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<span style='font-size]THE TORPEDO SYSTEM[/b]</span>
<span style='font-size] By David D Merriman III[/b]</span>
1. Completed torpedoes. The central unit is a “cutaway†used to demonstrate the internals of the gas type torpedoes I manufacture and operate. Note that the pick-up tube runs to about the middle of the weapon where it takes suction on the contained Propel gas, directing it aft and through the tiny hypodermic needle that forms the propulsion nozzle. Through experiment I found that the correct bore of the propulsion nozzle of small torpedoes (1/72 through 1/96) to be equivalent in diameter to a #95 drill bit.
2. A completed torpedo made up to a breech-mechanism that in turn is connected to a charge fitting. Note the cast resin torpedo blanks still in their mold, and torpedo body blanks below ready for machining and installation of bow cap and pick-up tube. The tool rubber is RTV silicon, 71-20, available from Baremetal Foil. An excellent tool making rubber that exhibits long life in the presence of polyurethane type casting resins.
3. Polyurethane resins used to form torpedo blanks. In this case 1/96 scale torpedo blanks. The small glass bottles are filled with part-A and part-B and are “ready service†from which I conduct mixing, the smaller bottles easier to handle than the large bulk quantities in the larger containers. A spray mold-release must be applied to the surfaces of the tools before casting – it eases release of the hardened polyurethane parts and contributes greatly to tool life. Typical tool cycle life is between thirty and eighty shots.
4. Using a hammer to lightly tape out the metal mandrel used to make the interior of the torpedo body blanks hollow. The entire torpedo structure is cast polyurethane resin. The torpedoes wall thickness is adequate to contain, safely, the pressurized charge of Propel liquid/gas. Wall thickness is driven by mandrel diameter.
5. Blanks being outfitted with resin nose caps. These are later worked on a machine lathe to the proper ‘pointed’ shape. CA adhesive is used to secure the cap pieces securely to the torpedo body. Incidentally, the dowels used to form the nose caps originated as part of the sprue networked used during the casting process to insure complete resin fill of the tool cavities.
6. Cutting the torpedo body blanks to correct shape on a precision saw. The torpedoes are cut to scale with a twenty-foot long submarine launched ‘heavyweight’ type weapon. After cutting the blanks to length, the interior of each is blown out with air, and a nose cap super-glued in place.
7. Turning the nose of each torpedo to correct contour. I use my small taig machine lather here. Initial forming of a nose is done with a cutting blade, and then I shift to hand held pieces of varying grades of sandpaper until the desired nose shape is achieved.
8. The torpedoes I produce represent modern acoustic homing ‘heavyweight’ submarine launched, twenty-one inch diameter, and weapons. Both American and Russian weapons of this class are predominantly green of color. Here I’ve painted the base green using water-soluble acrylic paint applied with a spray-brush. I find that mounting the torpedo on a length of one-sixteenth diameter brass wire through the cavity that will later accept an pick-up tube, is a great means of holding the little model torpedo as I paint and detail it. Not in this shot is a hair-dryer – I use it to accelerate the drying of the water-soluble paint so I can immediately apply a second coat to get a very deep ‘green’ color to a model torpedo. By the way, green shows up very well in the water, making recovery of ejected weapons all the more easier.
9. Mounting each torpedo on the lathe (set at minimum rpm’s) I marked out the radial breaks between torpedo sections with a black pen. Using a brush I painted on the yellow band around the warhead. Using the lathe for this task insures both precision and speed of work. Both the pen ink and yellow band dry very quickly permitting me to remove and chuck up another unit in the time it takes to undo the jaws of the chuck.
Edited By AntoineL on 1071921225
<span style='font-size] By David D Merriman III[/b]</span>
1. Completed torpedoes. The central unit is a “cutaway†used to demonstrate the internals of the gas type torpedoes I manufacture and operate. Note that the pick-up tube runs to about the middle of the weapon where it takes suction on the contained Propel gas, directing it aft and through the tiny hypodermic needle that forms the propulsion nozzle. Through experiment I found that the correct bore of the propulsion nozzle of small torpedoes (1/72 through 1/96) to be equivalent in diameter to a #95 drill bit.
2. A completed torpedo made up to a breech-mechanism that in turn is connected to a charge fitting. Note the cast resin torpedo blanks still in their mold, and torpedo body blanks below ready for machining and installation of bow cap and pick-up tube. The tool rubber is RTV silicon, 71-20, available from Baremetal Foil. An excellent tool making rubber that exhibits long life in the presence of polyurethane type casting resins.
3. Polyurethane resins used to form torpedo blanks. In this case 1/96 scale torpedo blanks. The small glass bottles are filled with part-A and part-B and are “ready service†from which I conduct mixing, the smaller bottles easier to handle than the large bulk quantities in the larger containers. A spray mold-release must be applied to the surfaces of the tools before casting – it eases release of the hardened polyurethane parts and contributes greatly to tool life. Typical tool cycle life is between thirty and eighty shots.
4. Using a hammer to lightly tape out the metal mandrel used to make the interior of the torpedo body blanks hollow. The entire torpedo structure is cast polyurethane resin. The torpedoes wall thickness is adequate to contain, safely, the pressurized charge of Propel liquid/gas. Wall thickness is driven by mandrel diameter.
5. Blanks being outfitted with resin nose caps. These are later worked on a machine lathe to the proper ‘pointed’ shape. CA adhesive is used to secure the cap pieces securely to the torpedo body. Incidentally, the dowels used to form the nose caps originated as part of the sprue networked used during the casting process to insure complete resin fill of the tool cavities.
6. Cutting the torpedo body blanks to correct shape on a precision saw. The torpedoes are cut to scale with a twenty-foot long submarine launched ‘heavyweight’ type weapon. After cutting the blanks to length, the interior of each is blown out with air, and a nose cap super-glued in place.
7. Turning the nose of each torpedo to correct contour. I use my small taig machine lather here. Initial forming of a nose is done with a cutting blade, and then I shift to hand held pieces of varying grades of sandpaper until the desired nose shape is achieved.
8. The torpedoes I produce represent modern acoustic homing ‘heavyweight’ submarine launched, twenty-one inch diameter, and weapons. Both American and Russian weapons of this class are predominantly green of color. Here I’ve painted the base green using water-soluble acrylic paint applied with a spray-brush. I find that mounting the torpedo on a length of one-sixteenth diameter brass wire through the cavity that will later accept an pick-up tube, is a great means of holding the little model torpedo as I paint and detail it. Not in this shot is a hair-dryer – I use it to accelerate the drying of the water-soluble paint so I can immediately apply a second coat to get a very deep ‘green’ color to a model torpedo. By the way, green shows up very well in the water, making recovery of ejected weapons all the more easier.
9. Mounting each torpedo on the lathe (set at minimum rpm’s) I marked out the radial breaks between torpedo sections with a black pen. Using a brush I painted on the yellow band around the warhead. Using the lathe for this task insures both precision and speed of work. Both the pen ink and yellow band dry very quickly permitting me to remove and chuck up another unit in the time it takes to undo the jaws of the chuck.
Edited By AntoineL on 1071921225
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