Brrrrrrrrrrrrrrt!

 Last week we looked at the background to the mighty A-10 and its development, now we continue the story.

The A-10 has been made famous by its weapon, the GAU-8 Avenger. A weapon so massive that the A-10 has to have a special jack under its tail should the GAU-8 be removed for servicing. The weapon itself is offset to one side, and the barrel that fires is actually the 9 o'clock one. This barrel is the one on the centreline of the aircraft. In later years it would be related to another US procurement mess. 

Video doesn't seem to be working correctly, so here's a link. http://i.imgur.com/2TFpP1G.gif

In the mid to late 1970's the US Army was facing a number of new issues, mostly helicopters performing pop-up attacks and a new generation of vehicles, the M1 Abrams and M2 Bradley's entering service. The later had a higher degree of mobility than previous chassis and would therefore leave those older vehicles behind. This included the M163 Vulcan and Chaparral SAM's. For that reason, the US Army instigated the Advanced Radar-directed Gun Air Defence System (ARGADS) program. The hull in all versions was to be a M48A5 with a new engine, and rear deck. This seems utterly perplexing, as this would not have been able to keep up with the new front-line equipment either. 

Several companies were invited to tender designs. These included General Electric with an AA vehicle based around the GAU-8. All four entrants received a designation number. Although there has been no documentation to confirm it, it is likely the General Electric’s entry was given the number XM248. This is down to published numbers of all the other competitors, XM246 (General Dynamics), XM247 (Ford) and XM249 (Sperry Rand). There was a fifth competitor in the shape of Raytheon, but they were proposing a German Gepard turret mounted on the M48 chassis, and it is not entirely clear what happened to this project. 

The General Electric entry, with its GAU-8 was only ever created as a model. But one can get an idea of how devastating it could have been. On 7th of November 1979 an A-10 was used to attack a company of tanks, spread out in an attack formation. These tanks were M47's, fully stowed with ammo and fuel. The A-10 made ten passes, with one quick burst per tank, a total of 174 rounds were fired (total ammo capacity for an A-10 is over 1,000 rounds by the way). Each burst lasted for about 0.57 seconds. 

Interestingly, the attack angle for this was only about 3-4 degrees, so the A-10 must have been almost flat to the ground! This dive angle was to simulate the nap of the earth flying needed to avoid Soviet air defences. 

Of the 174 rounds fired, ninety rounds hit the vehicles, thirty of which penetrated the tanks armour. Three of the tanks were destroyed, four more were immobilized, of which two had their main armament destroyed and one final tank suffered a minor degradation in its ability to use its main gun. Thus, the A-10 had rendered an entire company combat ineffective as only two tanks were still operational, and a third mostly operational. 

The ARGADS project seemed to roll on for a while, and then was re-named to DIVisional Air Defence System (DIVADS). At this point General Electric brought out their scale model, re-worked it with a new radar fit, and new optics modelled on and resubmitted. Of the competitors only the Ford (XM247) and General Dynamics (XM246) designs were selected for comparative trials. In a shootout the XM246 thrashed the XM247. The XM246 achieved twice the number of hits, at over twice the range of the Ford entry. By the end of the shoot out the XM246 had shot down fifteen helicopters and the Ford just 8. 

So, the contract was awarded to the Ford with the XM247 becoming the ill-fated Sgt York SPAA. I have no idea how this happened, but I suspect the words "Congress" and "Committee" will be included somewhere. 

If you read the US Air defence journals.. this is the most awesome Air defence tank of all time...

The Sgt York went on to perform disastrously badly, on one occasion managing to lock onto the spinning blades of a ventilator fan on a toilet block on the range. Another time, the gun locked onto, and laid its guns onto, the viewing stands containing large numbers of the Army's brass, only to be prevented from firing by the gunner. 

As the Army had no other backup they continued to press forward with the project. Eventually Congress stepped in again, this time for good. The Sgt York was ordered to be put through a series of battlefield tests to prove it was capable. At first the Sgt York could not score hits on the drones, even when just flying along in a straight line. So, the drones were just set to hover, and still the Sgt York missed. In the end the drones were covered in radar reflectors to increase the strength of the radar return. Further tests and checks showed that while the gun was sufficient the tracking and laying system was fault ridden. Operational reliability was given as just 33%, which means that only 1/3 of all Sgt Yorks would be working at any one particular time. In 1985 the program was terminated.

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