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SSN 22 submarine, RC conversion
Many years ago while still building my first RC model boats, I was thinking about how difficult to near impossible it would be for me to build a RC submarine, according to the hard times another modeler of our association was having in the subject, not to mention he is a high skilled modeler, and my limited knowledge and experience would be an additional obstacle.
Anyway I felt tempted to at least try to design an affordable, easy to build static ballast system, having in mind the possibility of installing it in a model submarine one day. Static ballast system let you make your submarine loose buoyancy and dive, or surface “blowing the tanks”, as opposite to a dynamic submarine, that relies on motor thrust and depth planes to dive and surface. Once I had a working prototype, the first tests were a success, and it was kept “top secret” until I felt confidence to start in this fascinating world of RC submarines, years later.
After building several model boats of different types (tugboats, luxury yachts, sailboats and rescue launches) I thought it had come the time to try a sub. I didn’t want to spend any time building a submarine hull from scratch, so I looked for a submarine plastic display kit to try a conversion to RC. The idea was to install a water tight hull inside the external hull. Nuclear submarines have bigger beam than older WWII and post-war designs, which gives greater room to accommodate a descent water tight cylinder, or WTC as they are known. My search ended when I met a guy that had converted the Trumpeter 1/144 scale Seawolf to RC with nice results. Luckily he was willing to share his experience and tips with me.
The external hull
The Seawolf class is a product of the Cold War, as a response to the Akula and Typhoon Soviet classes. The main task of this new weapon was to hunt enemy submarines, thus its classification SSN as a “fast attack submarine” in the USNAVY hull classification symbol. Three units were built, from a total of 29 originally planned, as a consequence of the end of the Cold War and high costs per unit: SSN21 “Seawolf”, SSN22 “USS Connecticut” and SSN23 “Jimmy Carter”, this one 100 ft longer than the original design with an added section known as the Multi Mission Platform.
The Trumpeter kit reproduces the SSN21 according to the decals, but as there are many Seawolfs sailing out there, I decided to build it as the SSN22 USS Connecticut, using spare adhesive decals for the numerals in the sail.
The hull comes in two halves, upper and lower, which from now I’ll name them the “upper” and “lower” hulls, with the bow and stern sections in halves too. To ease the process of attach and detach the hull and to work in the interiors without room limitations, I glued the bow section to the upper hull and the stern section to the lower one.
A length of the stern section (from the upper half) was cut and glued directly the upper hull in order to have more room to work with the servo linkages. The adhesive used was that provided with the kit, but I added epoxy (two components) for reinforcement. I followed the advice of painting the epoxy adhesive once cured in order to protect it from the water. Maybe that wasn’t necessary, but I did it.
The WTC is a 70mm external diameter acrylic cylinder, with just 64 mm of internal diameter. To accommodate it inside the hull, I glued three 2mm rubber strips to the lower hull, and a 80mm diameter acrylic section where a screw holds the upper hull in place.
The rudder and depth planes come in halves, which is fine because you just have to glue a 1/8” shaft between those halves and fill them with epoxy, that’s all. At the stern section, the model has two fixed planes which must be installed at a 45 degrees angle to the horizontal. As suggested by the construction guide they should be glued but I decided to fix them with screws just in case a replacement or repairing must be done.
I discarded the lower rudder that comes with the kit; it simply doesn’t seem to work due to scale inefficiency, so I built another to double size in area from plastic.
The bow planes are not operational in my model: I fix their position with screws as needed according with any inherent trend to dive or surface.
The sail comes in two sections too, which I glued after adding some polystyrene foam as reserve buoyancy.
Painting and decals
As far as I know the SSN21 had the lower hull painting in antifouling red, but after the first shakedown it was painted completely black; the SSN22 and SSN23 were launched already painted black, so that was my choice. I used gloss black enamel thinned to 50% with spirit thinner and applied using airbrush. After the third layer had dried, I applied the decals. As for the “22” numerals, I had some adhesive numbers, incredibly at the proper size, kept by years, forgotten in a box.
The final coat was an aerosol mate semi-gloss clear finish, to protect the paint and decals.
The WTC, or Water Tight Cylinder
As I told before, it’s an acrylic, 70mm (2.8 in.) in diameter, 42cm (16.5 in) long cylinder. That’s the greater size I could accommodate in the hull. The lids are two 12mm (0.4 in) thick acrylic sections which were turned in a lathe and shaped to fit in the cylinder, with a groove for installing the o-rings which seal the WTC. All the seals in my model are o-rings, a cheap and effective seal: servo linkages, propeller shaft and WTC lids.
Two brass tubes screwed to one of the lids run along the cylinder hold all the components: servos, ESC (electronic speed controller), batteries, ballast system.
Servo linkages
I used 2mm stainless steel bicycle wheel spokes as pushrods, they have a screw thread at one end with connects with the metal clevis linked to the control planes. To connect them with the servos pushrods I used plated wheel collars. The sealing is provided by a 5.5mm o-ring (one for each pushrod), which has a 1.5mm inner diameter. I drilled two 2mm hole in the lid which I enlarged from the exterior to 4.8mm, this way providing passage for the pushrods and at the same time housing for the o-rings.
I had to bend the spokes at 90 degrees accordingly because at the stern section the two (rudder and depth) planes and the shaft meet at one point, needless to say you can’t link the two rudders (upper and lower) or the depth planes with a single shaft, so every pushrod has to link two shafts. I had to measure everything twice and three times to make sure everything run fine and with proper geometry.
Motor, shaft and propeller
After many trial-and-error cycles I came to install a 280 type motor engaged to the prop shaft with double thin o-rings working as transmission belts, to a 3:1 ratio. The pulleys come from gutted CD-ROM devices.
To seal the shaft I used a special type of fluoropolymer elastomer o-ring, the shaft is a 1/8 brass tube, the o-ring has a smaller size in order to seal the shaft when stationary as well as when rotating. The shaft seal is installed inside a ¼” pipe gas connector, glued to the lid with epoxy. A small plastic tube holds the o-ring in place.
The coupling between that shaft and that of the propeller is a length of silicone hose. Simple and effective.
The prop that comes with the kit is just for display, it doesn’t even have any angle of attack. I discarded it. Instead, I modified two 55mm diameter toy props to create a 30mm, 10 blades propeller, I don’t know whether it is similar or not to the real one, submarines prop designs are a well kept secret. But it works!
Batteries
The main battery pack is a 6V, 2500mAh NiMH, AA size, and for running the pump I connected two 3.7V 800mAh Li-ion cell phones batteries in series (7.4V). This way both systems run independently. The 5 NiMh batteries are glued together to form a semicircle, then soldered properly. The pump batteries lay on the plastic bag of the ballast system. The master switch that “turns the submarine on and off”, is a magnetic window sensor like those used in alarm systems. They are made up of two components, the reed switch and a magnet, I screw the magnet to one of the lids, the switch remains inside the WTC: they work by proximity, when I approach the magnet, the circuit closes, and a 6V relay coil is energized (the reed relay cannot withstand the motor current, the 6V relay does the job).
Ballast system
My system works this way: to dive, an electric geared water pump (those used for windscreen wiper systems) fills a plastic bag, this is one of those used for intravenous infusion in hospitals, 100cc (cubic centimeters) in this case, and the air escapes from it through a small hole (0.5mm), like a spray nozzle, drilled through a piece of epoxy, connected to a plastic hose. In parallel with this, an aquarium non-return valve works as a bypass in order to alleviate the pressure build up inside the bag once it is full of water if the pump keeps on running. To surface, the pump is run in the opposite direction. You wonder whether it works or not underwater because as water is pumped out from the bag, more water enters through the hose to fill the vacuum inside the bag, but that doesn’t happen, because the small hole prevents water from entering the bag, at least in the same quantity as it exits (through 3/16 brass tubes). That simple. Once the sail surfaces the hose picks air again, and the pump empties the bag. It takes no more then 15 seconds to make the sub disappear under the waves.
The system resembles a snort, but I don’t need to surface and take air to blow the ballast, as in snort systems, because as the bag is flexible (but not elastic!) it collapses due to the vacuum inside created when “blowing the tanks”.
This is a homemade ballast system, and I spent just a few dollars, maybe less then $50 building it.
Radio system
To operate the sub I use 4 channels, but I bought a 6 channel, FM radio because the 6th channel is a knob which I find very comfortable for operating the pump. I added a plastic hose with a cursor to the knob, which indicates the pump position at every time: stop, taking water, or “blowing the tanks”. 35 MHz is the frequency of choice as it penetrates the water better than higher ones. Two micro switches attached to a micro servo run the pump in both directions.
Fail safe system
You simple shouldn’t build a submarine with static ballast system without a fail safe, i.e., a way to make it surface again in case of signal loss. Well, I did it and I ended diving for my sub the first time I took it to the lake. Thanks God it was summer. I will never forget those twenty minutes looking for it at more then 6 feet deep of water. At least the WTC and the seals proved to work fine.
One of our members is very skilled in electronics and he managed to program a PIC to send the servo the preset signal in case of signal loss. I just had to build the printed board and solder some discrete components. Now I dive the sub without worry: in case of signal loss (I loved to turn the transmitter off and test the system!), it gently returns to the surface.
Trimming, fixed ballast, buoyancy reserve
I know this was going to take some time. Patience gets the reward here. Having the sub already finished with all the gear installed, I added ballast in the shape of lead strips to the bottom of the hull, as much as needed to make the sub GENTLY sink with the bag full of water. You don’t want it to sink as a stone to the bottom, just slightly negative buoyancy. Then I glued pieces of expanded polystyrene foam to the upper hull until it had the needed stability to keep the self righting capability once submerged, without being affected by the propeller torque or while turning at high speeds.
Then it didn’t want to dive: I had to add one extra length of lead because of the added reserve buoyancy.
After 7 months of work since I opened the kit box, I took it to a pond near home (in the province of Buenos Aires) and to my surprise, it reacted well to every input. The ballast system works fine, at least at 4ft deep (no deeper waters available here). Not a single drop of water inside the WTC, all the seals work fine. The depth planes have descent diving authority. Surfaced, it has a poor turning radius but this is a known issue with this kind of submarines, designed to spend most of their operational live underwater. Once submerged, not only the rudders gain turning authority but also the speed increases, due to the hydrodynamic shape of the hull.
Conclusions
This is my first RC submarine and the results were worth the effort. I enjoy running it underwater while walking aside the pond. There is no room to accommodate an APC (automatic pitch control) or ADC (automatic depth control) so I must pay attention because I have to manually keep the depth which is not easy, but anyway interesting. You don’t get bored with this sub. Maybe it’s not easy to maintain periscope depth. I enjoy bottoming using just the ballast system and let other surface models pass over it, as a hunter awaiting for the preys!
Many experienced sub modelers simply didn’t understand how my ballast system works, mainly the possibility to surface without using the thrust and depth planes, as a true static ballast system but they were convinced once they saw it working. Cheap, easy to build and effective.
This is a nice model and there are many RC conversions worldwide. I hope to see many more sailing these southern waters here.
If you have any points or questions please contact me: rva1945@hotmail.com
Robert Villaverde
PHOTO CAPTIONS
SS01 L The finished model, SSN22 USS Connecticut, seawolf class attack submarine, rests in dry dock.
SS02 M The Trumpeter 1/144 scale Seawolf.
SS03 S A section of the upper stern hull is cut away…
SS04 S …then glued to the upper hull.
SS05 S Once assembled, the bow is glued to the upper hull.
SS06 M This acrylic semicircle holds the WTC in place. A screw holds the upper hull.
SS07 S Belt strips prevent the WTC from slipping.
SS08 L The lower hull besides the finished WTC.
SS09 L The WTC installed in the lower hull.
SS10 M The acrylic cylinder. The lids will be made by turning the two 12mm thick acrylic squares on a lathe.
SS11 M The control planes with their shafts.
SS12 S The bow planes are attached using screws that let adjust their position prior to sail.
SS13 S The oversized lower rudder gives plenty of steering authority.
SS14 M Two servos control the rudders and depth planes.
SS15 M Servo linkages. They protrude from the lid and are attached to the planes.
SS16 M The servo linkages, properly bended to allow for complete movements without interference between them and the prop shaft.
SS17 L Diagram showing how the running hardware, seal included, is installed.
SS18 M The transmission is provided by double pulleys and two o-rings as belts.
SS19 S The bushing that holds the prop shaft is glued to the lid with epoxy.
SS20 M The 280 motor is installed under the servos.
SS21 S The 10 bladed prop is made from two plastic 5 blades props.
SS22 L The ballast tank: a 100cc saline solution plastic bag.
SS23 L Two bended plastic tubes enter the bag: one connected to the pump, the other to the snort via a hose.
SS24 S The 12V electric geared water pump. Centrifugal pumps are not reversible, so cannot be used here.
SS25 M Above, the bypass; below, its components, the non-return aquarium between two aquarium hose connectors.
SS26 M The pump is operated both directions by two micro switches attached to a micro servo.
SS27 L The ballast system explained.
SS28 S Magnetic switch in OFF position.
SS29 S Magnetic switch in ON position.
SS30 M Inside the WTC, the reed switch. It works by proximity with the magnetic switch, attached to the lid by a screw
SS31 M Fixed ballast –lead strips glued to the lower hull.
SS32 M Reserve buoyancy glued to the upper hull.
SS33 M Reserve buoyancy inside the sail.
SS34 L The finished SSN22, peacefully bobbing in the pond.
SS35 L Bottoming at 4ft deep in the pond, possible thanks to the ballast system and negative buoyancy (and the fail-safe system!).
Many years ago while still building my first RC model boats, I was thinking about how difficult to near impossible it would be for me to build a RC submarine, according to the hard times another modeler of our association was having in the subject, not to mention he is a high skilled modeler, and my limited knowledge and experience would be an additional obstacle.
Anyway I felt tempted to at least try to design an affordable, easy to build static ballast system, having in mind the possibility of installing it in a model submarine one day. Static ballast system let you make your submarine loose buoyancy and dive, or surface “blowing the tanks”, as opposite to a dynamic submarine, that relies on motor thrust and depth planes to dive and surface. Once I had a working prototype, the first tests were a success, and it was kept “top secret” until I felt confidence to start in this fascinating world of RC submarines, years later.
After building several model boats of different types (tugboats, luxury yachts, sailboats and rescue launches) I thought it had come the time to try a sub. I didn’t want to spend any time building a submarine hull from scratch, so I looked for a submarine plastic display kit to try a conversion to RC. The idea was to install a water tight hull inside the external hull. Nuclear submarines have bigger beam than older WWII and post-war designs, which gives greater room to accommodate a descent water tight cylinder, or WTC as they are known. My search ended when I met a guy that had converted the Trumpeter 1/144 scale Seawolf to RC with nice results. Luckily he was willing to share his experience and tips with me.
The external hull
The Seawolf class is a product of the Cold War, as a response to the Akula and Typhoon Soviet classes. The main task of this new weapon was to hunt enemy submarines, thus its classification SSN as a “fast attack submarine” in the USNAVY hull classification symbol. Three units were built, from a total of 29 originally planned, as a consequence of the end of the Cold War and high costs per unit: SSN21 “Seawolf”, SSN22 “USS Connecticut” and SSN23 “Jimmy Carter”, this one 100 ft longer than the original design with an added section known as the Multi Mission Platform.
The Trumpeter kit reproduces the SSN21 according to the decals, but as there are many Seawolfs sailing out there, I decided to build it as the SSN22 USS Connecticut, using spare adhesive decals for the numerals in the sail.
The hull comes in two halves, upper and lower, which from now I’ll name them the “upper” and “lower” hulls, with the bow and stern sections in halves too. To ease the process of attach and detach the hull and to work in the interiors without room limitations, I glued the bow section to the upper hull and the stern section to the lower one.
A length of the stern section (from the upper half) was cut and glued directly the upper hull in order to have more room to work with the servo linkages. The adhesive used was that provided with the kit, but I added epoxy (two components) for reinforcement. I followed the advice of painting the epoxy adhesive once cured in order to protect it from the water. Maybe that wasn’t necessary, but I did it.
The WTC is a 70mm external diameter acrylic cylinder, with just 64 mm of internal diameter. To accommodate it inside the hull, I glued three 2mm rubber strips to the lower hull, and a 80mm diameter acrylic section where a screw holds the upper hull in place.
The rudder and depth planes come in halves, which is fine because you just have to glue a 1/8” shaft between those halves and fill them with epoxy, that’s all. At the stern section, the model has two fixed planes which must be installed at a 45 degrees angle to the horizontal. As suggested by the construction guide they should be glued but I decided to fix them with screws just in case a replacement or repairing must be done.
I discarded the lower rudder that comes with the kit; it simply doesn’t seem to work due to scale inefficiency, so I built another to double size in area from plastic.
The bow planes are not operational in my model: I fix their position with screws as needed according with any inherent trend to dive or surface.
The sail comes in two sections too, which I glued after adding some polystyrene foam as reserve buoyancy.
Painting and decals
As far as I know the SSN21 had the lower hull painting in antifouling red, but after the first shakedown it was painted completely black; the SSN22 and SSN23 were launched already painted black, so that was my choice. I used gloss black enamel thinned to 50% with spirit thinner and applied using airbrush. After the third layer had dried, I applied the decals. As for the “22” numerals, I had some adhesive numbers, incredibly at the proper size, kept by years, forgotten in a box.
The final coat was an aerosol mate semi-gloss clear finish, to protect the paint and decals.
The WTC, or Water Tight Cylinder
As I told before, it’s an acrylic, 70mm (2.8 in.) in diameter, 42cm (16.5 in) long cylinder. That’s the greater size I could accommodate in the hull. The lids are two 12mm (0.4 in) thick acrylic sections which were turned in a lathe and shaped to fit in the cylinder, with a groove for installing the o-rings which seal the WTC. All the seals in my model are o-rings, a cheap and effective seal: servo linkages, propeller shaft and WTC lids.
Two brass tubes screwed to one of the lids run along the cylinder hold all the components: servos, ESC (electronic speed controller), batteries, ballast system.
Servo linkages
I used 2mm stainless steel bicycle wheel spokes as pushrods, they have a screw thread at one end with connects with the metal clevis linked to the control planes. To connect them with the servos pushrods I used plated wheel collars. The sealing is provided by a 5.5mm o-ring (one for each pushrod), which has a 1.5mm inner diameter. I drilled two 2mm hole in the lid which I enlarged from the exterior to 4.8mm, this way providing passage for the pushrods and at the same time housing for the o-rings.
I had to bend the spokes at 90 degrees accordingly because at the stern section the two (rudder and depth) planes and the shaft meet at one point, needless to say you can’t link the two rudders (upper and lower) or the depth planes with a single shaft, so every pushrod has to link two shafts. I had to measure everything twice and three times to make sure everything run fine and with proper geometry.
Motor, shaft and propeller
After many trial-and-error cycles I came to install a 280 type motor engaged to the prop shaft with double thin o-rings working as transmission belts, to a 3:1 ratio. The pulleys come from gutted CD-ROM devices.
To seal the shaft I used a special type of fluoropolymer elastomer o-ring, the shaft is a 1/8 brass tube, the o-ring has a smaller size in order to seal the shaft when stationary as well as when rotating. The shaft seal is installed inside a ¼” pipe gas connector, glued to the lid with epoxy. A small plastic tube holds the o-ring in place.
The coupling between that shaft and that of the propeller is a length of silicone hose. Simple and effective.
The prop that comes with the kit is just for display, it doesn’t even have any angle of attack. I discarded it. Instead, I modified two 55mm diameter toy props to create a 30mm, 10 blades propeller, I don’t know whether it is similar or not to the real one, submarines prop designs are a well kept secret. But it works!
Batteries
The main battery pack is a 6V, 2500mAh NiMH, AA size, and for running the pump I connected two 3.7V 800mAh Li-ion cell phones batteries in series (7.4V). This way both systems run independently. The 5 NiMh batteries are glued together to form a semicircle, then soldered properly. The pump batteries lay on the plastic bag of the ballast system. The master switch that “turns the submarine on and off”, is a magnetic window sensor like those used in alarm systems. They are made up of two components, the reed switch and a magnet, I screw the magnet to one of the lids, the switch remains inside the WTC: they work by proximity, when I approach the magnet, the circuit closes, and a 6V relay coil is energized (the reed relay cannot withstand the motor current, the 6V relay does the job).
Ballast system
My system works this way: to dive, an electric geared water pump (those used for windscreen wiper systems) fills a plastic bag, this is one of those used for intravenous infusion in hospitals, 100cc (cubic centimeters) in this case, and the air escapes from it through a small hole (0.5mm), like a spray nozzle, drilled through a piece of epoxy, connected to a plastic hose. In parallel with this, an aquarium non-return valve works as a bypass in order to alleviate the pressure build up inside the bag once it is full of water if the pump keeps on running. To surface, the pump is run in the opposite direction. You wonder whether it works or not underwater because as water is pumped out from the bag, more water enters through the hose to fill the vacuum inside the bag, but that doesn’t happen, because the small hole prevents water from entering the bag, at least in the same quantity as it exits (through 3/16 brass tubes). That simple. Once the sail surfaces the hose picks air again, and the pump empties the bag. It takes no more then 15 seconds to make the sub disappear under the waves.
The system resembles a snort, but I don’t need to surface and take air to blow the ballast, as in snort systems, because as the bag is flexible (but not elastic!) it collapses due to the vacuum inside created when “blowing the tanks”.
This is a homemade ballast system, and I spent just a few dollars, maybe less then $50 building it.
Radio system
To operate the sub I use 4 channels, but I bought a 6 channel, FM radio because the 6th channel is a knob which I find very comfortable for operating the pump. I added a plastic hose with a cursor to the knob, which indicates the pump position at every time: stop, taking water, or “blowing the tanks”. 35 MHz is the frequency of choice as it penetrates the water better than higher ones. Two micro switches attached to a micro servo run the pump in both directions.
Fail safe system
You simple shouldn’t build a submarine with static ballast system without a fail safe, i.e., a way to make it surface again in case of signal loss. Well, I did it and I ended diving for my sub the first time I took it to the lake. Thanks God it was summer. I will never forget those twenty minutes looking for it at more then 6 feet deep of water. At least the WTC and the seals proved to work fine.
One of our members is very skilled in electronics and he managed to program a PIC to send the servo the preset signal in case of signal loss. I just had to build the printed board and solder some discrete components. Now I dive the sub without worry: in case of signal loss (I loved to turn the transmitter off and test the system!), it gently returns to the surface.
Trimming, fixed ballast, buoyancy reserve
I know this was going to take some time. Patience gets the reward here. Having the sub already finished with all the gear installed, I added ballast in the shape of lead strips to the bottom of the hull, as much as needed to make the sub GENTLY sink with the bag full of water. You don’t want it to sink as a stone to the bottom, just slightly negative buoyancy. Then I glued pieces of expanded polystyrene foam to the upper hull until it had the needed stability to keep the self righting capability once submerged, without being affected by the propeller torque or while turning at high speeds.
Then it didn’t want to dive: I had to add one extra length of lead because of the added reserve buoyancy.
After 7 months of work since I opened the kit box, I took it to a pond near home (in the province of Buenos Aires) and to my surprise, it reacted well to every input. The ballast system works fine, at least at 4ft deep (no deeper waters available here). Not a single drop of water inside the WTC, all the seals work fine. The depth planes have descent diving authority. Surfaced, it has a poor turning radius but this is a known issue with this kind of submarines, designed to spend most of their operational live underwater. Once submerged, not only the rudders gain turning authority but also the speed increases, due to the hydrodynamic shape of the hull.
Conclusions
This is my first RC submarine and the results were worth the effort. I enjoy running it underwater while walking aside the pond. There is no room to accommodate an APC (automatic pitch control) or ADC (automatic depth control) so I must pay attention because I have to manually keep the depth which is not easy, but anyway interesting. You don’t get bored with this sub. Maybe it’s not easy to maintain periscope depth. I enjoy bottoming using just the ballast system and let other surface models pass over it, as a hunter awaiting for the preys!
Many experienced sub modelers simply didn’t understand how my ballast system works, mainly the possibility to surface without using the thrust and depth planes, as a true static ballast system but they were convinced once they saw it working. Cheap, easy to build and effective.
This is a nice model and there are many RC conversions worldwide. I hope to see many more sailing these southern waters here.
If you have any points or questions please contact me: rva1945@hotmail.com
Robert Villaverde
PHOTO CAPTIONS
SS01 L The finished model, SSN22 USS Connecticut, seawolf class attack submarine, rests in dry dock.
SS03 S A section of the upper stern hull is cut away…
SS04 S …then glued to the upper hull.
SS05 S Once assembled, the bow is glued to the upper hull.
SS06 M This acrylic semicircle holds the WTC in place. A screw holds the upper hull.
SS07 S Belt strips prevent the WTC from slipping.
SS08 L The lower hull besides the finished WTC.
SS09 L The WTC installed in the lower hull.
SS10 M The acrylic cylinder. The lids will be made by turning the two 12mm thick acrylic squares on a lathe.
SS11 M The control planes with their shafts.
SS12 S The bow planes are attached using screws that let adjust their position prior to sail.
SS13 S The oversized lower rudder gives plenty of steering authority.
SS14 M Two servos control the rudders and depth planes.
SS15 M Servo linkages. They protrude from the lid and are attached to the planes.
SS16 M The servo linkages, properly bended to allow for complete movements without interference between them and the prop shaft.
SS17 L Diagram showing how the running hardware, seal included, is installed.
SS18 M The transmission is provided by double pulleys and two o-rings as belts.
SS19 S The bushing that holds the prop shaft is glued to the lid with epoxy.
SS20 M The 280 motor is installed under the servos.
SS21 S The 10 bladed prop is made from two plastic 5 blades props.
SS22 L The ballast tank: a 100cc saline solution plastic bag.
SS23 L Two bended plastic tubes enter the bag: one connected to the pump, the other to the snort via a hose.
SS24 S The 12V electric geared water pump. Centrifugal pumps are not reversible, so cannot be used here.
SS25 M Above, the bypass; below, its components, the non-return aquarium between two aquarium hose connectors.
SS26 M The pump is operated both directions by two micro switches attached to a micro servo.
SS27 L The ballast system explained.
SS28 S Magnetic switch in OFF position.
SS29 S Magnetic switch in ON position.
SS30 M Inside the WTC, the reed switch. It works by proximity with the magnetic switch, attached to the lid by a screw
SS31 M Fixed ballast –lead strips glued to the lower hull.
SS32 M Reserve buoyancy glued to the upper hull.
SS33 M Reserve buoyancy inside the sail.
SS34 L The finished SSN22, peacefully bobbing in the pond.
SS35 L Bottoming at 4ft deep in the pond, possible thanks to the ballast system and negative buoyancy (and the fail-safe system!).
Attached Files
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