King-styled howitzer bore depth, how many calibers?

[Terry C.]

I'm toying around with a somewhat freestyle King howitzer design. I'll be basing the project on existing stock in my inventory, so it won't be exact.

It'll be the best I can make of what I have on-hand.


What I need to know now is the approximate ratio of bore depth to diameter of a King howitzer. How many calibers deep?


This will be golfball caliber IF (and right now it's a big if) the stock I have will support a howitzer that size. Diameter is not the problem, length is. The pieces I have are rather short and stubby, more than long enough for a GB mortar but a howitzer is a whole 'nuther animal.

I already plan to machine the cascabel/knob from a separate piece and weld it on, to get the maximum yield from the stock.

[Cat Whisperer]

Here's a JPG (Wes did you get my emails?) of the profile of an ESTIMATION of what the Daniel King model looks like.

If you do the powder chamber at the back end according to the "one-caliber-rule" you could go reasonably large in ID on the front end.

[Cat Whisperer]

OAL 15.625
Max dia 4.5

[dan610324]

here are a few other designs if you would be interested
they are all from an handwritten artillery handbook from approximately 1743
as you can see , not all of them had cascables

[Cat Whisperer]

Thanks Dan!

At least one of those is going into a cad drawing!

[dan610324]

if you want more original drawings , just let me know .
specify if you want cannon , mortar or howitzer .

[Terry C.]

If you do the powder chamber at the back end according to the "one-caliber-rule" you could go reasonably large in ID on the front end.

That's the plan. The bore and chamber will be machined into a solid piece of steel, with a wall thickness of at least one chamber's diameter at the rear. This would be a completely functional tube even without the cascabel.

The cascabel will be welded on to complete the 'package' but it's strictly cosmetic and totally isolated from the chamber and bore.

Thanks to you and Dan for the images. They'll be a big help.

[dan610324]

just happy to be able to help someone , I suppose thats why we all are here .
to help eachother and to be helped .

[Terry C.]

Dan, I opened all the images you posted in my CAD software, and overlayed balls into the bores.

All of them are about 3 calibers deep in the bore, except #2 which is 3½ calibers.

I had guessed 3 calibers, so I was pretty much dead on.

#3, the one with the carriage in the image, is the one I'm going with for now.

Where I may have to fudge a little is the chamber. Because of the welded-on cascabel, I won't be able to take the chamber as deep (and still maintain proper rear wall thickness) as I would if the entire tube were solid. I've measured the stock and it's coming up a little short.

As it is, scaling the bore to GB size, I could only get ~72% capacity if I hold to the 7/8" diameter that the chamber scales to. If I bump up the chamber diameter to 1", and increase the rear wall thickness proportionately, I can get ~87% of the capacity. That should be more than enough.

Or should I stick with the 72% chamber?

I need to do some calculations and see how these chamber volumes relate to powder capacity...

[dan610324]

Im glad to be able to help .
I would guess that the 72% would be enough , as your projos also are lighter then the original .

[GGaskill]

If you are going to launch golf balls, you won't need a large charge.  1 lb spherical sinkers can use more powder.

[Terry C.]

Okay, here is how they estimate out:

7/8" diameter chamber, 2.9" deep = 390 gr

1" diameter chamber, 2" deep = 338 gr

7/8" diameter chamber, 2.125" deep = 280 gr


So, capacity to scale is 390 gr, I can have an approximate chamber capacity of either 338 gr or 280 gr.


Oh yeah, I forgot to mention that these volumes are based on a chamber with a hemispherical bottom.

[GGaskill]

What are the units of measurement in those drawings?

[Terry C.]

If you are going to launch golf balls, you won't need a large charge.  1 lb spherical sinkers can use more powder.

I want to be able to fire canister and solid shot, as well as golfballs.

As far as the units of measure in the drawings, I have no clue.

I can't read them.

I scaled the drawing to match the GB bore diameter, and dropped it into the background. I can lay out my design on top of it.

[dan610324]

most often they use 16th parts of the bore
thats why they always call them proportional drawings , all meassurements are based on the bore .
larger meassurements are often written as 2 3/4 , that 2,75 x bore diameter
but when you look at all small parts , they are meassured 1 , 2 , 3 and 4 . thats sixthents of the bore
so its easy to convert , just start and decide your bore diameter
with a gb bore you have a little less then 1/8" if the drawing say 1

so you can use the exact same drawing and meassurements even if you are building an golfboll , pool ball or bowling ball howitzer . its just proportions based on the bore you decide .

[Terry C.]

Makes sense.

But my way's easier. 

(assuming that the drawing is relatively close to scale)

[dan610324]

hehehe  they did it just to test your skills in math 

[Terry C.]

Very, very basic first draft.

A few liberties with the profile, and I beefed up the trunnions a bit.



1.725" diameter bore, three calibers deep. This one has the short, fat 338 gr chamber. It looks like there is less than one caliber behind the chamber, but that's an illusion. The cascabel will be machined to slip over the end of the tube ¼" (like a cap).

{edited for typos}

[dan610324]

nice to see that those old drawings can give someone inspiration for such an beautiful barrel .

[Cannoneer]

Terry, there's a typo in R #17; bore size.

[Terry C.]

Yeah, I saw that this morning.

Bore size is 1.725" not .725". Somehow the '1' got lost in the editing.

It's corrected now.