HMS Unicorn by ianmajor - Corel - Scale 1:75, 1748 to 1771

[mtaylor]

Ian,

 

Could it be that the tiller and sweep are below the deck and what is above the deck (rudder post) is for the emergency tiller?   I've seen this in numerous builds of English ships and it seems to be common.

[ianmajor]

Mark,

 

Thank you for your input. Following our PM exchange I am happy that the tiller of the Unicorn was on the quarter deck but with regards to the sweep the jury is still out. I have a bit of time to think about that because........

 

....... what should be last session of destruction begins!

 

Starting with the port side, I removed the cap and brass gun port lineings using Isopropyl to soften the glue. The cap was severed just ahead of the galery top casting. The bulwark was then reduced in height by 2mm.

 

Before refitting the cap I decided to reinforce the bulwarks to stop them splaying out. Using the threaded rod to pull it in to line I drilled 1mm holes down at the points indicated by the red arrows in the next photo. I selected these locations since the bulkhead extensions that support the quarter deck are at these positions and the holes go down in to them. (The green arrow shows a similar bulkhead extension in the waist area).

 

I then drove 1mm rod into each of the holes. I also forced some PWA glue in the crack twixt the bulkhead and deck then tightened up the nuts on the threaded rod a little further.

 

After a few hours I released the clamps and the bulwark stayed put. It is now nice and rigid. Hurrah!

 

 

I didn't want to reuse the brass gun port rings so I turned some replacements up in boxwood and stained them black.

 

I then fitted these and re-used the old cap pieces that just needed to be shortened slightly.

 

The next photo shows this done. It also shows a slight dip in the cap ahead of gun port 4. When removing this part of the cap the wood immediately below it splintered a little. I thought I could get away with tidying it up - not quite. I fear I will have to live with this. I only noticed the drop after the glue had hardened. To take it back off might make things even worse.

 

 

I will treat the starboard side in the same way before making the open rail.

 

In parallel I am upgrading(?) some of the cannon....

[ianmajor]

The kit comes with 32 cannon but the 1748 Unicorn only had 28.  I therefore have 4 spare. I decided to use the spares to try improving on the Corel offering for the quarter deck.

 

My inspiration was.....

 

Chuck's instructions for the cannon kit, which includes diagrams which are in the Article and Download area <here>

 

Roman Kraska's "Alert 1777" log in the CAD and 3D Modelling forum. It contains some excellent diagrams in pdf files, included exploded diagrams which show how the carriages are assembled. <here>

 

An interesting video by Modeler12 on scratch building carriages <here>   (Yet another of his great videos!)

 

I drew some rough working plans for parts to be made....

 

 

The next photo shows a pair of the Corel cannon before work began.

 

The outline of the carriage brackets is pretty good but is spoiled by the thick base.

 

For ease of manufacture the Corel carriages have the brackets parallel rather than convergent.

 

The slots for the trunnions are very deep which along with the trunnions being set on the mid line of the barrel means the barrels sit very low. This gives a very squat appearance.

 

My kit is one of the first produced back in 1974 and some of the barrels were distinctly cross eyed.

 

​

[ianmajor]

Starting with the carriage.....

 

Using a piercing saw I cut the two brackets off by cutting vertically through the thick base. The two brackets were then sanded down to 1.5mm thickness to make both sides smooth.

 

The next photo shows the result. The piece of 1.0mm walnut in the background is the only other wood used in this rebuild.

 

 

The axtrees were cut from 1.0 x 1.5mm walnut, the fore 15mm long and the hind 16mm long.

 

The slots on the underside of the brackets were slightly widened  so that the axtrees were a snug fit with their wide faces horizontal. 

 

The transom was cut from the walnut 5.0mm high by 5.5mm wide. The bottom edge was bevelled and the top edge has a curved cutout to clear the underside of the barrel. This piece was glued on to the middle of the fore axtree flush at the leading edge.

 

The bolster was a piece of 1.0 x 1.5mm walnut 6.5mm long. This was glued to the middle of the hind axtree at the leading edge making an "L" cross section.

 

The brackets were drilled to produce 0.5mm holes (see Chuck's diagram for layout). The front of the stool is supported on 0.5mm rod. The holes for this need to be such that the upper edge of the rod is the same height as the bolster when fitted so that the stool is horizontal.

 

The Corel trucks I sanded down to 1.5mm thick to make them less road roller like. Two of them I mounted in a Black and Decker mini drill arbour, then spinning them in a power drill I reduced their diameter to 4.5mm using a small flat file.

 

 

The two brackets were glued on to the axtrees, by pushing the axtrees in to the slots then squeezing the brackets on to the transom and bolster to get the correct width, making sure the two brackets were at the same angle.

 

The trunnion slots were partially filled with small offcuts of walnut and rounded so that the centre line of the trunnions were at the same level as the top of the brackets.

 

 

I then blackened and fitted the loops, simulated bolt heads and support bar for stool. The loops were made as per the earlier cannon.

 

 

The stool was made from a 10mm length of 1.0mm walnut 7.5mm wide. This was sanded to a taper so that the leading edge was reduced to 7.0mm wide. A quoin was made from a short length of 2.0x2.0mm walnut. The end was drilled to take a short length of bamboo for a handle. The quoin was tapered to a wedge shape.

 

The stool was glued in place but the quoin was not fixed until the barrel was ready for fitting.

 

 

The ends of the axtrees were carefully carved round so that the trucks fitted on and glued in place. Short lengths of wood splinters were glued above and below each axtree end to represent pegs holding the trucks on.

 

The next photo shows the completed carriage next to an unmodified one.

 

​

[ianmajor]

I turned to the barrel.

 

I wanted to move the hole for the trunnion to one side of the barrel centre line. This as per Chuck's diagrams - though Hahn shows  them on the centre line. Images of cannon show trunnions in both configurations. I don't know what the rule was!

 

To move this hole is fairly simple and can be done with simple hand tools. First I got a piece of brass rod that was a close fit. I then filed a flat on the side of the rod. The deeper the flat the closer the centre of the new hole will be to the centre of the original hole. In my case I took 0.4mm off to make the flat. I used a small ammount of superglue to secure a length of this rod in the hole. I pointed the flat in the direction that I wanted the hole to go ie in this case to the side of the cannon.

 

This produced a "D" shaped hole as shown in the next photo highlighted by the red arrow.

 

 

Having taken 0.4mm off the rod a 0.4mm drill bit passed through the centre of the "D". I put a 0.5mm drill bit in a pin vice and very carefully drilled part way in to the "D" and then all the we through from the other side. The "D" guided the bit all the way.

 

I ran steadily bigger bits through the hole which produced the new hole centred on the "D". I was using 1.3mm brass rod for the trunnion. So I took the hole up to 1.2mm then openned the hole with broaches until the trunnion was a snug fit.

 

The next photo shows the old hole plugged and the trunnion pin temporarily fitted in to the new hole.

 

 

It this point I silver soldered the trunnion in place. Also, since the bore was off centre, I pushed a length of brass rod in to the bore and silver soldered it at the same time.

 

The bore rod was cut off flush than filed and sanded flat and smooth. I then redrilled it with the drill press.

 

 

The barrel was then fitted to the carriage using caps that I prepared for the earlier cannon.

 

The next photos show the modified cannon next to an original. Hard to believe they are basically the same beast!

 

 

[ianmajor]

I was wondering what size of cannon the Corel offering is at 1:75. The Unicorn had 9 pounders on the upper deck and 3 pounders on the quarter deck.

 

Hahn's cannon diagram contains formulae and tables that allow the dimensional calculations for scales 1:48, 1:64 and 1:96 for weights 4, 6, 9, 12, 18, 24, 32 and 42 pounders. Not initially helpful for 3 pounders or scales 1:75!

 

All of the calculations in Hahn are based on the caliber. With his weight/caliber table, and assuming a spherical projectile I could work out the density of the cast iron. In all cases of his table the density is 0.2686 lbs/cu inch.

 

So knowing the density I can now work out the caliber for a specific weight. I created an Exel spreadsheet using this which enables me to generate all the "Hahn" dimensions for any weight and any scale.

 

One other thing required was the "barrel length to caliber" ratio.    

 

Chuck's diagrams of Armstrong long barrels gave me a ratio of 1:21. An entry in Modeler12's thread gave me a ratio of 1:15 for short barrels. I am sure there is more info on this somewhere!

 

So I tried out the spreadsheet using scale 1:75, 9 pounder, long barrel. I got:

 

Length of bracket - Hahn  17mm - Corel 19mm
Height of bracket - Hahn 6.3mm - Corel 7.5mm
Barrel length - Hahn 31.5mm - Corel 30mm

 

A reasonable match for the barrel but the Corel carriage is a little large. The carriage would be the right size for a 1:64 9 pounder though!

 

I looked at the dimensions for a 1:75, 3 pounder long barrel and got:

 

Length of bracket - 11.8mm
Height of bracket - 4.4mm
Barrel length - 21.8mm

 

Which got me thinking about mocking up a 3 pounder in card and wood. Will the barrel be too low for the quarter deck gun ports? Lets see. What I currently have is......

 

 

Hum.........

 

 

 

[Piet]

Great work and safe on the bulwarks Ian and not to worry about the cap, it isn't noticeable from Palm Coast, Florida    Fantastic work and research on the cannons.  Tip to the heat my friend, very impressive work.

 

Cheers,

[Martin W]

Very impressive work, Ian.  You've transformed some mediocre kit-supplied guns to some high-quality guns.  You did a great job of maintaining, and even improving the overall dimensions.  Great research, great craftsmanship.

 

Cheers,

 

Martin

[ianmajor]

Piet and Martin, thanks for your kind words, and thanks for the likes.

 

I have stripped the cap off the starboard side using Isopropyl. As a break from this nerve wracking activity and whilst the Iso dried up completely I roughed up a 3lb cannon out of wood for the barrel and card for the carriage. I used the spreadsheet with input of 3lb weight and long barrel. The information generated from the Hahn formulae was:-

 

3 pounder cannon:

 

 

I blackened the barrel with wood stain for (gratuitous) effect!     The exercise showed two things.

 

First - that the barrel was rather long. All the illustrations of very small cannon that I have seen have rather short dumpy barrels. Probably this would have been resolved by using the short barrel 1:15 ratio.

 

Second - as can be seen in the photos below the poor little thing can't "see" over the bottom edge of the circular gun port. When viewed from outside of the hull the round ports appear to be the correct height above the upper deck gun ports. If the quarter deck had been higher (as per the NMM Lyme and  Chapman Unicorn plans) the smaller cannon would be OK. As it is it looks like a will have to stick with the modified "9 pounder" Corel version. 

 

  

 

 

An entertaining little diversion! When seeing how small the 3 pounder is I am not surprised that they were not regarded as part of the main armoury when Unicorn was built.

 

I have also attached my spreadsheet calculations for a 9 pounder long.

 

 

So - back to the caps and new rail.

 

    ​

     ​

 

  

[BANYAN]

Hi Ian, now that I am retired I have more time to read more logs and came across your very interesting and very nice build of Unicorn.  Some great research and discussion here, and I look forward to taking the time to read through thoroughly in the near future.

 

cheers

 

Pat

[Landlubber Mike]

Really looks great Ian. The cannons and quarterdeck are much improved! You're a brave man tackling the quarterdeck like that.

 

I never had much confidence in the kit bulkheads. In fact, on my Unicorn, I must have leaned the model against something and now one of the bulkheads is warped. I have a similar splaying issue on my Pegasus because the redheart I used to replace the bulkhead extensions is weak - lot of flex to if and they broke in a few places. The upper hull planking seems to be fixing things but it's a pain because I need to clamp the opposite sides of the bulwarks with the quarterdeck support frames in place to keep the proper shape. I wonder if I might need to install similar posts as you did.

[ianmajor]

Pat, thank you for your encouraging words. They are greatly appreciated from someone whose skills and knowledge I greatly respect. Your Endeavour is on my "follow" flag list. I fear if you go through my log in full you will only see the bodger's view on life!

 

Mike, the brass rod made a huge difference. I thought 1.0mm diameter rod would just flex around but the result is very strong - like steel reinforcement in concrete I guess. I could have done without the concern that the drill bit would emerge in an embarrassing place - better to do it during initial build!

 

Following our PM discussion where I felt the Corel canon was a 12 pounder (based on Chuck's diagram), I played with my "Hahn" spread sheet - yep, the carriage is spot on for a 12 pounder at 1:75 but the barrel is a little short. Seems like our Unicorn/Lyme has much bigger teeth than the prototype.     Be afraid - be very afraid...........of our little boats!

 

 

 

​     

[ianmajor]

......actually Mike, brave is not the right word. Insane might be a better adjective. My wife was watching me a few days ago and said "Would it not be better to start again?". What answer can be given to a woman's logic that can explain a man's folly? 

 

 ​   

Edited February 3, 2016 by ianmajor

[mtaylor]

Ian,

 

I can't speak the English, but the French would use a taller carriage for the "light" guns of 3-4 pounds.  The only reason I can come up with was ergonomics -- didn't want the gunners on their knees while serving them. The added benefit is that if the guns were upgraded, new ports would not have to be cut.

[ianmajor]

Mark,

 

Interesting point you make. It did seem strange to me that Hahn's formula give a simple linear relationship between caliber and all of the carriage dimensions. As you say the gunners would have to be on their hands an knees with my 3 pounder. It also has me wondering about the form of tackle on the much smaller cannon. I found this photo on line <link> which seems to fit your description.

 

The round ports on Lyme and Unicorn seem to be very restrictive. An interesting comparison is with the 1764 Winchelsea  ( <link> to NMM model and <link> to NMM held plans) where the quarter deck gun ports are square open frames with a low sill at deck level (presumably to stop the gun and crew going over the side!).

 

If the quarter deck on my model had been at the correct height the circular gun ports would be much closer to the deck allowing the use of smaller guns. I think I will have to go with the bigger guns as supplied.  

[mtaylor]

Ian,

 

That picture is dead on.  Looking at the breeching rings on the side, I'd say it's not French.   And then I read the link....  yep.. not French so it should work for you.  The same form and numbers of tackles would apply even though they were small by comparison to the main armament, they were still heavy.  Just smaller lines.   I believe the general rule of thumb is that the breeching ropes are same diameter as the bore.

 

When in doubt, go with what you think is right or works.  

[ianmajor]

 Mark,

 

Thanks for the information. That was an interesting discussion we had.

 

I have had a few distractions from my modelling recently one of which may be of interest to modellers of older sailing ships.

 

I visited Dunham Massey house with my wife. It is a large house and grounds which is a few miles south of Manchester (UK) which owned by the National Trust (of which we are members). My wife found the house and gardens interesting. However I had a ferret around a small dark building called the "Well House" which was the original source of water for the main house. Inside are a pair of elm tree pumps of a similar design to those used on ships which would have been used to lift water from the well.

 

Below is a photo that I took of them. It is a view up the elm wood pipes towards the roof of the building. The right hand pump still has its handle which is visible in the photo. I could not see a handle on the other. There appear to be slots in the sides near the top from which the water would have emerged in to a header tank for the house.

 

 

[ianmajor]

I have finished the fixed caps on both sides of the quarter deck and am preparing the open rails. Some of the main supports are the swivel gun posts so I started with these.

 

For barrels I used Caldercraft 1:64 scale 0.5 pounders. At 14mm long they are about 2mm too long but I thought they would be OK.

 

They are nicely turned but where they had been parted were a little rough so some tidying with a fine file was needed.

 

At the rear of the barrel is a hole. To represent the handle I used 0.7mm nickle silver wire. For the knob on the end I cut 0.5mm lengths of 1.25mm brass tube which I threaded on to the wire and fixed with a blob of silver solder. A little tidying with the file produced the final ball shape. The wire was trimmed so that when fitted it protruded by 8mm from the rear of the barrel. The trunnions were more 0.7mm wire. All these items were silver soldered together, the handle shaped and blackened.

 

 

To make the "U" shaped supports I produced a filing jig similar to the one I used to make the chain links for the pump <here>    . In this case I produced one "link" per gun with holes 6mm appart. I silver soldered a length of 0.7mm nickle silver wire to the middle of these then curved the links in to a "U" shape. These were blackened and fitted to the barrels.

 

The trunnions on the barrels had been left slightly long so with the supports in place I filed them to length. This produces small burrs which lock the supports in place.

 

 

The following photo shows the first barrel mounted on a temporary piece of wood. Some of the blacking had not taken very well so I cleaned it up and repeated the process to better effect.

 

 

To get the construction of the post and cap right I produced a rough diagram:

 

 

I am using 3 x 3 mm beech for the posts which will be shaped in to a "squared D section". The caps will be brass with the same cross section. The caps will have a circular hole in the centre to fit on the end of the post.

 

The caps were made from 6mm diameter brass rod. I first mounted it in the lathe and drilled the centre 2.5mm. This was then moved to the dividing head on the mill to machine it to the "D" shape. The faces were at 0, 45, 90, 135, 180 and 270 degrees.

 

This was returned to the lathe and each cap was turned off 2mm long.

 

Each cap was then soft soldered on to a sheet of 0.3mm nickle silver to close the top of the cap. A 0.7mm hole was then drilled in the middle of this to take the cannon. The cap was blackened.

 

The cannon was then fitted to the cap and retained in place by glueing a short length of 1.25mm tube as a collar on the end of the support rod avoiding gluing it to the cap.

 

The top of the beech post was drilled 1.3mm to clear this collar.

 

 

The cannon and cap were temporarily fitted to the top of the post. When permenantly fixed it will swing from side to side and up and down - no doubt someone will try it in future!

 

 

 

Now to finish off the other 11 swivels.

 

[NenadM]

Whoa !!!! So small ... And just wonderfull!!!

[mtaylor]

Super nice work on some very fiddly parts, Ian. 

[Piet]

Nice job done on the metal work Ian, looks really good.

 

Cheers,

[Blue Ensign]

Great work on the swivels Ian

 

B.E.

[BANYAN]

Nice work Ian.  I am doing these at the moment also (well finish when I get back from holiday ) and your method for the ball/knob on the end of the aiming arm will help me greatly - thanks for sharing.

 

cheers

 

Pat

[ianmajor]

Nenad, Mark, Piet, BE and Pat thanks for the kind words and all the likes.

 

I have been out and about recently. One journey took me to Preston (UK). The docks there have mainly lost their original industrial purpose and have now been redeveloped as a leisure marina. We usually go to the Marina Cafe/Chandler's. In there we are surrounded by boating goodies whilst having a pot of tea. Hanging from the ceiling is a model of a ship that is 7ft long......

 

 

It was given to the Cafe by the builder's daughter. According to an attached plate it is called the Elizabeth after that same daughter rather than an actual ship. It is supposed to be based on "Nelson's Victory" but the rigging suggests an earlier ship. It is very well made but has a few oddities such as the channels are too low down. Worth a look at if you are in the area.

 ​

[ianmajor]

I am making steady (slow you may say) progress on the open rails. I have fitted the 8 swivel posts around the quarter deck.

 

 

For the rail I had bought some 5x2mm beech strip which would make it the same width as the cap. Looking at BE's <Pegasus>  and Dan Vadas' <Vulture>  I realised the rail should actually be narrower. So I ripped it down to 3x2mm.

 

Since the gap twixt cap and rail would not be as wide as Pegasus/Vulture I looked at other models for inspiration on supports and for the shape of the ends. The nearest was a contemporary model of a 24 gun sloop at the NMM which I am working towards. Below is an extract from a MNN photo the full version can be seen <here> .

 

 

I cut mortices in the rail to accommodate the swivel posts and had a trial fitting. To spport the rail at the rear I have fitted a length of 2x2mm beech stained black on top of the cap.

 

 

Looking at the rear of the rail in the photo I think I could attempt a tafferail which would have to sit on top of the quarter rails. If I go this route it will make it easier to mount a stern lantern.

 

The question then comes up about the shape of the leading end of the rail.

 

I have been following thibaultron's log on "going From a 2D Drawing to a 3D Printed Part Tutorial" <here> which inspired me to have a crack at using Sketchup to look at the rail options.

 

After a couple of evenings playing around I came up with the following two 3D plans. The first is in the style of the 1740 24 gun sloop, the second is in the style of a reduced version of the Pegasus/Vulture rail.

 

I think I am biased towards the first one. Any views on this? My Sketchup rendition is a bit ropey but not too bad for a first effort.

 

 

My wife watching me using Sketchup for the first time reminded me that I had sworn to turn my back on technology during retirement. As a result she says my epitaph will include the phrase "A Failed Luddite". I gave me such a severe attack of the giggles that any further work that evening was abandoned.

Edited March 19, 2016 by ianmajor

[Landlubber Mike]

Looking really great Ian.  You're pretty handy for a Luddite  For what it's worth, I like the first rail also.  Either is nice, but it might be worth seeing if that rail would give enough protection for folks on the quarterdeck?

 

Those portholes are interesting, particularly where they bulk of them extends above the bulwarks.  I'm wondering why they were like that?  Functionally they don't seem to have much value, but maybe it was for aesthetics?

[BANYAN]

Very nice work/progress Ian.  Add ne to option 1 also for the rail - looks more natural.

 

cheers

 

Pat

[S.Coleman]

The first sketch IMO. Looks to me like it would be more sturdy.

[ianmajor]

Mike, Pat and S,

 

Thanks for your input. You have helped me to decide on option 1. For the front curved part of the rail I have turned a ring of boxwood 8mm outside and 4mm inside diameter which is 3mm wide. This will be cut in to quarters to make the curve.

 

Mike, the rail stands just over a scale 6ft above the quarter deck so would give adequate protection. It looks low because the Corel quarter deck is too low IMHO. I have pondered the gun port rings before and agree that they don't seem to add anything structurally. Many of the ships prior to the mid 18th century seemed to have had circular decoration around the gun ports even where the ports were square. I was wondering whether the rings on Unicorn/Lyme were primarily to support such decoration. None of the plans give any clues on this.

[Landlubber Mike]

Hi Ian, I agree on the circular port rings.  Pretty odd, but unique looking I suppose.

 

On the rail for the quarterdeck, in the first option, does the rail extend to the fore end of the quarterdeck or nearabouts?  If it came up short, I wonder if it would have been a safety hazard.  Otherwise, aesthetically, I still say option 1 looks better.