Trunion placement and dolphins

[CaptTHighbiter]

When did the use of Dolphins start and end and why?

When did the trunion placement move from below centerline to be on centerline of the axis of the barrel?  What was the justification for the move?

Thanks People!

[RocklockI]

Dolfins are just handles ,like the castable ring on navel guns .

I know for sure that the Swedish Navy had them in the early 1600s  I've seen them on the old iron breechloaders . Napoleans had them ...sometimes I would bet the bronze ones more than iron .

And they look like the classic "dolfins" lots of them look like handles or even wild seamonsters to me .

they even used dolfins as castabale loops and instead of a ball .

in the US I think they deevolved into utilitarian handles . Like our guns by the time the Civil War came along

guns like the Parrot and Ordnance Rifle had become streamlined guns of efficent death .

They are a study in and of themsevles ! When out resident Swedish Cannon maniac shows up the lessons will begin. I am but a humble student of the Master Dan .

Below center truions are next semester ,I think !

gary

[A.Roads]

"When did the trunion placement move from below centerline to be on centerline of the axis of the barrel?  What was the justification for the move?"
 
There is no definitive answer to this question as different countries & designers were doing different things with cannon design throughout most of the history of ML ordnance.
The issue with trunnion placement was concerned with two primary issues:
1).  When fired the gun wants to rotate around the trunnions on recoil if they are not aligned with the bore, the lower the trunnions the more significant the impact of this & the more eventual stress/damage to the carriage. Carronades had a mounting completely below the bore & were bad for this & most designs eventually ended up with trunnions (called Gunnades in the U.S.). Congreve's patterns, for example, had low trunnions & were noted for their savage jumping recoil. Eventually most designs settled for trunnion axis slightly below the bore axis and some designs (usually the later RML pieces) aligned them exactly - this even allowed the gun to be rotated 180 degrees & given a new lease of life when the top of the bore was scoured by use.
2). The other issue was the contact surface area of metal to metal (trunnion to barrel) the smallest contact area was to be had when the axis were both aligned & the lower the trunnions the greater the contact area (to a point) resulting in a lesser weak spot. This could not have been too important when trunnion shoulders came into play.
Adrian

[dominick]

I think Muller advocated for those changes to British artillery in the late 1700's.

[dan610324]

first of all I just want to say that Im not an expert at this area , just an interested guy who likes to learn a little about early bronze cannons .

but it all started with vase shaped cannons in the 1300 , no trunnions or dolphines.
below you will find a picture of the swedish loshult cannon , dated to very early 1300 and the morko cannon that is estimated to 1390 .
but the "morko cannon" is more of an hakebus then a cannon , the earliest attempt ever found in sweden to make a rifle .

later in the 1400 they changed shape and got an more cannon like look to our standards .
but still without dolphines and trunnions .
then they started to add forged iron lifting rings to cannons .

approximately early to mid 1400 they started to produce cannons with trunnions , its difficult to specify exact dates as that varied very much from place to place in the world .
cannons made of wrought iron didnt have any trunnions even if they was made much later because they didnt know how to attach them to the barrel in an easy and strong way .

usual lifting dolphines was common from early 1500 , but almost only on bronze cannons .
of course there are some cast iron cannons also with dolphines .
I dont knowwhy tho dolphines wasnt used on all cast iron cannons also , but could be because of one or both following reasons .

maybe the cast iron was to frgile and wasnt safe enough to use as a lifting point for heavy artillery .
all iron cannons was also much heavyer then similar bronze guns because of the lack of strength in cast iron compared to bronze

or maybe it was to difficult to produce them when using iron instead of bronze , I have no experiance of iron casting so I dont know, just another thought .

in the mid 1700 they started to change the production of the cannons and they was more and more becoming weapons only and not so much decorated and they lost their lifting dolphines also, but the exact time varied there also depending on where they was produced . for example the napoleon still got dolphines even if its produced almost in mid 1800 .

the placement of trunnions have never been in center or below the bore , it changed from foundry to foundry during times , but most common have been the below center trunnions to approximately 1780 when they seem to change their placement to the center of bore .

but there are samples of 1500 cannons with center placed trunnions as well as there are 1800 cannons with trunnions below centerline of bore .

so the dolphines are nothing more or less then a lifting handle to have an secured place to attach the ropes when handling heavy artillery barrels .

sorry about the low quality of the pictures but Im not at home and this is just some small picture I found on internet now for this post .