Aircraft gun armament

30mm CARTRIDGES for small artillery

GSh-30 (GSh-30K) TWIN-BARREL GUN

GSh-23 (GSh-23L) TWIN-BARREL GUN

Today's armament systems in service with fixed-wing aircraft and helicopters of the world's leading countries widely use small-caliber automatic guns as a highly effective weapon to perform such tactical missions as:
- destruction of hostile fixed-wing aircraft and helicopters in the air;
- engagement of land-based light-armored and soft-skin targets and manpower;
- protection of aircraft from fighters and missiles, etc.
Specimens of modern aircraft gun armament were developed by the Instrument Design Bureau (Tula) between the 1970s and 1980s as part of a unified national system of gun armament designed for use by all fighting arms. A system-oriented approach has made it possible to attain the most favorable parameters of the "round-weapon-mount-sighting system" complex, minimal nomenclature of ammunition and guns, unification of armament and, consequently, shorter development and production time frames and lower associated costs. For example, on the basis of such criteria as the "round quality coefficient - r" which implies power, ballistic properties, weight and size characteristics of a cartridge used to engage light-armored and soft-skin targets and equivalent indicator "hit probability with constant armament group weight," an optimum caliber of 30mm has been found (see the r=f(d) chart presented in Fig. 1) as the major caliber of aerial guns.
Similar dependence, r = f(V0), for the 30mm round has revealed that the optimum muzzle velocity is 850 to 950 m/s. A 30mm round, type AO-18, produced domestically, approximates the optimal parameters most closely. Its HE shell is characterized by a moderate muzzle velocity and has a short flight time and high destructive action.
To find the most efficient solutions in designing the weapons system proper and forming the structure and selecting basic projects of system guns, the "weapons system sophistication factor," characterizing the unit productivity (rounds per second versus weapons system unit weight) of the automatic gun. This made it possible to objectively compare various specimens of the weapons system and their integration versions and, finally determine the most suitable nomenclature of basic specimens of 30mm aircraft guns, capable of the following firing rates:
- 6,000 rounds per minute (GSh-6-30) for use in fixed built-in mounts on board fighter-bomber class of aircraft;
- 3,000 rounds per minute (GSh-30) for use in fixed built-in mounts and on external stores of attack aircraft;
- 1,600 rounds per minute (GSh-301) for use in movable and fixed mounts on board light fighter aircraft.
The specific nature of certain platforms is considered in appropriate designs: GSh-30K is intended for use in fixed helicopter-borne mounts; a 30mm gun,

originally developed for ground fighting vehicle applications and characterized by selective supply and 200 to 600 rounds per minute firing rate (2A42), is recommended for use in movable mounts on board gunship helicopters. Ground targets can be attacked effectively by high-rate-of-fire 23mm guns GSh-6-23 installed in movable mounts (built-in and external) of attack aircraft.
For the structure of modern national small-caliber gun system, refer to Fig. 2. The system comprises series-produced Gryazev and Shipunov guns currently in service with the Armed Forces and available in three versions (single-barrel, twin-barrel and multiple-barrel). A 30mm round, type AO-18, has been accepted as the basic round for this gun. The 23mm gun's basic round is AM-23.
The system boasts a high level of unification and interchangeability and provides for the application of progressive manufacturing methods.
The system weapons are characterized by high reliability (probability of trouble-free operation in an attack is estimated at 0.9997 to 0.999). The high engineering level of the artillery weapons developed by the Instrument Design Bureau can be proved from a comparison between two six-barrel guns: 23mm Russian-made GSh-6-23 and 20mm American-made Vulcan. The first is twice as light in terms of weight, has twice the firing rate and does not require an external power source.
The full range of conceptual and design solutions can arbitrarily be combined (from the standpoint of realizable level of basic performance characteristics) into three principal designs: single-barrel, twin-barrel and multiple-barrel.
For the comparative characteristics and indices, characterizing the technical sophistication level of modern Russian 30mm aerial guns available in the aforementioned three designs (single-barrel, twin-barrel and multiple-barrel).
The single-barrel design is generally characterized by limited capabilities from the point of view of the possibility to increase the firing rate and enhance firing modes. However, a single-barrel gun is the lightest and smallest weapon that can easily be mounted on a vehicle. Given the high ballistic characteristics, it can form the basis for developing fairly efficient artillery systems, featuring enhanced accuracy.

The twin-barrel design makes it possible to increase the rate of fire and enhance firing modes two to four times, with the weapon's weight and overall dimensions of a single-barrel weapon.
Implementation in the multiple-barrel design of major principles of intensification of automatic equipment operation (nonstop movement and complete harmony of all processes and events, smoothness of cartridge belt feed and soft ramming) makes it possible to solve the weapon's survivability and reliability problem successfully and use the weapon on various platforms. Acceptable overall dimensions and weight are attained via common assemblies servicing all barrels, namely:


- a single-barrel weapons system automatics has been developed. Though the gearing arrangements of its actuating mechanisms are not precisely matched, it functions reliably and this 30mm gun is the world's lightest aerial gun;
- a unique crank-type moving mechanism with bevel-gear reducer has been developed. Following the appearance of this mechanism, a high thermal efficiency of the gas deflection system of multiple-barrel armament, featuring a continuously moving basic element of the automatic system, has been attained and, consequently, powerful small-size self-contained drives have come into being;



- fast-acting self-contained electric pyrotechnical reloading systems and starting devices have been developed;
- highly-effective self-contained water-evaporating barrel-cooling systems, ensuring a double-fold increase in the gun heat resistance virtually without increasing its weight and dimensions have been developed;
- cartridge belt feed sprocket drives and linkless feed systems, ensuring the high degree of ammunition feed smoothness and continuity have been developed.



For the external view of Russian-made small-caliber automatic guns in service with the Air Force, refer to Figs 4, 5, 6, 7, 8, and 9.
All specimens of aircraft gun armament developed by the Instrument Design Bureau are series-produced. They are integrated into various types of the latest installations in service with Russia's fixed-wing aircraft and helicopters.
Thus, in terms of diversity and engineering level, today's national system of small-caliber aerial guns fully meets the present and future needs of national Air Force for this type of armament and proves its supremacy over the best foreign counterparts.