Attention Redlegs, physicists and ballisticians!

[John Kettler]

I have a little artillery problem I need your help with, please.

Given a howitzer with a listed range of 6000

yards, a max elevation of 73 degrees, a listed muzzle velocity of 790 feet per second (presumably at max charge), a shell only weight of 84 pounds, and a Charge 1 (min charge) consisting of 130 grams of flaked nitroglycerin powder, and assuming a standard atmosphere, what is the minimum range for the howitzer while firing minimum charge at max elevation?

The reason I'd like to know the answer is that I think it might be highly important to CMBB and successors. The battlefields will be bigger, you see. That might be enough to put IGs which can't be on the board for indirect fire, on the board and able to fire indirectly and directly, depending on the tactical situation. Presently, IGs have only direct fire capabilities or are represented by FOs.

If my hypothesis is correct, we may be able to have scenarios in which the guns are on the board, fire indirectly at attackers, and if the line is penetrated far enough, could potentially then switch to the familiar direct fire mode. How cool would that be?

I suspect that the answer is going to be somewhere in the 2000 yard bracket, at most

3000. If so, then we'll have a strong case to make to BTS and whole new realms of potential scenarios.

Thanks for any and all help.

Sincerely,

John Kettler

[Paco QNS]

I give it 20-30 yards as maximum.

Check your data, you said:

<BLOCKQUOTE>quote:</font><HR>a shell only weight of 84 pounds,<HR></BLOCKQUOTE>

Later I´ll catch my data for the italian gun of 65/17.

((The proyectile weight of the IG 18 7.5 cm was of 5,45 Kg or 6 (12 or 13,2 lb), and 3 kg for hollow charge -6,6 lb-))

[ 06-23-2001: Message edited by: Paco QNS ]

[niles]

Unfortunatily your question can not be answered unless you had the gun with all those settings and were prepared to fire it with all of your listed settings, oh the charge isn't nitro glycirine powder--its mercury filmanate, and every outcome will be differint because of weather conditions, air resitance and wind shear all have to be taken into account, so unless you had the lab, the gun and what kind of weather you want it shot in it cant be answered ..sorry

-Niles "Fieldmarshall" Hirschi

[niles]

as of the guy above me thats an estimated answere not the EXACT ONE

[John Kettler]

Guys,

I specified "shell only" so that there was no possible confusion with added weight from the separate cartridge case.

The flaked nitroglycerin powder I mentioned was straight out of a reproduced formerly classified U.S.Military intelligence document. Fulminate of mercury is used as an initiator, NOT a propellant charge. It's much too shock sensitive. That's why it was used in percussion caps.

Are you really sure we can't get a first order solution to the problem I posed? Someone with a background in explosives ought to be able to provide an energy equivalent from the detonation of the flaked nitroglycerin powder in the amount listed, and that combined with a reasonable barrel friction number and a straightforward air drag calculation should, in theory at least, yield a reasonable answer.

Regards,

John Kettler

[niles]

What you could do (sorry about the propellent mistake I thought you meant procussion caps (primers) ) is you could write a letter to JPL with your problem (THIS IS NO JOKE) they are right near where I live (they are in arcadia or Cal tech my dad knows) and I could get you the adress hows that, e-mail me or something

[Kingfish]

Attention he who owes me a turn!

[niles]

CHECK YOURE E-MAIL JOHN

[John Kettler]

niles,

I got your E-mail. I plan to sit tight and see what other responses I get here before I write JPL. Frankly, I'd rather ask JPL rocketry questions. This seems more like one for Aberdeen APG or Ft. Sill.

Kingfish,

You should have 2-3Turn66.txt long since. It went out at 8:53 p.m. PDT.

Regards,

John Kettler

[Paco QNS]

Oh, well. Your data concurs with the sIG 33 of 15 cm:

(Calibre 149,1 mm; barrel 1,65 m; weight in action 1750 Kg; muzzle Vo 240 m per second (787 ft); max range 4700 m (5140 yards); and proyectile weight 38 Kg (83,8 lb)

But the weight of min charge puzzles me. My data for the 65/17 mm italian gives a charge of 65 grams of "balistite in flukes of 0,5*5*5 mm" ((that is, a mix of 43% nitroglyc. and 51,5% nitrocell. plus stabillisants -I think is your reference, since pure nitroglyc. is too unstable-)), for a proyectile weight of 4,15 Kg, and a max range of 2500 mts.

So, consider an almost ten times heavier proyectile with a charge only double. ???

For the exact data, we need the Vo given by that charge.

BTW, tactical doctrine for the 65/17 in spanish army, febr. 1945, INSTRUCCION E.80:

page 77

<BLOCKQUOTE>quote:</font><HR>1.4 Because of its characteristics, the 65/17 gun must be used:

a) Usually: with indirec fire, using defilade positions;

Eventually: with direct fire, using crests, camouflaged or covered from view. This kind of fire is the usual against tanks;

c) Over own troops, keeping the safeties indicated by the fire tables; or between them, using also the safety margins indicated in them.<HR></BLOCKQUOTE>

Here, you can see the density of the charge:

COMPOSITION OF SOLID ROCKET PROPELLANTS

[ 07-01-2001: Message edited by: Paco QNS ]

[Guest Babra]

You will get 3.04 x 10^3 joules out of 450 grams (1 pound) of standard nitro. I haven't a clue what flaked nitro is. Presumably it is more.

You can do the math from there -- I'm much too lazy.

[Guest Babra]

Using the stated data of V=790 feet per second (240.792 meters/sec) and E=73 degrees; and using g=9.8 m/s^2

Range is (V^2/g) sin2E. Plugging in the appropriate figures yields 3,308 meters range. Those are, of course, windless conditions on the biggest billiard table in the universe.

Quite frankly I've forgotten how to determine muzzle velocity from the energy data we know. Assuming it comes out less for that minimum charge, then yes, range will be under 3,300 meters.

[c3k]

John,

Your question reveals a common mistake. Just because a weapon is capable of a high trajectory does NOT make it suitable for OB use. You need more than a gun. You need trained observers, a communications network, an artillery plotting center, a surveyed site, accurate maps. Etc. Infantry Guns (almost all infantry regiments used them) WERE NOT USED FOR DIRECTED FIRE.

They fired at targets that the gun-layers could see. Now, whether they fired with the barrel at a low elevation or at a high elevation depended on range, target cover, etc. Just because the shell trajectory is described as "indirect" does not make the infantry gun an "offboard artillery" asset.

Sincerely,

Ken McManamy

[Radar]

130 grams? For a 38.1kg projectile? I don't think that would be the correct min charge(a bag weight, but not the fired amount for min range). It would probably be more. I'm sorry but I can't back that up, but it doesn't sound right.

[Guest Babra]

Okay, I went back to the books and did some calcs (which are suspect) and came up with a VERY low muzzle velocity of 78.85 m/s. That gives a range of about 355 meters.

That seems really low, but as Radar says, 130 grams is a pretty damn small charge, so my numbers may be good.

[Slapdragon]

Many mountain howitzers actually can fire very close to themselves, and can be positioned on ramps to achieve "plunging fire". Also, all howitzers could fire indirect directed with a flat trajectory, such as when fighting in fortresses.

Of course im a battle that only lasts an hour or so, we could just assume that by smacking the local forces you smaked the arty behind it. Adding rear area artillery also add s the need to model blacksmith and vet unitss, echelon two medical units, logistics units, and field kitchens, all of which often populate the space between a front line unit and the artiilery. Otherwise we are modelling a very special case: "What if these guys had real short range artillery, no support units, the artillery could not run away and the battlefield was 3 kilometers long or the commander stupidly or deperately positioned his artillery close to the front."

Seems like a lot of coding work for the CM I engine that could be used very little in the scope of CMBB. Perhaps this is a feature of a division level game.

[John Kettler]

Ooops! I missed something important. The weapon is indeed the 15 cm sIG 33, but I inadvertently left out part of Charge 1. There was a second component, consisting of 40 grams

of diglyconitrate powder. This must be added to the previously listed 130 grams of flaked nitroglycerin powder. Sorry about that!

As far as the use of these big howitzers in the cannon companies of infantry regiments, does anyone have a detailed breakdown on manpower and skills within these units? I freely grant that they may not necessarily work well as offboard fire vs. a range of targets, but I see no fundamental reason why they couldn't have been used to at least generate presighted defensive concentrations called in via star cluster, radio or field telephone. I believe I've even read accounts along this line.

We're talking only two guns, after all, which are firing from only a few kilometers away. I bet I could put something together in very short time, and I have zero artillery training.

Regards,

John Kettler

[Guest Babra]

Never heard of diglyconitrate powder. Presumably it's some sort of catalyst, but I haven't a clue what it would do to a given weight of nitro.

Your range problem is thus unsolveable. You might have better luck with a book dedicated to the gun specifically.

[Paco QNS]

Mr John Kettler,

as I have said before, I own the book titled INSTRUCCION E. 80 "Instrucciones provisionales para el empleo del cañón de 65/17 como arma pesada de Infantería", Madrid, Nov. 1944 (written), Febr. 1945 (distributed). ((Provisional Instructions for the use of the 65/17 gun as an Infantry heavy weapon)).

((it was a really! old gun, given to the Infantry since it was too obsolete as an Artillery gun. But it was dirt cheap, and quite useful against all targets -included the T 26 tanks-))

It is not what you are asking, but it can give you an approximative idea (simply put more men to crew the sIG 33).

If you are interested, I can traduce and post a few excerpts from it. (and a link about tactics in the Spanish Civil War, with an example detailing its use in combat).

BUT, before, as a matter of fair info trade, P L E A S E post us here some information from your source -which I presume is the US Army captured materials manual for the sIG 33-. ((and all of it, if possible!))

Finally, since have been mentioned the full names of explosivs in this thread, I want to send a couple of salutes:

Hola, mami!

and Hullo, Echelon´s mother!

Regards,

[ 07-01-2001: Message edited by: Paco QNS ]