Destruction of Aircraft in the Air: The Fighter's Role to Achieve Air Superiority

The ability of bomber and ground attack aircraft to severely damage surface targets demanded a forceful defense to protect civilians and troops. Passive defenses have the goal of reducing the impact of bombing attacks: smoke screens to prevent good aiming, barrage-balloons to discourage low-flying incursions, camouflage to render the target invisible, dummy sites (that appear identical from the air like a real target) to re-direct the assault to an unimportant location, jamming to upset enemy navigation sending him off-track, and early-warning systems to implement preventive actions with plenty of time, can all become quite effective.

If the worst possibility should occur and the enemy hits the proper objective then measures to minimize material damage (like firefighting, blow out walls, etc.) and human casualties (i.e. shelters, rescue brigades, etc.) can make the difference between a disaster and a manageable situation.

However, passive measures alone are an invitation for further strikes and yield the enemy the strategic initiative. Means to make the enemy pay a hefty price are required.

Germans installing decoys on a dummy airfield
Germans installing decoys on a dummy airfield

By the time of the German invasion of the USSR, the two most important methods to destroy flying enemy aircraft consisted of land-based anti-aircraft artillery and airborne fighters .

Light Anti-aircraft Artillery

Anti-aircraft guns or Flak (the German term) consisted of either small-caliber rapid-firing cannons that could unleash a wall of projectiles quickly or large-caliber slow-firing guns that fired hefty projectiles. The former, called light anti-aircraft artillery, found use when the aircraft flew at low heights while the latter, called heavy Flak operated against high-flying airplanes.

The German light Flak made use of 20mm and 37mm cannons while the Soviet PVO utilized light and heavy machine guns as well as 37mm guns in their batteries (and a few 25mm guns although these remained rare).

Left. German and Soviet light anti-aircraft guns were used during Barbarossa. Right. German 20mm Flak 38
Left. German and Soviet light anti-aircraft guns were used during Barbarossa. Right. German 20mm Flak 38

Armored vehicle designers stipulated that the thinnest armor employed by tanks should make them invulnerable against armor-piercing bullets fired from rifle-caliber machine guns at short range (30 meters). This minimum thickness measured 14mm but protecting an aircraft with such heavy plates entailed a prohibitive weight penalty.

Weight reduces aircraft performance and thus armor remained limited to small 8-10mm steel plates for the pilot and a handful of critical areas .

The thin aluminum fuselage of German aircraft and the equally slender mixed wooden-metal structure of Soviet aircraft , stood vulnerable to machine guns and small caliber cannons. The 20mm cannon saw widespread use in Flak batteries because it was relatively light, enjoyed an adequate rate of fire, its muzzle velocity allowed it to shoot in semi-straight lines at normal operational ranges, and the comparatively heavy 20mm high-explosive projectile carried much more punch than heavy or light machine gun projectiles.

A. G. Williams and E. Gustin devised a formula to estimate the lethality of a projectile. The damage that a shell causes is equal to its momentum multiplied by a factor that can be one in the case of ball bullets, or higher in the case of high-explosive (HE) shells . Using this formula, a 20mm HEIT projectile fired from a Flak 38 boasts a lethality of 167 kg m/s. A 13mm MG 131 heavy machine gun and a 7.92mm rifle-caliber MG 17 light machine gun rounds attain a value of 27 and 10 respectively.

A single 20mm round could not shoot down an aircraft . On average a single-engine fighter required 4 impacts and larger aircraft proportionally more as shown in the following graph .

The number of rounds needed to bring an enemy aircraft down. Larger size targets required more impacts. Since a target is on the aiming sights for a brief moment, increased lethality of the round proved necessary.
The number of rounds needed to bring an enemy aircraft down. Larger size targets required more impacts. Since a target is on the aiming sights for a brief moment, increased lethality of the round proved necessary.

The 220 rounds/min-20mm Flak 38 had to deliver a 1.1-second burst on the target to destroy a fighter and a 3.3-second burst on a twin-engine bomber. The Flak 38 was aimed initially through open sights (metallic sights) and after the first shots, the aim was corrected by watching the tracer rounds. With this firepower and method, destroying a 12-meter (40 feet) twin-engine target moving at 400 km/h (250 mph) required extraordinary skill. Practical range against an airborne target was 1000 meters which gave at most, a window of only 18 seconds to fire . Hitting this target during 22% of the aircraft path with a single land-based gun is almost impossible. For this reason, multi-gun batteries of half-dozen pieces or more deployed to direct their fire against a single attacking airplane. This wall of tracer prevented deliberate slow-speed bombing runs or multiple passes by an attacker. The tracer also helped friendly fighters to rapidly identify the location of enemy aircraft.

The higher up the airplane flies, the slower it seems to move because angular speed is reduced. Flying against light flak is more hazardous at the higher end of the gun’s ceiling. So, the attack airplane either flies higher than 1000 meters (3500 feet) (which reduces bombing accuracy compared with very low altitude attacks) or else flies at the lowest possible altitude (which makes things more difficult for the gun and increases bombing accuracy).

Expenditure of AA projectiles for each airborne aircraft destroyed by German Flak (Caballero Jurado, 2012).
Expenditure of AA projectiles for each airborne aircraft destroyed by German Flak (Caballero Jurado, 2012).

The big drawbacks of light Flak consisted in its relative lack of mobility, range, and ceiling as compared with the enemy aircraft, forcing it to defend point targets exclusively. Beyond 1000 m of height the attacker remained practically invulnerable.

If these small-caliber cannons could be brought to bear at the appropriate altitude and distance to target during the approach and withdrawal phases of the enemy aircraft attack, they would be exposed to firepower for longer periods and thus suffer heavier losses.

The fighter aircraft was designed with this goal in mind. It was a gun platform that could take these guns close to the enemy and bring them to bear on him. The 20mm cannon became a de-facto standard for German and Soviet fighters equipping the Bf 109F, the Bf 109E-7/N , the Polikarpov I-16 Types 17 and 28, the Yak-1, and the LaGG-3 .

Ww2 Clash
Same weapon (20mm cannon), same purpose (destroy enemy aircraft), but two different approaches: used as a land-based AA gun or as an airborne installed cannon. The advantage of the latter is that the fighter became the platform to bring the weapon to bear on the target at altitudes and distances that the Flak could not reach.

The firepower of the fighters that engaged in combat during the Barbarossa period varied widely. The Yak-1, MiG-3, Bf 109E-7, and Bf 109F1 to F4 were lightly armed, requiring a longer burst of fire to destroy a twin-engine bomber . The Polikarpov I-16 Types 17 and 28 as well and the early LaGG-3 could destroy the Luftwaffe’s fighters and bombers to smithereens with short bursts of fire from their heavy gun batteries.

Firepower lethality of fighters on the Eastern Front in 1941. The I-16’s and LaGG-3’s gun batteries outgunned all other single-engine fighters and could destroy a light bomber with a very short burst. The rest of the fighters could not destroy a light bomber with a 1-second burst and needed longer times.
Firepower lethality of fighters on the Eastern Front in 1941. The I-16’s and LaGG-3’s gun batteries outgunned all other single-engine fighters and could destroy a light bomber with a very short burst. The rest of the fighters could not destroy a light bomber with a 1-second burst and needed longer times.

During World War II, German fighters destroyed more enemy aircraft than the Flak, although the margin may be less spectacular than we would like to think: 58% vs. 42% respectively.

Luftwaffe fighters destroyed most of the enemy aircraft, but the Flak shot down a substantial number and it also remained highly successful throughout the whole war while the day fighters were neutralized by 2Q/1944. Source: Caballero Jurado, 2012
Luftwaffe fighters destroyed most of the enemy aircraft, but the Flak shot down a substantial number and it also remained highly successful throughout the whole war while the day fighters were neutralized by 2Q/1944. Source: Caballero Jurado, 2012

Fighter Design Considerations

Fighter design is an exceedingly complex task because of the conflicting nature of the qualities the aircraft must possess simultaneously. By 1940 it became clear that fighters should be capable of destroying bombers and the fighters that escorted them. The primary role a year before emphasized bomber destruction and for this the fighter required fast speed and swift rate of climb to catch the bombers. It also needed the heaviest armament it could carry to shoot them down but without impairing the previous qualities. Range and maneuverability were lower in priority: sufficient range to catch the bombers and return to base, and the capacity to maneuver in the airspace to bring the weapons to bear on clumsy targets.

But now that fighters invariably escorted bombers, the need to engage them became a priority too. Therefore, to the above qualities, it now needed improved maneuverability, to ensure hits on agile targets, and a fast dive speed . And to escort bombers range should also increase .

To meet these tall demands, the air force technical departments set forth specifications in great detail that aircraft designers sought to meet or exceed.

Standard V-12 engine layout
Standard V-12 engine layout

Aeronautical engineers tinker with two main variables when designing a fighter: power-to-weight ratio (PWR/Weight) and wing loading . These two define the design space.

The fundamental property that sets the limits of fighter performance is the power available. As a result, engineers design a fighter around the most powerful powerplant they can get .

The Luftwaffe and the VVS installed the most potent engines to their best fighters, the Bf 109F-2 and the MiG-3, respectively. The first came equipped with a Daimler Benz DB-601N delivering 1175 brake hp at sea level at 2600 rpm for take-off for a weight of 610 kg (1.90 hp/kg) . The second donned the Mikulin AM-35A that afforded 1350 brake hp at sea level at 2050 rpm for take-off for a weight of 830 kg (1.63 hp/kg).

Both were liquid-cooled V-12 powerplants with single-stage superchargers to compensate for their lower power delivery at higher altitudes . The AM-35A displaced 46.7 liters while the DB-601N was more compact at 33.9 L. Although the more powerful AM-35A appears to have an edge, its inferior power-to-weight ratio and larger size negated this advantage .

Ww2 Clash
Left: Mikulin AM-35A 1350 HP engine (1.63 HP/kg) Right: Daimler-Benz DB-601 which in its N version developed 1175 HP (1.90 HP/kg) Both were V-12, but the DB-601 was an inverted V. During the war engineers and scientists participated in a bitter race to continuously increase engine power and fuel quality.

The engine itself cannot deliver more power than what the fuel it burns is capable of furnishing. Reciprocating engines utilized aviation gasoline which is a complex mixture of liquid aliphatic and aromatic hydrocarbons that pack a great amount of energy, roughly 44 MJ/kg . Besides high energy content, a good aviation fuel must be highly resistant to prematurely and spontaneously igniting, that is, to have good anti-knocking properties . Engine manufacturers knew that increasing the compression ratio increased power, but by doing so the charge became too hot and tended to explode (rather than burn) too early, thus reducing the engine’s power efficiency and oftentimes damaging it as well.

Daimler Benz engineers increased the power of the DB-601Aa that equipped the older Bf 109E-4 by increasing the compression ratio from 6.9 to 8.2 in the DB-601N used in the Bf-109F-2. This they did by substituting the concave cylinder heads with flat-top ones. In this manner, they increased power from 1050 hp to 1175 . However, this change required 96-octane fuel (C-3) in place of 87 (B-4) .

Refueling a Messerschmitt Bf 109E with B-4 fuel. Bundesarchiv.
Refueling a Messerschmitt Bf 109E with B-4 fuel. Bundesarchiv.

German and Soviet refineries processed crude oil to obtain gasoline of about 70-octanes and then further refined it and added additives (like Tetra-ethyl lead @ 1.15 cc/L) to obtain gasoline of around 90-octanes. To get C-3 fuel it was necessary to blend 15% of synthetic isoparaffins with 85% of supplementary refined B-4 gasoline to increase its aromatic content (isoparaffins and aromatic hydrocarbons increase octane rating). The higher difficulty to obtain C-3 fuel meant that its supply was never abundant . The Soviets used B-95 on their fighters throughout the war .

It is not an overstatement to say that there is nothing like too much power. Drag increases with the square of the velocity and any speed increase require enormous additional power. For instance, the 1175 hp Daimler-Benz DB-601N engine propelled the Messerschmitt Bf 109F-2’s to 495 km/h at sea level . If a speed of 700 km/h at sea level was desired (40% increase), a new engine with over triple power would have been necessary !

Three months after the invasion onset, the Luftwaffe introduced the Bf-109F-4 with the even more powerful DB-601E. This engine operated at 2700 rpm (100 rpm increase), boasted a larger supercharger and incorporated the GM-1 system which injected nitrous oxide to the intake manifold, increasing oxygen supply at high altitudes . With these improvements, the power increased to 1350 hp at sea level and 1300 at 5500m. The Bf 109F-4 maximum speed improved to 523 km/h at sea level and 606 km/h at 6500m .

The DB-601E continued in production until March 1942 when the Germans decided to discontinue further development in favor of the newer, larger displacement DB-605 .

Engineers in all combatant nations strived to extract the last ounce of power from their engines, but metallurgical limitations set an ultimate limit to their efforts. An aviation engine converts at most 34% of the fuel’s energy into power, 32% is lost through the coolant systems, and 34% through the exhaust gases. And this is under economic cruise conditions (lean mixture), under combat power, thermal efficiency decreased to 26%, and during take-off to 20% (the last two conditions require rich mixture) . If alloys could be found that permitted the engines to operate hotter, more power could be extracted, but during WW II, that level was state-of-the-art.

Engine selection, although indispensable, represented only the beginning of the design process. Knowing the available power, the next step consisted of establishing an adequate power-to-weight ratio since this factor alone decided much of the theoretical performance of the aircraft . The higher the ratio the better, but since power was now fixed, the only alternative to improve this ratio entailed the reduction of the aircraft’s weight, specifically take-off weight, to the smallest possible value .

Take-off weight is the sum of empty weight plus payload. For our purposes, we will define payload as the weight of the pilot and parachute, fuel, oil, and ammunition, that is, the variable weight. Empty weight is the fixed weight and includes the complete aircraft fully equipped to carry out its mission, comprising the engine, airframe, radios, weapons, armor protection, self-sealing fuel tanks, and other equipment (i.e. gunsights, etc.).

For the designers, the decision over what should be included and how much, remained a dilemma. To save on weight, the airframe was made as small as possible and the structure stressed to withstand the projected flight loads, but not much more. Since a pilot could endure a maximum of +6g without blacking out, the structural limit applied to fighters was somewhat higher (+7g or more). A structure built without enough sturdiness implied risks. The wings of the Bf 109 remained its weakest point reaching their load limit at 750 km/h and instructions were broadcasted not to exceed this speed because instances of wings breaking off occurred.

Other alternatives to reduce weight included the installation of less powerful (lighter) weapons, reduced armor protection, and less ammunition or fuel. All of this meant better performance at the cost of a reduction of other fighter capabilities. Finding the optimum configuration required practical experience and inspiration.

Professor Messerschmitt designed its Bf 109s within narrow weight margins (2700 to 2900 kg) to achieve a PWR/Weight ratio of at least 0.40 hp/kg, while the newer VVS fighters were heavier (2900 to 3300 kg) because of bulkier engines or wooden airframes.

The more modern LaGG-3, Yak-1, and even the MiG-3 started the war with a disadvantage in PWR/Weight ratio (between 2 to 27% depending on the model). When months later the Germans introduced the F-4 the disadvantage grew even more.

Comparison of Power to weight ratios and take-off weights of the fighters of the Barbarossa period
Comparison of Power to weight ratios and take-off weights of the fighters of the Barbarossa period. The German fighters boasted better ratios except against the diminutive I-16, considered by some historians obsolete. This fighter had other disadvantages but in 1941 it remained a contender. The introduction of the Bf 109F-4 increased momentarily the German advantage.

It should be mentioned that the diminutive I-16, considered by many historians obsolete had the best power-to-weight ratio of all the contenders, including the not yet deployed Bf 109F-4.

Having specified the power (by selecting the most powerful engine available), and weight (to keep the PWR/Weight within parameters) the next step consisted of deciding the area of the wing. This was done by calculating the wing loading and using the known weight of the aircraft (wing loading is aircraft weight/wing area) .

Wing loading affects maneuverability and speed. A large wing area produces more lift so climb and turn performance improve, everything else being equal. Also, the low-speed regime, so important for landing, improves since stall speeds are lowered. However, a larger wing also produces more drag, so maximum speed is reduced.

The philosophy of the use of the fighter affected greatly the wing-loading selection. The Luftwaffe and RAF had differing visions for what a good fighter was. The former preferred high speeds with its associated relatively high wing loadings and war experience only reaffirmed this trend. Every new model of the Bf 109 had a higher wing loading than its predecessor and the introduction of the Fw 190 within months of the Barbarossa initial assault, made this proclivity even more evident.

The Luftwaffe started deploying the Focke-Wulf Fw 190A to JG 26 in the West by September. The considerable problems with its new radial engine prevented its use on the Eastern Front during 1941 but it is instructive to see the trend in fighter design exemplified by the A-2 and the Bf 109F-2, which was the best fighter the Luftwaffe held on inventory on 22 June 1941. The A-2 was faster, it could change direction more rapidly, it could out dive the F-2 easily, it boasted a longer range, and its firepower exceeded the F-2’s by a wide margin. The Messerschmitt fighter retained superiority only in minimum turn radius and vertical climb speed. The Fw 190A-2’s wing loading of 243.5 kg/m2 easily exceeded the 200.3 of the Bf 109F-2 . Although the British recognized the importance of speed, they emphasized turning ability, which dictated lower wing loadings. At the same time, they targeted the same PWR/Weight ratios. Despite this philosophy, the newer models of the Spitfire moved towards increased wing loadings as the war went on . The VVS started with a preference towards maneuverability until 1940, but afterward, the Soviets emphasized speed.

What did this mean for the fighters that would face each other?

Fighters were designed within narrow PWR/Weight and wing loading parameters
Fighters were designed within narrow PWR/Weight and wing loading parameters. The better PWR/Weight ratios of the German 1941 fighters as compared with the newer Soviet models gave them an edge because their wing loadings were similar. On the other hand, there is no obvious winner between German and British fighters but clear conceptual differences.

The comparison between the different models of Luftwaffe fighters and the newer VVS fighters is on the first analysis relatively straightforward. Both had similar wing loadings, but the Germans achieved superior power to weight ratios, and this gave the Jagdwaffe and edge . The assessment with the British is more difficult. The power to weight ratio was similar but wing-loadings markedly different. The advantage would fall with the side that set the conditions of the fighting to favor its selected characteristics.

The Devil is in the Details: Revealing the best fighter in the summer of 1941

Power to weight and wing loading ratios embody the major decisions made by designers to meet the air force specifications but based on these, many more detailed choices follow until an effective prototype is ready: One of the most critical is the type and shape of the wing because the wing produces almost all the lift and most of the drag in an airplane. The selection of the optimum lift/drag ratio of the wing is paramount. Other crucial choices are the aerodynamics of the plane to minimize drag, the altitude at which the supercharger speed is fastest, weapon selection, aircraft controls and degree of stability , structural strength and construction type, all-around visibility , communications equipment, and others.

These decisions are further complicated because the fighter needs to fly under different flight regimes. Low-speed, low-altitude for landing and high-speed, higher-altitude for combat operations at a minimum. Other operational regimes may be involved, like very-high altitude interceptions for instance.

Decisions made for one regime sometimes negatively affect performance on another (an example is a short wingspan to attain high maximum airspeed, but which also increases stall speed, making landings more difficult, and increasing accident rates).

To complicate matters further, the technological state of the country, availability of raw materials, skilled labor, and machine tools, all become part of the overall equation. Fighter designs is not an easy task.

How can we assess fighters and select the one that surpasses all the others?

Fighter comparisons are intricate because air combat is a fluid action where numerous important factors intervene, many of them interconnected. We can approach this with more objectivity by selecting and contrasting the performance attributes that are most relevant for the mission, although as will be seen, this still leaves some important gaps.

The fighter’s mission is to destroy other airplanes and to accomplish this the aircraft must maneuver in the airspace to attain the same plane where the enemy is moving until the weapons are in range. Then it must fire with sufficient lead (firing ahead of the target) to achieve hits and keep firing until the target is wrecked.

Against an unsuspecting target achieving a firing solution requires minimum steering while attacking a rival that is fully aware and flying an agile aircraft requires time-consuming, hard maneuvering to attain a firing opportunity that lasts only a few seconds. Because hard maneuvering reduces situational awareness and this endangers the attacker, the most fundamental tactic is to achieve surprise. The best aces applied ambush tactics and shunned dogfighting as a low-payoff activity. However, some pilots embraced dogfighting, and these differing styles required divergent attributes in their planes.

Pilots that preferred surprise chose boom and zoom tactics, where they launched a swift attack from a superior position (usually from a higher altitude and behind) and then converted speed into altitude to avoid exposing themselves. Airmen that selected dogfighting, flew forcefully to position their airplane in the rear quarter of the enemy and then tightened their turns until they achieved sufficient lead.

With this introduction it is possible to outline the main attributes that a fighter needs to be effective:

• Good visibility on every quarter to detect the enemy first and avoid being surprised.

• Superior communication equipment to broadcast sightings quickly by any pilot in the unit and for the leaders to direct the action of the formation.

• High speed to catch up with the enemy rapidly or to escape from him.

• High climb rate to attain an advantageous position for attack or to reduce exposure after it.

• Fast dive speed to overtake the enemy or to break off the action.

• Heavy firepower to maximize the short-lived openings during combat.

• Exceptional maneuverability to attain a good firing position or to negate one to the enemy (this can be subdivided into tight turn radius, fast roll rate, rapid acceleration, and as much power as feasible to maneuver horizontally or vertically).

• A high ceiling that furnishes altitude advantage.

• A respectable range to penetrate the enemy airspace .

• Capability to absorb damage and return to the base

The fighter’s main attributes that impinged on combat. Maneuverability is further broken down into turn radius, rate of roll, acceleration, and power to weight ratio.
The fighter’s main attributes that impinged on combat. Maneuverability is further broken down into turn radius, rate of roll, acceleration, and power to weight ratio.

To make a good comparison it is necessary to have accurate and complete data. Erik Pilawskii , the author of a book about WW II fighter performance, did extensive research to properly quantify many relevant attributes and corrected many errors found in the historical literature. For the comparisons that follow I have used his data for the most part although I have used other reliable sources to fill up some gaps (i.e. max speeds at different altitudes). It has to be said that unfortunately, some relevant information is not available (rate-of-roll, dive speeds, and durability to damage is non-existent except as anecdotal information, while visibility is somewhat subjective).

Maximum speed is without a doubt the parameter that more readily comes to mind when comparing fighters. From WW I to the end of WW II (and thereafter) the different manufacturers embarked on an endeavor to increase the maximum speed at almost any cost since this factor, more than any other, conferred the initiative in combat.

When Hitler launched Barbarossa the latest Luftwaffe fighter, the Bf 109F-2, equipped 70% of the Jagdgruppen while almost a third kept the older Bf 109E-7, at least until the German factories provided replacements.

On 22 June 1941 the Bf 109F-2, the MiG-3, and the I-16 represented the bulk of the fighters on the Eastern Front
On 22 June 1941 the Bf 109F-2, the MiG-3, and the I-16 represented the bulk of the fighters on the Eastern Front. The older Bf 109E-7 was being phased out as soon as production permitted. The newest Bf 109F-4 started to appear in front line units until September. The LaGG-3 and Yak-1 appeared in relatively small numbers initially, but high production levels meant that during the next 6 months, many IAPs received these fighters. The Bf 109 was faster than its Soviet counterparts except for the MiG-3 that enjoyed an advantage at high altitudes.

The I-16 outfitted most of the VVS’s IAPs whose pilots felt confident in the model. This fighter remained in production until early 1942. The MiG-3, the most numerous of the new generation of Soviet fighters, surpassed in numbers all the Bf 109s combined! The VVS also introduced the LaGG-3 and Yak-1 in very small numbers initially, but they soon equipped many regiments thanks to increased production.

As can be seen from the previous chart, the German fighters enjoyed a significant maximum speed advantage against all Soviet fighters, especially over the I-16 whose designers preferred to emphasize maneuverability (low wing-loading) over speed.

Although at first sight it appears as if the MiG-3 was the champion of this category, the fact is that this fighter was only faster than the F-2 at high altitudes (over 6000m) and since the Kampfgruppen and VVS’s BAPs bombed from altitudes below 5,000m there were very few combats above that height. The faster speed of the Bf-109F under 6000m gave it the advantage where the battles were fought. For this reason, the maximum speed parameter alone is insufficient to make a proper comparison. What we need is a chart that plots maximum speeds at every altitude as the next one, compiled by the Soviet TsAGI .

This plot corroborated that the Bf 109F-1 flew faster than any Soviet fighter at every altitude except over the almost empty skies above 6000 meters where the MiG-3 reigned alone. The LaGG-3, Yak-1, and MiG-3 surpassed the Bf-109E-3, but the Germans did not deploy this type for Barbarossa. The Bf 109E-7, which was 21 km/h slower than the F-1, was slightly faster than the Soviet fighters at all altitudes. It used the same engine as the F-1 but it was not as clean aerodynamically)

The next important virtue of a fighter is a good climb rate. The greater PWR/Weight ratio of the German fighters helped them achieve a higher climb rate . The I-16 excelled in PWR/Weight ratio, but its climb rate was mediocre due to a draggy airframe as revealed by its high Drag Coefficient (0.055 vs 0.30 to 0.040 of the other fighters making it the least aerodynamic efficient of them all). While the rest of the fighters utilized relatively small liquid-cooled engines, the I-16 was the only one equipped with a radial engine which gave it the largest frontal area while its power was no greater. This, along with its relatively large wing (low wing loading) negatively impacted its speeds, climb, and acceleration.

Altitude vs. max speed plot prepared by an important Soviet Union testing center comparing the performance of the Luftwaffe and VVS fighters.
Altitude vs. max speed plot prepared by an important Soviet Union testing center comparing the performance of the Luftwaffe and VVS fighters. The Bf-109F-1 (identical to the F-2 except for the cannon caliber) was the clear winner up to 6000m. Note: I-16 data added by the author using Pilawskii data.
The superior climb rate gave the Bf 109F an advantage in the vertical plane
The superior climb rate gave the Bf 109F an advantage in the vertical plane. Acceleration, on the other hand, is useful when it is necessary to decrease the speed to reduce closure to attack a slower moving target and once the kill is achieved to regain energy as soon as possible

Several factors have a bearing on a fighters’ maneuverability. Acceleration is a nifty quality because air combat is not fought at a constant speed. Often, the fighter is trying to avoid an excessive closing speed against a slower moving target to improve aiming and to increase the time the opponent will be in the gun’s sight. Once the kill is achieved, the fighter wants to regain a high energy condition to reduce vulnerability and to chase after the next target. The Bf 109 held the cards against its opposition as seen in the previous chart while the heavy LaGG-3 possessed the lowest performance. Turn radius or the ability to turn in the smallest possible circle is considered by many the quintessential mark of maneuverability. Some authors even go as far as considering it a more important trait than maximum speed. Turn radius is effective when defending to prevent the enemy from obtaining a good firing position and when dogfighting on the horizontal plane. Combat flight simulators enthusiasts usually fight on the horizontal plane and thus tend to stick to tight turns as the means to win a dogfight. However, when battling trained pilots in energy tactics turn radius loses much of it allure. The unmistakable trend in air combat from World War I to World War II to contemporary fighter jets reveals the increase of maximum speed at the expense of turn radius. This evidence should be a powerful argument on why speed is more important.

Compared with the previous three attributes, turn radius is a more subjective parameter, partly since it is difficult to measure accurately but mainly because it depends on the pilot’s skill . The same aircraft will also have widely different turn radii depending on how fast it is flying at the moment of starting the turn . The data in the next chart was calculated by Pilawskii at the same altitude for each airplane and compared with actual observations, so it is the best comparison available .

The superior climb rate gave the Bf 109F an advantage in the vertical plane
The low wing loaded I-16 enjoyed an overwhelming advantage in turning radius. The historical trend, however, favors higher speeds at the expense of turning radius. The I-153 biplane fighter, still in the VVS arsenal, had a turning radius of 141 m. World War II German and Soviet monoplane fighters had turning radii of around 300 m while modern-day combat jets require 840m or vastly more. To obtain the lowest turning radius the airplane must have a high lift coefficient, the lowest altitude, a high load factor (bank angle), low wing loading, and sufficient power.

Given the similar wing-loadings, it is not surprising that the calculated turn radii of all of the Eastern Front fighters were comparable. The much lower wing loaded I-16 as expected, enjoyed a significant advantage over all the monoplanes fighters on 22 June 1941. The Bf 109s had to avoid turning battles and stick to vertical plane fighting to overcome their adversaries.

The plot of Wing loading (kg/m2, vertical axis) vs turn radius (m, horizontal axis) for German, British, and Soviet fighters of the Barbarossa period and early 1942 shows that the latter was directly proportional to the former.
The plot of Wing loading (kg/m2, vertical axis) vs turn radius (m, horizontal axis) for German, British, and Soviet fighters of the Barbarossa period and early 1942 shows that the latter was directly proportional to the former.

The capacity to change direction quickly is arguably more important for a fighter than turn radius, but sadly, quantitative information of roll rate is lacking, and it will not be considered in the comparison. An interesting point, however, is that the soon to be deployed Fw 190A, would excel in this category, as evaluated subjectively. In general, the roll rate tends to suffer near maximum-air speed because of strong stick forces caused by intense dynamic pressure.

Power/weight ratio affects all the aircraft attributes, not only maneuverability, but it is included as a factor in this category because the execution of any maneuver from a straight and level flight (turns, climbs, aerobatics) demands plenty of excess power (that is, power above that required to keep the aircraft flying straight and level). This excess power is proportional to the power/weight ratio and the Polikarpov I-16 shined in this category. This partially explains its extraordinary agility.

The human eye remained the only inboard sensor available to detect enemy aircraft in World War II during the daytime. The cockpit design helped or hindered the ability of the pilot to see outside and until the Fw 190A introduction, the cockpits of the fighters that faced each other off were very similar, allowing good visibility to the front and the sides and poor visibility rearwards because of turtle-decking to improve aerodynamics . The bubble canopy of Kurt Tank’s fighter commanded better visibility to the all-important rearward sector and was deemed superior. Eventually, most new fighters would feature it.

Fighters of the Barbarossa period came equipped with flush canopies
Fighters of the Barbarossa period came equipped with flush canopies (top). Although aerodynamically clean, they suffered from a wide blind cone in the rear quarter. The innovation of the bubble canopy by the end of 1941 incorporated in the Fw 190 provided the pilots with better visibility into the all-important 6 o’clock position.

Until late in the war, the VVS fighters suffered from poor quality Perspex. When exposed to sunlight the canopies tended to become opaque. This could have been disastrous, but the Soviet pilots removed the side panels and flew with open cockpits. While this solved the short-term problem, it created another: more drag. The speed data shown before was compiled with new fighters with full enclosures. The open cockpit caused a speed decrease of 20-25 km/h, which means that the speed advantage of the Bf 109 was more pronounced than what the reports say.

Given the limits of the human eye to consistently detect approaching aircraft at distances of more than 3.0 - 4.5 km and the enormity of the search space, the importance of flying in formation with every pilot scanning a specific sector should be clear. Although using the fovea a pilot can detect an aircraft at 18.5 km under ideal conditions, the narrow field of view of 2 degrees at that distance means that without a clue of its position, the aircraft would remain undetected even by a squadron actively seeking targets.

When detected, it is critical to convey the information to the leader quickly for him to take immediate action. The lack of transceivers in most Soviet aircraft (except the leader) placed the Russian pilots at a grave disadvantage because the German pilots received the information of the enemy presence and position immediately upon detection, while several seconds elapsed before the Soviet leader became aware.

An aircraft that can absorb punishment and continue fighting (or at least escape) could live to fight another day instead of being permanently lost. This durability-to-damage quality is of great consequence in a protracted attrition campaign.

A study carried out by the US Navy between 1944 and 1945 on the causes of lost and damaged single-engine aircraft during air combat provides enlightening information. For every five stricken aircraft, two did not return, and three returned damaged (2:3 ratio of loss vs damaged).

The aircraft structure exhibited the highest probability of sustaining hits since it is the largest part of the aircraft. 43% of the airplanes suffered damage on it (only) but of them, 89% returned reflecting its toughness.

The second area with the highest probability of receiving hits was the pilot and cockpit controls. 19% of the airplanes suffered damage in this area. Despite the small size of the pilot and cockpit, this appears logical because most of the attacks come from the rear quarter, and from this sector, there is a high likelihood of hitting this exposed part. When hit there, 76% of the aircraft were lost, despite the armor protecting the pilot and cockpit. The penetration power of armor-piercing ammunition at the average distance of attack shows that it was more than a match to the armor plates defending this sector.

Smaller areas like the powerplant, the oil system, fuel system, and hydraulic system were proportionally less likely to be shot (between 5 and 7% of the time) but when struck the likelihood of receiving a fatal blow stood high (between 62% and 85% of the planes failed to return) demonstrating their extreme vulnerability despite self-sealing tanks, and the use of radial engines without coolant system. Had the Americans used liquid-cooled engines in the Pacific Theater, the proportion of aircraft destroyed when struck in the engine would have been much higher. The I-16, the only aircraft equipped with a radial engine during Barbarossa had higher durability to damage as compared with the rest.

The Americans found a 2:3 ratio of destroyed to damaged aircraft when hit
The Americans found a 2:3 ratio of destroyed to damaged aircraft when hit. Pilot, engine, and systems (oil, fuel, hydraulic) proved to be most vulnerable but more difficult to strike. The structure was the easiest to hit but it rarely caused the loss of the aircraft.

Summarizing the above results and adding ceiling , we can present an impartial comparison for the fighters that fought during the Barbarossa period (see the next table).

To prepare it we chose the Bf 109F-2 as a benchmark giving it a value of 10 in every parameter for an overall rating of 100. We then contrasted all the other models against it. Each model received a higher or lower value depending on their relative superiority (or inferiority) in each specific attribute vis-à-vis the F-2. For instance, the I-16 Type 28 received a lower score in maximum speed, climb, acceleration, radio (for lack of transceiver), and service ceiling compared with the Messerschmitt, but it scored higher in firepower, power-to-weight ratio, turn radius, and durability to damage (because of its radial engine). They were both evaluated as having the same visibility (flush cockpits) and although the range of the Polikarpov fighter was inferior, this characteristic was omitted from the final tally because the focus is on air combat.

Also, given that not all of the attributes are equally important we assigned the following importance: 30% to speeds (the most important group category), 20% to maneuverability, 20% to detection, 15% to firepower, 10% to durability to damage, and 5% to service ceiling.

Fighter Evaluation Table.
Fighter Evaluation Table. All the Bf 109 models surpassed their Soviet counterparts with the F-4 the overall winner. The Yak-1 bested its brothers by a small margin, while the I-16 shows it was not a sitting duck. The LaGG-3 resulted in the worst performer: it did not have the speed or the maneuverability to compete on an equal basis with its adversaries.

The performance of the Soviet fighters stood remarkably close. We can classify them from best to worse in the following order: Yak-1 (score 92), MiG-3 (90), I-16 (90), and LaGG-3 (88).

The Yak-1 rated highest, despite its low power-to-weight ratio (0.35 hp/kg) due to outstanding aerodynamics (the lowest drag coefficient of VVS aircraft at 0.030 and equal to the Bf 109F-4) that permitted acceptable all-out speed (561 km/h), adequate climb (918 m/min), and acceptable firepower. On the other hand, the LaGG-3 rated the worst because of the lowest power-to-weight ratio: it was too heavy for the available power. Even though it was a clean aircraft (drag coefficient of 0.033) its heavy weight worsened its speed (535km/h), climb (828 m/min), and maneuverability. The two light machine guns were removed early to reduce weight. Losses in combat were high and the morale in the IAPs equipped with this fighter became very low by the end of the year. So much so, that Lavochkin himself had to tour the units to hear the complaints of the pilots. The VVS High Command terminated the production of this fighter in favor of the Yak-1 by the summer of 1942 .

Main VVS fighters.
Main VVS fighters. Clockwise from the top (left): MiG-3, Yak-1, LaGG-3, and I-16. At the war’s onset, the I-15bis and I-153 biplane fighters were numerous, but they were relegated to attack missions very early.

It is noteworthy that the diminutive I-16, considered by many authors obsolete, rates higher than the LaGG-3 and equal to the MiG-3 notwithstanding being the slowest fighter and its poor climb. The main reason is the astonishing maneuverability that kept it competitive and its heavy punch . Compared with the much faster Messerschmitt’s however, its disadvantages are more pronounced. Production of both the I-16 and MiG-3 ceased in early 1942.

Left Messerschmitt Bf 109F-2 and right, the Bf 109E-7. Both had the same engine, but the former better aerodynamics gave it the edge in speed and climb
Left Messerschmitt Bf 109F-2 and right, the Bf 109E-7. Both had the same engine, but the former better aerodynamics gave it the edge in speed and climb

The Messerschmitt Bf 109F-2 had the same engine as the Bf 109E-7 but its more developed aerodynamics gave it an advantage in most parameters. The F-2 was the best fighter in the Eastern Front in 1941 until the F-4, with its more powerful engine and much improved power-to-weight ratio arrived at the front. Against its adversaries, the F-2 had better max. speed and climb, better maneuverability (except against the I-16), and the key tactical advantage provided by the transceivers in all aircraft.