of less-sophisticated units will tend to be successful over a smaller number of more advanced ones; the damage dealt is based on the square of the number of units firing, while the quality of those units has only a linear effect on the outcome. This non-linear relationship favors the light and lightweight fighter.[35]

Additionally, as pilot capability is actually the top consideration in maximizing total effectiveness of the pilot-aircraft system,[b] the lower purchase and operational cost of light fighters permits more training, thus delivering more effective pilots.[36] For example, as of 2013, total heavy F-15C operating cost is reported at US$41,900 per hour, and light F-16C cost at US$22,500 per hour.[37]

4. Weapon systems effectiveness.[49][50][51] This area is one where the light fighter can be at a disadvantage, since the combat load of a single engine light fighter is typically about half of a twin engine heavy fighter. However, modern single engine light fighters such as the General Dynamics F-16 Fighting Falcon and the Saab JAS 39 Gripen generally carry similar cannon and air-to-air missile fighter weapons as heavier fighters. Actual aerial combat in the modern era is of short duration, typically about two minutes,[52] and as only a small fraction of this is spent actually firing, modest weapons load outs are generally effective. The ideal weapons load for a modern fighter is considered to be an internal gun and two to four guided missiles,[52] a load that modern light fighters are fully capable of while maintaining high agility. For example, the JAS 39 Gripen, despite being the lightest major fighter in current production, carries a combat load of a 27mm cannon and up to six air-to-air missiles of the same types as carried by heavy fighters. Additionally, combat experience shows that weapons systems "effectiveness" has not been dominated by the amount of weaponry or "load out", but by the ability to achieve split second kills when in position to do so.[14][53][54]

Superior technology has often been quoted as a strong factor favoring the heavy fighter. The specific argument usually presented is that heavy fighters have superior radar range and longer range BVR missiles that take advantage of that range. This radar range advantage is one of the major reasons for the existence of the modern heavy fighter, but it has not turned out to be a significant advantage in air combat history to date for several reasons. A major reason has been because long range BVR missile shots have often been unusable, and often unreliable when they could be taken. The weight of the larger missiles also reduces performance and range needed to get in position to fire. Due to these factors, between 1958 and 1982 in five wars there were 2,014 missile firings by fighter pilots engaged in air-to-air combat, but there were only four beyond-visual-range kills.[55]

While the technology advantage for heavy fighters that better supported the pilot may well have been a valid point in the 1970s (when the F-14 and F-15 first entered service), this advantage has not been maintained over time. Engine performance improvements have improved load carry capability,[c] and with more compact electronics, the lightweight fighter has, from the 1980s onwards, had similar pilot enhancing technical features.[58][59][60] The lightweight fighter carries equally effective weapons including BVR missiles, and has similar combat range and persistence. The modern lightweight fighter achieves these competitive features while still maintaining the classic advantages of better surprise, numbers, and maneuverability. Thus, the lightweight fighter natural advantages have remained in force despite the addition of more technology to air combat.[59]

Due to their lower costs, modern light fighters equip the air forces of many smaller nations. However, as budgets have limits for all nations, the optimum selection of fighter aircraft weight, complexity, and cost is an important strategic issue even for wealthy nations. The budgetary and strategic significance of light fighters is illustrated by the defense investment at stake. As an example where well referenced data is available, though numerous trial and combat references consider the lightweight F-16 to be as good or better on a per plane as the excellent but expensive F-15,[61][62] fielding and maintaining a light fighter force based on the F-16 is approximately half the cost of the same number of F-15's. The US Air Force reports the total loaded cost per hour (as of 2013) of operating the F-16C to be US$22,500 per hour, while that of the heavy F-15C is $41,900 per hour.[37] Numerous authoritative sources report that it takes about 200 to 400 flight hours per year to maintain fighter pilot proficiency.[d][63]

Lanchester's laws on military superiority suggest that any technical superiority of the heavy fighter on a unit basis will not always translate to winning wars. For example, late in WWII the greatly superior German Messerschmitt Me 262 jet fighter, flown by the finest pilots Germany had left, many of them very high scoring aces with kill counts far in excess of Allied pilots, in its relatively small numbers suffered heavy losses and was unable to fundamentally alter the air war over Germany.[64] Such issues are relevant to future military planning and deployments.[65]

The light fighter class originally stemmed from concern at the growing size and cost of the frontline fighters in the 1920s. During the late 1920s and 1930s the light fighter would receive significant attention, especially in France.[66]

One early light fighter project was the French Air Force's 'Jockey' interceptor program of 1926. Several aircraft, including the Nieuport-Delage NiD 48 and Amiot 110, were trialed without much success as they offered little over aircraft already in production[67] In the late 1920s the British similarly issued specification F.20/27 for a short-range fast-climbing daylight interceptor. The de Havilland DH.77 and Vickers Jockey monoplanes were among seven designs tendered to meet the specification but neither went into production, the heavier but faster biplane Hawker Fury being preferred. 2ff7e9595c