HMS Bellona 1760 by SJSoane - Scale 1:64 - English 74-gun - as designed

[mtaylor]

Well-researched, Mark and a beautiful drawing.  As for the carriages, I would suspect that they changed them with time as shortcomings cropped up.

[druxey]

I would not be too concerned with minor variations in gun proportions. As there was shrinkage when casting, I doubt if the same caliber gun from different foundries would be identical. Even the weights of the individual cannon in a battery varied.

 

The carriages definitely would be made to a height where the bore would be centred in the port: you are on safe ground!

[Siggi52]

The plans are looking great, I'm waiting for the first ready cannon. They must look even greater!

 

Don't worry about measurements, they had large tolerances in those times. For an example, the look plate of the Brown Bess musket had a quarter inch tolerance in length. Not two muskets where identical, because it was all made by hand. 

 

Regards,

Siggi

[SJSoane]

 

Thanks, Mark, druxey and Siggi. It is always nice to get some affirmation on those many moments when you have to make educated guesses on  historical information.

 

I forgot to mention that the Muller book was exceptionally interesting as a glimpse into the early dawn of the industrial age in Great Britain in the mid 18th century. He dutifully reports on the proper, historically received proportions for guns. But he then complains about how arbitrary these are,  not based in reason or fact. Some examples:

 

After explaining that the proportions given apply to all sizes of cannon, he says "The reader may easily perceive the perplexity of these constructions, arising from the different scale that are used with the least necessity. That the greatest part of the mouldings should have the same dimensions, from a 3 pounder to one of 32, appear contrary to reason..." He then complains that experiments on a 24 pounder for weight of powder and distance and trajectory, were then extrapolated to other sizes of guns without then testing these.

 

He also complained about the location of the trunnions so that the top of the trunnion is located at the center of the cannon. He said "...it is so absurd, that is is amazing no author or artist has thought proper to change it...to show the absurdity of it, suppose AB to present the center line of the bore, and CD the distance of the center line of the trunnions from that of the bore. Now because when the piece is fired, the explosion acts against the breech B, and makes the piece recoil, but being fixed to the carriage by the trunnions, endeavours to turn about the point D....the piece therefore acquires a pendulous motion about the center D."

 

And he complains about the tradition of breaking the cannon into three different diameter cone shapes (first and second reinforce, chace), because powder does not explode in stages but rather continuously, suggesting a design for a cannon with no breaks in its profile.

 

I think we see here the first signs of challenging traditions handed down for their own sake, and proposing a more scientific view of designing ordnance. Of course, this kind of thinking eventually leads to artifacts more functional than beautiful. Or, perhaps we eventually find a different kind of beauty in more functional objects. But then I wonder why so many of us are drawn to the beauty of these pre-Industrial Revolution artifacts?

 

I love how history provides endless opportunities to ponder the great imponderables!

 

Mark

[Siggi52]

To the location of the trunnions I have a question. Did he say in witch direction the pendulous motion goes? If it goes down, as I would say, then it would be ok. That would press the cannon and carriage down at the deck and the cannon would not jump. 

 

A good example as it should not be, you could see here: http://vimeo.com/109787499 I wouldn't stay near that cannon.

 

Yes, the powder would burn down continuously, but the most pressure is at the start, to get the cannon ball moving. When the bullet moves, the pressure releases the faster the ball moves and the walls of the cannons could be thinner. 

 

For example, the Brown Bess has at the breech a diameter of  ~ 34 mm and at the muzzle only ~ 22 mm, the wall is here only 1,5 mm thick.

 

Regards,

Siggi

[druxey]

I agree with Siggi that, as the gases expand, pressure will diminish as the charge moves along the bore.

 

The number of small wood splinters flying in the video Siggi refers to is also terrifying!

[SJSoane]

 

Hi Siggi,

 

Here is the diagram from Muller's Treatise on Artillery, from Google books online. It would cause it the gun and carriage to jump up, since the line of force is along AB, and it is resisted at D. Someone more knowledgable than I am would need to say if this would make any difference at all.

 

Best wishes,

 

Mark

[SJSoane]

 

Hi Siggi and druxey,

 

Here is the passage regarding the three sections to a barrel:

 

"It is a universal custom in Europe to make the guns with reinforces; that is, they are, as it were, made of three frustrums of cones joined together, so as the least base of the former is always greater than the greatest of the succeeding one, whereby the metal breaks off in two places on a sudden, a the reader has seen in the construction of pieces given here before. But since powder acts uniformly and not by starts, it is hard to judge from whence this ridiculous custom has arisen, which seems to be as old as the invention of guns....Since then powder acts gradually and not by starts, there should be no breaking off in the metal..the piece should be cylindric, from the base ring to the end of the charge, and from thence, by the nature of the explosion, a curve line bending inwards quite to the mouth of the piece..." pp 38-9.

 

He is describing the guns as they came to be in the early to mid 19th century, where the outer barrel is a smooth curved surface not broken by these old mouldings. And he was writing maybe 75 years before this became common practice.

 

Best wishes,

 

Mark

[mtaylor]

He was ahead of his time and then there was the reluctance of the various Boards to change things.  That reluctance of "if it works, don't change it" and "that's the way we've always done it" seems to be a big factor. 

[SJSoane]

HI everyone,

 

I forgot to mention that my gun drafting came as part of re-drafting the Bellona in CAD. Here are a couple of screen shots of progress so far....

 

Best wishes,

 

Mark

[Alex M]

That is a very fine drawings, Mark! A warm welcome and have fun :D :D

the buts of two plank rows of main wale aft of main mast - shift the lower one further aft...

 

Alex

[SJSoane]

 

Thanks, Alex, the shift of the planks, while avoiding gunports, has been challenging for me!

 

Best wishes,

 

Mark

[AnobiumPunctatum]

Really nice drafting skills. I like to see more of your drawings.

[SJSoane]

 

Thanks, Christian, I'll post a few more drawings when I have a little more to show. I am drafting in CAD right now to clarify some issues coming up in the build, so they are not yet in a finished form. But someday I may develop a full set of the drawings, just because it would be fun to do!

 

 

Alex, I read your comment again, and realized that you were talking about the unusual planking butt in the main wale. I was just at a workshop with David Antscherl, and he noticed the same thing when I showed him the drawings.

 

It turns out that I faithfully copied the planking arrangement for the main wale from a NMM photo I have of the original 1760 Bellona model (the one I show photographs of earlier in my build log).

 

It does seem odd, and not the strongest way of planking this wale. Since this particular model shows two different ways of framing, port and starboard, perhaps this was also a way of showing a proposed change to wale planking?

 

I decided when I started this project that I would be as faithful as I could to the original 1760 model, and so I decided to include this distinctive detail. As it turns out, I have discovered a number of discrepancies between this model and the drawings done at the same time. A very complex history! I have not been able to look closely at the 1780s model of the Bellona, to see if the main wale in that model has this same pattern.

 

Best wishes,

 

Mark

[Alex M]

Hi Mark,

 

I know what you mean, it looks really odd and unusual. But doing this to show two ways of planking the wale, is probably an idea, if also a little odd

 

Alex

Edited December 29, 2014 by Alex M

[Siggi52]

Hi Mark,

 

James Doods & James Moore say in there book „Building the Wooden Fighting Ship" about this Bellona model:  this model is particularly interesting because it shows that an innovation in the way the main wales were planked had been introduced by 1760. This method, known as anchor-stock waling....

And there I think they mixed up some things. According to Goodwin the anchor stock planking has even sides. The top and butt planking has uneven sides, but no hocks. Somewhere I read that this is named butt and hock, but I could't find it again.

 

The 1780 Bellona model has a straight conventionally waling and for the Superbe they made only one thick plank as wale! I used the top and butt.

 

Regards,

Siggi

[michael mott]

Very nice drawings Mark.

 

 

A good example as it should not be, you could see here: http://vimeo.com/109787499 I wouldn't stay near that cannon.

Watching that slow motion of the inside of the side of the test panel of the ships side, it is a wonder that anyone would venture below decks during a sea battle. what a dangerous place to be.

 

michael

[SJSoane]

 

Hi everyone,

 

Well, after a number of rejects, I finally made a master 32 pound cannon for casting. A few details. First, I decided to use the Sherline angle cutting device for the angled cuts, since the angle to the hind of the second reinforce is different from the angle ahead of the reinforce. I used some very handy angle gauges to set the device to the 1 degree and then 1 1/2 degree parts. This was infinitely easier than calculating the tangents of the angles,  and then trial and error setting the angles. The second photo shows setup using the 1 and 1/2 degree gauges.

 

I have a digital readout on my lathe, but this does not work on the angle device. So I had to count turns for distances. To facilitate this, I adapted an old Sherline hand wheel that can reset to 0, turning it down to fit the angle device. This helped enormously with incremental counts down the length of the cannon.

 

And then I drew up a recipe (fourth photo), converting actual scale lengths to numbers of full turns of the hand wheel plus numbers of increments in part of a turn. You can see this in the photo as, for example, 9T 38, which means nine full turns plus 38 increments. Each horizontal and then vertical cut is color coded the same so I could keep track of where I was.

 

Inspired by Michael Mott's machining, I used a center bit in the mill as seen in the first photo, for drilling the hole for the trunnion. This helped keep the hole accurately located while drilling into a curved surface (the trunnion is off center by half its diameter). It worked perfectly. Thanks, Michael!

 

I intend to cast these, so the muzzle mouth has a dowel on it, onto which I will attach a funnel head for making the mold.

 

At last, I can think about making molds!

 

All for now,

 

Mark

[dvm27]

Beautiful machining Mark. Those angle gauges are terrific. Just happen to have those laying around?

[druxey]

Very nice work on the lathe, Mark. I think I'll use a centre bit the next time I try to drill an off-axis hole. With its rigidity, this make a lot of sense.

[Siggi52]

Really great workmanship, Mark. I could't do that in this quality.

 

When I compared your plan with my cannons, I found a real big mistake I made. But only at the 32 pounders, all other cannons are ok. I made mine on a wood lathe where I normally made things 1:1, free hand and cast them then in pewter. I don't know why that happens and why I did't noticed it earlier. Now they have to do it as they are.

 

Regards,

Siggi

[gjdale]

Lovely work Mark, and very instructive too.

[EdT]

Great precision, Mark.  What do you intend to cast these in?  Have you thought about shrinkage?  With all this accurate work, you may want to research a low shrinkage alloy.  Also, if you cast these vertically in RTV you may get some swell at the bottom.- but this may not be an issue with the size of these - I assume about 2" long.  If you use pewter you may want to get an alloy that has some bismuth added to reduce shrinkage.

 

Knowing your thirst for precision.....

 

Ed

[druxey]

Lead-free pewter has very little shrinkage. I assume that it is the bismuth content that provides this characteristic.

[SJSoane]

 

Dear Greg, druxey, Siggi, Grant and Ed,

 

Thank you for the kind comments. It took me almost a week of long days to produce this one master cannon, and your support on this website kept me going at times.

 

When I first laid out my "recipe" of dimensions, I did not account for the fact that the pointed cutting bit has an angled face. Cutting up to the line on the fine moldings meant that I had already cut away half of its thickness. So If you look closely at the drawing (actual sizes on the lower half, the cutting dimensions on the upper half),  I thickened up the various moldings so that when I cut to the line, I ended up with the right size. But I only got to this through a number of failed trial and error recipes. I confess it got tedious! I did try switching cutting bits to a face perpendicular to the moulding on each side, but then I got so lost in where I was. I finally had to figure out how to use a pointed cutter for the entire length.

 

Greg, I am an admirer of your own machining skills, and I can share with you that the angle gauges did have to come into the shop only after I got very tired of setting angles by trigonometry (moving the cutter in the X dimension down a set length, then dialing in the Y direction to see if it hit the blank forming a 1 degree triangle, then adjusting and doing it again). The manual method was OK at first, but not after so many failed trial and errors. That was one of the reasons it took me so long to produce this master.

 

Siggi, I know how it feels to discover information after you have completed something that is now out of reach for repair. I have a few of those in my project that I keep thinking about. But I looked at your photos, and your cannon look great to me. Also, I discovered that there are a number of variations on this cannon pattern, so who will know!

 

Ed, I have not cast anything before, and I am going to follow the directions in David Antscherl's volume II of the Fully Framed Model. I found lead free pewter at a local jewelry supply, and will see what happens.  I also just bought some Micro Mark casting resin, to see how this turns out in comparison to the pewter. 

 

I would give a special acknowledgement to Michael Mott, whose magnificent machining precision on his skipjack engine inspired me to work a little harder at getting this as right as I could, within my own skill level.

 

Best wishes,

 

Mark

[Siggi52]

The bismuth makes the pewter harder, frost resistent and it should better cast.

 

Here a picture of my cannon foundry 

 

 

Regards,

Siggi

[SJSoane]

 

Very nice, Siggi. What are the white objects in your moulds?

 

I have been thinking about painting my gun carriages red, and your photo just convinced me. They are red in most 18th century models I have seen that have guns.

 

Best wishes,

 

Mark

[Mirabell61]

love your ship Mark,

 

its so beautiful and accurately built, a pleasure to see....

 

Nils

[Siggi52]

Mark, with that question you got me, or better my english. My translating program told me it's modeling clay, Plasticine or play dough. As children we had these things for modeling in all colors. I presst the cannons also in this material to make the under side of the form. Here I will make the upper side of the form. It's a good idea to put a stripe of paper around the wood form, then the cast silicon would't stick at the wood.

 

 

The cannons at Chatham, but I would't make the red so red, better is the english red as you could see at Prince Frederick's bark in the NMM.

 

 

 

Regards,

Siggi

Edited January 4, 2015 by Siggi52

[SJSoane]

 

Thanks, Nils, Siggi and also Ed.

 

Nils, I appreciate your comments, thanks.

 

Ed, I got an email telling me of your post, but it does not show up in my build log on my computer. Strange.... Thanks for the information about shrinkage in casting. I confess I did not even think about it when I was making the master, although I was vaguely aware of it from reading about manufacturing processes years ago. I'll see how much shrinkage will happen in 2", with lead-free pewter. I may moderate my quest for perfection, since I don't fancy right now turning another master. At 3/16" scale, a quarter or a half an inch is not really perceptible, I keep telling myself...

 

Siggi, thanks for the pictures of the barge. I admired that every time I visited the National Maritime Museum. I haven't been in years to Greenwich; is it still in the main building at Greenwich, or has it been moved to Chatham?

 

Best wishes,

 

Mark