Guns, Carronades, Obusiers and divers Ordnance

As part of an ongoing project, which has recently spawned a batch of 1:2743 (9ft to the mm) FDM prints, which now need painting and masting, I have been looking at Smoothbore ordnance and the 'plausible' ballistic performance of the divers ordnance types in their various loading conditions (both from windage and from variation of powder charges).

I am currently using my own spreadsheet for the trajectory modelling, based on the NACA drag data as interpolated by Dr Collins, and with internal ballistics after the model presented in Lafay "Aide Memoire d'Artillerie Navale", which provides a common basis for the modelling both of well documented and rather less well described ordnance - based on bore length, diameter, windage and shot weight, allowing the variation in velocity and carry for all of the high gauge, middling gauge, found low gauge and service low gauge states, as well as for hollow shot or shell.

I do currently describe the displacement of the muzzle with elevation relative to a fixed trunnion (and trivial to extend to a joint, once I have calculated the geometry as it differs), as well as the trajectory which arises from a 'mean trajectory' at each of any of angle of fire, angle of fall, range, penetration or 'point of aiming'.

There are a great many questions I can ask of the dataset and model, and 'common input' results which are the outputs are interesting, but I am interested in what 'particular targets' might be considered as of especial value.

I see 'levelled ordnance' falling from a position mounted on a carriage on a nominal platform to the platform height, or perhaps down to the sea level, as being obvious, as well as the same, but pointed by line of metal to a horizontal sight line. For carronades, which from 1782 had dispart sights fitted with notches for several discrete angles, also intermediate angles from the levelled piece to elevated to the line of metal.

An elevated sight line of the LOM to the top of the main yard of a 74 is also something I have investigated.

Penetrations of "thick" targets by reduced, standard and distant charges, and the ranges at which they become marginal according to the Didion/Poncelet form are easy to derive, but I am uncertain what I should consider as "thick" especially as it relates to the lighter natures of ordnance.

The influence of motion/error in pointing relative to the ease of pointing/impact of errors in range is of interest.

Any questions/suggestions/observations are most welcome, and will help refine the questions I ask, and the usefulness of the answers the model can supply - though note it is more for producing a consistent set of data than strictly reproducing a singular firing range day. (Values are in the same 'scale' as those published from tests in the last decades of the C18th and first decades of the C19th though).

From data from Boxer, Douglas, Dr A.R. Collins, John Muller (for his description of ship guns of the "new construction"), and using the internal ballistics model from Lafay "Aide Memoire", I obtain the following set of 'common standing' velocity vs length for the 'Common' Naval ordnance (1/3rd distant charges, 1/4th standard charge (not shown) and 1/6th reduce charge), as well as the few 'medium' guns seeing service by the turn of the C19th - including one 'obscure' 6ft 18pdr and the 7.5ft medium pattern 24pdr, the 'last' references to various sized swivels (of 1/2pdr to 2pdr for completeness of the ballistics table/package, more than utility by this period), and the longer pattern of carronades of 'around' 7 calibres overall, except for 9 and 6pdrs which are slightly longer.

I see little variation in 'reduce' performance of guns with length (there is a weak maximum, and slightly lower performance for both shorter and longer guns, but essentially the only variation in performance is 'downrange' where guns firing heavier shot carry better and penetrate better both because of higher sectional density and higher retained velocity.

With the distant charges there is a fairly strong advantage in initial velocity for guns which are relatively longer - often the smaller calibre ordnance in their longest forms... but this initial difference makes little practical difference at the longest ranges, with again the advantage really lying with a heavier shot.

Muskets have significantly higher windage with their nominal shot than is called for by the official gauges for naval shot, so despite larger charge ratios and longer barrels they don't see especially high velocity "as specified".

Guns are provided with the low (and nominal) windage as 1/20th of the shot diameter. The high gauge is larger, with the 'average' windage being close to 1/25th of the bore (in the first few decades of the C19th, the windage was 'revised' to 24/25, with this nominal value being the 'average' gauge, but with no actual change in specification). A subsequent *actual* revision left the high gauges unchanged, but increased the low gauges and the 'average' windage was reduced for all guns, with some of the newer pieces also being bored with a smaller diameter.

Muller's artillery was apparently specified and produced for civilian and foreign customers (but not RN naval service) by Carron Ironworks, with a 'nominal' gauge of 24/25. I have assumed that the low and high gauges are the same as for RN ordnance, but the bore is smaller, based on this ratio rather than 21/20.

Carron's more widely adopted carronades were bored with much narrower windages, and with powder chambers for their smaller charges, as well as a muzzle cup (part flash-hider, part loading assistance) Their ordnance was a mix of jointed (true carronades) and trunnioned (gunnades/gasconades) but almost all of the RN requirement was fulfilled by jointed pieces. Carronades were fitted with sights from 1782 or thereabouts.



French ordnance (not presented here) is broadly similar (with tighter windage and shorter lengths giving a slightly higher velocity for similar powder quality, and length, but with overall performance very close). Calibre by calibre, French shot is considerably heavier (their 8Livre piece, although quite close to the 9pdr, is still throwing a smaller diameter shot). For most other calibres, French ordnance is roughly midway between British sizes in the 'upper' interval. Their pre-1805/1808 (ish - depending on source) Obusier de Vaisseaux is relatively weak, using a small charge to throw a middling weight hollow shot (or unfilled shell) or grape/cannister down a very short barrel using a very small powder charge. Their later carronades are longer, heavier and tighter windage than the RN types, but still of 'broadly' similar performances.

Attachment 54638

Do you have any data for the Russian Yedinorog?

I see nothing about the data I have available which would suggest very different performance to other shell guns (looser windage, than most, but still within the range used by British artillery).
I could do with more data for them for external shape and the different gauges for shot and shell... and haven't yet run the analysis in detail.
(The original datatable I referred to (Napoleon Series) suggests a range of up to 1835m for the 1/4 pood version to first graze in land service, and 2000+m for the 1/2 pood), with canister up to 833m for the large canister and 540 for small canister ammunition (similar to the field guns).

Larger powder charge than carronades, and a longer tube... but both lower than the guns, and windage is *larger* than that for field artillery.
Recoil is probably a bit more 'vicious' than for normal ordnance - but I could tell more after actually running the data. (I did RN and French first as I have much more comprehensive data, and in language that I can read fluently (or for French 'make do' in). Russian is a language I can read, but I lack the technical vocabulary for obsolescent terms, and my technical dictionaries are for WW2 technologies.

For context, the French Canon-Obusier 16cm/30Livre - which has a tighter windage, gives 1466 fps with hollow shot/shell and 1186 fps with the solid shot. (The same diameter of shot - the weights in English pounds are 22.05lbs/34.89lbs). The carrying and penetration are better for the solid shot, but initial trajectory is flatter for the shell at closer ranges.

Licorne shell is heavier (quoted as in the ratio of 40 shell/48 shot (trade pounds)), so the 'shell' velocity will be a bit lower, in addition to the lower velocity associated with a looser windage.

Interesting. Most I've read about them have not been too positive, but I'm unsure if that was biased.

On ships the Licornes were used differently to Spanish Obusier (otherwise similar) or British or French Shell guns/Canon-Obusier/Obusier, as they were usually supplied 'common bore' as replacements for a pair of guns with a weaker gun capable of firing a less safe shell.

The other nations used a *heavier* shell gun in the same situation (48Livre Obusier/36 Livre or 24 Livre guns within the main battery for Spanish, 8 Inch/32lb guns for British (1830s), or 22cm/30 Livre for French use (1830s)).
Shells were considered dangerous to the users, and were avoided until the 1820s even for guns designed to use them, until better shell handling/shell roms/enclosed percussion fuses, replacing exposed powder trains lit by firing the gun.
This made the Obusier de Vaisseau less useful than it *could* have been, and might have had some effect on Russian practice - the pieces were only supplied on mobilisation for war (which cannot have improved proficiency and safety, but their employment seems to have been very successful vs Ottoman fleets).