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Using AltaVista, I translated the aforementioned web site. I am posting below in full form (not quoted) for easier reading...as you can see not everything translates well, but you can get the general idea of the article.
Cheers! M2
GAU-8/A Avenger
General Electric
General information
With the GAU-8/A manufactured by General Electric concerns it one of the most enormous and most effective automatic cannons, which were ever blocked in a combat aircraft. In the use as anti-armored force in of Fairchild Republic of built ground-combat engagement airplane the A-10 Thunderbolt II the GAU-8/A worked already several times and its abilities proved. Although the cannon is a relic from times of the cold war it, although also for dividing changed fields, still successfully used.
Development
The development of the GAU-8/A began for instance with the start in the A-10 American A-X of program (see - > " A-10" Thunderbolt II "),come up, for the building of a close support airplane for the fight of the feared tank armies of the east. For this airplane an appropriate weapon was needed. The current enemy picture consisted at this time of large, predominantly of T-62 battle tanks existing, tank fleets. Against these one looked for now in the middle of the 60's an effective weapon system. Bombs were to be supported for the fight against tanks only reduced suitably around the own troops at the soil from air. At guided air-to-surface rockets one built of course, but the measure of the things were they not yet. Due to the Unausgereiftheit of these weapon systems, which reflected itself in precision and achievement lacking, and to high costs, one deliberated oneself upon proven systems. By claimant studies the responsible persons successes of flying tank hunters became conscious like the IL-2 Schturmowik, which was equipped with large-caliber cannons. Thus one came on the idea a similar variant as main armament for the A-10 to use.
Different demands were made to their operational area accordingly against the main armament of the A-10 which can be developed. Between 1968-69 an official catalog of demands was set up. In its function as antitank weapon used from air the automatic cannon had to order among other things over high precision around a large effect in the goal relatively small working by the distance to reach. One can favour these on different ways. On the one hand with caliber that good ballistic characteristics has, thus on larger distances of its optimal flight path, on the other hand with a high muzzle velocity the one penetrierenden, tank-piercing effect not excessively deviates made possible. As suitable caliber one determined the caliber of 30 mm in various bombardment tests, even if selbiges is quite heavy. Further attention was put on a particularly high cadence. This appears under the criterion the fact that the pilot of a combat aircraft in the flight only to it aim to little time and shoots has conclusively. With a high cadence one can reach now that particularly many projectiles achieve the goal before the goal from the visor are.
The straight last demand limited the selection of the suitable systems. This led nearly inevitably to the selection of an automatic cannon working after the Gatlingprinzip to the preferential system. In the area of these gun cannons made itself since that 2. World war above all the manufacturer General Electric a name why it for the order was almost suited. On 16 November 1970 took place the official advertisement for 30 mm an automatic cannon according to the described requirements. In the June of the following yearly the two companies General Electric and Philco Ford received as expected the addition for the building prototypes of the automatic cannon called now GAU-8. However the GAU-8 could not be finished placed in time to the comparison between Fairchilds YA-10 and Northrops YA-9, why into the YA-10 first 20 mm M61 an automatic cannon one blocked. Shows the fact was very important to the responsible person the completion of the flying panzerbrechers that independently of this order the Hughes Tool company was assigned one as GAU-9 designated 30 mm of cannon to develop. This are based on Swiss Oerlikon 304RF automatic cannon, likewise in the caliber of 30 mm. With the fact one wanted to guarantee that the A-10 can be equipped with a main armament even if the project GAU-8 fail should.
This second option had only walked in front rejected there in the spring 1973 the development of the GAU-8 now far. In an accomplished, direct comparison of the two automatic cannons on the test area of the Armament development and test center of the Eglin air Force cousin the GAU-9 of the GAU-8 was underlaid, so that the further development was stopped. In June 1973 the development of the GAU-8 had so far progressed that General Electric received now an order in the value from 23.7 million dollar around 11 pilot lot models of the GAU-8 to manufacture. While eight of the automatic cannons were intended for the installation into the A-10 of pilot lot models, the remaining three for quality and material testing at the soil should be used.
For the first time the enormous GAU-8 automatic cannon was inserted and flown on 26 February 1974. The GAU-8 was shot first during the flight on 19 June 1974. From now on the automatic cannon was tested extensively under all conditions. However a quite serious problem arose, which through not completely burned propellants one caused. The not burned arrears caught fire and formed a dangerous fire ball in front of the airplane. This problem could be repaired by a new composition of the propellant. In September 1974 the GAU-8 automatic cannon was removed by the responsible persons places and certified.
Technology
With the GAU-8/A acts it around seven laeufige 30 mm a gun cannon after the long-proven Gatlingprinzip works itself. That means it that each of the seven runs has its own catch with pins. The seven runs are arranged in a circular, by General Electric rotor mentioned, bundle and turn, propelled from 26 HP (35.4 KW) a strong electric motor, around a common axle center. During the engine the run bundle is turned follows the cam tappet of the catch belonging to the run synchronously a cam career inside the housing, whereby the catch is opened and closed once per revolution. This rotation principle with several runs brings several advantages with itself. Thus several runs are present, give it for the runs despite the large cadence sufficiently cooling time whereby all too fast overheating are avoided. Nevertheless one can deliver only short fire bursts, since the enormous recoil would slow the A-10/OA-10 down otherwise too strongly.
The mmunition of the GAU-8/A is in 1174 shot seizing, 1.85 m is enough for cylindric magazine drum, which is accommodated at the end of the entire weapon system. The ammunition is beltless arranged along a spiral guidance in such a way in the drum that the cartridges are arranged radially, with ogives of shell to the axle center and the case soil to the outer edge of the drum. From the magazine drum the cartridges arrive on turn of the internal drum into the supply mechanism at actually the cannon lead. In addition they must go through first a turning mechanism. A rotary receiver disk carries the cartridges thereby to a guard ring. These the cartridges partly go through before it into the supply mechanism change, which feeds the cannon. The empty cases are however not ejected after the shot taken off from the cartridge chamber. To avoid instead it back into the drum magazine led around damages at the outer hull of the airplane. The load mechanism, which alternatively supports a cadence of 2100 or 4200 shot per minute, of two hydraulic engines with an achievement of altogether 42.2 HP (57.4 KW) is propelled. One of the two engines falls out can the system with a cadence by 2100 firing/minute be still operated. Thus that is externally propelled the cannon is unnecessary also the problem of supply disturbances through not ignited cartridges. Taken off in such a case the not ignited cartridge exactly the same as an ignited, it comes by it not to the failure of the system. Also for other problems often simply running back of the entire system in opposite direction hands on which the cannon normally continues to fire. At all the GAU-8/A an extremely verlaessliges system, which also the statistic supports value, which arises a jam only all 150000 shot, is. The runs have a respectable life span of approximately 21000 shot per run. Beyond that the GAU-8/A Avenger is a relatively precise weapon system. The accuracy is indicated as 5 mil 80%. This designation describes the fact that 80% of the projectiles fired from a distance of 1200 meters hit within a circle of 6,1 m diameters.
Ammunition
With American armed forces altogether four different 30 mm of ammunition sorts for the GAU-8/A automatic cannon are in use. All together they have the community that a Alluminiumlegierung for the patronenhuelsen was used here instead of the two otherwise usual materials steel and brass.
The with priority used ammunition sort with the designation API PGU-14) became particularly for the primary order of the A-10, which chase and destroying armored vehicles and tanks develop. The abbreviation API reads written out Armor Piercing Incendiary and meant as much as armor-piercing projectiles. API is a general name for armor-piercing projectiles of different calibers. The exact type designation in the A-10 used 30 mm API of projectile reads PGU-14/B. This kind projectile does not contain any explosive in the goal to the effect to come could, instead of becomes the armor-piercing effect only by the kinetic energy of the projectile working in the goal. The actual projectile, the Penetrator has smaller extents of approximately 15 mm and is thus smaller than the case. The small diameter has the consequence that the kinetic energy on a small point comes to the effect whereby the penetration of heavy armoring is ensured. Around same aerodynamic characteristics as comparable 30 mm nevertheless projectiles to have this projectile core is surrounded by a light alloy coat, which lends the form of a comparable 30 mm of projectile to it.
The Penetrator consists of a material with particularly high density, since another metal would not have comparable effect. A material which due to its high density and the small price as particularly suitably turned out is during the enrichment of resulting and therefore quite cheap depleted uranium (YOU - Depleted Uranium). This was used by the Americans in large quantities. Particularly during Desert Storm large quantities of it in the Iraqi desert were fired. Only afterwards the health risks, which proceed from this heavy metal, came to the daylight. Alternatively it also different materials, which are to furnish similar penetration performances, gives to be used however not to such extent.
The API of projectiles is manufactured in accordance with American supply philosophy of two competing companies the always sufficient supply wars and in addition the price to press to be able. The projectiles of the two companies Honeywell and Aerojet differ due to the used materials slightly in their characteristics. Thus the muzzle velocity is with the ammunition with 1030 m/s, manufactured by Honeywell, slightly more highly than the 980 m/s of aero jet. In the meantime there are numerous other variants in its specifications easily differs, but on the same operational principle are based nevertheless.
Second into the GAU-8/A used ammunition sort carries the designation HEI PGU-13 (High explosive Incendiary) whereby it around a projectile filled with highly explosive materials acts. This explosive effect is used particularly against easily armored and soft targets so mentioned. This explosive effect of the fragmentation effect caused by the projectile covering is combined. One of these cartridges weighs 662 g that projectile leaves run with a speed of 1021 m/s. Combat-moderately the A-10 is equipped with both ammunition sorts. The relationship from API to HEI amounts to in this 4:1, on a HEI projectiles follows thus 4 API of projectiles.
Particularly for purposes of practice the practice ammunition TP PGU-15 (target Practice), particularly cheap in the acquisition, stands ready. Particularly large quantities were manufactured by this ammunition marked by a blue projectile.
The Aufmunitionieren of the system does not take place naturally by hand, what with such a complex system would be much too aufwaendig. Instead particularly for this task a battery charger with the designation was developed AS (Ammunition Loading system). Removed this equipment fastened on a trailer, after it was attached at the appropriate places, automatically and at the same time new ammunition loads the empty cases after. A complete exchange of the ammunition can thus go in 13 minutes of.
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