In an earlier life as an instrumentation techician for the US Gov't, I measured and recorded the behavior of internal ballistics energy on the outside of the barrel of the GAU-7 (caseless ammo, 25 mm gatling gun). It was abandoned due to the mechanical synchronization problem between feeder, loader and rotating chambers at high speeds.
Philco-Ford was competing against GE. In the ammo dept it was Hercules against Brunswick (I think). GE and Philco, I believe were also competing feeders. Each contractor supplied a gatling and a single shot breech loader (for ammo testing). GE's item had six barrels as I recall and Philco was five-barreled. I don't believe the GAU-7 was targeted for the F-15, but I could be wrong. I thought it was an A-10 project. The A-10 was a new project then too.PUT THE FIRE OUT? ARE YOU CRAZY? We ran like fugitives! Pretty much ruined the firing bay it was in, but as I recall, the test item (gun) was unharmed. 'Don't remember which one it was (GE vs Philco).
There's a quote earlier in this thread:ikke666 said:i didn't kwew there were 2 different GAU-7 models. very interesting
And I was only getting started. I did search for F-15 but this thread didn't even come up on page one of searches... Well I'll forget the aviation guns from Chinn and focus on the Army stuff...PaulMM said:Nice, Abe, but someone already posted most of those
I can almost visualize it -- barrels and chambers rotating separately and only coming into alignment for firing. Imagine it like a revolver cannon but instead of one barrel, there are several. This would give a little more time for each chamber to cycle while keeping the barrel mass down. It might give you a higher potential RoF, or a somewhat gentler cycle (and the GAU-7 ammunition was reportedly pretty fragile). But my god, the mechanical complexity this would entail.Lauge said:Six barrels and ten chambers? How the Niflheim was that supposed to work ???
I have one of the cartridges in my collection; it's basically a cardboard cylinder with the projectile buried inside.Colonial-Marine said:Is there any more information about the ammunition itself out there? I recall reading that the cartridges were wrapped in some sort of flame-resistant packaging which had to be stripped before firing. Factoring in everything else, the entire setup must have been very complicated and heavy.
As it happens, that issue was what doomed the famous H&K G11 Assault Rifle of the same general era as the GAU-7, back when CTA was all the rage. The G11's evaluators were quick to disqualify it when they found out about that, as it would be a bit of a downer for a rifleman to have a weapon pressed against his cheek explode like a pipe bomb;Tony Williams said:I have one of the cartridges in my collection; it's basically a cardboard cylinder with the projectile buried inside.Colonial-Marine said:Is there any more information about the ammunition itself out there? I recall reading that the cartridges were wrapped in some sort of flame-resistant packaging which had to be stripped before firing. Factoring in everything else, the entire setup must have been very complicated and heavy.
One of the problems with combustible case ammo is that if the magazine gets hit by an enemy shell, the whole lot goes up in fire/explosion. So each round had to be wrapped in a fireproof sleeve which had to be stripped off the round before loading. Far too much trouble...
Errm - you do know that the British Army has selected the 40mm Cased Telescoped Armament System for the Warrior MICV upgrade and for the new FRES SV recce vehicle, don't you? It has been exhaustively tested and is due to enter service in 2016. The pic below shows a sectioned APFSDS round, the projectile and the armour it penetrates. It comes from my web article here, where there is lots more about it: http://www.quarry.nildram.co.uk/WLIP.htmBlacktail said:CTA (Cased Telescoped Ammunition) technology predates the F-15 and GAU-7 by almost two decades, but it never worked.
The G-11's technical problems were because it used caseless ammunition, not because it was telescoped. So unlike with the 40CTAS, the propellant lacked the protection of a cartridge case.As it happens, that issue was what doomed the famous H&K G11 Assault Rifle of the same general era as the GAU-7, back when CTA was all the rage.
The LSAT programme explored both caseless and cased telescoped ammo. The caseless version never really got going (they bought the G-11 tech package from HK) with only a few hundred rounds fired, but the plastic-cased version has seen 100,000 rounds fired from eight different LMGs. It seems to work pretty well, but is unlikely to lead to a service weapon any time soon, if only because there's no money...And guess what the US military is doing now, to try a totally-new approach to ammunition technology? More CTA ammunition!;