It's actually more the role then any overt changes. The O means observation, and the OA-10s here in Alaska are used in the forward air control role. Basically they are spotting targets for the fast movers (F-16s and F-15E strike eagles). This role started in Vietnam first with Cessna Birddogs and later Mixmasters and OV-10s and other aircraft. Traditionally the FAC would mark targets with smoke rockets. These days they may do it by transmitting GPS co-ords--maybe one of our active service guys knows. The beauty of the A-10 is that it is well armored to protect the pilot and should somebody take a shot at them, well they can defend themselves unlike a Birddog. I understand one of the reasons behind the change from tank buster to FAC has to do with the gun supposedly being able to starve the engine of air in a prolonged burst. I think that's an urban legend, as I've never seen it substantiated in print.
The rumor as you heard it is just that, a rumor... *however* it is based in a fact: the fire rate and recoil from the gatlin gun is high enough that a bust over 3 seconds would push the aircraft from operating speed into a stall. You have to realize exactly how big this cannon is. The A-10 is almost a cannon with an airframe built around it (the cannon is bigger than most cars). However, it's also not an issue. The cannon fires enough rounds and the rounds are large enough that there isn't a need for a sustained burst. A very short tap of the cannon will take out a tank.
I promise they are effective, I have a friend who was in the marines who unfortunately had his column get on the wrong side of a trigger happy A-10 pilot during the initial invasion of Iraq.
More A-10 stuff at the bottom.
Actually the Warthogs are the second aircraft to carry the OA-10 designation. The first was certain models of the PBY Catalina. The Catalina wreck at the Aviation Heritage Museum in Anchorage is one such.
Don't laugh, but back when I was nominated for the USAF Academy I wanted to fly either A-10s.....or C-130s!
There more of a story here?
More information:
http://www.af.mil/news/story.asp?storyID=123028579Calls the Eielson aircraft "A-10s"
http://www.eielson.af.mil/library/factsheets/355FS.docRefers to Eielson having both A-10s AND OA-10s, not *only* OA-10s.
A/OA-10 Thunderbolt II
The A/OA-10 Thunderbolt II, assigned to the 355th Fighter Squadron, is Eielson’s close air support and forward air control aircraft. Working side-by-side with the F-16, the OA-10 is used to direct air strikes in support of Army forces in Alaska, while the A-10 performs close air support missions.
Equipped with rockets, flares and other light ordnance, the OA-10 can perform many other missions, including observation, armed reconnaissance, ground attack, gunfire spotting for ground forces, target marking, search and rescue, and night/flare illumination.
The A/OA-10 is a highly reliable, austere and rugged aircraft that may be operated from highways, semi-improved runways and dry or frozen lakebeds, with little support besides fuel and ordnance re-supply. All routine maintenance can be performed without ladders or stands, and the single-point-refueling receptacle is at chest level in the left wheel nacelle.
The A/OA-10 is designed to survive in the very dense anti-aircraft environment of Europe. Most parts, like the engines, control surfaces, wheels and flaps are interchangeable left and right. Nothing behind the nose section has any compound curves, so any damaged panels can be cut from sheet metal and simply bolted on. One-third of a main wing, one vertical stabilizer, one engine, half of the horizontal stabilizer and everything forward of the cockpit can be shot away and the aircraft will still fly.
Notice that it differentiates, saying the OA-10 will do FAC while the A-10 does CAS. Sounds like there is something different in the aircraft. IE, a normal A-10 isn't used in the OA-10 role.
Oh, and here's the Air Force inventory:
Inventory: Active force, A-10, 143 and OA-10, 70; Reserve, A-10, 46 and OA-10, 6; ANG, A-10, 84 and OA-10, 18