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Old Nov 14, 2012, 12:21 PM
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Rich215's Avatar
United States, CT, South Coventry
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Are Water Rudders Really Needed

I'm building an E-Flite 25 size J3 on floats and the cable sysyem they provide to drive the water rudder leaves a lot to be desired. So my question is, for this plane anyways, is the water rudder really needed? How affective is it? If I leave it off will I end up regretting it?

Thanks

I ended up adding the rudder. As I stated I wasn't impressed with the cable setup that came with the kit so I added a sub micro servo to the left float and connected it to the rudder using a flybar from a Trex 500. I did some test runs with it in the water and seems to track straight.
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Last edited by Rich215; Nov 30, 2012 at 12:04 PM.
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Old Nov 14, 2012, 02:49 PM
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Sopwith Mike's Avatar
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You will need a water rudder on any single-engined floatplane. On twins, differential throttle is best: if you can mix it with air rudder, even better.

The main reason is that turning downwind can be very tricky with just an air rudder and steering at all in any sort of breeze is just plain difficult.

The most elegant method is to bury a servo in one of the floats and have a single water rudder with a pull-pull action. If possible, the rudder should be able to trip up if it hits an obstruction.

Good luck!
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Old Nov 14, 2012, 04:08 PM
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Or a BIG rudder with lots of throw !!
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Old Nov 14, 2012, 04:10 PM
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I have several without water rudders and often wished that they had them , as Mike says turning downwind can be difficult .
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Old Nov 14, 2012, 04:50 PM
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how much's Avatar
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what they all said...

a water rudder on a single engined float plane is very very usefull... especially on a Cub.



it does however work better when its in the water... a different version of the perfect 2 point landing




David
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Old Nov 14, 2012, 08:24 PM
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United States, CT, South Coventry
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Thanks everyone for the replies. You've convinced me to use the rudder.

Quote:
Originally Posted by Sopwith Mike View Post
You will need a water rudder on any single-engined floatplane. On twins, differential throttle is best: if you can mix it with air rudder, even better.

The main reason is that turning downwind can be very tricky with just an air rudder and steering at all in any sort of breeze is just plain difficult.

The most elegant method is to bury a servo in one of the floats and have a single water rudder with a pull-pull action. If possible, the rudder should be able to trip up if it hits an obstruction.

Good luck!
Mike:

I picked up another servo that I'll mount on the float and connect it using a flybar rod from a Trex 500 that I had left over. The rudder that comes with the floats is brass and hinged so it will swing up if it hits something.

Dave:

Nice picture. I hope it survived...
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Old Nov 14, 2012, 09:20 PM
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There are techniques to taxi without a water rudder.
Most flyers can't be bothered to read the article, much less to understnd and practice the techniques. They are taught by the EAA for taxiing full-scale floatplanes.......
http://www.smilesandwags.com/Floatsi...%20skills.html
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Old Nov 14, 2012, 10:27 PM
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Water rudders are nessesary with ANY little wind.
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Old Nov 15, 2012, 12:14 AM
Art Schmitz
United States, TN, Crossville
Joined Jan 2012
392 Posts
Yep !! Even one water rudder is a tremendous improvement. Hard to tell the difference between one or two.
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Last edited by lindart; Nov 15, 2012 at 04:00 AM. Reason: added info
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Old Nov 20, 2012, 10:21 PM
Itchy scratchy
Joined Aug 2011
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water rudders

air boats work just fine with water rudders or turn fins.
i have a pby the water rudder (WR) broke off and there is no difference
my icon a5 has a little no effective WR
my skorsky s39 has a tail wheel that dosen't help much
i have learned move around just fine
generaly the prop blast is greater than the wind
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Old Nov 21, 2012, 03:26 AM
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Sopwith Mike's Avatar
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Quote:
Originally Posted by JimCasey View Post
There are techniques to taxi without a water rudder.
Most flyers can't be bothered to read the article, much less to understnd and practice the techniques. They are taught by the EAA for taxiing full-scale floatplanes.......
http://www.smilesandwags.com/Floatsi...%20skills.html
Hi Jim,

A very interesting article, and many thanks for posting it. My preference is still for a water rudder but I might unplug the one on my Fun Cub and try some light wind air rudder taxiing.

Mike
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Old Nov 21, 2012, 04:50 PM
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The trick to turning without a water rudder is to intermittently rev the throttle and quickly blast the air rudder... keep doing this in small increments to get the tail turned in the right direction, then do a fast-taxi (nearly on step) to keep sufficient air moving over the rudder. Of course, it helps to plan ahead and use the wind to your advantage... you might have to tack back and forth to keep out of direct cross-winds that could tip a high-wing plane. Then once you get to your spot, let the wind weathervane you into the headwind. Half of my seaplanes (I have over a dozen) have no water rudder and I manage just fine.
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Old Nov 25, 2012, 02:05 AM
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The seaplanes seem to turn better without a rudder than the float planes. Maybe it's because the seaplanes are so much lower to the water and catch a lot less wind. It's to the point now that I put water rudders on all my float planes without even thinking about it.
Putting a rudder on each float looks cool, but doesn't seem to work any better than a single one.

Dave
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Old Nov 25, 2012, 03:32 AM
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United Kingdom, England, Wigan
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Quote:
Originally Posted by Rich215 View Post
I'm building an E-Flite 25 size J3 on floats and the cable sysyem they provide to drive the water rudder leaves a lot to be desired. So my question is, for this plane anyways, is the water rudder really needed? How affective is it? If I leave it off will I end up regretting it?

Thanks
just worth mentioning.. if you havent flown it yet?

i assume you are talking about the eflite 25e Cub.. not the eflite 25 super Cub?

(there is a big difference)

then i would recommend

disregard the "equal control throws" for the ailerons in the handbook... the ailerons are massive on this model and really need taming.. set as described in the book the model is "a flying tip stall"

set the aileron neutral with both ailerons around 2mm up at the tip

dial in some aileron differential.. you want at least 3:1 ratio of up to down

set your dual rates on the ailerons to reduce throws even further if required

couple some rudder in with the aileron, i use around 60% rudder mixed

be extra carefull with the c of g.. make sure it sits slightly nose down

this really does tame the tip stall and turns it into a very pleasent model to fly

and

get some stick time on the model without the floats and get used to it first. fitting the floats adds a lot of weight and drag and will effect the handling.

all the above will matter a lot more than the water rudder
just my 2 cents worth

David
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Old Nov 26, 2012, 09:07 PM
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David,

Thanks for the suggestions. I'll definately take them into consideration.
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