Black Powder advice please

[troddenmasses]

I'm thinking about making a reproduction medieval 'Handgonne' as per http://www.handgonne.com/ and http://www.musketeer.ch/blackpowder/handgonne.html. It will be .75" bore, and i'm trying to work out how thick the barrel needs to be. I can do all of the stress calculations no problems, but have no data on the pressures created by black powder. Does anybody have any sources of data/formulas to give an idea of pressures? I can then work out how thick the barrel needs to be in my chosen material, add a good safety margin and then crack on with manufacture. Obviously, I will be sending it for proof afterwards to make sure that everything is ok, but after all the work to make it, I want it to be ok first time.

[Jim McArthur]

I can't answer your question, but I sure want to see pics of your finished product.

Jim

[harricook]

I'm thinking about making a reproduction medieval 'Handgonne' as per http://www.handgonne.com/ and http://www.musketeer.ch/blackpowder/handgonne.html. It will be .75" bore, and i'm trying to work out how thick the barrel needs to be. I can do all of the stress calculations no problems, but have no data on the pressures created by black powder. Does anybody have any sources of data/formulas to give an idea of pressures? I can then work out how thick the barrel needs to be in my chosen material, add a good safety margin and then crack on with manufacture. Obviously, I will be sending it for proof afterwards to make sure that everything is ok, but after all the work to make it, I want it to be ok first time.

Why don't you give Andy Allwood a call - he has just had four cannon fettled & was using one to good effect at the NRA/NSC?Bisley Open Day yesterday

www.tfsa.co.uk

Mention my name if you want to - wont get you anything though

Roy Harrington
.

[airgunnut]

I'm thinking about making a reproduction medieval 'Handgonne' as per http://www.handgonne.com/ and http://www.musketeer.ch/blackpowder/handgonne.html. It will be .75" bore, and i'm trying to work out how thick the barrel needs to be. I can do all of the stress calculations no problems, but have no data on the pressures created by black powder. Does anybody have any sources of data/formulas to give an idea of pressures? I can then work out how thick the barrel needs to be in my chosen material, add a good safety margin and then crack on with manufacture. Obviously, I will be sending it for proof afterwards to make sure that everything is ok, but after all the work to make it, I want it to be ok first time.

all the people i know who shoot black powder tend to go for guns that have thicker barrels, so my advice would be to get the barrel as thick as possible without ruining the overall look of the gun then you know it's as safe as you can make it!

[davederrick]

Just ensure that you can shoot it where you intend to, range certificates usually have limitation on M.E and/or calibre. .75 is quite a biggy !
p.s. wow - I'd like to see it shoot

[loiner1965]

Just ensure that you can shoot it where you intend to, range certificates usually have limitation on M.E and/or calibre. .75 is quite a biggy !
p.s. wow - I'd like to see it shoot

me too......from a safe distance

[robkayak]

I will sell you the insurance

[troddenmasses]

Just a quick update on the progress of this thing. To answer some questions:

Just ensure that you can shoot it where you intend to, range certificates usually have limitation on M.E and/or calibre. .75 is quite a biggy

I shoot at two ranges - one in Worcester where the limits are .577 for breech loading, and .75 for muzzle loading (hence the reason I decided on .75") and 5160 ft lbs. I made an excel sheet to calculate muzzle energies (available for download here) which tells me that the limit is 1915 ft/sec, much higher than I anticipate. Tests on other cannons show me that 1000 ft/sec is much more realistic, so I will be well within that range certificate.
I also shoot at a range in South Wales, which has no calibre limit, just an ME limit is 7000 Joules (5162 ft lbs). I have on ticket a 1.75" cannon which just happens to be about the size of a golf ball.

I will sell you the insurance

One of the first things that we did as a club is go to our insurers to check that this kind of thing is ok - along with cannons. We are insured with the NRA, and after much discussion, there are no problems so long as the item is aimed, and is within the range safety certificate.


I have nearly finished the handgonne (but not drilled the touch hole, so it is still just a model), and was about to write it onto my ticket as a cannon - as I have a slot for a .75" cannon. After having a think about it, I have decided that it is a 'pistol', so have put in for a variation. The reason for this is that if it goes down as a cannon, nobody else can have a go - it is a bit of a strange one under the firearms act. As it will be controlled by one hand (the other one will be lighting the thing), I reckon that it's a muzzle loading pistol - which means that anybody at the club can have a go.

I am going to test it a few times first with a heavy load of powder and lead to make sure that it doesn't explode (and that my calcs are correct), and will then probably send it for proof - just to be secure in my own mind. Pics to follow as soon as it is on ticket.

[enfield2band]

I'm thinking about making a reproduction medieval 'Handgonne' as per http://www.handgonne.com/ and http://www.musketeer.ch/blackpowder/handgonne.html. It will be .75" bore, and i'm trying to work out how thick the barrel needs to be. I can do all of the stress calculations no problems, but have no data on the pressures created by black powder. Does anybody have any sources of data/formulas to give an idea of pressures? I can then work out how thick the barrel needs to be in my chosen material, add a good safety margin and then crack on with manufacture. Obviously, I will be sending it for proof afterwards to make sure that everything is ok, but after all the work to make it, I want it to be ok first time.

I don't have any formula but blackpowder has a detonation velocity of 950fps, or, the maximum velocity of 950fps.
Don't use semtex it has a detonation velocity of 5mps (5 Mile per second).

[andrew375]

Use stainless hydraulic tubing, you can even get it supplied ready proofed!

Of coarse in the 14th. century everyone worried about stress calculations.

[troddenmasses]

Use stainless hydraulic tubing, you can even get it supplied ready proofed!

Of coarse in the 14th. century everyone worried about stress calculations.

That's what I have used for the golf ball sized cannon - the wall thickness is huge - there is no way that I could ever blow it up - having done the calcs, there is a 14x safety margin over the proof load, so there really isn't a problem.

You're right - they didn't worry about stress calcs, but then I want to be able to count to 10 after I have shot the thing - without taking my socks off.

[mat BRC]

I'm thinking about making a reproduction medieval 'Handgonne' as per http://www.handgonne.com/ and http://www.musketeer.ch/blackpowder/handgonne.html. It will be .75" bore, and i'm trying to work out how thick the barrel needs to be. I can do all of the stress calculations no problems, but have no data on the pressures created by black powder. Does anybody have any sources of data/formulas to give an idea of pressures? I can then work out how thick the barrel needs to be in my chosen material, add a good safety margin and then crack on with manufacture. Obviously, I will be sending it for proof afterwards to make sure that everything is ok, but after all the work to make it, I want it to be ok first time.

mabie you can source some original plans from either amusiem, or someone who has already done this, ive watched a few programs on sky and there are many societies that do this profesionaly, and are very willing to give out data

[troddenmasses]

Strange you should mention that - i'm going over to Germany in a couple of weeks, and have been speaking to the curator of the museum where the 'Tannenberg Handgonne' is on show. I have arranged to go and have a look / take some measurements. It is for interest only though - the materials are so vastly different.

On a side note, the club that we started in order to shoot these things and others - the 'National Cannon association of Great Britain' now has Home Office approval.

[MikB]

I don't have any formula but blackpowder has a detonation velocity of 950fps, or, the maximum velocity of 950fps.

This is not so. Plenty of Victorian black powder rifles achieved MVs of nearly 2000 fps - including the black powder driven .303" Ball Mk.I at about 1830 fps and 38,000 psi.

You might be thinking of BP in open air. Higher pressures and temperatures will increase burning speed and gas evolution - though not as much as with nitros.

Regards,
MikB

[troddenmasses]

This is not so. Plenty of Victorian black powder rifles achieved MVs of nearly 2000 fps - including the black powder driven .303" Ball Mk.I at about 1830 fps and 38,000 psi.

You might be thinking of BP in open air. Higher pressures and temperatures will increase burning speed and gas evolution - though not as much as with nitros.

Regards,
MikB

I completely agree - I know that the pressure created is somehow proportional to the volume of powder, the temperature and the pressure - what I don't have is the proper formula. Never mind - I just made it "REALLY thick" - much much thicker than really neccessary. Thanks for all the replies, by the way - very much appreciated.