The Ship Model Forum

Superbe.

Thanks for those 'work in progress'-drawings. It shows how much detail work actually goes into them.

That is the curse of relatively long-lived ships, that they had refits or even rebuilds, resulting in multiple drawings.

Fascinating, and beautiful, work.

Pascal,

Nice work!

I doubt the "conical" pieces around the shaft in front of the struts are galvanic "sacrificial" electrodes. These fairings are there to streamline water flow around the struts. But they are a complex shape that would be somewhat difficult to reproduce and replace.

Most sacrificial electrodes ("zincs") were just simple bars attached to the hull. They were easy to make and replace. Any shipyard could cast them and divers could replace them while the ship was afloat. The fairings could be replaced only in drydock, and they would require a much more sophisticated manufacturing process.

****

I found the struts shown in the plans and in your model interesting. When I was creating these for the Cleveland class cruiser USS Oklahoma City CL91/CLG-5 the blueprints used for manufacturing them showed the cross section "airfoil" shaped as in the Bretagne, but the plane of the strut was rotated/twisted slightly along the strut axis from the hull to the strut hub. The twist was to match the different directions of water flow close to the hull surface and out to the hub. Considering that these were designed before computers and CAD it is pretty amazing that they added this detail just to get a slight improvement in water flow and minor reduction in drag.

The manufacturing instructions in the blueprints were entertaining. The entire strut assembly (hub and two legs) was cast in one huge piece, oversized by one half inch (about a centimeter) for final finishing. Then they were attached to the hull and the bearing seats were bored in line with the shaft axis. I would love to be able to go back in time and see the machines they used to bore these things in place on the hull!

Phil

Thanks all, and Phil for the informations.

The 4 propeller shaft lines are almost complete.

Design of the propellers.

Their diameter is 3 meters, designed for speed. The propeller pitch is 2m54.

Although the Bretagne is not very powerful compared to what will be done later, 43000 hp, 21.5 knots. A French destroyer of the 50's is powered by 63000 hp, max speed 32 knots.

Luckily, I have quite complete plans for once (thanks Chris). Among other things, the plan of the blades (called wing on the plan), the sections at different heights, it's really easier to realize with this information.

You can also see on the plan, how the central nut is braked after tightening and how its flats are protected by a sleeve which comes to fit from above, closing the hub cone. The 3 screws that can be seen around are used to fix it.

Nice work!

The small screw on the cone of the nut is probably used to fill it with hot liquid tallow that will freeze in the cone later on, thus protecting the thread from corrosion and water ingress. It's just an hypothesis on my part, but it seems to me that it reads "filling with tallow" on the plan, technically, it makes sense.

I could use this propeller for other ships by transforming it into 3 or 4 blades depending on the model

To make a left or right hand propeller, one click is enough.

Pascal,

Very nice work on the propellers! The proportional pitch, varying blade width and the curvature where the blade joins the hub were real challenges for me.

Again I see some interesting comparisons for the Cleveland class cruiser propellers of half a century later. The outboard propeller blades were a bit wider (perpendicular to the blade axis) than the inboard props, but they were all the same diameter. This was another small change to increase blade surface area to compensate for the lower water density at the outboard props than it was inboard close to the hull. This would give the same thrust for all propellers at the same RPM. They did all these calculations before computers and CAD!

Like the struts they were cast in single pieces with an extra half inch (1 cm) of metal to be removed during finishing. They were all balanced for several hundred RPM (350 RPM was about 32 knots on the cruisers).

I could never figure out how to make scale propellers at 1:96 by machining or casting. The blades were just too thin. But they came out perfect with 3D printing.

Phil

I did not know this particularity, interesting Phil.

I'm going to redraw the rudder as I have the exact plan, I had drawn a head one which is not very accurate except for the profile which is.

Propellers in place:

New rudder design following the plan, it gave me a bit of trouble, quite complicated shapes:

All the layers of the cutting plan laid on their respective plan.

The rudder is 7 meter long.





On the right is the old rudder, much simpler.











Thanks to Chris' plan, I was able to start drawing the famous Moissenet stopper.

To my knowledge, there is no photo of this device.

So we will discover little by little what it looks like in "virtuality" thanks to the magic of 3D, then in reality, once printed. �:)

This morning I also studied the functioning of this stopper to better read the plan (which is not so simple) and to understand the drawing in good conditions. �

I'll talk about how it works with a little animation at the end of the drawing.

Battleship Libert�.

chris wrote:

..

Indeed, such anchor chain compressor tend to be fairly complicated items, owing to the need to deal with the complex shape of the chains ...

This device is only used for cables, aft.

OK, that explains, why I didn't see 'sprocket'-like provisions to lock the chain. You want to compress the cable without squashing it - much like what cable-cars do.

Exactly.

Too sad, no direct access to this slide show.

https://imagesdefense.gouv.fr/fr/le-sto ... senet.html#

"This device is used when towing a large tonnage vessel and allows the operation to be made safer by braking or stopping the tow-roap, so that the personnel can control the speed at which the tow-roap is pulled.

After these generalities, the slide show moves on to the description of the stopper: its general diagram and its frame for attachment to the deck.

The next part is devoted to the operation of the stopper, the hawser spinning is explained by diagrams.

The last part is devoted to the use of the stopper, diagrams and commented photographs explain how to prepare and carry out a tow with the stopper.
Presented by the Navy's military schools.
Prepared by the Manoeuvre School."

The drawing of the stopper continued today a bit.

The top gears and screws are in right-hand pitch on both sides, I'll rectify that later. �:)

I didn't make much progress today, I wasn't at home.

Still trying to figure out, how the thing actually works ... the two diagonally knurled wheels are strange, do they grab the cable?

You can see how it works here:

The two shoes move apart thanks to the screw at the bottom (one step to the left and one to the right), the lower yellow friction pad which is placed on top of it rubs more or less on the cable, braking it with the help of the upper wedge. This screw is driven by the bevel gear return, the chain and the large flywheel.

The upper wedge with the two handles is also adjustable with the other handwheel, it can be slid into the device, so that the wear due to friction can be compensated. Spare parts are available for the top corner and its opposite wedge.

I don't know what the material is, maybe a Ferodo type material.

Ferodo is a British automotive supplier based in Chapel-en-le-Frith in the non-metropolitan district of High Peak, Derbyshire. The group specialises in the manufacture of braking products for both consumer and competition use1.

History
In 1897, Ferodo began manufacturing brakes for carts.

In 1902, Ferodo introduces the first brake lining: an innovative and revolutionary step in the world of braking

In 1922, Ferodo became the first company to supply original linings for production cars, equipping the Austin 7.

Ferodo became the first company to stop using asbestos in brake linings by 1980

There's still a lot of stuff missing, the design is far from finished.

Small progress:

The cable brake still needs to be designed.

We can see the spare corners and counter corners on the intended platform.

It's coming to an end, I'll be able to continue the ship. There are still a few things to rectify and draw.on the brake.

A new and different rendering, the Fusion360 app on IPad, this app only allows visualization and measurements.