Most captains equip their ships to fire using mechanical poppet valves (Clippard SMAV-3) as pilots for their MPA-7 or MPA-5 actuators. Opening the pilot valve with a servo allows pressurized CO2 to reach the actuator, which in turn pushes open the main firing valve in the turret body, firing the gun. This is a simple method, tried and true. The mechanical/pneumatic operation is easy to understand, easy to troubleshoot, and very reliable. An example of this system is documented in Safe, Effective CO2 Delivery.
The APC Mk III is an easy to build, inexpensive Automatic Pump Circuit. It is a major improvement over the original Mk 1 (Pizl) circuit that used a TIP120 to drive the pump directly and the Mk II which still used the TIP120 and copper contacts for sensors.
Lessons learned after a season with an MTroniks Marine ECO 20 ESC, and other people’s experiences over the year. If there is an example or something specific listed, someone has experienced it.
Special contribution from Phil Sensibaugh, of the Midwest Battle Group
Obviously, the whole point of warship combat is to be able to sink your opponents by firing ball bearings at their ships. Hulls are designed specifically to allow penetration, and damage control countermeasures are restricted so as to make the threat of sinking a very real possibility for any combat ship. Even so, a weapon system that is capable of punching a hole through thin balsa sheet is going to also have the potential to inflict harm on people or animals, or damage property if certain safeguards are not built in, and safe practices followed. While part of the fun of building models – combat or not – is in the “tweaking”, experimenting, and learning while you try to make something work, there are some aspects of warship design where it’s best to go with a proven solution. In particular, those areas of warship construction that involve safety – the prevention of injury or property damage – should not be built by “trial and error” methods. It’s one thing to waste a bunch of your time, trying a new and clever method of building a hull, controlling motors, rotating guns, etc. It’s quite another when the potential consequences of error can involve serious injury. Working with gasses under pressure certainly has the potential for causing injury and/or damage if proper care is not taken in the design, construction, and operation of these systems.
One of the early problems I had to solve when I built my first ship was the construction of stuffing tubes for the propeller shafts. Stuffing tubes (or stuffing boxes) are needed to allow the rotating shafts to exit through the hull, while keeping water outside where it belongs. They also serve to stabilize the prop. shafts and position them solidly where they belong.
It’s a good idea to have a working knowledge of how Radio Control (R/C) systems work. One doesn’t need to be an Electrical Engineer (EE) or Radio Frequency (RF) guru to make off-the-shelf R/C systems work. Fortunately, most of the heavy lifting has been done for us. Still, most R/C systems need to be adapted in some ways so that they can be used to operate a fighting combat ship.
Most R/C systems with enough channels for model warship combat are designed to be used with aircraft or helicopters. This is just a simple fact of life in the R/C business – that’s what the greatest demand is for, so that’s what gets built. Limited angular motions are used to control ailerons, rudders, flaps, elevators, and throttles, while landing gear is always in 1 of 2 positions. That’s really all that a R/C system does, is to convert a range of motion on an input into a range of motion on a remote device (usually a control surface in aircraft). Almost all radio systems available today are 2.4ghz, which offers many more available frequencies (allowing for more RC vehicles to operate simultaneously). The challenge is to adapt this system to a use for which it was not designed, and is not necessarily optimum.
Part 6 – Skinning the Hull; Decks, and Superstructure
There’s a lot of good material out there about how to skin a ship’s hull, so we won’t go into all the details of how to do it. Instead, in keeping with the themes of this series, we’ll discuss what actually happened, including some false starts and mistakes.
Part 5 – Fitting Out
So far, everything seems to be coming together quite nicely. We’ve clearly got the outline of a fine looking ship. But looks can be deceiving, and we’re about to expose some problems caused by early design and construction decisions. The choice of ship, while being a sleek and handsome design, presents its own problems when it comes to installing equipment to make her a fighter.
Part 4 – Framing The Hull
As noted in prior installments, I believe in preparation. I also like cutting, bending, sanding, filing, and in general making the dust fly! All the preliminaries up until now have been about getting ready to actually build something, but even the best planning and preparation won’t settle everything – there are going to have to be decisions made while the actual work is in progress. Things that you think will work won’t, or you’ll figure out a better way of doing something, while you’re in the process of doing it the way you originally planned. This is normal, and is part of the process. Knowing this, you can take things in fairly small, logical steps, so as not to over commit yourself to a particular direction and allowing yourself the luxury of being able to change your mind later.
Part 3 – Tools
I figure I’m probably pretty typical, in the sense that I’ve accumulated a variety of hand and power tools over the years. It’s likely that anybody who considers building their own model R/C combat warship already has a fair selection of tools, and is reasonably handy when it comes to using them. However, many of us aren’t that experienced at scratch-building models – and there are some differences between building a full-scale house, gun cabinet, or even bird feeder and building a model warship.