GAU-8 / A Avenger
| GAU-8 / A Avenger | |
|---|---|
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| General Information | |
| Manufacturer country: | United States |
| Developer / Manufacturer: | Martin Marietta (General Electric) |
| Development year: | 1970 |
| Production time: | 1977 to discontinued (year unknown) |
| Weapon Category: | Gatling cannon |
| Technical specifications | |
| Overall length: | 6400 mm (with ammunition drum) |
| Pipe length: | 2229 mm |
| Caliber : |
30 × 173 mm |
| Number of trains : | 14th |
| Twist : | progressive right |
| Weight ready for use: | 1830 kg |
| Cadence : | (1800-) 3900 (4200) rounds / min |
| Furnishing | |
| Ammunition supply: | strapless |
| Drive: | hydraulic |
| Muzzle energy: | ~ 193 kJ (HEI) ~ 246 kJ (API) |
The General Electric GAU-8 / A Avenger (Avenger) is an American seven - barrel Gatling cannon in 30 mm caliber. It was originally developed for the US Air Force's Fairchild-Republic A-10 “Thunderbolt II” ground attack aircraft , but is now also used in the Dutch CIWS Goalkeeper .
The GAU-8 / A was developed by Martin Marietta - owned by General Electric at the time - for the sole purpose of fighting tanks and armored vehicles from the air and fires very powerful projectiles. Apart from the special artillery weapons of the AC-130 Gunship attack aircraft , the GAU-8 / A is the largest, heaviest and most powerfully purpose-built cannon of all aircraft worldwide.
history
The development of the GAU-8 / A was a parallel program to the "AX" tender, which had the aim of developing and building a ground attack aircraft. The A-10 and Northrop YA-9 aircraft, competing in the “AX” program, were intended primarily to carry the GAU-8 / A and were literally constructed around the weapon.
Since the GAU-8 / A was not yet available in the fly-off phase (decision phase as to which aircraft type - YA-9 or YA-10 - should be used) of the "AX" program, the M61 Vulcan was temporarily used as a replacement used.
Shot tests: Martin Marietta, Philco Ford and Oerlikon
The requirements for the weapon were drawn up during the late 1960s and announced in 1970. Martin Marietta and Philco-Ford each built three prototypes for the shooting tests (two for shooting, one as a back-up or for spare parts) according to the Ministry of Defense's specifications. The tests were held from January 3 to April 6, 1973.
Of the 100,000 rounds of test ammunition that each manufacturer had to provide, Martin Marietta's prototypes fired over 70,000 rounds, while the Philco-Ford prototypes fired fewer than 16,000 rounds. The reason for this significant difference was jams . The Martin-Marietta prototypes fired an average of 8,800 shots from one jam to the next, while those from Philco-Ford jammed after an average of 728 shots.
However, Martin Marietta had not yet won, as the GAU-9 / A ( Oerlikon 304RK) was also supposed to complete a shoot-off with the winner of the first tests. The results on June 5, 1973 were similar. The Martin Marietta prototypes achieved their 8,800 rounds, while the Oerlikon cut off similarly to the Philco-Ford and jammed after an average of 846 rounds.
The A-10 and with it the GAU-8 / A were put into service in 1977. The cannon is no longer made today; Martin Marietta is still responsible for servicing the weapon, although Martin Marietta is no longer part of GE.
Data and function
The GAU-8 / A alone weighs 281 kg and is 285 cm long. The entire system of weapon, ammunition feed system and ammunition drum is 6.4 m long and weighs 1830 kg when fully loaded. The ammunition drum has a diameter of 87.6 cm, a length of 181.6 cm and a maximum capacity of 1350 cartridges, but is normally ammunitioned with only 1174 cartridges.
In the case of the A-10, which finally went into series production, the GAU-8 / A takes up around a third of the fuselage length and makes up almost a fifth of the unladen weight of the aircraft. Since the weapon is installed in the middle, it was necessary to move the nose landing gear to the side.
The muzzle velocity of 430 g of heavy projectiles of the type PGU-14 / B API (API: armor piercing incendiary - armor-piercing fire floor ) is 990 m / s, the muzzle velocity of 360 g of heavy projectiles PGU-13 / B HEI (HEI: high explosive incendiary - highly explosive fire projectile) is 1036 m / s. According to the manufacturer, the scatter is five milli- radians for 80% of the projectiles fired, which means that at a distance of 1000 meters, 80% of the projectiles strike in a circle of five meters in diameter.
The original theoretical rate of fire was 4200 rounds per minute. It was later reduced to 3900 rounds per minute and added a second mode with 1800; however, this was removed again in the 1980s, so that the rate of fire remained at 3900 rounds per minute.
With standard equipment, the ammunition drum contains a mixture of PGU-13 / B HEI and PGU-14 / B API . On four PGU-14 / B while following a PGU-13 / B . The PGU-14 / B projectile contains a core made from depleted uranium to increase penetration. The penetrator weighs 301 grams (4650 grains ). The weapon is very effective against any form of armored vehicle.
The casings of the ammunition used are made of an aluminum alloy instead of steel or brass. Thanks to this innovation, a 30% larger supply of ammunition can be carried with you due to the weight saved. The bullets have plastic guide bands to increase the life of the barrels. The length of the cartridges is 290 mm, the weight 694 g, depending on the type of bullet a little more.
The very high recoil force of the weapon (44.5 kN), which is greater than the thrust of a single A-10 engine (40.32 kN), is noteworthy. Above all, therefore, the bursts were limited to a maximum of two seconds duration (mechanical lockdown) to the braking of the aircraft to keep within limits and a possible stall to prevent the aircraft. This two-second limit also serves to prevent the barrels from overheating and to keep ammunition consumption low. This is also intended to extend the service life of the barrels, as the USAF specifies a minimum service life of 21,000 rounds per barrel set.
Each barrel of the barrel set is relatively simply constructed as a non-automatic weapon, each with its own breech. All reloading functions are activated by the rotation of the barrel set, according to the functional principle of the original Gatling cannon . The locking movement is controlled via a cam . The barrel set itself is set in rotation by the hydraulic system of the A-10.
The ammunition of the GAU-8 / A is not belted, which saves additional weight and eliminates a possible source of malfunctions. Since empty cases of fired cartridges flying around could endanger the aircraft, they are not ejected but returned to the supply drum. The ammunition feed system is similar to that of the newer versions of the M61 Vulcan , but improved technical solutions and higher quality materials are used throughout, primarily with the aim of saving weight.
Developments based on GAU-8 / A
A four-barrel version of the GAU-8, the GAU-13 , was also developed. As far as possible, this relies on the use of GAU-8 components. For the GAU-13, weapon containers were developed (GPU-5 / A) with which, among other things, the ground combat test versions of the F-16 were equipped (it was also planned to equip the F-15). The containers were not a success for the aircraft, as the entire aircraft was shaken by the recoil when fired, and so the accuracy was no longer given due to the vibrations. It was also feared that these vibrations would damage the aircraft's airframe. The entire inventory of GAU-13 and GPU-5 / A were sold by the Air Force to the Marines, who used them for the LCAC 66 hovercraft .
The Thai Air Force uses the GAU-13 / A for some of its F-5 and F-20s , albeit in a different mounting arrangement than the US Air Force.
The Dutch CIWS Goalkeeper , an air defense system for the Navy, also based on the GAU-8 / A .
Based on the technology of the GAU-8 / A , the 25-mm automatic cannon GAU-12 / U Equalizer was developed, which is about the same size as the M61 Vulcan , but has a significantly higher firepower.
Technical specifications
| Parameter | Data of the GAU-8 / A Avenger |
|---|---|
| Type | Seven-barreled Gatling cannon |
| caliber | 30 × 173 mm |
| Manufacturer | General Electric |
| drive | External drive - electrically driven by two hydraulic pumps; 57.4 kW |
| cadence | (1800 to) 3900 rounds / minute; originally 4200 rounds / minute |
| Muzzle velocity | 1067 m / s (983 m / s with API-PGU-14 / B ammunition) |
| Ammunition supply | 1350 cartridges in ammunition drum |
| Ammunition feed | strapless |
| ammunition | API (Aerojet) 748 g, API (Honeywell) 717 g, TP PGU-15 / B 694 g, HEI PGU-13 / B 662 g |
| Gun weight | 281.2 kg |
| Ammunition weight | 936.9 kg |
| total weight | 1830 kg |
| overall length | 6400 mm (with ammunition drum) |
| Weapon length | 2900 mm |
| Pipe length | 2229 mm |
| Ammunition drum | 870 mm diameter, 1816 mm long |
| Tube bundle diameter | 356 mm |
| Penetrating power | 69 mm at 500 m; 38 mm at 1000 m |
| Recoil force | average 44.5 kN with sustained fire at 4200 rounds / min. |
Web links
- GAU-8 / A AVENGER Factsheet on the National Museum of the US Air Force website , English, accessed December 28, 2015
- FAS.org: GAU-8 Avenger (English)
- YouTube video of the Gatling cannon GAU-8 Avenger
Individual evidence
- ↑ GAU-8 Avenger. FAS.org, accessed March 11, 2018 .
- ↑ PGU-14 / B API Armor Piercing Incendiary [DU] 30mm ammunition. In: fas.org. Retrieved February 16, 2017 .