Hi all,
I am 90% finished with some blown up Sig Floats for my Balsa 1/3 Scale Cub. Does it make any difference if the water rudder is on the right float? The plans had HUGE TYPE that said to put it on the left float. Any reason??

-Patrick

p.s. I am NOT asking because I accidently put the rudder on the wrong float or anything! -lol

MOST airplanes need a little right rudder just after liftoff, to compensate for engine torque, P-factor/gyroscopic precession of the rotating powerplant masses/ and-or onboard evil spirits.

If the water rudder is in the left float, it will cause a drag toward the left, so you will already have some right-rudder dialed in assuming you were able to hold the plane straight on the takeoff run.

If the water rudder is in the right-side float, you may lift off with some left rudder, causing the airplane to be in a cross-controlled configuration, low, and slow all at the same time. Things can get real bad, real quick when that happens, and you might have to go for a boat ride.

However, it's not all bad. The water rudder SHOULD NOT be in the water except when you are taxiing slowly. Once you are up on-step, it should be high and dry, and it shouldn't matter which float it's on. Check your WR, and see if it sticks down more than the height of the step (1/2-3/4") below the transom of the float. If it does, you can trim it or adjust its position, or at least install a kickup rudder that will ride out of the water at high speed.

I'm a little confused. Don't talk to my wife she would say I'm a lot confused.
If the water rudder causes drag located on the left float, wouldn't the drag point the aircraft to the LEFT? Doesn't that offset the right rudder input? And since the aircraft is level on floats, wouldn't the P-factor be much less than an aircraft on land with a tailwheel?
How about two water rudders?

Bob

In my opinion, here is Jim's most important point and why you really don't need to worry about it much:

"However, it's not all bad. The water rudder SHOULD NOT be in the water except when you are taxiing slowly. Once you are up on-step, it should be high and dry, and it shouldn't matter which float it's on."

I have one set of floats with an Ernst rudder, and another with a very similar type. I leave the little rubber band OFF, for the above stated reason.

I agree with Jim totally, but there is another factor that affects water stearing. If your floats are too small for your plane, they will ride too deep in the water and you end up with 2 long objects stearing your plane straight ahead. With the proper amount of floatation the floats ride much higher in the water resulting in better stearage. You really should'nt rely solely on the rudders for stearage anyway. The skillful use of the throttle in turns will reduce the need for water rudders. In fact, I only have one plane with a water rudder and the rest I fly without one. You just have to remember to not let yourself into a position where you don't have enough room to make your turns, as they will be a bit wider..........Seaplane

My opinion, and obviously that of many others I have seen with large scale birds, is dual rudders. In fact look at full scale birds, they have 2.

Something I have also done with my planes is to set a second rate, if you have a tx that has adjustable rates, with max travel for low speed water travel. Once on step I flip my rudder rate switch to normal and away I go.

One thing I have not seen in r/c is rudders you can pull up??? Full scale you can/and do pull the rudders. Maybe I am missing something. I belong to a large float club and have seen a couple hundered planes of various set up's and never retractable rudders.

One thing that works great if you have a Northstar is to steer with the rudder and ailerons. The ailerons when deflected make great brakes in the water.

Have fun and happy flying.

ps. If you want a good picture referance go look at the forum FLOAT CUB PIX in the seaplane catagory

these guys have a bunch of scale pics and they look great.

1. If the rudder is on the left, its drag pulls the airplane left, and you throw in a little right rudder to compensate.

2. Ernst rudders are very scale-like in their retract mechanism. All you need is a retract servo to pull a cable.

3. I can get long-winded about this, but if the motor is running, you can turn the plane with the air rudder(and a combination of elevator ant throttle). If the motor is not running...it does not matter.