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Easiest way to install a water rudder


Old 12-09-2006, 10:46 PM
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Default Easiest way to install a water rudder

I got a pair of seemingly nice plastic floats off of Ebay to install on my Alpha 40. So far, the modifications to the fuse is going well, but I'm kind of stuck on the water rudder. The kit I bought doesn't have directions, but it does include a water rudder with about a 12" long 1/16" rod sticking out of it. I'm assuming this rod is for connecting straight to the air rudder, but I can't do this on the Alpha because the horizontal stabilizer extends past the rudder. So I need another option.

I'm looking for whatever is quick and easy, appearance means nothing. I've been reading about the nyrod setup, and that seems to be the route to go, but I haven't seen any clear pictures or schematics on how this setup is supposed to work. Can I just buy the nylon encased braided cable and other hardware from Ace Hardware, or do I have to go to a hobby store for specialty stuff? What's the best way to connect the cable to the rudders? Also, what's the best way to attach the water rudder to the float? I'm thinking that using a small hinge would work, but I'm nervous about screwing something into the back of the float and causing it to take on water. Should I be?

Thanks for all the help guys, with any luck I'll be flying off water on my birthday next weekend!
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Old 12-10-2006, 07:48 AM
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Default RE: Easiest way to install a water rudder

There are at least seventeen other ways to do everything I mention here.

If your floats have a flat transom like a ski boat, it's OK to screw the water rudder assembly to it. A smear of silicone before you tighten the screws will keep things dry. $6 for a medium-sized ERNST water rudder will be a good investment. If there is no reinforcement to the transom of the float, epoxy on a plywood plate first.

If your floats look like this

Then you have to get creative.

Probably easiest in this case would be a tailwheel bracket with the long extended rudder you mention.

Some people epoxy a tube vertically thru these floats and use a rudder mounted underneath.
Some people have built up a transom (like the bracket for a trolling motor) to mount a rudder to one of these.

Steerng: Remove your nosewheel assembly and replace all the pieces but the strut with a small piece of the same diameter music wire. If the nose wheel tiller on the alpha is below the firewall, then just attach the linkage to that. If the nosewheel tiller is above the bottom of the firewall, get another one at the hobby shop and mount it just below the bottom of the plane. Then you can run two pieces of fishing line back to the water rudder (my preferred method) or a single nyrod pushrod.

Here's a good shot of the NYROD linkage

You don't need 2 rudders. THey just get misaligned with each other like the plane in the pic.
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Old 12-10-2006, 02:05 PM
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Default RE: Easiest way to install a water rudder

I prefer to mount the servo in the float. Enclose in a latex glove or large balloon. The servo wire enters through the wrist hole in the glove, the pushrod exits one of the fingers. Bunch the excess 'finger' material up a bit and secure to the pushrod and it will move back and forth like a bellows. The wire entry and pushrod exit are tied off securely and easily with fishing line.

Mount the servo just as you would any other servo, using a washer and screw right through the latex 'bag' containing the servo and into the servo mounting rails. It will seal just fine around the washer. I have used this in salt water, no problem. The harder of the two holes in the glove or balloon to seal is the one with the servo wires passing through. I use just a bit of silicone seal just before finally tying the latex 'bag' closed and have never had a leak.

The other system I have used is a pull-pull setup using Kevlar based (non-stretch) fishing line such as FireWire and Power Pro. These lines are 'slippery' and can be run even around 90° corners without loading the servo too badly. I use small fishing rod line guides. I use these: get the smallest you can. You can attach the guides to the strut supports and the system is so smooth it will allow two 90° turns in the fishing line with almost no friction to speak of. Both lines, go through the same line guide, you do not need separate guides for each line.

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