Testing the Tannenberg Gonne.

Here's my first set of findings from the test I volunteered for. And they were exactly what
I felt they would be.

Measurements:
I took measurements at what I felt were the three critical places where I felt failure may occur,
if there was to be a barrel rupture.

120 Grains FFFFg Goex Blackpowder - Single Patch Ball
A1.) 1.58 B1.) 1.56 C1.) 1.566 D1.)1.556
A2.) 1.226 B2.) 1.229 C2.) 1.231 D2.)1.277
A3.) 1.135 B3.) 1.135 C3.) 1.138 D3.)1.138

80 Grains FFFFg Goex Blackpowder - Two Patch Balls
A1.) 1.58 B1.) 1.56 C1.) 1.566 D1.)1.556
A2.) 1.226 B2.) 1.229 C2.) 1.231 D2.)1.277
A3.) 1.135 B3.) 1.135 C3.) 1.138 D3.)1.138

60 Grains FFFFg Goex Blackpowder - Three Patch Balls
A1.) 1.58 B1.) 1.56 C1.) 1.566 D1.)1.556
A2.) 1.226 B2.) 1.229 C2.) 1.231 D2.)1.277
A3.) 1.135 B3.) 1.135 C3.) 1.138 D3.)1.138

Comments:
Ignition was acheived by means of an Estes rocket igniter and a squib. In my video clips
you can see how the smaller charges had more recoil and smoke discharge as opposed to the
first charge of 120 grains and a single patch ball. I feel that medieval gonne makers
anticipated such pressures, hence the sub caliber powder chamber. Modern commercially made
blackpowder is glazed and not porous like homemade or powder of medieval times. The glaze,
while protecting the powder from the moisture of enviromental humidity, actually retards
the powder's rate of ignition when compacted. However, when powder is loose, the rate of
burn is multiplied and higher pressures are achieved. Overall, no ill effect occured or was
discovered from testing.

Photos:

Tannenberg prepared for firing, ignition by means of squib and Estes rocket igniter.

Link

tan_1.jpg - Cropped to focus content
tan_1a.jpg - Resized cropped photo for web use
tan_1fs.jpg - Full size photo, unedited

Holes in 1/4" plywood from double ball, 80 grain charge.
tan_2.jpg - Cropped to focus content
tan_2a.jpg - Resized cropped photo for web use
tan_2fs.jpg - Full size photo, unedited

Holes in 1/4" plywood from triple ball, 60 grain charge.
tan_3.jpg - Cropped to focus content
tan_3a.jpg - Resized cropped photo for web use
tan_3fs.jpg - Full size photo, unedited

Holes in backstop from triple ball, 60 grain charge.
tan_4.jpg - Cropped to focus content
tan_4a.jpg - Resized cropped photo for web use
tan_4fs.jpg - Full size photo, unedited

Tools of the day:
A: Tannenberg Gonne
B: 4Fg Blackpowder
C: Digital Caliper
D: Brass Hammer/Short Starter
E: Pre-lubed pillow ticking patch material
F: .69 Musket Balls
G: Powder Flask
H: Powder Measure
tan_5.jpg - Cropped to focus content
tan_5a.jpg - Resized cropped photo for web use
tan_5fs.jpg - Full size photo, unedited

Movies:
tan.wmv - 120, 80, 60 grain Discharges in that order
tan_120.wmv - 120 grain Discharge
tan_80.wmv - 80 grain Discharge
tan_60.wmv - 60 grain Discharge
tan120.wmv - 120 grain Discharge with title and credits
tan80.wmv - 80 grain Discharge with title and credits
tan60.wmv - 60 grain Discharge with title and credits

 

[benvenuto]

nice work!
:thumbsup:
BTW what was the distance to the target?

 

[robinghewitt]

So it didn't bulge :g

Love the movie, sounds like you get more bang with a smaller charge but more lead :hmm:

I suppose with more than one ball it will obturate and contain the burning powder while pressure goes up and up.

What's next? :thumbsup:

 

[trigger mortise]

Good report and very well presented, but I am willing to bet that if this Gonne is filled with bp (almost to the muzzle) and a tight patched ball is tightly rammed on top of the powder, this piece would survive without any damage and with minimal dimensional changes.

 

[CrufflerSteve]

Good report and very well presented, but I am willing to bet that if this Gonne is filled with bp (almost to the muzzle) and a tight patched ball is tightly rammed on top of the powder, this piece would survive without any damage and with minimal dimensional changes.

I agree. I have a Tannenberg in 1018 steel from the same fellow and it is a hefty hunk of steel.

I am determined to blow up a handgonne. I'm working with the same fellow and he sent me a series of 4 gonnes in 1018 with varying wall thicknesses. He also included some steel projectiles in two sizes averaging 962 and 1440 grains. That is roughly twice the weight of a round lead ball for a .69 caliber gonne.

I tried to blow it up Saturday but had to halt testing due to an unforseen problem. I was shooting the projectiles point blank into a sandbox. When multiple projectiles were shot they seemed to bang into each other which led to burrs at the end so I couldn't get them back in the barrel. It did lead to some fun detonation tests with a mostly empty bore with a 1440 grain slug stuck in the end. Next timeI bring a file.

The final test was 50 grains of 3fg Goex with 3842 grains of projectile. That's over 1/2 pound of steel coming out of a .678 barrel! The gonne is made from 1" 1018 so the walls are roughly .16" thick. This was done with the gonne seperated from me by a big pile of sandbags. The final result was no bulge or any evidence of trouble. The recoil was considerable. I was worried about shattering the platform so I made a gonne holder with a rear buffer of scrap 2x4. I shattered a couple of 2x4's but the platform is okay.

Steve

 

[trigger mortise]

Well, the scary thing would be that if a gap were left between a heavy black powder charge and a tight projectile, a .160” wall would almost certainly burst.
It all comes down to proper and safe loading procedure I suppose.

 

[Patrick Hemken]

The biggest help to this barrel not bursting is that it has a touch hole in it. Make it a percussion and watch out. I seem to remember an artical in old DIXIE catalog of a section of barrel breached to both ends with a fuse sticking out of it. They lit it and low and behold all that energy vented out the touch hole. I have built a lot of barrels well over thirty, and I can't seem to blow them up. My proof load is 300 grains of powder with two equal charges of shoot on top. In this winters testing the load will move the gun set in a tire back 3 feet every time I lit the fuse on snow. You would really have to mess something up to miss load that. I really want to play with overloading the same piece of barrel with a percussion cap set up.

 

[benvenuto]

I think we've finally laid to rest the old and much repeated myth peddled by armchair gun "experts" that early firearms were as much a danger to the users as to the enemy
:hatsoff:

 

[robinghewitt]

if a gap were left between a heavy black powder charge and a tight projectile, a .160” wall would almost certainly burst.

This may be an urban legend started by Benjanin Robins in his book New Principles of Gunnery of 1742, "no bullet should at any time be placed at any considerable distance before the Charge".

Many have tried it since then without bursting but it never seems to go away. The British Army tests of 1810 showed that it actually reduce the power or the gun :thumbsup:

 

[robinghewitt]

I think we've finally laid to rest the old and much repeated myth peddled by armchair gun "experts" that early firearms were as much a danger to the users as to the enemy
:hatsoff:

Or maybe it was just an occupational hazard, God's will and hardly worth mentioning. We do have this from Eldred... :g

It is said that if a brass peece explodes, the parts do not cause as much damage as an iron gun. This I have found not to be true and can cite many cases when brass fragments did kill men

 

[trigger mortise]

In “The Complete Black Powder Handbook” (by Sam Fadala) there is an article on the rupturing of a percussion test barrel.
They apparently tried all sorts of different powder and projectile combinations, but without much success.
What finally did ruptured the barrel, was 400 grain of powder with three minies and separated some distance from the powder charge. And this combination according to the article demolished the test barrel, which had a .200” wall thickness.

 

nice work!
:thumbsup:
BTW what was the distance to the target?

Distance was 15 yards.

 

So it didn't bulge :g

Love the movie, sounds like you get more bang with a smaller charge but more lead :hmm:

I suppose with more than one ball it will obturate and contain the burning powder while pressure goes up and up.

What's next? :thumbsup:

On the last discharge, not only was there an extra ball, there was a total of three. The powder 120 grain powder chamber was only half full. 60 grains charge with 3 patched balls. The balls were so tight I actually hammered them in to start them. I thought that between the effects of detonation and the blocked bore something had to give. It didn't. The Tannenberg spat out the three balls in a fairly nice group, as you can see below. The holes circled in green shows where the balls penetrated the 1/4 inch plywood. In the second photo, you can see where two of the balls enter the backstop, another 3 yards behind the plywood.
[url] http://www.handgonne.com/images/tan_3a.jpg http://www.handgonne.com/images/tan_4a.jpg[/url]

Its my feeling that the Tannenberg gonne was designed so that it would not blow up. I don't know who here is fimilar with Ulrich Bretscher's research, pay attention to his findings under the heading:
The secret of the peculiar powder chambers.

http://www.musketeer.ch/blackpowder/handgonne.html

Also, when you watch the movie of the different discharges, take note of the differences in recoil. Discharges are 120 grains FFFFg , single patched ball, 80 grains FFFFg 2 patched balls, 60 grains FFFFg, 3 patched balls. The smallest charge had the most recoil.
[url] http://www.handgonne.com/images/tan.wmv[/url]

I feel the reinforced subcaliber powder chamber was designed to take advantage of the dynamics of powder "detonation", also known as "flashover" in cartridge guns.

 

Well, the scary thing would be that if a gap were left between a heavy black powder charge and a tight projectile, a .160” wall would almost certainly burst.
It all comes down to proper and safe loading procedure I suppose.

Actually, both pieces have subcaliber powder chambers. Mine had a powder chamber of .4375 [7/16] x 2.625", approximately 120 grain volume capacity, with a bore of .703125. The projectiles were .690 with a pillow ticking patch prelubed with moose snot, Thanks Stumpy!. HAMMERED in to start them, with a 60 grain charge. I was going for what is an UNSAFE loading in other types of guns. IMHO, the Tannenberg was designed to take advantage of such a loading. I can't wait to get a tiller on it and see what it can do.

 

I think we've finally laid to rest the old and much repeated myth peddled by armchair gun "experts" that early firearms were as much a danger to the users as to the enemy
:hatsoff:

I don't know that I would go that far. We're working with modern metals and commercially made powder that are set to certain standards. Our barrels were drilled and milled from a solid piece of steel. The original Tannenberg was cast bronze, and used powder made of mixed chemicals, not the kerneled, glazed and sieved for uniformity commercially made powder of today.

My point was to prove that modern reproductions are safe for general use by a responsible adult. Not to dispell any myths, which I'm still not sure didn't actually happen. To dispell such myths would require that we reproduce the techniques of the day for producing both period gonnes and powder.

 

[BillinOregon]

Are the Tannenberg replicas available for purchase?

 

[benvenuto]

well, there is a certain Iowa gunsmith on the board that might feel like hand forging a gun to test

If my forge welding skills ever progress I will definitely have a go when i get the chance...

Meanwhile I'll just keep piling up the manure in hopes of getting saltpere

 

[GunneyG]

While I am not in the business of making gonnes/cannon for others, another poster here is. Check out the Tannenberg Gonne thread below for further details. His images are not displaying but his Tannenberg plan is the same as mine.

 

[GunneyG]

A further note: The plan I used is not a duplicate of the original; it uses only one taper for all three courses. Each course of the original has a different taper which makes the machining setup more than three times as complicated. If they were being produced on a CNC milling machine, it would be no harder to make the three tapers different but I have only a manual machine.