All right, I'll consider the keel done. Using a 14" section of 2" PVC filled with lead shot will give a keel weight of about 15 pounds. The circle on the previous drawing is actually 2", not the 2.375" OD of 2" PVC, but you can see the basic proportions. Next question. What diameter is the prop from the Tamiya submarine motor? I would like to include a provision to mount the motor in the keel or rudder, or maybe even in the hull. That way you could run wires inside and have the on/off of the motor controlled by the radio.
OK, just found it. The Tamiya Submarine motor is designed to mount to a 10mm dia. x 16mm long tube. The plastic housing is exactly 1 inch dia, and its kort nozzle is 27mm dia. Overall length is 115mm. I was able to secure one on Mini-Constitution's 1/8" thick rudder using just blue painter's tape. The kits that I ordered include two spiffy mounts, one for a single motor and one for two side-by-side. Remember that the whole use of auxiliary motors will subject to change based on experience. Mini-Constitution never really needed one, since I could scull it forward with the rudder just as fast as the motor could move it, and of course even the lightest breezes were even better. I honestly doubt that a single motor will be enough to provide any reasonable motive force, but until we actually get some 1:48 scale ships up and running, I have no idea how to structure the rules on emergency propulsion motors.
I've been working on designing the sail control mechanisms. Sail control isn't as simple as running some lines down to a sail winch servo, because of trigonometry. As the yards rotate, the total length of the line changes. The minimum required line is longest when the yards are perpendicular to the keel, so some slack develops as the yards rotate to either side. Unless this slack is dealt with somehow, it introduces slop in the sail controls which makes it easier to accidentally back your sails and more difficult to recover. So an important part of any sail control mechanism is a way to deal with slack. I have two different designs that I'm working on. The first is pretty basic, it's a fairly traditional servo mount with a pair of springs that pull any slack back and away from the servo drum. This is functional, but requires the use of a sail winch servo and drum control. It also requires two springs, each of which has to be able to take up the entire amount of slack. The second design has both servos sliding on a pair of 3/16" brass rails, with a single spring (or bungee) each. By sliding along rails, I can halve the effective travel distance needed to absorb the slack, while simultaneously increasing the effective travel as the servo itself moves. It can also be used with parallelogram sail control, so you can use standard-sized metal geared servos if you want, instead of sail winch servos. I'll try to get some drawings up over the next few days.
The sliding servo tray method is well used on other square rig ships and the method I was planning on using on a square rigger.
No real progress on the kit for now, but I have been making progress understanding sailing terminology. I picked up a book on building display models of 5 different sailing ships from the Maine Maritime Museum. It's an excellent book, not only having patterns for the ships but also explaining all the rigging for both square riggers and fore and aft sails. So now I know the difference between a shroud and a stay. I've been working on a couple of things. First is an experiment on using the rudder for propulsion. If it works out I'll share the results. The second thing I'm working on is how to handle the removal of the masts and standing rigging. I'm aware of the model where the entire deck comes off with the masts, but I'm wondering how other modelers deal with attaching the rigging when just the masts are removed for transportation. Can anyone share their technique or refer me to some how-to web sites?
The book that the Coast Guard Academy publishes for cadets to learn to sail the barque Eagle is very helpful and like $9 on Amazon.
I was going to leave the lines on the masts with the sails and use fishing swivels to attach to eyerings that are on the deck. For more historical data, try the mystic seaport museum in CT. That place is just plain awesome.
It's been a while since anything has happened with this project. However, yesterday I showed up at Tugboat's house with this drawing: http://www.rcnavalcombat.com/Portals/0/Users/Kotori87/Scan0001.jpg A couple hours later, and the prototype slack-absorbing sail control system was complete. The premise is simple. Two sail-winch servos are mounted on a pair of rails suspended beneath the deck. The servos slide back and forth along the rails to absorb and release excess line as the yards swing from side to side. My drawing is somewhat simple. All the plates are constructed from plywood. Four copies of the plate on the left will form the two servo mounts. Each one has two slots cut, one for the standard-size sail-winch servos from Strike Models, and one for the ubiquitous Hitec sail-winch servo. Either servo will work. The holes on either side of each plate are for 5/32" brass tube. Other shipbuilders using this type of mount reported binding issues when just using plates, so I designed this one to use 5/32" tubing to smoothly slide over the 3/16" brass rails. The plate on the right side of the drawing is for mounting the rails. The only real requirement for them is to hold the two 3/16" rails the correct distance apart, the rest is open to adjustment. I intend to hang them down from the subdeck, rather than up from the keel. This allows the entire space below to be used for batteries, or CO2 bottle, or solenoids, or other systems. The actual mechanism is to be mounted between the main and mizzen masts, leaving the large area between main and foremast open for armament. That's it for now. Hopefully more to follow soon.
I believe that he plans larger diameter rods, and stainless... he was just prototyping in the shop with what I had laying around.
Very similier (if not identical) to the sliding trays use on model airplanes. It is exactly the type of system I was planning on using in Mark's frigate. An elastic band or light spring between the servo tray and a solid hull anchor will keep tension on the sheets and allow for the tray to move as the yard geometry slackens/tightens the sheets.. Perhaps a possible concern is the servo mounts may bind on the rods without solid support between the end peices. Perhaps a box type frame around the servo would be better to keep the two end pieces from twisting and binding up on the rods. Another option is to glue the end pieces on a larger diameter tubing that will slide on the rods and prevent twist binding.
I was contemplating printing an entire sliding unit that you slip the tubing into, that then goes onto the solid rods. It would have the two ends connected.
@Mark, the rails are not cut to length. I just used what was available without cutting up good propshaft material. @Mike, it isn't readily apparent in the photos but the actual wooden servo mounts aren't riding directly on the rails. They hold a pair of 5/32" diameter brass tubes, which slide smoothly over the rails.
