R/C Naval Combat

Wow... I'm all buttered up. What would you like to know?

Its a square-ish piece that fits under your the rear of the boat.

Make sure you get the right size rudder or rudders.. check your rules for area specs

rudders change the boats direction by adjusting the water streams created by the props; so make sure your rudder / rudders are infront of your props

Some people say "wing shaped" rudders are better than just a straight flat piece b/c of water-aerodynamics. I can't say I subscribe to that.

Well, I've played with a lot of rudders and I do subscribe to the "wing shaped work better" if you chose the correct airfoil. (That and the physics demand it to be so) Now how significant an advantage I am less sure, and I wish that I had done some testing with my old yamato... (she turned wonderfully tight with her thick airfoil shaped rudder). If you are wondering why, it is because we get a net force (lift as far as the rudder is concerned) to turn the ships off both sided of the rudder. The flat plate will cause the flow to separate on the aft side of the rudder prematurely which reduces the turning force applied to the ship (and greatly increases the drag). The net result will be that you will be able to turn the same diameter at a faster forward speed. Definitely worth the trouble if you can find airfoil shaped rudders or make them. check out www.profili2.com I used their software to pick an airfoil for my yamato rudders (not that I remember which one). We have relatively low reynolds number flow and we want an airfoil that is symmetric and functions well at high angles of attack...

As far as driving there are several options that I have used,

Servo with rod linkage and ball ends- This is by far the simplest but it will generally restrict rudder throw.

If you are making your own rudders, one should balance them with ~1/3-1/2 of the rudder in front of the post and the rest aft (depending on rudder design). This helps offload load on the servo by balancing the forces that the water puts on the rudder about the post, thus reducing the work the servo has to do.

Charlie's Gears- glue the big gear to a servo horn and the small ones attach to the rudders, probably the second easiest to set up and the best all around system I have used in combat.

Belt/Chain drive- I am using this on my tirpits. I am using a timing belt and pulleys and a custom mount that allows me to properly tension the belt. A pulley is attached to the servo output by cutting a length of 1/4 stainless tubing (the same stuff that is used for the cannon barrels) to just the right length (and turned down on the end just so) that it almost snaps into the servo wheel's center depression and allows a long threaded screw to tighten it down. the pulley is setscrewed to this. The roughness on the cut end digs into the servo wheel preventing relative rotation. We will see how well this works...

I have that much I was looking for how do you mount and drive it different ways chain linkage that sortof stuff and really dumb question how do you go thru hull with it?

thanks Greg

>Now how significant an advantage I am less sure

That's why I don't subscribe... I might play with the airfoil shape some other year, but for today I can't imagine it makes toooooo much difference. Seems to me like one of those "works well on paper" theories.



I do like the idea of using pulleys for the rudder. Not sure why I never thought of that! That solves a problem I was about to face this weekend! THANKS GREG!

any new un blury pics and where would I get the belt & pully ?

And a little off topic but well I have you here what are the specifics on ESC I know I needed something or not on it different from my old RC cars

I got my belt and pulleys from www.mcmaster.com I used the MXL series belts.

i might try this however my only trouble is going to be turning down the shaft i dont have the fance tools

I've created a new topic for your ESCs...

http://www.rcnavalcombat.com/rcnavalcombat/forum/topic.asp?TOPIC_ID=308

thanks

turning down the shaft? I just found pulleys with the proper ID

quote:

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Originally posted by Powder Monkey

i might try this however my only trouble is going to be turning down the shaft i dont have the fance tools

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I also have problems saying no to the shaft. The shaft sometimes has a mind of its own. Especially around tools.

When it comes to rudders, in a boat like the Liberty Ship you have lots of room so you don't need to use fancy stuff like pulleys or gears. You can, so you know how to when you decide to build a ship with a tighter stern like Bismark or Scharnhorst, but it's not necessary. I also do not use airfoil-shaped rudders. I prefer thick, solid sheet brass to anything plastic or wooden. I've seen wood and plastic rudders damaged by gunfire, but I've never heard of anyone losing a good brass rudder in action.

The way I build rudders is like this. First you need a 1/8" brass rod, and a length of tubing (brass or stainless steel) that the rod fits in. You also need a sheet of brass plate, I like 1/16" but other folks like lighter. Cut out the shape of your rudder from the brass plate, and smooth the edges with a file. Position the brass rod (make sure it is much longer than it needs to be, you will trim off the excess once you have installed it) and solder it in place. You may want to make a jig so that when you solder the rudder to the rudder shaft, it is centered. Try not to use too much solder, but it's better to use too much solder than too little. File off excess solder and polish your rudder bright and shiny.

Once the rudder is built, its time to install the rudder post. Check your plans to see exactly where the rudder is supposed to go, and mark it on your hull. Check to make sure the rudder won't interfere with props, hull, etc. and if it does, move it so it doesn't. Then carefully drill a hole the same size as the brass or stainless steel pipe on the marked spot. Test-fit the pipe, and decide how much you want for your rudder post. Make sure that the top of your rudder post will be above the waterline of your ship, otherwise you'll let in water. Cut it, remove any burrs, and test-fit again. Tack it down with a bit of CA glue and try inserting the rudder. If it isn't perfectly vertical, break the pipe loose and tack it down again, using only a bit of CA glue per attempt. Once you are satisfied, secure the pipe, now called the rudder post, with your favorite glue.

I like to use a 1/8" ID collar to hold the rudder in place, and there's a nifty item by either Great Planes or Du-Bro that I use for a rudder arm. I think it's called a wheel pant bracket or something like that, but I like it because it's designed to take control rods on both sides. Not only that, but it's short so you get a good range of motion with standard servo arms. DO NOT use a control rod on only one side, because it will not move the rudder equal amounts in both directions. I would also beware of using pulleys or anything else that can shift and permanently change your rudder's centering, because rudders get shot during combat (especially transports) and you don't want to pull a Bismark and spend the day driving circles.

http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXFV63&P=M

is this the duhicky you are talking abought

No. I searched through Tower Hobbies, but didn't see it. I'll see if I can get a picture of it.

here are some pictures of my rudder setup

http://thetriphome.blogspot.com/2007/04/more-running-hardware-shots.html

Here's a picture of the steering arrangement that I use, including the rudder arm that I like:

The rudder is not installed in the photo, but you can see how it all would be laid out if the rudder were present. Also, please note how the servo arm is much longer than the rudder arm. This gives a good range of motion for your rudder, so you can turn really sharp when you want to. It uses 4-40 threaded rod for the control rods, with 4-40 ball joints on the ends. You can also clearly see rudder arm that I like to use. If you see it at a hobby shop, get it because it's good stuff :)

If you are interested in better ball links, check out the replacement parts for RC helicopters. Generally stronger and easier to use than the fully encapsulated versions shown in Carl's photo. (also if you go with ball links, get a pair of ball link pliers, they are a great thing to have around)