27 X 70B aircraft cannon

Here's a couple more odd rounds I've picked up on my travels.
I have only managed to find one book with them in and understand that they are Navy T-45 experimental Aircraft cannon rounds from the late 1960's.

Overall round length is 167.4mm
Case length is 70mm
Base diameter is 29.5mm
Diameter of projectile 27mm

Both of these cases are aluminium. Brass cases do also exist (I've got on in a box somewhere and can't find it!!) as does a longer cased version with a 96mm case.

If anyone has any further information on these rounds, gun used etc. I'd be interested in hearing from them.

Both are inert etc.

Dave.

These were designed for use in a version of the M61 6-barrel "Vulcan" aircraft cannon, in place of the usual 20x102. The intention was to maximise the HE shell size within the limits of the overall size of the 20x102 cartridge, so all that was needed was new barrels.

If you ever feel that one of them needs a new home, you know who to contact ;-)

Thanks for the information Tony, I'll let you know if I get a spare.
Dave.

I've found the brass one.

I've finally found the one I had in a box!! Attached a photo of the brass cased version. Shown next to a teflon coated Vulcan 20 X 102 round for scale - reference Tony Williams post above that mentions why the 27mm was developed.

All INERT, hole in the back etc.

Dave.

Found a bit more information out about these:

The manufacturing contractor was Olin Mathieson ammunition and development department, East Alton. USA
The contract finished in 1955
A pilot production of 50000 rounds were made.
Variations included:

T142 (TP)
T143 (Dummy)
T144 (HEI)
T145 (High pressure test)
T147 (Incendiary)

Muzzle velocity was 2000 ft/second
Projectile weight was 3500gn (250g with fuze)
The filler in the T144 was 66.4g of MOX-2B+RDX

A longer cased variation was made with a case length of 96mm
Overall round length was kept the same.

If anyone has any further information or an example of the longer case length I'd be interested in seeing a photo of it.

Dave.

Thanks for that, Dave, useful info.

Rick, I think Tony now has one, from a recent ECRA show. Thanks anyway. Dave.

Yes indeed I have, thanks Rick.

I don't have a long-case one, though....:evil:

Here's some photos of the dummy version.

Dave.