12lb and 6lb 18th century french guns range

[MESSIS]

Have looked up all my books and as much I could the internet, but it seems to be a secret!

 

The effective  range of those cannons I assume it had to be ca 600-800 m for the 12lb and 400-600 for the 6lb.

 

I would appreciate any help. 

[mtaylor]

Tough question to say the least.   The best answer I've found is here:  https://en.wikipedia.org/wiki/Naval_artillery    About halfway down the page is a table. 

 

The problem is that wind, waves, etc. could impact the range and accuracy as well as the age and condition of the gunpowder.   Wear on the barrels and the degree of precision or lack there of during casting usually meant that the bores were never exact and thus the "windage" varied or the space between the cannon shot and the barrel.  

 

Which probably leads us to how far apart the ships were in battle?  From accounts, they could be practically muzzle-to-muzzle or at the maximum range.  Accuracy did decrease as the range got longer, though.   And since the normal strategy was "close with the enemy", I'd assume they were pretty close to each other.

[mgdawson]

Hi Messis,

Some time back I found online a pdf of 'A Treatise on Naval Gunnery' by General Sir Howard Douglas, 4th Edition, 1855, 'Dedicated by Special Permission to the Lords Commissioners of the Admiralty', 689 pages, apparently scanned by google in Harvard College Library.

A quick look in the tables in Appendix D, 'Tables of Gunnery Practice', I found found some tables with ranges, projectile velocity and penetration over various ranges mainly for larger guns but some tables go down to 12lb, I didn't look extensively to see whether there were tables for 6pounders. There are a lot of different tables which may be of interest, likewise the whole book. Unfortunately some of the tables are quite poorly reproduced and at a glance are unreadable while others are crystal clear, but they may reveal some relevant info with a bit of effort. It appears this was a problem with the source rather than the scanning.

The book is obviously British but I imagine performance would be comparable with French cannon.

Sorry, I can't give you a link, I downloaded it quite a while ago and don't remember where from.

Mark

[mtaylor]

The book Mark recommends is here:  http://www.google.it.ao/books?id=PK50sbOOfjUC&pg=PA400&focus=viewport&dq=editions:STANFORD36105044360084&lr=&output=html_text

 

You can also order the book from various sellers, just Google: "'A Treatise on Naval Gunnery' by General Sir Howard Douglas"

[MESSIS]

@mtaylor @mgdawson  thankyou for your help gentlemen. I really appreciate it.  

Edited November 13, 2019 by MESSIS

[Chapman]

Am I late ?

I have no data directly for French 12 and 6 pounders, but for 18 and 8 pounders.

That certainly gives an impression as well

The data are from Vol. 4 of The Ship of the Line by Boudriot.

 

 

In a test trial under ideal conditions on land.

The French 8-pounder has a theoretical range of 2500 meters by a elevation of 16-degree

But the penetration force through oak with 1,5 KG charge is 0.27 m at 1000 meters and 0.90 m at 100 m.

For the French 18 pounders with 3,0 KG charge, the data is 0.40 m at 1000 m and 1.10 m at 100 m.

More than I expected.

For comparison: The maximum hull thickness of a french 74 gun ship Ship of the period is about 0,8 m.

[MESSIS]

@Chapman its never late! As far as we are alive. Thank you very much for your response. Interesting facts and figures. So I guess a 16 degree elevation gives the maximum range.Its been a long time since I learned mechanics at the uni....so I cant recall the ballistic formula 😊.

 

So the 18lb figures suggest that a reasonable worth  shooting, long and  effective range, would have been about 800 to 1000m, isnt it?A 12 lb should then have been a little less than that. Lets say 600 to 700 or 800m.

Edited November 13, 2019 by MESSIS

[Lieste]

The maximum range would be found at ~35-42 degrees depending on initial velocity and shot density.

However, even with the beds and quoin removed, the carriage won't permit more than ~16 degrees (and this is in practice limited, by portsills to ~9-11 degrees).

Earlier guns and their carriages were limited more (the Vasa cannon was capable of being elevated to 3.5 degrees according to notes from the recent test programme), and with some the quoin and beds present later carriages have a lower useful (and controllable) range of elevation as well (probably more than 5 degrees, but I'd have to do some additional calculations to get a figure for this for an example gun to confirm it).

But-en-blank/line of metal - i.e. the line of direct pointing will give different ranges according to the (fixed) shape of the gun, the powder charge and windage, and the number and weight of shot.

A single shotted 32lb gun pointing at a nominal 2/3 degree might reach 425yds to the muzzle height, and 540 to the water, from a lower battery, with the middling charge, 370yds to muzzle hgt, 485 to the water, with the small charge, 285yds to muzzle hgt, 395yds to the water. Double shot is harder to estimate, but a reasonable guess for the small charge would set the faster shot reaching to 140 yds to muzzle hgt (95 yds for the slow shot) and 245 yds for the fast shot (185 yds slow) to the water.
It would be normal to engage at close ranges with reduced charges or even using double shot, and only to drive shot with large charges for distant work

Carronades, firing a large shot, with lower velocity, but at a 'steeper' line of metal have similar distances of direct pointing to that of the long gun with distant charge, but have similar velocity, trajectory and penetration performance to the 'top' shot of a reduced charge double shot. This 'high' trajectory tends to make untrained carronade gunners fire rather high over closer distances, and to fall shorter than a similarly pointed gun much sooner at longer distances, but the absolute range of guns and carronades is not as dissimilar as many writers declaim (16 degrees from a carronade of 32lb would reach to 2390 yds, while the distant charge of the 9.5ft gun would require 8 degrees to drive a shot to the same range.

[mgdawson]

Hi Messis
 

I just found this page with formulae for smoothbore cannon internal and external ballistics. Unfortunately not an online calculator but perhaps someone who knows javascript could put it online.

 

https://www.arc.id.au/CannonBallistics.html

[Lieste]

The Robbins formulae are a little simplistic**, don't account (except by a 'guessed' parameter) for windage and were reputed to overestimate both the effect of changing charges and increasing barrel length more than matched with observed values. Plus when I attempted to replicate worked examples I didn't get the same results, so something appears to have been confused in the setting/printing of the method. I didn't follow up on getting agreement as contemporary discussion indicated they had limited accuracy off the narrow band of parameters they were tuned to suit.

The 'form' used in either Aide Memoire d'Artillerie Navale or Ingalls' text which reproduces the work of Abel and Nobel give a more generally usable form (though both assume a later period more powerful black powder, not necessarily appropriate for earlier guns, and neglect discussion of an appropriate correction for old/damaged powder or weaker mixtures).

The French document provides a useful estimate for both shot velocity lost to windage, and also an adjustment to recoil from these windage losses. This adjustment is usefully computationally derived, so the variation in shot performance with defect in size and weight across the full range of the permitted shot gauge for any selected weapon is possible.

**To be fair to him he was one of the first to be looking at ballistics from a solidly empirical manner, with experimental results described and explained by a series of Axioms. He didn't have any prior catalogue of experimental results and limited equipment and funding to explore this over a wide range of scales, something which government ordnance boards did have available during the middle part of the C19th, although by then black powder was a 'comparison' powder to the newer smokeless powders being introduced, as were smoothbore roundshot in comparison to rifled elongated shot and shell.

Black powder and roundshot tend to get the briefer discussion in the later papers, but they are reported as baselines, and useful information can be found from them (Bashforth is another with useful data, using his Chronograph - mostly for rifled ammunition, but there is some round shot from smoothbores as a baseline for comparison).

Edited January 9, 2021 by Lieste