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Most of the tools, consumables and devices discussed in these instructions are available through Caswell Inc. http://www.caswellplating.com/models/index.html For on-line help and useful information about this and other r/c model submarine products join, http://forum.sub-driver.com/

3.5 SubDriver

GENERAL DESCRIPTION The SubDriver is intended for use aboard wet-hull type r/c model submarines, operating in fresh water.

The job of the D&E SubDriver (SD) is to provide propulsion; control surface actuation; and the means, through the gas type ballast tank, to change the submarines displacement. All in one removable, easily accessed system. We’ve done the hard work for you – all you have to do is outfit the SD with your r/c system, angle keeper, ESC, fail-safe, and battery and mount the SD into your wet-hull type model submarine. This single motor, 3.5-inch diameter SD is designed for use within intermediate sized wet-hull type r/c submarines employing a single propeller, and having a length between 40 and 70 inches. Included with your 3.5 SD is the hardware needed to make up and make watertight the internal servo pushrods; a propel charging adapter; external and internal electrical cables; and our unique Kli-Con magnetic linkage couplers, used to make up the SD pushrods to your model submarines pushrods. The 3.5 SD arrives to you already leak checked; the ballast system dialed in and tested; and the propulsion motor installed, its shaft made water tight, and spark suppressed. It’s

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now up to you to outfit your SD with the r/c system and other devices needed to make it operational, and to then mount the system into your model submarine. Through the use of simple rubber bands and our unique Kli-Con magnetic pushrod couplers, installation and removal of the SD within your model submarine is an operation that takes only seconds. The portability of the system permits you to operate multiple hulls from a single SubDriver.

Typically, the 3.5 SD will be situated on or near the center of the model submarines hull, with either a sealed lead-acid battery sitting forward of the SD or a battery contained in a separate water tight cylinder (WTC) occupying that same space. The only mechanical connections between the SD and the hull are the propeller universal connection, Kli-Con type magnetic couplers, and a set of power cables that lead forward to the battery. Two rubber bands act to hold the SD down on saddles you mount within the hull to accept and index the SD securely in position. PHYSICAL CHARACTERISTICS OF THE 3.5 SD Length 20.5 inches overall Diameter 3.5 inches Ballast Tank Capacity 38 ounces Displacement, Ballast Tank empty 102 ounces SubDriver Weight, outfitted 52 ounces Clear Lexan Cylinder material Polycarbonate Bulkheads and other selected Parts Polyurethane

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WHAT WE’VE PROVIDED WITH YOUR 3.5 SD 1. 4, Kli-con magnetic coupler sets 2. Air-Brush propellant can adapter 3. 2, 6-32X3/8” flat-head machine screws 4. 2, 4-40X1/8” stainless set-screws 5. Extra length of on-board bottle flexible hose 6. Comprehensive set of written instructions

WHAT YOU’LL HAVE TO PROVIDE TO OUTFIT AND MAINTAIN YOUR 3.5 SD UNIT

1. Can of air-brush propellant 2. R/c system 3. Automatic Pitch Controller 4. Electronic Speed Controller (ESC) with BEC 5. Fail-safe 6. Battery (3Ah capacity minimum), and appropriate charger. 7. Rubber Bands 8. Various hand tools and consumables 9. Low Pressure Blower ballast sub-system (optional)

FUNCTIONAL DISCRIPTION AND ASSEMBLY

Your SubDriver system has three primary sub-systems which provide propulsion through the single 500 size, 7-volt motor; house and integrate the devices needed to control the motor, ballast, and control surfaces; and provide the means by which ballast water is moved in and out of the ballast tank. The SD cylinder is fabricated from a length of 1/8” thick polycarbonate (Lexan) shatter resistant, clear, plastic tube. The forward, ballast, and motor bulkheads and associated items are cast from polyurethane resin. The bulkheads divide the SD into two compartments: The bulkhead that caps the forward end of the cylinder and an internal ballast bulkhead define the ballast tank -- this is a ‘soft’ tank, so described because it is open to water at the bottom through three holes. Therefore the contents of the ballast tank are equalized to that of the surrounding environment. The after dry space of the cylinder, divided by the ballast bulkhead and motor bulkhead, is pressure proof to a depth of 30 feet … that’s about 25 feet deeper than you need ever operate your model submarine. In short, your SD performs the three functions needed to operate your r/c submarine: propulsion, control, and variable ballast. Here’s a detailed look at the 3.5 SubDriver and what you need to do to get it up and running:

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PROPULSION SUB-SYSTEM A single 7-volt, 500 size electric motor is mounted against the dry side of the motor bulkhead with two machine screws that are accessed from the wet (aft) side of the motor bulkhead. The motor shaft is coupled to an extension shaft that passes through a cup-type watertight seal set within the center of the ballast bulkhead. The after end of the motor extension shaft makes up to a small pinion gear that in turn engages the nylon spur gear of the 3:1 gear reduction unit. The motor has been spark-suppressed and should not contribute any ‘electrical noise’ that would interfere with your r/c system, or other on-board devices ability to operate effectively. Use the Installed Gear Reduction Unit or go Direct-Drive? The output of the 3:1 gear is presented as a Dumas type coupler. The coupler in turn makes up to a Dumas ‘dog-bone’ universal connector – from that union you can either install an intermediate drive shaft, with a dog-bone universal connector at each end (the after end engaging a Dumas coupler attached to the forward end of the propeller shaft), or you can elect to extend the propeller shaft forward, all the way up to the gear reduction unit and couple to it directly. Whatever option you elect, its up to you to work out the rest of the running gear.

The installed 3:1 gear reduction unit, mounted on the wet-side of the motor bulkhead, acts to lower the motor RPM’s and raise the torque to the propeller. In most applications you will want to use the gear reduction unit as is. However, you have the option of removing the 3:1 gear reduction unit, placing the Dumas universal coupler directly to the motor extension shaft and connect the models propeller directly to the motor – this is recommended for propellers of a diameter less than 1.25-inch. Rule of thumb for brushed motors: if the propeller diameter is equal to or less than the diameter of the motor, it’s OK to run the propeller direct-drive from the motor without fear of overheating. The only subjects of the recommend hull lengths in which the 3.5 SubDriver would be suitable and whose propellers are smaller than normal are the British R-Class and Soviet/Russian KILO – these models would benefit from the direct-drive running gear configuration. Most other scale submarine hulls in the 40-70 inch long range would require use of the gear reduction unit.

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However, there are further exceptions: The 1/96 OHIO hull kitM comes to mind. This big hull with its large, slower turning propeller requires an even higher gear ratio. For that boat I recommend adding another stage of gears. This is done by outputting the installed SD 3:1 gear reduction unit into another 3:1 gear reduction unit, achieving a 9:1 ratio between motor and propeller. Hooking up the Battery and ESC Cables Two 6-32 brass all-thread lugs run through the left and right side of the SD’s motor bulkhead. They perform two jobs: They pass current from the battery cables into the SD and also serve as foundations to mount the two equipment support rails to the inboard side of the motor bulkhead. The external battery-to-SD cables make up to the wet side of the lugs. Inboard, on the dry side of the motor bulkhead, the ESC battery cables make up to the lugs. These cables are hard-wired to the battery input leads of the ESC. If a separate BEC is used to power up the receiver bus, the input leads to the voltage regulator are also made up to the lugs, in parallel with the ESC-battery cables. The SD-to-battery cable is long enough to reach the battery terminals – the battery located just forward of the SD, as low as possible in the hull. We don’t recommend any efforts being made to make waterproof the battery terminals – fresh water is a poor conductor and what little corrosion you get at the positive terminal after a days play can easily by removed with a soft wire brush and a quick shot of WD-40. Same goes for the exposed positive connector on the wet side of the motor bulkhead. However, if you wish to make the connections maintenance free, simply coat them with some RTV gasket making rubber (Permatex ‘blue’ is the brand I prefer, available through Caswell Inc).

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Pushing a typical r/c model submarine hull through the water at a 2/3 bell, this SD’s motor will pull about 3 Ampere’s of current. The stalled current load (something went terribly wrong if that happens!) of the motor is nearly 20A. It’s a good practice to place a re-settable or one-shot fuse between your ESC and motor that will trip or burn at 15 Ampere’s. Of course, you should use an ESC rated for at least a continuous 30A load. As your ESC is likely to also produce the power for the receiver (and all other control devices aboard your SD) it is imperative that you do not place any fuse between the battery and ESC – remember: put the fuse between the ESC and the motor!

Servicing the Motor and Motor Watertight Seal Should the propulsion motor ever require removal for service of the watertight seal or motor replacement (brushed motors such as the one installed have a reasonable, but not unlimited, service life), here’s how you remove it from the motor bulkhead: First, remove the gear reduction unit; remove the brass pinion gear off the shaft extension; removing the two mounting screws that secure the motor to the motor bulkhead (you’ll have to dig away the cured RTV sealant used to make watertight the screw heads); and pull the motor free. Re-installing the motor and other components goes like this: First, insure that the extension shaft Oilite bearing is cleaned, then apply low viscosity silicon oil; carefully install the motor onto the motor bulkhead, taking care to guide the extension shaft slowly into the Oilite bearing, through the watertight seal, pressing the face of the motor against the inboard face of the motor bulkhead; rotate the motor to line up its two screw holes with the corresponding holes in the motor bulkhead; make up the two mounting screws,

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then apply RTV sealant to make watertight the screw heads; check for unbinding rotation of the motors extension shaft; make up the pinion gear; and re-install the gear reduction unit. Then test for proper operation.

The Battery The battery will be mounted forward of the SD’s ballast tank, the after end of the battery butting up against the forward bulkhead of the SD. Work out a sound mounting bracket to hold the battery into the hull, placing the battery as low in the hull as possible. Typically you can expect an hours run time with a 3-Ampere hour, 7-volt battery. If you swap out batteries at the lake or pool for additional run time make sure, before hand, that they weigh the same. Batteries of the same part number and even lot number will vary as to weight. The trick is to gather the batteries and weigh them. Mark the exact weight on each batteries case. Using the heaviest battery as a base-line add a wafer of lead of appropriate weight to the other batteries till they all weigh the same. Use Electrician’s tape or RTV sealant to secure the lead wafers to the batteries. Failure to get all the batteries to the same weight will introduce trim changes to the submarine each time you exchange a battery. Though we recommend you use a 7-volt battery, you can use a 12-volt battery as long as you don’t lean on the throttle too much – this will prevent over-taxing the 7-volt motor which would overheat possibly damaging it or, worse yet, creating so much heat within

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the SD that the expanded air within would unseat the motor bulkhead off the cylinder with catastrophic flooding being the result. You’ll note that at the bottom of the motor bulkhead is another all-thread lug. The inboard side of the lug is made up to the receiver antenna wire (cut back to a length that will reach from receiver to lug). The outboard (wet) side of the lug has already been made up to a waterproof antenna, sized for a 75mHz band receiver. CONTROL SUB-SYSTEM The after dry-space within the SD contains all the propulsion and control devices needed to animate your model submarine. Provided are cast resin and machined aluminum mounting fixtures upon which you will secure the servos, receiver, angle-keeper, fail-safe, low pressure blower (LPB), electronic switch, ESC, BEC, and other devices that must be housed in a dry environment. Quick, Easy Access to all Devices The SD is designed so that the majority of the devices that operate the submarine are affixed to the motor bulkhead -- when the motor bulkhead is removed from the cylinder the devices, in mass, come with it, without disturbing their electrical and mechanical couplings. The only device that remains in the cylinder when the motor bulkhead is removed is the ballast sub-system servo, which is mounted to the ballast bulkhead. The only internal connection that needs to be made up or undone as you remove or install the motor bulkhead is the ballast sub-system servo.

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Mounting the Devices We recommend you use standard sized servos. You have plenty of room for them and they have the torque to push the largest of control surfaces against any flow resistance your model submarine will encounter. I recommend, for simplicities sake, that you either glue the base of the servos to the aluminum tray (this tray is secured between the two resin equipment support rails that in turn attach to the motor bulkhead) or hold the servos down with ‘servo tape’ (a self-adhesive, foam core, double-backed adhesive tape). You will have room on the tray to mount other devices as well. I use servo-tape to secure the ESC, receiver, fail-safe and angle-keeper to the resin equipment bulkhead shelves and to the underside of the aluminum equipment tray. Before doing so scrub the resin contact areas with a lacquer saturated abrasive pad to remove mold-release oil. Wipe clean. And you’re ready to lay down servo tape and mount the devices.

If you elect to install a low pressure blower device, we recommend securing the air-compressor-motor and electronic switch to the underside of the servo tray. The LPB induction and discharge flexible hoses run to the forward end of the ballast bulkhead 3/32” brass tubes. On the wet side of the motor bulkhead two more flexible hoses run forward atop the cylinder – one curves up and terminates atop and within the model submarines sail. The other flexible hose terminates in a fitting over the ballast tank.

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BALLAST SUB-SYSTEM The forward half of the cylinder, divided from the after dry-space by the internal ballast bulkhead, comprises the ballast tank. The ballast tank is categorized as a ‘soft tank’ as it’s open to its surrounds at the bottom, therefore the structure is subjected to little differential pressure whether the tank is full of liquid or a gas, regardless of depth. The installed gas sub-system employs stored air-brush propellant, contained within the copper on-board bottle which is secured within the ballast tank. At room temperature the stored liquid propellant (no matter the quantity contained) sits at a nominal 70 PSI pressure. When released through the blow valve, the Propellant gas acts on the water within, forcing it out through the three openings in the bottom of the tank from whence the water came in. A restrictor, between the on-board bottle and blow valve, limits the flow rate of propellant gas – reducing the rate at which water is discharged from the ballast tank during the blow. Note the use of flexible hose between the on-board bottle, restrictor, and blow valve: this hose will burst at a pressure well below the failure pressure of the copper on-board bottle. The flexible hose constitutes a gas-relief ‘safety valve’ to protect the gas type ballast sub-system from damage: Before the on-board charge of liquid propellant rises to a dangerous level the flexible hose will fail, dumping the contents of the on-board bottle into the ballast tank and from there out the three holes at its bottom. Spare flexible hose has been provided to replace a burst hose if an over-pressure event occurs.

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So, what would cause such an event? Simple: you failed to perform the required pre-mission checks and left the SD in the hot car where the propellant charge within the on-board bottle rose to the critical flexible hose burst pressure of 400 PSI. Bad on you! Below I’ve laid out a SD with the components of the gas ballast sub-system installed and below that an on-board bottle with its attached restrictor and blow valve.

The ballast water is introduced into the ballast tank by opening a vent at the top of the ballast tank. Gas formerly trapped in the ballast tank finds its way out (air initially, then propellant gas after the first vent-blow cycle) and is displaced by water entering through the three big holes in the bottom of the ballast tank. The water is forced from the ballast tank when the blow valve is opened – the gas creating a very slight over-pressure within the ballast tank that pushes the water out the three holes in the bottom. In the decades since we developed the line of SubDriver’s (formerly called, WTC’s) servo types, shape and torque rating have changed. Today there seems to be an endless choice of servos. That’s why you see a servo adapter used in the dry side of the ballast bulkhead. The adapter insures correct placement and rigid mounting of a specific type servo within the ballast bulkhead. The adapter can be removed and replaced by other adapters designed for other servo types. Pull out the adapter and you can drop in a standard sized servo if that is your want.

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The vent and blow actions are achieved through a common linkage operated by the single ballast sub-system servo. The linkage and blow valve are mounted on the wet-side of the ballast bulkhead. A gas-saver device works to disable the blow end of operation when the tank is dry – this feature works to minimize unnecessary discharge of propellant during the blow cycle. The ballast system vent valve is mounted atop the cylinder and is acted upon by the head of an ‘adjustment screw’ located atop the linkage arm.

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Adjusting the ballast sub-system Three points of adjustment of the ballast sub- system linkage are provided. Keep in mind though that your SD is delivered set-up and ready to go. However, servo end-points commanded by other type r/c systems than the one I use here may vary, requiring re-setting of the ballast linkage. This is how the ballast sub-system should work: With the transmitter stick that controls the ballast sub-system centered (neutral), both the blow and vent valves are closed. When the stick is moved to the left, only the vent valve opens, flooding the tank. When the stick is moved to the right, only the blow valve opens, blowing the tank dry, yet is forced shut (even if the transmitter stick is still pushed all the way to the right) by the gas-saver end of the linkage. In normal operation a small amount of water will remain in the ballast tank when the gas-saver kicks in to stop the blow. If you wish to blow out the remaining water, push the transmitter sticks trim lever all the way to the right and put the stick over to the right – this over-rides the gas-saver portion of the ballast sub-system linkage. Gas will continue to be discharged as long as you hold the stick in the blow position, even though the ballast tank is dry. Four conditions exist that will call for a re-adjustment of the ballast sub-system:

1. Gas fails to escape through the vent valve when you command a vent from the transmitter.

2. Gas continues to bubble out of the vent valve when the transmitter stick is in neutral.

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3. The blow valve emits little or no gas when you command a blow and there is still a significant amount of water in the ballast tank.

4. Gas continues to be discharged through the blow valve when the ballast tank is dry and the transmitter stick is in neutral.

You may have to restore proper operation of the ballast sub-system by making one, two, or maybe three adjustments, outlined below. If so, make sure to re-test the sub-system with each single adjustment you make. Do not make more than one adjustment between tests! And make adjustments in the order outlined below: First, adjust the position of the two wheel-collars on the servo pushrod. Moving the wheel-collars forward provides more vent and less blow. Moving the wheel-collars aft provides less vent and more blow. Insure that you maintain an approximate 1/16” gap between the inboard faces of the wheel-collars, this to prevent their binding up on the linkage arm during servo pushrod travel. After each adjustment make sure to re-tighten the wheel-collar setscrews. If moving the wheel-collars did not resolve the problem, go on to the second adjustment:

Loosen the blow valve setscrew. Moving the blow valve forward will cause earlier operation of the blow valve. Moving the blow valve aft will retard blow valve actuation. You’ll need two hands for this – one on the setscrew wrench, the other holding a pair of thin-sectioned, long, needle-nosed pliers. The pliers, when grabbing the body of the blow valve, will clear the centrally running pushrod. As you make the adjustment, move the

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blow valve only a 1/16” at a time. After each adjustment make sure to re-tighten the blow valve setscrew and test.

You should never have to do this last adjustment. But … if you must: Remove the vent valve body off the cylinder. You do this my removing the two short 2-56 machine screws that hold the valve body down onto the cylinder. Very carefully, with a sharp putty-knife, peel the vent valve clear of the cylinder. Note that it was made watertight by a bead of silicon RTV adhesive. Pulling the vent valve off the cylinder reveals the linkage arm vent valve adjustment screw. You will be altering the height of the screw to change the degree of force applied to the vent valve as the linkage moves in accordance with your commands. As you adjust the height of the linkage arm adjustment screw make no more than a half-turn between tests. Turning the screw clockwise reduces the closure pressure on the vent valve element. Turning the screw counter-clockwise increases the closure pressure on the vent valve element. As you can imagine, setting the vent valve adjustment screw is a long and laborious procedure and one you should avoid if at all possible! Once set you then apply a fresh bead of RTV sealant around the vent valve body where it makes contact with the cylinder. Take care not to squirt the adhesive under the vent valve body where it will might make contact with the rubber vent valve element, locking it in

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place. It’s a good practice to move the entire linkage to the ‘vent’ position before laying on the RTV – this will help keep the rubber element away from any goo that squirts through.

The forward end of the cylinder is capped with a removable bulkhead. You can reduce the water capacity of the tank by removing the bulkhead, cutting off a portion of the cylinder, replacing the cap and testing – repeating the process until you have just enough reserve buoyancy in the ballast tank to take the model from submerged trim to sitting with the waters surface at the submarines designed surfaced waterline when in surfaced trim. Or, instead of cutting off a portion of the ballast tank cylinder, which would render the SD unserviceable for larger r/c model submarines in your collection, you can place a removable hunk of foam high in the ballast tank. Doing so reduces the tanks floodable capacity. However if you use the displacing foam trick, you’ll have to add fixed ballast weight in the models keel to overcome that added buoyancy when the boats in submerged trim (ballast tank full of water, less the space occupied by the foam). But the additional foam and fixed ballast weight works to your advantage; doing so increases the boats static stability.

CONTROL SUB-SYSTEM DEVICES

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The SD will have to be outfitted with the devices needed to provide control of the motor, the servoes and the ballast sub-system(s). You’ll need a battery (one battery provides electrical energy for all SD systems); an electronic speed controller (to control the direction and torque of the propulsion motor); a receiver (detect and interpret the signals from your transmitter); fail-safe (provide for autonomous operation of the ballast system to blow the ballast tank in the event the radio signal is interrupted); and an automatic pitch controller (to detect changes in the submarines pitch angle and send corrective commands to the stern plane servo). These are the basic devices. You may wish to add more capability to your SD. One such optional device is the Low Pressure Blower ballast sub-system (a means of using outside air to empty the ballast tank, reducing reliance on the on-board propellant gas supply). Below are pictured those devices, less the battery:

Battery You’ll want a gel-cell, sealed, lead-acid battery of a capacity (which drives battery size and weight) as high as you can fit into your submarine hull and still have enough room around and near it to install the compensating foam needed to counter the gatteries weight. Typically, a 12-volt, 4-Ampere hour battery is the biggest you can fit in the smaller hulls in which you would use a 3.5 SubDriver. You’ll also need a dedicated charger suited for charging lead-acid batteries; likely from the same source you secured your battery.

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You may wish to go with the new Lithium-polymer type batteries. If so you will be compelled to use a battery charger designed for that type battery and to fabricate or purchase a separate water tight enclosure in which to house the battery – with the attendant complexity of running all-thread studs through the WTC bulkhead to make up to the battery, through the battery cables. However, all this work is worth it as the Lithium type battery exhibits a power-density nearly four times that of the lead-acid type battery. Battery Eliminator Circuit Even the larger SubDriver’s, such as the 3.5 SD described here, have precious little internal dry space to give up to redundant or inefficiently packaged devices. Such is the situation with the electrical power source and voltage regulation required for most of the devices aboard the SubDriver. Specifically, there is no room for a dedicated battery to provide the 4.8-volts fed to the devices through the receiver bus. That is why you want to employ a battery eliminator circuit (a voltage-regulator) – a device that takes the main battery voltage and reduces it to the desired voltage needed at the receiver bus. It’s off the receiver bus where power is distributed to the other devices that require a 4.8-5 volt power supply. The BEC is either built right into the ESC or is a dedicated unit mounted somewhere in the SD’s dry space. Below are pictured three BEC/VR’s: The one I’m pointing to in lower foreground is a component of the fine Mtronics ESC I use in almost all of my bigger r/c submarines. Note that mounted on the end of the ESC is an attached VR – a very good design, getting the solid-state device in the open hastens heat dissipation, permitting the unit to pass currents (for brief periods) greater than the 1.5 Ampere’s most of these things are designed to pass without damage. Two freestanding BEC/VR’s are also pictured. The one to the right shows the simplicity and compactness of the device: just two wires to make up to the 7-12 volt battery (these run in parallel with the ESC cables that make up to the battery lugs on the dry side of the motor bulkhead), and two output wires that deliver the regulated 4.8-5 volts to the receiver ‘battery’ port through a standard J type connector. I’m also pointing to a BEC mounted to the underside of this 3.5 SD’s equipment tray – doing so permits the semi-conductor to dump excess heat quickly into the aluminum tray/heat sink, improving device efficiency and life.

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Automatic Pitch Controller Without doubt the most important, purpose built piece of technology in the r/c submarine field is the automatic pitch controller (APC). The principle inventor of the APC is Skip Asay, the Godfather of American r/c submarining. This guy, back in the 70’s, realizing the need to artificially stabilize the model submarine about the pitch axis (angle, or ‘bubble’ in submariner speak), first experimented with modifying helicopter rate gyros. He converted them into pendulum type gravity displacement reference units. Skip went on to produce proper APC’s of his own design, each new effort rendering a smaller more capable device. Finally, getting his APC’s to the point today where Skip’s APC’s (and similar units offered by those who have paralleled his work) will fit into the smallest of r/c submarines. The APC is connected between the stern plane servo and receiver channel-2 port (transmitter right two-axis stick, up/down axis), or channel-6 port (transmitter control dial, upper left). The APC device parallels your transmitted stern plane commands with corrective signals it generates as a consequence of the angular displacement it detects. If you don’t send any commands to the stern planes then the APC works alone to tend the stern planes, stabilizing the submarine about the pitch axis; working to maintain a zero bubble angle. Most APC’s permit you to negate a portion of the APC error signal to the servo when you move the transmitter stern plane stick or dial – the APC corrective signal is still presented in the resolved output to the servo, but the major component of servo travel will be what you command. You are in the loop as to what pitch angle your submarine assumes, but

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the APC is a vital piece of gear in that it greatly reduces your workload. Proof of point: Once your submarine is trimmed out and running fine, disconnect the APC from the loop and try to drive the model underwater. The model will be nearly uncontrollable in pitch and if you get it under control you’ll have to be so engaged that the sweat will soon by flowing into your eyes! No APC, no fun! As with any complicated device, follow the manufacturers instructions when you set up, install and dial in the product.

Fail-Safe An electronic monitoring device we inherited from the r/c racing car and hydroplane folk: this device is intended to act if and when the receiver looses the transmitted signal. In our application the fail-safe device works, once it detects loss of signal, to command (immediately, or after a pre-set time delay) the ballast sub-system servo to the ‘blow’ position, surfacing the out-of-control submarine. The fail-safe device is connected between the ballast sub-system servo and, typically, the channel-4 port of the receiver. The fail-safe device is another must-have item aboard your r/c submarine. Follow the manufacturers instructions. The left/right motion of the transmitters left two-axis stick normally controls the gas ballast sub-system servo. Right motion of the stick opens the blow valve. Left motion of the stick opens the vent valve. With the stick in neutral, both vent and blow valves are closed. R/C System Not much to talk about here, other than just about any r/c system you buy will work to control your r/c submarine. At the minimum get a 4-channel system. But the price on the gear today has come down so much that most of you can spring for a 6 or 8-channel system without breaking the bank. Just make sure you purchase a system that operates on an Federal Communications Commission (FCC) approved band of frequencies. In America, those of us without the appropriate license are restricted to using r/c systems on the 75mHz band. Incidentally, the FCC has assigned 72mHz for model aircraft operation, only. Never … NEVER use an aircraft r/c system for any purpose other than controlling model aircraft! Also, don’t use any of those new, fancy 2.4 gHz scanning r/c systems for r/c submarine use. The higher radio frequency they work at mostly bounces off water, and what RF energy that does get to the submerged model won’t be of a magnitude great enough to assure reliable control of the systems aboard. Electronic Speed Controller The Electronic Speed Controller (ESC) takes the raw electrical energy from the battery and, if it’s equipped with a BEC, does two things: Primarily, it works to control, as you work the transmitters throttle stick, the amount and polarity of electricity sent on to the single propulsion motor.

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A secondary, but vital function (performed by most modern ESC’s) is to reduce the battery voltage to 4.8-5 volts and send it on to the receiver bus (through the red and black wires) where it is distributed to the other electronic devices aboard the vehicle. Almost universally the ESC will connect to the channel-3 port of the receiver, which is controlled at the transmitter through the up/down positioning of the left, two-axis stick Many ESC’s feature an ‘on/off’ switch which isolates both the battery-to-ESC and BEC-to-receiver circuits. You may wish to form a pushrod to actuate the ESC switch, running that pushrod through an unused 1/16” watertight seal. That would permit you to remotely turn the SD system on and off if you connected the pushrod to some linkage you could move with the model hull assembled.

Low Pressure Blower An optional device, but one that will shift the status of the gas ballast sub-system to ‘emergency use only’. The Low Pressure Blower (LPB) ballast sub-system takes air from the surface (the sail of the model submarine must broach the surface so the tip of the LPB’s induction hose has access to air), and pump it into the ballast tank, displacing the water within. Venting of the ballast tank is still performed by the gas ballast sub-system servo working to open the vent valve. However, blowing of the tank with the LPB is controlled through another channel of the r/c system. The LPB compressor can either pump air or water. However, the ballast tank can only be emptied by the LPB if its induction hose intake is above the surface. The robust nature of the compressor negates the need to isolate the LPB motor from its power supply when the intake of the induction hose is submerged.

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The LPB motor can either be controlled through a mechanical switch, controlling battery power, worked by a servo, or you can use an electronic switch to direct battery power to the LPB motor when commanded. I typically control the LPB using the channel-5, two-position toggle switch on the upper right hand face of the transmitter. Within the SD you plug in either the LPB’s servo or its electronic switch into the channel-5 port of the receiver. The brush type motor of the LPB unit is not spark suppressed when you get it. Spark suppression must be installed to reduce the amount of ‘electrical noise’ that otherwise would be sent through the control leads and into the receiver, diminishing its performance.

A typical spark suppression network comprises two small ceramic capacitors, which should be rated .01 microfarad mF. You’ll find these at your local Radio Shack or electronic parts supply house. Make up the two capacitors as shown below. Solder the outboard end of each capacitor to a pole on the motor; solder the common inboard end of the capacitors to the motor case; then make up the motor-to-switch wires. That’s all there is to it. For this work I recommend a 25 Watt soldering iron – it’s big enough to hold the heat needed to solder the capacitor wires to the motor case.

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I’ve presented two different sized motor-compressor units for you to examine. The bigger the unit, the more air it will push, but also the more current it will draw from the battery. Note that I’ve hooked up an electronic switch to control the LPB motor. When using an electronic switch make sure that none of the motor power is derived off the receiver bus. You do this by disconnecting the electronic switch-to-receiver lead red-wire. See the separate cable wires leading from the electronic switch? Those make up to the internal battery lugs at the motor bulkhead. It’s the job of the electronic switch to route current from the battery to the LPB motor, NOT to route any of that motor current through the battery bus!! Remember: You don’t want the total current load on the BEC to exceed 1.5 Ampere’s for any significant length of time. Examine the J connector in this photo: Note that I’ve disconnected the red power lead between the electronic switch and the receiver – just to make damn sure I don’t pull motor current off the receiver bus! Be ever mindful that the systems BEC is current limited, and that if you fry the BEC, your boat is dead in the water – and if that occurs while submerged … Well, buddy. You’re going swimming!

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TOOLS AND CONSUMABLES

TOOLS You’ll need the usual array of hand-tools to set up and maintain your SD. Additional tools needed include little hex wrenches for the 4-40 and 6-32 setscrews; a tire-valve (Schrader valve) wrench; short and longed nose alligator hemostats; and a Volt/Ohm/Ampere meter. These items can be purchased at hardware stores, automotive supply stores, and hobby shops. Rosary and Rabbit’s-foot are optional. CONSUMABLES The consumables you’ll need include cans of air-brush propellant; rubber bands to secure the SD within the model submarines hull; RTV adhesive; a needle applicator filled with silicon oil to lubricate the various watertight seal o-rings and cup-seals; a small tube of silicon grease (distributor cap grease is a good alternative) for the bulkhead o-rings; and lint free paper towels.

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MAINTENANCE Proper maintenance of your 3.5 SD is the only way you can be assured of the units long-term successful operation. I’ve defined three phases of maintenance. Procedures you have to perform before, during, and after playing with your r/c submarine model. First, there’s the preparation of the SD and model submarine, the ‘Pre-Mission’ checks; maintenance performed periodically at lake or pool side as you play with your model, the ‘Mission’ checks; and the maintenance, repair and preservation tasks required to prepare the SD and model submarine for the next outing, these are the ‘Post-Mission’ checks. PRE-MISSION Before taking your r/c model submarine to the lake or pool for an afternoon’s fun, you’ll have to get your SD up and running. The post-mission maintenance operation (done the last time you had the model out for use) left the SD with the motor bulkhead (and its attached devices) separated from the Lexan cylinder. With a clean lint-free cloth wipe the inside edges of the cylinder, where the motor bulkhead o-ring will seat. Grease the motor bulkhead o-ring with silicon grease. Make up the fail-safe circuit to the ballast system servo leads and carefully push the motor bulkhead into the cylinder and seat the motor bulkhead o-ring within the after end of the cylinder – as you do this rotate the cylinder in your hand, checking that you don’t get any wires caught between the o-ring and cylinder. Hold the motor bulkheads equalization valve (the tire-valve on the face of the motor bulkheads wet side) next to your ear and depress the valve stem. You should hear a pronounced ‘whoosh’ of air escaping. That’s the air within the cylinder initially compressed as you pushed the motor bulkhead into the cylinder a few minutes ago. If you don’t hear that sound (five-minutes is the minimum time to wait after installing the motor bulkhead onto the end of the cylinder), you have a leak somewhere and that has to be found and fixed before you proceed with anything else. And you’ll open the equalization valve each and every time you install the motor bulkhead into the cylinder – if you don’t, the over-pressure caused by the bulkheads compression of the space, coupled with the further expansion of the air within caused by heating of the internal devices, might pop off the motor bulkhead. Bad Ju-Ju!

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A drop of clear silicon oil is placed on all running gear bearings within the model submarine. And oil at all bearing points on the SD’s gear reduction unit and pushrod seal body exit points. Don’t forget the ballast sub-system servo pushrod seal – you access that through the aftermost hole in the bottom of the ballast tank. Don’t make a mess of things. Use those lint-free wipes! Install the SD into the models hull, as you do make up the intermediate drive shaft between the SD’s gear reduction unit and the models propeller shaft. The magnetic couplers that interconnect the SD and models pushrods should make up on their own as you sat the SD down on its saddle. Run out the external antenna atop the cylinder (under the rubber-bands) as high as you can manage. If installed, make up the external flexible hoses of the LPB ballast sub-system to the tubes set into the motor bulkhead. Tighten the on-board bottle tire-valve and give it a charge of propellant. Here’s how you do that: We’ve provided you a ‘Propellant Charging Adapter’, used to transfer Propellant liquid from the Propellant can (that you purchase at the local hobby-shop, typically used as the gas source to operate small spray-brushes) to the SD’s on-board bottle. The objective is to transfer liquid, not gas, into the on-board bottle. Therefore you have to invert the propellant can as you make the transfer. When you press the propellant charging adapter down tight on the on-board bottle charging valve (a modified Schrader valve) a small quantity of the liquid will be transferred, but not enough to be useful. To get more liquid into the on-board bottle, you

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press its valve stem momentarily to vent off some of the gas. This cools the bottle, lowering its energy, and you charge it again – this time you get much more liquid transferred, enough maybe for 10 vent/blow cycles. Propellant is typically comprised of a near even blend of Methane and Butane (two highly flammable items, something to be mindful of), a mixture that will assume the liquid state if at or below room temperature and confined to the point below its vapor pressure of about 70 PSI. The propellant within the on-board bottle, when the ballast sub-system blow valve is opened, experience a rapid pressure drop and a portion of the liquid flashes to a gas – it’s that gas that is picked off within the on-board bottle and sent through the flexible hose where the rushing medium-pressure gas is slowed as it passes through an in-line restrictor. From the restrictor the gas enters the open blow valve where the gas is discharged into the ballast tank, forcing the water out.

Turn on your transmitter (insure first that the throttle stick is in neutral), then power up your SD (either by hooking up the battery or switching on an internal switch, if that’s how you control power to the system) It’s vital that every time you make up the battery to the cables that you observe correct polarity – failure to do so will likely ruin the ESC or any other device (such as the LPB electronic switch) directly connected to the battery cables. Check all control surfaces and other r/c features for proper operation and direction of travel. Check the propeller setscrew tight -- don’t over-tighten. Range check the r/c system in accordance with manufacturers instructions.

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Place the model submarine in fresh water (a dedicated test-tank or the bathroom tub) and check for proper operation of the ballast sub-system and that the model assumes proper trim in both surfaced and submerged trim. Turn power off to the SD, switch off the transmitter, box up the model, prepare your field-box, and load up the car … you’re ready to go play! MISSION At the lake or pool you will perform the mission checks. These include unshipping the model from its box, inspection of the model, turning on the transmitter and SD, a quick check of all r/c functions, and immersion of the submarine in the water. Initially, with the submarine only feet away from you, command a dive. Once the submarine has submerged check for correct operation of the fail-safe feature by turning off the transmitter and waiting for the model to surface. Turn the transmitter back on. That check successfully over, dive the boat again and maneuver out a bit. Bring the boat back, surface, retrieve it, and march it back to your workstation. Open the hull up and inspect the SD’s for any signs of flooding – a foggy dry space or when you roll the model over and there are droplets of water appearing on the inside of the cylinder. These are big warning signs … you have a leak somewhere! Every five-blow/vent cycles bring the model back to the workstation and recharge the on-board bottle with propellant. Monitor the condition of the battery and replace it when you notice a drop in speed performance. Check the physical condition of the control surfaces and linkages every now and then. Stay away from model ships and boats; especially racing boats and deep-keeled sailboats operating in your patrol area. You hardly know where you’re submerged r/c submarine is most of the time … it’s a sure bet the other model boaters don’t! They’ll run your ass over in a heartbeat! Like it or not, in any group of r/c boater’s and submariners, the submarines out there are regarded by the target-drivers as little more than submerged speed-bumps. Act accordingly.

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When you’ve had you fill of r/c submarining (you’re tired, your boat broke, or it got creamed by a Skimmer): Open up the hull and disconnect the battery; turn off the transmitter; using the Schrader valve tool, vent off the remaining propellant from the on-board bottle; when you can no longer hear the hiss of escaping gas, box up the model; return all tools and consumables to the field-box; load up the van, and head back to the shop. POST-MISSION With the model back on the shop bench, it is vital that you attend to the disassembly of the model, removal of the SD, and perform the preventive maintenance steps needed to insure the long and useful service life of both. Don’t wait till after dinner… do it now! Turn on the transmitter, then connect the battery and make the model ready in all respects (do not re-charge the on-board bottle). Check the transmitters trim settings – you likely cranked some into the control surfaces while you were running the boat today – time to take those trim levers on the transmitter and set them back to neutral, but only after adjusting the boats control surfaces to the new ‘neutral’ positions. Open up the model and adjust the appropriate Kli-Con connectors length in the direction and amount needed to place the surfaces in the same position they were when you had cranked in the trim offset. Remove the battery from the boat and turn off the transmitter and put both items on charge. To get them from under foot, wind up and rubber band the antenna and battery cables; if installed pull the LPB external induction and discharge flexible hoses off the motor

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bulkhead tubes; grab the motor bulkheads white-handled lanyard in one hand, and holding the cylinder down firmly on a table with the other hand, pull slowly till the motor bulkheads o-ring clears the end of the cylinder; pull the motor bulkhead out a bit further, enough to get access to the ballast sub-system servo lead. Reach into the cylinder and disconnect the ballast sub-system servo connector – a set of hemostats is a useful means of reaching into the cylinder to perform this operation; pull the motor bulkhead and attached devices clear of the cylinder; place a drop of oil on the inboard and outboard sides of the pushrods where they enter the seal bodies; put your nose right up to the motor and other devices and sniff for indications of any burnt insulation or fried semi-conductors (acrid or burnt rubber smell), repair or replace defective or suspect devices. Store the motor bulkhead assembly in a dry, room temperature, well ventilated and dust free environment. Examine the dry space within the cylinder, checking for water – if any is found, wipe it out with a lint-free cloth and find out why! Put a drop of oil on the rubber face of the vent valve; put another drop of oil on the ballast sub-system servo pushrod (accessed through the aftermost flood/drain hole in the bottom of the ballast tank). Place the cylinder in a dry, room temperat6ure, well ventilated, dust-free environment. Check over the model submarine for damage or ware and take appropriate actions to make the model ready for the next outing. Put the model submarine back on display or secured within its transportation/stowage box. Inventory your field-box and replenish the consumables and replace missing or damaged tools. INTEGRATING YOUR SUBDRIVER WITH YOUR MODEL

SUBMARINE How you mount your SD within your models hull and where you place it are two important matters: MOUNTING THE SD WITHIN THE MODEL SUBMARINE The Saddles The recommended means of supporting and holding the SD fast within the hull is to manufacture two horseshoe shaped ‘saddles’ in which the SD is cradled and held fast with rubber bands. The saddles can be manufactured from wood, plastic, or any other suitable material – just make sure that the material is either impervious to water or is made watertight with some kind of overcoat. Indexing The SD to The Hull To insure that the SD, when installed aboard the model submarine, is fixed in position, install a pin in the forward saddle – this pin fits into a hole you drill into the bottom of the SD’s cylinder. Of course this hole has to be located in the ballast tank portion of the cylinder.

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MAKING UP THE SD AND MODEL SUBMARINES PUSHRODS A number of years ago Brian Stark invented the magnet coupler, a means to interconnect the SD pushrods to the model submarines pushrods quickly and with near zero backlash. Use of magnets in this application simplifies the task of making up and breaking those connections (as you either install or remove the SD from the model submarine hull). Each set of Kli-Cons interconnects the pushrods of the SD and the submarine. We provide 4 sets of Kli-Con’s with this kit, giving you the ability to magnetically interconnect pushrods to operate the rudder, stern planes, bow/sail planes, and a fourth mechanical function (bow plane retract mechanism or torpedo launcher for example). The threaded brass fitting at the end of each Kli-Con has a bore to accept the end of a 1/16” diameter pushrod – we recommend you glue this fitting to its respective pushrod with CA adhesive. To break the bond of cured CA all you need do is touch the brass connection with a hot iron a few seconds, the CA fails and you can separate the Kli-Con from the pushrod.

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The Kli-Con connectors are uniquely advantageous when you need to interconnect linkages that have elements in each half of the model submarine – the magnetic attraction between the two ends of such a linkage makes it any easy matter to place the upper hull over the lower hull, move it around a bit till you hear the distinctive ‘click’ as the two magnets join, then all you have to do is secure the two hull halves together. Such is the situation with the1/72 SKIPJACK r/c submarine model I’ve been using as an example in this document: The sail plane pushrod is attached to the bell crank up in the sail and that pushrod is part of the upper hull half of the model. However, the SD and it’s half of the sail plane linkage is in the lower hull half. The Kli-Con connector solves the problem when it comes time to join or take apart the two model hull halves. Below I’m pointing to a forward facing Kli-Con half-connector that will make up to its counterpart attached to the after end of the upper hulls sail plane pushrod. Note that I’ve removed the threaded coupler from the end of this Kli-Con half and replace it with a ‘U’ shaped piece of 1/16” brass rod. The after end of the rod in turn is soldered to a 1/16” wheel-collar that screws tight to the sail plane pushrod. Adjustment of the sail plane linkage is done by moving the wheel-collar forward or aft on the SD pushrod. Simple! An added benefit of using the magnetic couplers is that at some force level, in tension or compression, the magnetic force will be overcome by mechanical force and the magnetic connection between the set of Kli-Cons will fail. The force required is much greater than the fluid motion induced drag presented to the control surface operating shafts, so you can be assured that linkage disconnect will occur in situations that involve collision, or mishandling of the model itself, not the normal forces experienced by the linkages as a consequence of the vehicles motion through the fluid.

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MAKING UP THE INTERMEDIATE DRIVE SHAFT Output of the SD gear reduction unit terminates in a standard Dumas type Universal couplers. An intermediate drive shaft fits between the SD and propeller shaft – you manufacture this item. You have to come up with a Dumas ‘dog-bone’ type coupling rod (Dumas part number, 2019), cut it in halve, and mount the end of each dog-bone into the end of a length of 7/32”diameter aluminum tube (K&S part number, 105). It’s not enough to CA the plastic dog-bone piece within the aluminum tube, you also have to drill a 1/16” diameter hole through both tube and dog-bone shank and press a short length of 1/16” diameter brass rod into the hole – this to insure that the dog-bone and tube union does not come apart under high torque situations.

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The spacing between the models propeller shaft Dumas coupler, and the SD’s Dumas coupler will dictate the length of the intermediate drive shaft. Size the intermediate drive shaft so that about 1/16” of fore and aft slop exists, this to prevent binding or unnecessary wear on the propeller, or SD gear reduction unit motor thrust bearings. The intermediate drive shaft is made up as you place the SD upon its foundation saddles. TRIMMING THE HULL FOR SURFACED AND SUBMERGED OPERATION Where do you place the SD in the submarine? Best general recommendation is to place it so that the center of the ballast tank is at the center of the hull – the idea is that you will arrange the boats center of gravity (c.g.) and its center of buoyancy (c.b.) at the center as well. You establish the c.g. by balancing the completely outfitted model and moving the fixed ballast weight till the c.g is centered longitudinally. The objective is to permit the ballast tank to change the submarines displacement without changing its longitudinally positioned c.g. or c.b. The fixed ballast weight and buoyant foam are so arranged so that the submarine is statically stable on the surface and submerged on an ‘even’ keel (or zero bubble-angle). The buoyant foam you RTV into the hull will be placed as high as possible, but most of it must remain below the surfaced waterline – you will wind up with a rather narrow band of foam running the inside perimeter of the upper hull half. Through experimentation, as you trim the boat, you’ll find how much and where to place a fraction of that foam above

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the water line in order to achieve static stability on an even keel in both submerged and surface trim. The amount of buoyant foam affixed within the hull is there to insure that the submarine, with the ballast tank flooded, will assume submerged trim with only enough reserve buoyancy remaining to lift the top of the sail an inch or so above the surface; and with the ballast tank dry, to assume surface trim on or near the submarines designed waterline.

CATASTROPHIC EVENTS AND HOW TO PREVENT THEM

A catastrophic event is just that; one or more situations that result in the loss (sinking) of your model submarine, be it at the local community pool or a 200-foot deep lake. It’s a nice day, spectators are gathering around you at the waters edge as you drive your submerged r/c model submarine along, the tip of the periscope the only evidence of the machine-in-motion just inches below. Everything’s running perfectly and you feel great about it. You’ve adopted an all to obvious air of superiority: confident in your mastery of the sciences and crafts, your jaw unconsciously jutting out in a Prussian Officer posture of supreme self-assurance and dominance. You are a God! The arrogance you project is stifling. THIS is your moment in the Sun! ... … So, what could possibly go wrong? Dumb question maybe, but multiple answers to which you should have worked out before you plopped your expensive toy into the drink and made a fool of yourself. Below are some of those unasked questions – and the answers. Over time I have experienced just about every problem one might expect to encounter during the operation of an r/c submarine model – some of those problems I never anticipated. Here are the ‘lessons learned’: HOW ABOUT A PROTECTIVE BOX FOR YOUR EXPENSIVE SUBMARINE MODEL? Slamming the van door on the models stern as you rush off to make a meeting at the lake; somebody accidentally brushing up against your unattended model, sending it crashing to the floor; having your model leap off the cars back seat as you slam on the brakes to avoid running a red-light. All these things have happened to me, and each time the model involved was badly damaged. In frustration at all the stupid repair work, I began building custom sized, sturdy, transportation and stowage boxes for my fleet of r/c submarines. That’s right: make a box to protect your model from the above hazards and more. You’ll be glad you did! Can’t figure out how to make a simple wooden box? … Then, you’re in the wrong game, pal! Take up knitting or something else simple.

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FLOODING OF THE SUBDRIVER’S DRY SPACE The most obvious cause of catastrophic loss is flooding of the SubDriver. Water in the after dry space will not only decrease the boats reserve buoyancy, it will also quickly work to short out the many devices you use to control and power the submarine – once those devices start to wink out, you’re dead! And this is where rigid discipline, exercised during your pre-mission, mission, and post-mission checks will save you. You don’t install that SD until you are absolutely sure it is watertight. And remember that in the mission operations, one of the first things you do after running the model a few minutes in the water after its initial dunking, is to pull it out, remove the upper hull and invert the SD to check for water within the dry spaces of the cylinder. Neglect to do these things and someday you will loose a model submarine to flooding. It’s an awful feeling, at the end of the day, to bring back home at an empty boat stand! LOSS OF ELECTRICAL POWER What I’m talking about is loss of power at the receiver bus. This usually is the result of an over-taxed BEC. You will either be using an ESC with an installed BEC or you will provide a dedicated BEC to convert the high Voltage of the battery to the desired 4.8-5 volts needed at the receiver bus. Keep in mind that the receiver bus feeds power to all the other devices aboard the SD and if the BEC fries you are dead in the water – fine if you’re on the surface … devastating if the lights go out submerged!

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What usually scotches the deal is when you permit high current devices, such as solenoids and motors to dine off the receiver bus – insure such devices are hard wired (through a suitable switch) into the battery for their electrical energy. The solution here is to know the maximum current rating of the BEC installed in your boat and to measure and know the actual load, knowing that the load presented is within the capability of the BEC. Most r/c systems, APC’s, and fail-safe devices combined won’t come close to drawing the maximum BEC current – even with all the servos in motion, working against reasonable forces. But, you can’t make that assumption -- you have to KNOW! It’s a wise move, during SD set-up, to place an Ampere meter in series with the battery and, with the all devices hooked up to the receiver, measure the load as you wiggle all the servos through the transmitter. If the average current draw does not exceed the rating of the BEC, then your fine. Any spikes over the rating and you have a potential BEC killer on board – a stalled/binding servo gear train or maybe a short somewhere. Find the problem and fix it before you get underway. As you take the measurement the throttle stick must remain in neutral. BALLAST SUB-SYSTEM FAILURE Even if you trim the submarine to have a few ounces of positive buoyancy in submerged trim, at some critical depth, usually only a few feet beneath the surface, ‘box compression’ will reduce the displacement of the dry space of the SD and foam to the point where the boat becomes neutrally buoyant. Deeper yet and the boat becomes negatively buoyant, and starts to sink unless you get it in motion and use the dynamic lift of the hull and control surfaces to bring the boat back up above the critical depth. So, don’t count on those few ounces of reserve buoyancy near the surface to bring your boat back up from the deep if it suffers a ballast sub-system failure. Forget it! That boat’s on its way to the bottom! Again, perform those pre-mission checks so you KNOW the ballast sub-system is working fine. And keep count of your blow/vent cycles as you operate the boat, and bring it in for a propellant re-charge every now and then. UNDERWATER ENTANGLEMENT No problem in a pool or a well surveyed and examined body of open water. However, we all eventually operate in water of low visibility and unknown depth, bottom type, and obstacles. Too often public lakes are used as a dumping ground by idiots and kids: at some sites you’ll find cut away fishing lures, shopping carts, bicycles, house-hold appliances, and even cars littering the bottom. Such obstacles all to often ensnare a submerged r/c model submarine – and the only means of recovery is to slip on some fins, snap a mask on your puss and go down there and get it! Or you find a SCUBA diving friend or pro to do the dirty work for you.

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If you can’t swim, don’t have any SCUBA buddies, or are too cheap to spring for a professional Diver, then I would suggest that you find another hobby!

SO, IN CONCLUSION … A guy who’s been inventing, testing, improving, and producing product for the r/c model submarine hobby for over 20 years has made this 3.5 SubDriver available to you. I’m one of the acknowledged experts in the field today. You, by purchasing this SubDriver, assume the responsibility of using and maintaining this product correctly as you pursue success in this hobby/obsession of ours. All the above words and pretty pictures contained in this document are there to guide you in that endeavor. Use ‘em! I would be remise in my responsibilities as Historian if I didn’t acknowledge those inventors and practical Engineers who introduced me -- through their writings, lectures, and demonstrations -- to the activity of r/c model submarine building and operation: Norbert Bruggen, David Wick, Mike Dorey, Skip Asay, ‘Brother Otto’, Arthur Meyer, Simon Smith, Bob Dimmack, Dave Copeland, Ron Perrott, Greg Sharpe, and Dan Kachur. Not a complete list, but these guys come to mind immediately as the best in the field … in my not-so-humble opinion. This is such a fun hobby for me – demanding an understanding and practical application of engineering, design, methodology, materials selection and use; fabrication, painting and weathering; and operation of a submerged r/c vehicle. All these activities rolled up into one field of endeavor. So many things to ‘get right’ before your model will look good and perform as a fair representation of the ‘real thing’. And, when you get it right, what a wonderful feeling that is! We successful r/c submarine enthusiasts are, because of the complexities of our activity, a small group. Are you up to the challenge? If so, then welcome aboard. David D Merriman lll D&E Miniatures-Caswell Inc.