The Fighters

The Fighters

We can now have a look at the armament of some WWII fighters. For convenience, I sorted them by hitting power, in terms of fired weight per second. There is also a chart of the evolution of fired weight per second, which requires Java, or a plot in static gif format.

Fired weight per second is at best a rough approximation of destructive power. It is a reasonable approximation if the destruction is to be caused by the high-explosive or incendiary chemicals contained in the ammunition. The amount of explosive or incendiary material is of course related to the weight of the projectile, but it is not a linear relationship: Rounds of smaller calibre have proportionally thicker walls, and a smaller fraction of their weight is available for chemical loads. Therefore the fired weight per second is usually more relevant for larger calibre guns.

As a second measure of the destructive power, the muzzle power is given, in kilowatt. This is the rate of production of kinetic energy. AP or "ball" rounds that contain no chemical load only have this kinetic energy to cause damage to the target. More is not always better; a round with a too high kinetic energy might pass clean through the target without doing more damage than two neat, round holes. The optimal velocity to do maximal damage a metal plate is just below that required to penetrate it. Of course projectiles lose a lot of the muzzle energy before they hit the target, because of drag. In general larger calibre projectiles retain their kinetic energy longer.

A disadvantage of AP rounds is that they cause damage in a more limited area than incendiary or explosive rounds. Therefore semi-armour-piercing explosive or incendiary rounds were used more often. These require kinetic energy to penetrate the armour, and have chemical energy to cause destruction afterwards.

A third number given is the number of projectiles fired. If the target is not armoured, the same weight of non-explosive projectiles does more damage when distributed over numerous small projectiles than in a single large one, and the number of projectiles is the most important. But if the target carries armour the smaller projectiles are more likely to be stopped, and that reduces the effectiveness, especially of the rifle-calibre weapons. On the other hand, a larger number of projectiles means that the probability of a single hit increases.

To summarize: Fired weight per second is given as an approximation of the chemical energy that can be transferred to the target, muzzle power as a measure of the kinetic energy, and the number of rounds fired indicates the spreading of this transfer over a number of hits. All three are factors that must be considered in a consideration of the firepower installed in an aircraft. A "firepower formula" that would allow us to actually calculate a single number as a measure of the firepower, would be a nice thing to have. However, too many factors are involved, and the effectiveness of ammunition depends very much on the nature of the target.

Occasionally, firepower effectiveness was measured experimentally. The Germans famously determined that a large sturdy bomber such as a B-17 or B-29 could be shot down with 20 hits of 20mm ammunition, three hits with 30mm HE ammunition, or one single 55mm hit.

Fiat C.R.42 Falco

CR.42

The CR.42 is a good candidate for the best biplane fighter ever built. But it was a contemporary of the first generation of monoplane fighters, and completely outclassed. [21]

Nakajima Ki.43 Hayabusa

Ki.43

A captured Ki.43 in Chinese markings. The superficial similarity to the A6M is obvious, and caused considerable confusion. The Ki.43 was extremely agile, but by the standards of 1942 it was slow, undergunned and woefully vulnerable. Nevertheless the type stayed in production until the end of the war! [60]

Supermarine Spitfire Mk.IA

Spitfire I

A Spitfire Mk.I with a three-bladed de Havilland airscrew. The gun ports in the wing have been patched over with fabric, a standard practice at the time to protect the guns from frost. [19]

Yakovlev Yak-3

Yak-3

Yakovlev Yak-3. This was a highly specialized low-altitude interceptor, with brilliant performance and handling at low levels. [57]

Messerschmitt Bf 109E-3

Bf 109E-3 Bf 109F-1
Left, a Bf 109E-3. [14] Right, armament installation of a Bf 109F-1, with its engine removed. The breech of the MG 151 gun was in the cockpit, between the feet of the pilot. The cowl guns are MG 17s. [14]

Mitsubishi A6M2 model 21 Reisen 'Zeke'

A6M2

Mitsubishi A6M2 taking off during the Battle of Santa Cruz. The A6M2 had good performance for a carrier-based fighter and a long range, but it was a poor basis for development. [59]

Mitsubishi A6M5b model 52B Reisen 'Zeke'

A6M5c

Later developments of the A6M remained inferior to their opponents. This is an A6M5c, armed with two Type 99-2 20mm cannon (inboard) and two 13.2mm Type 3 machineguns (outboard) in the wings, and a third Type 3 gun in the engine cowling. [58]

North American P-51D Mustang

P-51D

Compared with previous Mustangs, the P-51D had two more .50 guns, and the armament installation had been redesigned to make it more reliable. [20]

Yakovlev Yak-9T

Yak-9T

Yakovlev Yak-9T. The Yakovlev family of fighters were small aircraft, very manoeuverable and with good performance below 5000m, where most combat at the Eastern front occurred. [56]

Lockheed P-38 Lightning

P-38J

The P-38 was the most successful twin-engined fighter of the war. Some early models had one 37mm cannon, two .50s and two .30s, but production soon standardised on one 20mm cannon and four .50s. [32]

Supermarine Spitfire Mk.XIVE

Spitfire XIV

A late-production Spitfire FR Mk.XIVE. Note the modified nose contours for the Griffon engine, five-bladed propeller, bubble cockpit and camera port in the aft fuselage. [18]

Kawasaki Ki.61-I-KAI-Hei Hien 'Tony'

Ki.61

The Nakajima Ki.61 Hien, or Army Type 3 Fighter, Allied codename Tony, was at first believed to be a copy of a German or Italian design. In fact only its Ha-40 engine was a licensed version of the Daimler-Benz DB 601. [17]

Republic P-47D Thunderbolt

P-47D

With eight .50s, the P-47 carried the heaviest armament of the US single-seat fighters. [31]

Focke-Wulf Ta 152H-1

Ta 152H-1

Above, a Ta 152H-1. Note the slender long-span wings of this development of the Fw 190, and the Jumo 213 V-12 engine with annular radiator. [11]

Hawker Tempest Mk.V

Tempest Mk.V

Hawker Tempest Mk.V. This one is armed with Hispano Mk.V cannon. Early Tempests had Mk.II cannon, and the longer barrels extended in front of the wing leading edge. [63]

Messerschmitt Me 262A-1a

Me 262

A Messerschmitt Me 262, photographed in April 1945 in Switzerland.[55] Allied observers at first criticised the choice of four 30mm cannon, estimating that the rate of fire could scarcely exceed five per second.[64] But the MK 108 fired two times faster than that.


Comparison Table

Name Rounds Weight Energy
  (1/sec)(kg/sec) (kW)
Fiat CR.42 Falco 23 0.86 248
Nakajima Ki.43 Hayabusa 30 1.14 362
Supermarine Spitfire Mk.IA 152 1.72 480
Yakovlev Yak-3 26 1.92 703
Messerschmitt Bf 109E-3 54 2.37 532
Mitsubishi A6M2 Reisen 50 2.62 414
Mitsubishi A6M5b Reisen 46 2.80 681
North American P-51D Mustang 75 3.64 1374
Yakovlev Yak-9T 17 3.70 1470
Lockheed P-38J Lightning 60 3.73 1421
Supermarine Spitfire Mk.XIVE 45 3.81 1464
Kawasaki Ki.61-I-KAI-Hei Hien 58 3.95 1306
Republic P-47 Thunderbolt 100 4.85 1835
Focke-Wulf Ta 152H-1 35 5.96 1118
Hawker Tempest Mk.V 50 6.50 2292
Messerschmitt Me 262A-1a 40 12.50 1592

A longer list of fighter armaments is reproduced elsewhere. It is clear from this table that muzzle energy and weight of fire are related, because a heavier weight of fire usually means a proportionally higher muzzle energy. This simply reflects the fact that the muzzle velocities of the guns used are typically around 825 m/sec, so that the kinetic energy per unit of projectile weight is approximately 340 kJ.

The exceptions are the MG-FF, Type 99-1 and MK 108. These are all low-velocity weapons, and fighters equipped with these weapons have a lower total muzzle power, although the weight of fire might be quite high. The best example is of course the Me 262.

There is no obvious relationship of either weight of fire or muzzle power with the total number of rounds fired per second. This value also does not show any clear trend towards either an increase or a decrease, although there are a few exceptionally low or high values.


Next: Analysis

© 1998-1999
Emmanuel Gustin
gustin@uia.ua.ac.be

Introduction What preceded Gun Tables Ammunition
WWII Fighters Analysis Firing Up Big Guns
Fighter Armour Bomber's Defense Postscript Korean War Fighters
Fighters Table Fighters Charts Ballistics  
Questions Answers Sources Notes