Seaplanes Aircraft that typically take off and land on water...radio control seaplane discussions are in here.

anybody using twin water rudders on Goldberg Superloats??

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Old 11-24-2013, 01:29 PM
  #1
nwright27
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Default anybody using twin water rudders on Goldberg Superloats??

yeah I know its not needed, but just for "scaleness", is anyone using a water rudder on each float? how would I set that up?
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Old 11-27-2013, 03:05 PM
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JohnBuckner
 
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Hi NW, I have a set of the superfloats that I built and installed with cantilever single struts on a Killer Kaos, non scale of course. Now if I remember correctly the kit included all the hardware to use a tie rod all the way across to bind both rudders together. I even on one outing flew the ship that way once. Looked silly and of course that is certainly not what you would see on any full scale ship, at least that I know of.

My response was to immediately remove one of the rudders and use it on the next ship. I suppose you could if you really needed to was install two servos in the floats and Y cord them but I have always hated servos in float as that's so often seems a source of trouble that I have noticed with the fellows. Also pretty hard to hide the nasty looking servo wires up the struts. On the same thought I suppose you could come up with some sort of dual mechanical linkage the that could be a real rats nest of adjustment problems and be even more work when it came time to remove floats for wheels.

Now to the real problem. Two rudders fully extended and down during takeoff is a major drag deficit, noticibly effecting takeoff even possibly precluding a successful takeoff in cases where your engine may be marginal anyway. In my opinon two rudders swiveled down an in the water is a real bad idea. Remember we have no way to raise the rudder before the takeoff run which is a mandatory check list item the the full scale floatplanes that I have flown.

Two rudders tend to make the airplane works so hard getting off the water that it definitely precludes the beautiful floatplane type departures we all dream of. I would suggest you accept the slightly non scale use of only one rudder unless your are participating in scale contests with your ship.

John
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Old 12-05-2013, 08:00 PM
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ive never figured out how to post a picture, but i have a semi custom set up on a goldberg cub with the matching floats. i bought a pull pull cable kit, made a second rudder, and some pulleys out of lego wheels to essentially build a full scale style cable system. once i got the cables made and rigged up its worked extremely well dispite the pulleys being kind of half assed. run a cable from horns on both sides of the rudder, forward to the rear float attachment, then down to the float and back to the water rudders, and a third cable forward from the water rudders to the struts and accross, tighten em up and your off to the races.

if the rudders are mounted loose enough they will fold back with any amount of speed in the water, with the full scale you dont hardly notice if you forget to put them up, unless you need a ton of rudder input before you get on step, then its a bit stiff. otters and beechcraft had a clutch mechanism to disconnect the water rudders completely when up. the biggest problem you will likely have leaving the rudders down is having to get to the beer store before it closes
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Old 12-07-2013, 11:10 PM
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Floats on what aircraft?

The very simplest linkage is on low wing aircraft with strip ailerons.
Just mount normal control horns on the bottom of each aileron in
line with the floats & run a single wire pushrod straight back to the
rudders.

Steer with the aileron stick until lined up to take off then steer with
the air rudder for take off. - John.
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Old 12-08-2013, 07:53 AM
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If you want to do it for "scaleness", check out the photos of the cubs at Brown's seaplane base.
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Old 12-08-2013, 08:02 AM
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If you want to do it for "scaleness", check out the photos of the cubs at Brown's seaplane base.
The cable linkage starts at the rudder horn, goes forward, thendown, then back to the rudders. Easy to make with fishing line.
Instead of pulleys, I use 2-56 screw-eyes-like the guides on a fishing pole.
Additional cables are used to retract the rudders. They are only used for taxiing, and retracted for high-speed operation (Takeoff, landing) or momentarily retracted to drop weeds from the rudders.

Ernst rudders have the retract feature built-in as an optional hookup.

You can see the linkage at the start of this video. http://www.youtube.com/watch?v=mcE6RXGZkp8
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