on a cleveland class and in general how far should a rudder move in degrees i am thinking it should be about 30 degrees but need confirmation so i can buy servos the one's i have been looking at are 60 degree and i plan on a 2 to one gear drive so if i put the bigger gear on the rudder i get 30 degrees on the servo i get 120 on strikes site it says the large gear goes on the servo but i have seen many setups here where the larger gear is on the rudder suggestions please
180-ish, we'll really until it hits the props. Easy enough to adjust end points so it doesn't hit and that gives the most room for testing and tweaking to find the throw / turning you like the best. Some servos can turn that far, it's pretty easy to do with gears, people have even had impressive results using pushrods, personally I think gears are the way to go.
Everyone I know puts the large gear on the servo and small gear on the rudder shaft. If you reverse it you are limitting your throw, which is generally not a good thing. As Snipe mentioned, lots of folks have used pushrods very effectively. I second going with gears!
depending on geometry, the rudder will have a peak side force between 45-85 degrees off axis (further maybe with some of the odd geometry rudders), after which the side force that turns the boat is directed more to drag, stopping the boat. Years ago with an airfoil geometry I ran the cfd on the rudder to see what impacted the peak force / angle thereof. the peak can be steep and fall off fast as the rudder stalls.
If you can find a servo that fits in your allotted space and has around 180 degrees of travel, you can run 1:1 on the gears and still have plenty of throw that you will want to limit it with the end stop adjustments on your radio. I had found a neat servo chart somewhere that compared numerous servos and one of the criteria was the degrees of rotation, making it easy to pick one that fits your requirements. Usually it's listed in the servo specs how many degrees of rotation they have. I will try to find that chart, but it's been well over a year since I have seen it.
Servocity.com has that kind of info for Hitec and Futaba servos. In addition, they will modify some servos for 180 degree rotation for a little extra $. They also have gears with servo splines in them. What % thickness did you look at?
rudder design | R/C Warship Combat sadly much of the important data (position, shape, etc.) has been lost. I recall the airfoil profile was generally fat in the front and I tried convex throughout as well as concave in the trailing portion. I moved the rudder post around and other things lost to time.
if I recall, it meant that the trailing half of the rudder had a concave shape (CC) so that would make CX-CX be a convex everywhere rudder shape while CC-CX was concave for part, convex for part. I know I have the files somewhere I just have to find them
not quite goldfish cracker. both airfoil shape. one was curvy out all the way, the other was concave for most of the trailing 1/2 similar some of the super high AOA slow electric airplane wings
