How much slack in breeching Lines?

[ASlrWnt2C]

Hello, 

I'm working on the  Revell 1/96 Constitution. Before too much longer I'm going to be assembling the gun deck and rigging the breeching lines that absorb the cannon's recoil. 

 

Something that is puzzling me is how much slack would have been in those lines? It seems like you'd want as little as possible when the gun was run out, to be effective, but if so, how would they have run the guns in for access to the muzzle with long handled tools? 

 

I thought I had it figured out. They must have unlooped the breeching line from around the cascobels and let the gun slide under the breeching line when it was run in. But I have seen some pictures of real ships where the cascobel has a ring, and some models where a cut splice is in place around the cascobel. So that can't be right. 

 

Of course many details on the gun deck won't be visible in the model. But I would still like to know how this worked for my own satisfacation 

 

Any thoughts? 

[popeye2sea]

The guns recoil about 18 inches when fired.  That is all the slack that is in the breeching.  That will bring the muzzle a short distance inside the gunport. The reloading was done by sticking yourself or your implements outside the gunport.  A flexible rammer made from a large diameter rope could be used to help keep personnel inside the ship.

 

The breeching remains affixed to the bulwarks and the cascabel during the entire loading operation.

 

Regards,

[Kris Avonts]

Hello ASlrWnt2C,

 

As a first indication you can take a look at this picture which is part of plate IX in William Falconer's dictionary.

 

 

The middle gun shown is run in as far its breeching lines allow.

Maybe that can help you further.

 

best regards,

   Kris

 

[Dr PR]

The breech rope did provide the final stop for recoil. But most of the recoil energy was absorbed by the gun tackle. If you have ever used multiple block tackle to hoist an object and then let the loose end go you will have seen that the tackle slows the fall.

 

The loose end of the gun tackle rope was laid out straight on the deck (or held by the tackle men) so it would run through the blocks without fouling. The line running through the blocks served as a shock absorber to slow the gun. The breech line then stopped it in the loading position. This is described in detail in several 19th century ordnance manuals.

[ASlrWnt2C]

Thanks for the helpful information @popeye2sea, @Kris Avonts and @Dr PR

 

That makes sense. I will rig the lines accordingly 

[allanyed]

For long guns, assuming the Falconer drawing is accurate, it looks as if the recoil is closer to 4 feet plus/minus.  According to Caruana in volume II the History of English Sea Ordinance, for a nine foot   32 pounder for example,  in the Regulation of 1723 the breeching line was 6" in circumference and 30' long.  In the updated Regulation of 1747 the circumference was 7.5", then reduced to 7" in 1765.  He could not find circumferences for later years but comments that with the introduction of cylindrical powder about 1800 and the resultant more bang for the buck, the circumference of the breechings may have increased yet again.  The length remained the same, 30 feet for 32 and 42 pounders.    The length of the breeching for 9 to 18 pounders was 28 feet and 27 feet for smaller caliber guns.  This seems it would allow more closer to 4 or more feet of recoil.

Allan

[Sooty]

A bit of Engineering geekiness...

 

32 pounder, weighing 5500lb, firing at say 200m/s (guesstimate), would cause the gun to recoil at ca. 1.16m/s.

 

That translates to a kinetic energy of 1,682Joule.

 

To absorb that energy over a 1.5m recoil (just over 5ft), a constant force of ca. 1100N would be required, i.e. ca. 110kg force.

 

Now, those guns were ca. 2.5te and the carriages had small diameter wooden wheels on wooden axles with fairly primitive bearings. I make the friction factor 0.1 or so, for a friction force of 250kg.

 

Which means the gun would be very unlikely to ever recoil enough to get the breeching line violently taut, as the wheel friction alone would have stopped it a couple of feet before that.

 

My guess is the breeching lines were probably an assurance. 

[Gregory]

^ With that in mind, it makes one wonder if the breaching line was more of a safety line, to keep the gun from rolling out of control on a rolling deck?

[jud]

If you have ever chased anything massive that has came adrift at sea, you will understand why the large Breaching Rope was in place, not to stop recoil, but to stop the gun from becoming a massive ram powered by gravity. Would only expect the guns to make the breaching taught if the gun was fired on the up-roll and gravity was assisting. Much of the forces of recoil would be consumed in getting the mass moving, once that was done, all the recoil forces would be expended and coasting to a stop would be the norm. Putting a gun crew down from a near hit, would place that gun out of control and depending on the seas, on it's wheels or not would have little effect on it potential travels, hence the heavy breaching keeping that gun from taking others out. The length has been well defined and explained above

Edited December 9, 2020 by jud

[Dr PR]

The friction of the wheels does absorb some of the energy, but as you can see from this video, the gun does recoil until the breech line stops it.

 

 

 

 

In this video there is no breech line and the gun rolls quite a distance.

 

 

[Sooty]

Keep in mind, the 200m/s muzzle velocity was just a guess, and that affects the calculation considerably. So does the friction coefficient I assumed on the wheels.

It's great to see the cannon fire from the Bofors test centre! I was looking for such a video and all I could find was field guns firing actual shot, with everything else firing blanks. Cheers for that!

[davyboy]

Hi ASirWnt2C,

 

According to Lavery in his book the Arming and Fitting of English Ships of War breechings were 3 times the length of the Gun Barrel. However,this is for English Ships but I suspect US Warships were similar if not the same .

 

Dave 

[mtaylor]

Dave has it as it was pretty much "standard" but not always.  One difference, for example, is the French.  The breach rope went through the carriage and not around the breeching knob as other countries used.

[BANYAN]

Again for RN ships, but I am sure there will be an equivalent for the USN guns, the breeching rope sizes were tabulated and published.  The following is from 'The Sea Gunner's Vade Mecum_Robert Simmons (1812)"

 

cheers

 

Pat

[wefalck]

We had this discussion some place else, I think, already ... anyway, it seems that the friction in the gun tackles also transform a considerable amount of the recoil energy into heat. The breech rope was sort of the ultimate stop, as also the movement of the gun depends on the movement of the ship after the gun is fired. In later times, when slide carriages with different types of recoil brakes were introduced, the breech rope lengths were reduced to a minimum. There is a balance to strike between the maximum allowable strain on the parts of the gun and the breech-rope on one hand and the space for the movement of the gun on the other hand. Also, the further the gun moves away from the bulwark, the more difficult it becomes to control and bring back into loading and firing position.

[Lieste]

On 12/9/2020 at 12:57 AM, Sooty said:

A bit of Engineering geekiness...

 

32 pounder, weighing 5500lb, firing at say 200m/s (guesstimate), would cause the gun to recoil at ca. 1.16m/s.

 

That translates to a kinetic energy of 1,682Joule.

 

To absorb that energy over a 1.5m recoil (just over 5ft), a constant force of ca. 1100N would be required, i.e. ca. 110kg force.

 

Now, those guns were ca. 2.5te and the carriages had small diameter wooden wheels on wooden axles with fairly primitive bearings. I make the friction factor 0.1 or so, for a friction force of 250kg.

 

Which means the gun would be very unlikely to ever recoil enough to get the breeching line violently taut, as the wheel friction alone would have stopped it a couple of feet before that.

 

My guess is the breeching lines were probably an assurance. 

The 24lb Vasa cannon (a light piece, half the weight of the gun of the period, or of Napoleonic era pieces) was tested at 360m/s using powder 'suitable in quantity and quality' for artillery of the early C17th)

For late age of sail period gunnery and the 32lb gun of 55cwt:
Distant charge gives approximately 1489 fps or 454m/s (according to available numbers for dimensions, plus the estimated internal ballistics from "Aide Memoire d'Artillerie Navale"), this is sufficient to drive the ordnance alone backwards at 3.83m/s (using the augmented recoil according to AMAN), which is immediately moderated by an impulsive transfer to the carriage to 3m/s, with 4.46kJ absorbed from the original 20.68 kJ, leaving 16.22 kJ to be absorbed by friction and breeching.
I neglected side tackle, but can consider what they might provide in a follow up calculation, but did allow for the 0.1 mu at the trucks, which might already factor in some part of that requirement - and assumed that the muzzle after recoil would be brought to the position of the trunnion when run out.
With the friction alone recoil at the 'stop' still had 5kJ to absorb into the breeching, with a 'free recoil' length of 15.7 ft if not restrained. (or 3.5 times the recoil distance selected).

Reduced charges give lower recoil with single shots, but double shot with the middling charge is significantly sharper. ~1000 fps for top shot, and ~800 for the second (though admittedly this should be considered a much more tentative estimate) with this giving a 4.43 m/s initial recoil of the bare gun, 3.47m/s after taking up the carriage - with 6kJ nearly being lost from an initial 27.66kJ - recoil energy remaining at the selected recoil distance increases to 6.68kJ and free recoil to 20ft.

Smaller bore guns are much heavier, for their shot and the longer, heavier small bore guns (e.g. the 8.5ft 6lb will only free recoil around 3 ft with the same assumptions, compared to 4.3ft for the lighter, shorter 6ft gun).

Carronades are significantly sharper than guns in recoil, despite their lower performance.

[Sooty]

1 hour ago, Lieste said:

The 24lb Vasa cannon (a light piece, half the weight of the gun of the period, or of Napoleonic era pieces) was tested at 360m/s using powder 'suitable in quantity and quality' for artillery of the early C17th)

For late age of sail period gunnery and the 32lb gun of 55cwt:
Distant charge gives approximately 1489 fps or 454m/s (according to available numbers for dimensions, plus the estimated internal ballistics from "Aide Memoire d'Artillerie Navale"), this is sufficient to drive the ordnance alone backwards at 3.83m/s (using the augmented recoil according to AMAN), which is immediately moderated by an impulsive transfer to the carriage to 3m/s, with 4.46kJ absorbed from the original 20.68 kJ, leaving 16.22 kJ to be absorbed by friction and breeching.
I neglected side tackle, but can consider what they might provide in a follow up calculation, but did allow for the 0.1 mu at the trucks, which might already factor in some part of that requirement - and assumed that the muzzle after recoil would be brought to the position of the trunnion when run out.
With the friction alone recoil at the 'stop' still had 5kJ to absorb into the breeching, with a 'free recoil' length of 15.7 ft if not restrained. (or 3.5 times the recoil distance selected).

Reduced charges give lower recoil with single shots, but double shot with the middling charge is significantly sharper. ~1000 fps for top shot, and ~800 for the second (though admittedly this should be considered a much more tentative estimate) with this giving a 4.43 m/s initial recoil of the bare gun, 3.47m/s after taking up the carriage - with 6kJ nearly being lost from an initial 27.66kJ - recoil energy remaining at the selected recoil distance increases to 6.68kJ and free recoil to 20ft.

Smaller bore guns are much heavier, for their shot and the longer, heavier small bore guns (e.g. the 8.5ft 6lb will only free recoil around 3 ft with the same assumptions, compared to 4.3ft for the lighter, shorter 6ft gun).

Carronades are significantly sharper than guns in recoil, despite their lower performance.

It sounds like I was completely off with my assumptions 😂

Thank you for the velocities, with over 2x what I had assumed, it now makes sense that the breeching line would take a serious beating on every shot!

 

[thibaultron]

As a side note. During the firing they discovered that the 24 pound shot would go through both sides of the ship, even if it hit one of the frames dead on. It was actually (realitively) better for the crew if it missed the frames, as there were fewer splinters created. This info was from a lecture I found on several ship wrecks, given at the Texas A&M university, I think.