Question about 30mm "apache" rounds


#1

hello
i have a question about “apache” 30x113 rounds
i see many pictures of loading operation of these apaches but i only see m789 hedp rounds (with black and yellow shell) ,i never see m799 hei rounds (with yellow and red shell)
i would know if these m799 exist or not ?
thank in advance for your responses


#2

Probably not. I have a note from last year that the M799 does not appear to be in series production. Also, in January 2009 ATK was given a $36 million contract to supply Apache ammo to the UK; but only M789 HEDP and M788 TP.


#3

ATK still offers it but there not much interest in it.


#4

My ATK product listing shows only M788 and M789, but that does not mean they don’t or can’t make the M799. Of course the M788 is a training round. ATK’s description of the M789 HEDP:

Height (max): 199.75mm
Weight: 339g
Muzzle Velocity (nominal): 805 m/s
Chamber Pressure (typical): 335 MPa
Penetration (typical): 25mm RHA@ 50 degrees at 500m

“Our LW30mm HEDP features a spin-compensated shaped-charge liner for superior armor defeat plus additional growth potential. Outstanding armor penetration, combined with blast, concussion, and fragmentation characteristics gives the LW30mm ammunition superior multi-role and multi-target capabilities.”

I have a question - just how is the shaped charge spin-compensated? Also, what is the meaning of “additional growth potential?” Is that maybe code for “kills people inside better?”


#5

DennisK,

Check out this thread at BOCN:

bocn.co.uk/vbforum/threads/4 … mm-cutaway

Not sure I understand it but this indicates the compensation is provided by fluting of the shaped charge’s liner cone interior.

I don’t know what the “additional growth potential” is referring to.

Dave


#6

My shaped charge experience is from more than 40 years ago, and at that time, shaped charges didn’t penetrate so well if the projectile was spinning. Obviously the liner flutes have something to do with overcoming this limitation. See freepatentsonline.com/3726224.html

By the way, I found this comment regarding the M799:

“M799 HEI round is not used by the US Army due to the danger of a round exploding in the gun barrel”

I remember reading something about in-bore detonations with the 30mm chain gun, so it may well be true. I don’t know any more than that.


#7

DennisK,

Seems the M789 was also involved with in-bore detonation and other undesirable events:

asc.army.mil/docs/pubs/alt/2008/ … 200801.pdf

I’ve always been impressed with the design of such intricate mechanisms (fuzes) that can withstand the intense g-forces and still function at all. Working out bugs must be quite the challenge!

Dave


#8

Malfunction in these designs is high.


#9

There was a brief piece on last night’s (Thursday) NBC Evening News about a female Apache pilot in Afghanistan. It clearly showed a belt of the yellow-banded M789, and nothing else but.


#10

Hi,

the M789 HEDP and the M799 HEI use exactly the same projectile body and nose fuze.
The only difference is the shaped charge liner inside the M789, the space of which is filled with high explosive in the M799.

Because they use the same basic components, any problems with the M799 also apply to the M789.

Which still leaves the question, why is the M789 the only combat type used?
The answer is possibly the small cost difference between these two, with the HEDP being more versatile than the HEI type.
The slightly higher costs of the HEDP compared to the HEI are most likely compensated by the reduced logistics when having only 2 round types (HEDP + TP) instead of 3.
So I guess not all decisions are based on technical issues…

Chris