Testing the Tannenberg Gonne.

[claypipe]

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.

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

[uz2busmc]

What type of metal is that gonne made from? Good info too.

[Cat Whisperer]

Good experiment, Dude!

I assume this is a steel (1018 or 1218?) and the measurements were (as stated, in 3 places) and after each of 4 shots at 3 loadings?

I would assume the measurements to be well within the range of normal measurement error of several measurements by one person and perhaps some expansion from warming up a little.  If so that, to me, would indicate any stretching had returned back to the original dimension, hence the conclusion of it not being over-stressed.

Classic definition of assumption is assumed.   :eek:

[Double D]

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

Photos:

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

 

Let me see if I understand this. I had to think about it for a second.  You took measurements from three critical points. At each point you took a measurement across the flats.  Flat A to flat  E; Flat B to F; Flat C to G; Flat D to flat H.

It appears after the first test shot there was no change.  Do you have a chart for preshot measurements?  Was there any expansion from that first shot?

[GGaskill]

I assume this is a steel (1018 or 1218?) and the measurements were (as stated, in 3 places) and after each of 4 shots at 3 loadings?

This one was made from 12L14.

[claypipe]

Good experiment, Dude!

I assume this is a steel (1018 or 1218?) and the measurements were (as stated, in 3 places) and after each of 4 shots at 3 loadings?:

The gonne was acclimated to the test enviroment and allowed to cool after each shot. There was a decent breeze and the temperature was in the high 40's fahrenheit . I didn't want to measure the heat expansion, and the true sign of failure would be a devivation from the original measurements at the original temperature.

I would assume the measurements to be well within the range of normal measurement error of several measurements by one person and perhaps some expansion from warming up a little.  If so that, to me, would indicate any stretching had returned back to the original dimension, hence the conclusion of it not being over-stressed.

Any metal when exposed to heat is going to stretch. That's a given. However, the point of failure is not always herald by a bulge in the metal. Stress fatigue in harden metals is discovered by means of x-ray or magnaflux. What may past casual measurement and visual inspection may still fail due to the metal crystalizing.

12L14 has give in its Molecular structure, and why I favor it so.

[kappullen]

Claypipe and others,

IÂ’ve been a machinist for thirty some years and just love to see a job made of 12L14 steel.
I havenÂ’t found that exact alloy in the MachineryÂ’s Handbook.
 
Some Free Machining steels have sulpher, and some have lead.  
It’s main quality is that it is a “free machining steel” (according to “Machinery”s Handbook).

Free machining steels according to the handbook are not to be used for critical parts.
I take that to mean crank shafts, connecting rods, and gun receivers.

The handbook also says that it is not suitable for welding.  I know that a skillful welder can tig it having had that done before.
With my craftsman welder, the lead (thatÂ’s what the L stands for) will come out giving a porous piece of turd job.

In the past, I have tried to use this material for grate pins for a steam engine.
This application required the end of the pin to be riveted over to hold the bars and spacers togather.
When trying to rivet the pins, they split like the end of a cold chisel from a hardened hammer.

This material probably has ample strength for the “lightly loaded” handgonnes as described here.

I would be interested in talking to a stress engineer about itÂ’s use as a gun receiver.
I am not interested in getting into a battle over this.

The user should beware of what he is using for a cannon barrel.
I would not recommend this material for “critical” parts.

Kap

[CrufflerSteve]

I'm not surprised Claypipe couldn;t blow it up. I have one of George's Tannenbergs in 1018 steel it is hefty.

I am determined to blow up a handgonne. I'm working with George and he sent me a series of 4 gonnes in 1018 with varying wall thickness. He also included some steel projectiles in two sizes averaging 962 and 1440 grains. That is roughly twice the weight of a .678 round lead ball which matches the bore diameter. The thinnest has overall diameter of 1". The thickest is so hefty that I could probably use dynamite in it without damage.

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 in the sand 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 time I 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 platform 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

Steve

[GGaskill]

... I could probably use dynamite in it without damage.
 
 :grin:  
 
Dooooooooooooon't even think of that.  The pressure in the reaction zone of a high explosive like dynamite is on the order of a million PSI and it wouldn't even feel that 50,000 PSI steel around it.  Might make a good hand grenade, though.  (-:

[claypipe]

I'm not surprised Claypipe couldn;t blow it up. I have one of George's Tannenbergs in 1018 steel it is hefty.

Steve

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.

http://www.handgonne.com/images/tan.wmv

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

[uz2busmc]

See, I am impressed with how hard some of you guys will push on testing. I now feel more confident, after seeing this, about the "hot" loads that I put into my mini .69 cal cannon. Especially with a wall thickness of about .65 at the breech area, and I don't put nearly that much strain on it, although it is patched very tight.

[Cat Whisperer]

See, I am impressed with how hard some of you guys will push on testing. I now feel more confident, after seeing this, about the "hot" loads that I put into my mini .69 cal cannon. Especially with a wall thickness of about .65 at the breech area, and I don't put nearly that much strain on it, although it is patched very tight.

Testing is fundamental.  Be aware that one of the issues is that as the limits are approached pressure goes up exponentially - so finding the limits and keeping well away from them is only prudent.

Knowing the limit, and repeated testing of a slightly lesser charge gives one a lot more information about the design.

[Double D]

I for one am not impressed yet.

I am still waiting to see the pretest fire measurments.  Then I may be impressed.

[claypipe]

I for one am not impressed yet.

I am still waiting to see the pretest fire measurments.  Then I may be impressed.

Just for you DD

Pretest Measurements:
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

If you look closely at photos of gonne between the numbers you can see a black spot that I use to determine where to take my measurements. Short of using smokeless powder, you can't blow this piece up.