4.5-inch XM 54 Chemical rocket/projectile

[US-Subs]

Time to push some discussion back to the future - this is the XM54, 115mm / 4.5-inch projectile/rocket. It was intended for use by the USMC as a chemical delivery system. The dates are unknown, but 50s-60s is probably reasonable. The system made it quite far through the development/procurement chain, with examples being found at a number of sites. I have no idea what system was supposed to fire it.

The first three photos are of a nice unfired piece, you can easily tell the large rocket motor vs the relatively small warhead. The base of teh munition is fairly complicated, with two nozzles partially covered by a large plate which remains in place after firing.

I had owned this piece for several years when I was surprised at a recovery site in the southeast US to see that they had pulled out a significant number of these, mostly fired, but some not.

The items had been segregated into loaded/unloaded, contaminated (CW) and clean. Those items identified as clean and empty were being crushed by bulldozer. I was given permission to recover some samples, I removed two fired pieces with different base styles. An unusual detail was that on the unfired examples, the cartridge case was still partially present.

The case appeared to have been of the spiral steel type, with the thin steel wrap already rotted away. Very unusual though, was that the case had a full length primer, which actually screwed onto the projectile. On the unfired ones that I saw, several still had the case affixed in this way, but only one had not been crushed. I had to physically break the steel to recover the remains of this cartridge case, as you can see in the photo.

The last thing of interest is the label (sticker) attached to the unfired piece, it reads: "For Special Test! Warning! Not For Combat Use!" I've never seen a label like this before.

 

[HAZORD]

The samples I have came from the Southwestern U.S. I believe the Rocket motor has Picatinny Arsenal Experimental, and the firing temperature limits. All of the projectiles I have seen were brown laquer finish for the full length, like the motor on your version with the OD warhead. I didn't know that it was supposed to be a chemical round though. Do you know if there were both HE and Chem versions?

 

[TonyE]

Rifling

Not my area of knowledge at all, but I do find it interesting that the rocket was fired from a rifled weapon and the projectile appears to have a proper copper driving band and not a slip ring.

Also, surely a solid fuel rocket burns from the rear face of the propellant, whereas the long flash tube would ignite the propellant from the centre?
...or am I just outside my comfort zone?

Cheers
TonyE

 

[HAZORD]

The rocket assisted projectile was not crimped in the case. The ACME threaded piece that extends from the bottom of the rocket nozzel center which Jeff has shown, screws into the top of the primer flash tube and holds the two together as a complete round. When the round fires, the connector piece shears. The complete cartridge case looks like an oversized 105 howitzer case.

 

[jvollenberg]

Question

I have no records of this rocket. I have the T164 / T165 / T166. Is there markings on this to push you to this nomen, or do you have some records of this? I would also think it would be fired from the M21 Launcher, since this is the system that delivered the T series. Does it have the M81 fuze?

Joe

 

[US-Subs]

I'm going off from my photos logs here, but as I recall the nomenclature is stamped, as normal in the normal location. I can e-mail home to my son to check for anything additional or lot #, but it may take time. As I recall the fuze in it is a standard 51 series, but that doesn't necessarily mean anything - as you know, if its not in its original wrapper, fuzes come and fuzes go. Each are exactly as I received them, but not necessarily as they were meant to be.

What I find strange (other than everything on this round) is the plate you see at the bottom. It actually obstructs much of the nozzles. My best guess was that perhaps this was intended to limit the range of test items for recovery purposes, but that is only a guess. John are yours the same way?

 

[HAZORD]

First of all, this item was fired from an artillery piece, not a multiple launch rocket launcher. It was for Marine Corps use, and I have a photo somewhere as it made it into one of those hardbound books of ordnance used by the military back in the 60s or so. I am looking for the photo.

My base pieces look like yours, but I haven't seen the hooks that hang down into the case around the center threaded piece on my examples.

The lettering on the warhead for mine should read 115MM, INERT, SHELL XM54E2

Lettering on the motor body:
LOT PA-E 37121
SAFE Temperature Limits +50 to +90 F.
0 % thrust only

My first one was a drill round or cartridge firing dummy. It had been in a trash pile, and the contents inside the motor had been burned up, and it evidently had some wood and lead to simulate propellant weight, as all the lead had melted into a glob. Thus the 0 % thrust note.

I haven't examined the second one in detail. They both have the U.S. standard 2 inch threaded fuzewell in the nose.

 

[jvollenberg]

Interesting

Yeah ... the plate is weird, (my other images of the T164 do not have it) as is the whole round. I just discussed this with someone else and they are wondering about the propellent. How does it get attached to the cartridge case? Is it clipped, much like a mortar round, or is it possible the cartidge case is combustible?

Joe

 

[US-Subs]

No, the case should be a standard case like you see for the 105, made out of the cheap spiral wrapped steel. Its thin and rusts away pretty quick. At least that is what I think it is - what you see is what I've got to go on, but it looks typical.

I'm thinking that the nomenclature is stamped, but I could be wrong. When you've got a few pieces rolling around and you are away from the collection for long periods it is easy to mistake (imagine?) things. Can you post or pm me a scan of the diagram you have and I can see how it looks?

 

[weberoed]

Is there anymore information on this round?

 

[HAZORD]

I'm glad this got bumped, to remind me to go looking for more info on this weapon. The first key was finding the designation XM70 Rocket Launcher. It was designed to be towed or air-dropped in for the USMC and weighed in at around 3,000 Lbs. It fired cartridge boosted rockets from a closed chamber, so the crew could remain close while it was firing, because there wasn't any back blast. It was a revolving chamber design, with six chambers roughly the length of the rocket round with cartridge case attached. A complete round of ammunition is about 40 inches long. The gun could fire all 6 rounds in the chambers in 2-1/2 seconds!

I'm still thinking it was really designed to fire HE ammunition, although the explosive volume per round is not much larger than a 105 Howitzer projectile, and the warhead is a thinwalled design and won't give the same type of fragmentation as a normal projectile. It takes a 2 inch diameter standard nose fuze, with no provision for sealing any chemical contents from direct contact with the fuze.

There were only 7 of these pieces made with progressive improvements. The one shown is in a military-owned artillery museum.

More info here:

http://en.wikipedia.org/wiki/XM70E2

Even though the article says they were tested at Rock Island Arsenal and Aberdeen Proving Ground, they were also tested at Quantico and Yuma Proving Ground.