7.2" artillery shell, how heavy is it?

[kitnut617]

OK, maybe someone can answer this question. I am trying to figure out how heavy a Triplex RP was. I've recently come across some snippets of information, but when I apply them to the problem, it doesn't seem to work out.

First bit of info I read, was the RP3 weighed a 100lb, and they were talking about one with a 60lb warhead. That would mean the rocket motor (3" pipe stuffed with cordite) weighed 40lb.

Then I read that a Triplex weighed 180lb  ---- so this is where things go a bit skewy  A Triplex had three 3" rocket motors, so 3X40=120 which leaves only 60lb for the warhead, which seeing as the Triplex RP had a 7.2" artillery shell as a warhead, doesn't seem heavy enough.

I couldn't find exact information about a 7.2" so I had to figure out how long the shell was, one type of shell sort of worked out to be 3 feet long, can't imagine that it weighed 60lb though. The Triplex had a different 7.2" shell from what the photos of the real ones show, shorter and more pointed, I think they're armour-piercing ones. So what did it weigh ?  I'm thinking the 180lb is a typo, maybe it was around 280lb, perhaps more.

Can anyone shed some light on this ?

[scooter]

A quick Wiki-fu bout on the 7.2" howitzer gives an HE shell weight of 202 pounds.

[Old Wombat]

This may be where the "180" comes from;

BL 7.2-inch howitzer
From Wikipedia, the free encyclopedia

7.2 inches (180 mm)

NOTE: The same article also states;

Calibre   7.2 inches (182.9 mm)

Go figure!



Found this, which looks pretty good when you read through it:

http://nigelef.tripod.com/72inchsheet.htm

[Weaver]

This may be where the "180" comes from;

BL 7.2-inch howitzer
From Wikipedia, the free encyclopedia

7.2 inches (180 mm)

NOTE: The same article also states;

Calibre   7.2 inches (182.9 mm)

Go figure!

Looking at the code on that page, on both occasions, the author has typed "7.2 inch" and then told Wikipedia to automatically convert it. Unfortunately, they've specified different rounding precision each time...

I've got myself a Wikipedia account now, so I've fixed it. 

[Old Wombat]

Ha! So you have!

[kitnut617]

Thanks guys, and wiki was my first stop when looking for info. Although, the 7.2" page I looked through didn't show all of that info especially -- 'shell weight'

OK, so next question, are these shells in this picture the HE variant ?



Which look a bit different to the shell in this photo Harold (Weaver) had posted in my MB6 thread

[kitnut617]

A quick Wiki-fu bout on the 7.2" howitzer gives an HE shell weight of 202 pounds.

Thanks Scooter --- that would make the Triplex around 322lb.  But it looks like the shell warhead on the Triplex has been shortened, just to the front of that band at the rear of the shell. I'm actually thinking my guess of 280lb is what it weighed.

[scooter]

Thanks guys, and wiki was my first stop when looking for info. Although, the 7.2" page I looked through didn't show all of that info especially -- 'shell weight'

OK, so next question, are these shells in this picture the HE variant ?

If the photo is clearer, you might be able to read the stencils on the shells themselves.

And if that's a 3.25 inch (GI Joe action figure) scale playset, I want one.

[kitnut617]

I believe it's a 1/35 scale kit by Accurate Armour

[The Rat]

No matter how heavy it is, don't drop it. 

[NARSES2]

Right according to my copy of British and American Artillery of WW II the 7.2" Howitzer had 6 different marks and the charge used had up to 4 different bags, plus a 5th specifically designed for the Mk 6 howitzer. All the shell weights are listed as being a standard 200 lb though. Only one type of projectile was ever designed for the howitzer and only 3 types of fuse were ever approved. As the fuse's were only installed prior to use this MAY account for the extra 2lb's

So the shells in the picture are H.E. as no A.P. was ever designed and indeed why would it if the "gun" was a howitzer ?

[kitnut617]

Thanks for that Chris, I remeasured the shell in that model photo, the length is 5 times the diameter = 36". But what is your opinion that the warhead of the Triplex has been shortened. I'm looking at it from where the casings starts to curve towards the tip, back to the end where the rocket motors are attached.

But I think I've just discovered where the 180lb comes in --- I've been looking in my steel section technical book, and specifically in the seamless mechanical tubing section. That's because you can buy just about any diameter tube in various wall thicknesses. 7.2" is close to 7.25" for what I'm thinking and the weight of a one foot of 7.25" tubing with .375 wall is 27.53lb. But I'm thinking the shell has been shortened to just forward of the brass/copper band which happens to measure out to about 7" from the rear end. So say about 16lb has been lobed off, plus the weight of the explosive reduced, the 200lb shell becomes 180lb.

So a Triplex RP could weigh 300lb

[Old Wombat]

Assuming the 7.2" HE shell was derived from the 8" HE shell (as the gun was a re-bored 8" barrel) there may be some reduction in mass by removing part of the rear of the shell & fitting a thinner base-plate, but is it really worth the increased effort & cost?

[PR19_Kit]

(as the gun was a re-bored 8" barrel)

How do you re-bore an 8" barrel to make it smaller? 

[Old Wombat]

OK, sleeved, if you want to get technical ... Either way, it changed the bore diameter.


PS: Also allowed it to cope with higher gas pressures from the bigger charges & send shells further.