Author Topic: Cannon pressures  (Read 2109 times)

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Offline Double D

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Cannon pressures
« on: July 07, 2010, 06:36:23 AM »
During last weeks discussion on the construction guidelines found in the N-SSA and AAA rules, there were concerns that the materials and method recommended were not strong enough.  

Some thing that really wasn't discussed were the pressures we deal with in muzzle loading cannons.  

In 1971 and again in 1986 Matt Switlik and or own Artilleryman Norm Gibson conducted pressure tests with a 3 inch Ordnance rifle.  The results were used as the basis for establishing the rules and load charts found in N-SSA and AAA rules.  

If you wish to see a report of these pressure test contact the The Artlleryman Magazine and ask for a copy of the article "Powder test yield new guidelines, pressure data" in Volume 9, No. 4 Fall 1988. A photocopied article is $3 including postage.

Offline Double D

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Re: Cannon pressures
« Reply #1 on: July 07, 2010, 07:54:01 AM »
Here is an extract from that report that is relevant this time of the year.  

Table V Results with blanks for 3-inch Ordnance Rifle
Powder        Wt       Wad                Avg PSI
Fg Sporting  16 oz    none                 3,500
Fg "            16 oz    1•lb flour           7,500
Fg "            16 oz    1 cal wet paper 10,100
FFg "          16 oz     none                5,200
1 cal  wet paper in this gun is a 3 inch long, 3 inch diameter plug of wet paper. A cylinder of just water 3 inches in diameter and 3 inches tall would weigh just over 3lbs.

Offline Cat Whisperer

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Re: Cannon pressures
« Reply #2 on: July 07, 2010, 11:16:52 AM »
So how does this compare to full-charge service loads?
Tim K                 www.GBOCANNONS.COM
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Offline Double D

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Re: Cannon pressures
« Reply #3 on: July 07, 2010, 03:06:49 PM »
Results with 16 oz. charge for 3 inchn Ordnance Rifle

Wt.      Powder            Lb/Oz                  Avg.PSI Avg    FPS
16 oz   Cannon (GEOX) 11/7                    16,400           888
16 oz   Cannon            11/6                   17,100            875
16 oz   Cannon            11/5                   20,685            935
16 oz   Cannon             9/3 wadctr         18,000            950
16 oz   Cannon             9/1 shell             17,260           1010
16 oz   Cannon          11/4 brass/sabot    18,500            885
16 oz   Fg Sporting     11/6                    24,800            968
16 oz   Pyrodex CTG   11/6                    26,300            920
16 02   Class I Mil.      11/6                    21,600            904
16 oz   2FA               11/5                    20,800            885
16 oz   1FA               11/6                    13,500            810

Offline oyvind

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Re: Cannon pressures
« Reply #4 on: July 07, 2010, 07:48:55 PM »
Hi..

16 oz are not service loads for 3 inchn Ordnance Rifle today.

Oyvind

Results with 16 oz. charge for 3 inchn Ordnance Rifle

Wt.      Powder            Lb/Oz                  Avg.PSI Avg    FPS
16 oz   Cannon (GEOX) 11/7                    16,400           888
16 oz   Cannon            11/6                   17,100            875
16 oz   Cannon            11/5                   20,685            935
16 oz   Cannon             9/3 wadctr         18,000            950
16 oz   Cannon             9/1 shell             17,260           1010
16 oz   Cannon          11/4 brass/sabot    18,500            885
16 oz   Fg Sporting     11/6                    24,800            968
16 oz   Pyrodex CTG   11/6                    26,300            920
16 02   Class I Mil.      11/6                    21,600            904
16 oz   2FA               11/5                    20,800            885
16 oz   1FA               11/6                    13,500            810

Offline Double D

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Re: Cannon pressures
« Reply #5 on: July 07, 2010, 08:45:57 PM »
That is the service load they tested.  For full details contact the Artilleryman Magazine for a copy  of the report,

Offline Victor3

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Re: Cannon pressures
« Reply #6 on: July 08, 2010, 03:52:34 AM »
 I'm curious DD; does the article go into detail as to how the data gained from the 3" ordnance rifle testing was extrapolated to determine the various loads listed in the N-SSA charts? If it does, I'd be interested in ordering it.

 BTW...

A cylinder of just water 3 inches in diameter and 3 inches tall would weigh just over 3lbs.

 I get .766# for that volume of water.
"It is a capital mistake to theorize before one has data. Insensibly, one begins to twist facts to suit theories, instead of theories to suit facts."

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Offline Cat Whisperer

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Re: Cannon pressures
« Reply #7 on: July 08, 2010, 05:47:13 AM »
Must be HEAVY WATER.   :D
Tim K                 www.GBOCANNONS.COM
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Offline Double D

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Re: Cannon pressures
« Reply #8 on: July 08, 2010, 06:07:00 AM »
Your right, I used diameter and not radius.  .766 pounds. Which make the pressures involved with wet news paper as wad in a blank even more of an eye opener.

The article says the 1971 crusher test results were used to create the N-SSA tables.  The article states that prior to the 1971 crusher tests the rule was maximum safe loads allowed were 1/2 of service load for a given piece. Crusher tests are time consuming, so the test conducted in 1971 were limited in scope.  In 1971 they did not have Cannon grade powder available to test.  Those test in 1971 were the test that were used to develop the N-SSA Load.  If you wish to learn how those tables were created from that test data, I suggest you contact Matt Switlik and question him.

In the mid 1980's Switlik acquired piezo electric testing equipment to do pressure testing and in 1986-87 testing was conducted. Cannon Grade powder was available then for testing. The results recorded with the piezo electric pressure equipment were compared with pressure tests conducted by the Manufacturers and the Military.  Installing the transducer required required drilling a hole in the barrel over the chamber and installing the sensor.    Switlik did not test a smooth bore as one wasn't available for installation of the sensor.

There is a lot to be learned from from this article and it will help you formulate your questions for when you contact Switlik and learn how the tables were formed.  For 3 bucks  what's to lose?

Victor, I really think you should contact Switlik with questions you have about the safety of N-SSA and AAA rules.


Offline guardsgunner

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Re: Cannon pressures
« Reply #9 on: July 08, 2010, 10:13:49 AM »
The chart in the NSSA rules is based on 65% of service load pressure.

Offline Victor3

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Re: Cannon pressures
« Reply #10 on: July 09, 2010, 03:22:52 AM »
 For 3 bucks  what's to lose?

 I agree. I'll order it.

 Check this out...

http://www.shootingsoftware.com/pressure.htm

 Not that I've got $800 to buy one, but I wonder if it could be used for our purposes? Sure would be a handy tool if it could provide accurate data for cannons.
"It is a capital mistake to theorize before one has data. Insensibly, one begins to twist facts to suit theories, instead of theories to suit facts."

Sherlock Holmes

Offline Double D

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Re: Cannon pressures
« Reply #11 on: July 09, 2010, 05:03:18 AM »
 For 3 bucks  what's to lose?

 I agree. I'll order it.

 Check this out...

http://www.shootingsoftware.com/pressure.htm

 Not that I've got $800 to buy one, but I wonder if it could be used for our purposes? Sure would be a handy tool if it could provide accurate data for cannons.

I have that for testing the Martini's.  I have been eyballing it thinking of trying int on on my Cairo Gun.

Offline Parrott-Cannon

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Re: Cannon pressures
« Reply #12 on: July 09, 2010, 07:07:25 AM »
 For 3 bucks  what's to lose?

 I agree. I'll order it.

 Check this out...

http://www.shootingsoftware.com/pressure.htm

 Not that I've got $800 to buy one, but I wonder if it could be used for our purposes? Sure would be a handy tool if it could provide accurate data for cannons.

I have that for testing the Martini's.  I have been eyballing it thinking of trying int on on my Cairo Gun.


I look into purchasing one of these units about one year ago.  The company could not assure me that the unit would work with a cannon.
For a people who are free, and who mean to remain so, a well-organized and armed militia is their best security. (Thomas Jefferson)

Offline Double D

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Re: Cannon pressures
« Reply #13 on: July 09, 2010, 10:30:18 AM »
That's my concern also.

Offline GGaskill

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Re: Cannon pressures
« Reply #14 on: July 09, 2010, 12:49:42 PM »
I have the Oehler equivalent and I have talked to them about testing black powder and cannons.  They said that it doesn't work well with lower pressures in conventionally dimensioned barrels but if you take the wall thickness down, it will work.  I have reduced the wall thickness on one of my test barrels for this reason but have yet to actually glue on the strain gauge and fire any shots.

One of these days.
GG
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Offline Parrott-Cannon

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Re: Cannon pressures
« Reply #15 on: July 28, 2010, 08:35:22 AM »
Does the article address how the average pressure was calculated?  Does it address peak pressure?  I thought a crusher gauge measured peak pressure pressure.
For a people who are free, and who mean to remain so, a well-organized and armed militia is their best security. (Thomas Jefferson)

Offline Double D

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Re: Cannon pressures
« Reply #16 on: July 28, 2010, 09:12:13 AM »
Does the article address how the average pressure was calculated?  Does it address peak pressure?  I thought a crusher gauge measured peak pressure pressure.

Yes it addresses how pressure data was collected.  First test were made with with a copper crusher.  The later test were done with a piezo electric pressure transducer that was installed in the barrel right in front of the vent.  I suggest you contact Artilleryman here on this forum by searching the member list.  Norm was part of the crew doing the pressure tests.  Norm might be able to get you in contact with Matt Switlik.  Switlik was the compiler/coordinator of the test and he may provide you with the information you need.


Offline Parrott-Cannon

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Re: Cannon pressures
« Reply #17 on: July 28, 2010, 01:14:41 PM »
Does the article address how the average pressure was calculated?  Does it address peak pressure?  I thought a crusher gauge measured peak pressure pressure.

Yes it addresses how pressure data was collected.  First test were made with with a copper crusher.  The later test were done with a piezo electric pressure transducer that was installed in the barrel right in front of the vent.  I suggest you contact Artilleryman here on this forum by searching the member list.  Norm was part of the crew doing the pressure tests.  Norm might be able to get you in contact with Matt Switlik.  Switlik was the compiler/coordinator of the test and he may provide you with the information you need.




Thank you for the information
For a people who are free, and who mean to remain so, a well-organized and armed militia is their best security. (Thomas Jefferson)