Gau 22
- Thread starter Lc89
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Not that I'm aware of so far.
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It's kind of a weird gun, AIUI.
Both LM and Boeing actually preferred the BK-27 and selected it for their JSF candidates. Then after award, LM decided to switch to the GAU-12. And then discovered that the GAU-12 was too heavy, requiring a redesign to the GAU-22, basically chopping out a barrel to save weight. I can't see anyone else willingly adopting it when other options are available.
Both LM and Boeing actually preferred the BK-27 and selected it for their JSF candidates. Then after award, LM decided to switch to the GAU-12. And then discovered that the GAU-12 was too heavy, requiring a redesign to the GAU-22, basically chopping out a barrel to save weight. I can't see anyone else willingly adopting it when other options are available.
marauder2048
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That's funny because according to Moore ("The Need for a Permanent Gun System On the F-35 Joint Strike Fighter"),
the BK-27 was rejected in part because of weight.
What the GAU-22 has going for it is the large array of ammunition qualified on it and the related live fire results.
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I'm skeptical, because the published weight of the BK 27 is about 20% less than the published weight of the GAU-12 and the same as the GAU-22. The 27mm ammo weighs almost exactly the same as 25mm, maybe a coupe of percent more at most. And both teams had this information before they selected the BK 27 the first time around.
As for ammo compatibility, it's great, except that Moore notes that they had to develop a new ammunition type (Frangible AP) just for the F-35 because the only extant round that met the lethality requirements was a DU penetrator that no one wanted to make anymore. There was no DU round for the BK 27, but a 27mm Frangible AP type was developed quite a while ago for other users and thus could have been made for JSF as well.
Moore: https://apps.dtic.mil/dtic/tr/fulltext/u2/a476815.pdf
F-35 specific 25mm FAP: https://www.defenceconnect.com.au/key-enablers/3608-rheinmetall-launches-f-35-specific-munition
27mm FAP: http://www.defense-aerospace.com/ar...einmetall-wins-ammunition-order-from-raf.html
As for ammo compatibility, it's great, except that Moore notes that they had to develop a new ammunition type (Frangible AP) just for the F-35 because the only extant round that met the lethality requirements was a DU penetrator that no one wanted to make anymore. There was no DU round for the BK 27, but a 27mm Frangible AP type was developed quite a while ago for other users and thus could have been made for JSF as well.
Moore: https://apps.dtic.mil/dtic/tr/fulltext/u2/a476815.pdf
F-35 specific 25mm FAP: https://www.defenceconnect.com.au/key-enablers/3608-rheinmetall-launches-f-35-specific-munition
27mm FAP: http://www.defense-aerospace.com/ar...einmetall-wins-ammunition-order-from-raf.html
marauder2048
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Total system weight (w/150 rounds) for the Bk 27 was reported at 524 lbs.
Total system weight (w/180 rounds) for the GAU-22 was reported at 406 lbs.
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That number for the GAU-22 total system weight does not pass the small test, IMO. The bare weight of the GAU-22 (230 pounds) and the ammo (180 rounds x 1.19 pounds/round equals 214 pounds) is more than 406 pounds. (That ammo weight is for PGU-20, but PGU-47 can't be that much lighter unless they snuck in an aluminum case without telling anyone.) And there's nothing left for the drum or feed system.
Comparing apples to apples, the BK 27 comes in at about 230lb for the gun and 170 pounds for ammo (150rounds x 1.14lb). That gun weight is estimated but it's for a "complete" gun, same as the GD number for the GAU-22, and I rounded up.
marauder2048
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You're right; Tony Williams' site has 406 lbs w/181 rounds. But going back to his source, 406 lbs looks like empty weight (gun + AHS) of the system.
The Flight Global article I have is the source of the 528 lbs figure for Bk 27 + AHS + 150 rounds.
Not quite: LM subcontracted the gun installation to GD, who promptly switched from the BK 27 to the GAU-12/U which is made by.....guess!
Bit OT but why they never considered Gast cannon? You can get good RoF in you want it in much lower mass than Gatling. But still US tried it only once in one somewhat obscure AA project and never really touched it again.
The GE-225 was a Gast type aircraft gun in 25 mm NATO calibre. I agree that it seems to be a very good system - judging by the GSh-23 and GSh-30, it is one of the best all-round cannon systems if you want to combine compact dimensions, light weight and a high rate of fire. Ironically, the one that beats it is the GSh-301, a single barrel short-recoil gun.
I suspect that the GE-225 didn't get anywhere because it was a technology demonstrator not linked to any specific procurement requirement or budget. It is also possible that GE killed it off in favour of the GAU-12/U.
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One issue with the conventional Gast is that it relies on one barrel to operate the other, meaning that if you have a failure to fire on one side, the gun stops, unlike the externally powered Gatlings, which just extract the unfired round and go on. IIRC, there was an externally powered version of the GE225, but that's presumably giving up some of the weight and mechanical simplicity of the Gast action.
That's true - but as with any rapid-firing externally-powered gun you just have to hope that you don't get a hangfire....
