LtDoc

I'm thinking about retrofitting a 'Becker' rudder on an 'A.Latina', "Amsterdam". It could use a little 'help' in the steering department (I knew I should have put in a bow-thruster!). I'm debating on what kind of hinges to use, not worried about how 'scale' it looks (much), just want the thing to work. Since it won't require another servo (controled from the 'main' rudder's movement) it 'seems' like it should be fairly easy to do ['said the blind pig']. If anyone here has had any experience doing this, I'd certainly appreciate any advice.

For those that don't know what a 'Becker rudder' is, it's a sort of 'flap' on the trailing edge of a rudder which turns in the same direction as the rudder when the rudder turns. Imagine your hand pivoting at the wrist as the 'main' rudder. A 'becker rudder' would be like your fingers curling in the direction of the turn.

Dizzy Dingo

Doc,

I've never built one so much, but I get the concept and have seen them working. The rig I have seen was on a small trailer sailer. The ruffer was built like an offer door hinge, big rod and overlapping eyelets. It would turn the extended rudder first, until it hit a stopper in the linkages, which would then pull the main body of the rudder with it. The thing could turn on a dime, for it's size, and jibing was savage and fast!

So with a pushrod rig (single or double) you would have a control arm with an "eye" on the main rudder and the end conected to another control arm on the extended rudder. Then put "stoppers" on the pushe rod that move hit the EYE and turn the whole rudder at a point!

I never knew that is what they called that kind of rudder. Live and learn.

Yeap, forgot the question. Air plane tail hindges shuld do. They even make brass ones for the larger planes. That should beable to hold the force of the water.

Cheers

DD

Umi_Ryuzuki

I would imagine that some nylon hinges from Dubro, or Goldberg would be strong enough. It's not like that extra flap is going to weigh a lot.

I am curious to see how connect the linkage.[:-]

PondSkimmer

I have never heard of them before but here is one on E*ay item # 5921482346

http://cgi.msn.ebay.com/ws/eBayISAPI...921482346&rd=1

LtDoc

Umi,
haven't figured out how to 'add' a picture yet, but lets see if this works;

'Doc
Pic came from "Modelboatmayhem" website... http://www.modelboatmayhem.co.uk/

Umi_Ryuzuki

That is really interesting.[:-]
Am I correct, that the further out the pivot point for the becker rudder is from the main rudder axis, the larger amount of throw it will achieve?

Here are some quick time movie and 3d files for the becker rudder.[8D]
http://www.hatlapa.de/bms/flap_rudder.html#

Gee, now I wish I had a ship that used one of those.
Doc, it's all your fault...

LtDoc

Umi,
I think you're correct about the pivot point. But, I also think you can move the pivot point too far very quickly (if that makes sense). It really shouldn't take 'much' movement of a Becker rudder to have 'more' affect than you'd want, turning the rudder into a 'brake'. Once the 'becker' reaches something close to 90 degrees from the 'main' rudder, it would seem like it would add more drag than turning force. Right?
- 'Doc

(Rats! Can't get the animations to play.)

Bill Noon

available off the shelf from Graupner
If you up for buying from UK..."Scoonies" in Scotland have a few different types.

Umi_Ryuzuki

Yes, but that takes all the fun out of making something that is so blessedly simple.

LtDoc,
Yeah, you wouldn't want a brake or any thing, you could almost creat a thrust reverser.
Can't wait to see how your build up comes out.

Umi

texmac1

I am fitting the robbe becker ruder to the amsterdam now, the design is simple and if you look at the robbe becker rudder the rear section acts like a flap when the rudder turns, a guide pin kicks the flap out as the rudder is turned. The robbe rudder has more surface area then the one with the kit and with the deflection should add to the steering with out adding to the vessel roll too much.

drspiff

At the risk of closing the barn door after the fact, I use a "knozzle" as rudders on some of my boats. The first one went on an LCP(R) and was made of 1 1/4" schedule 40 PVC pipe. The pivot point is about 25% aft of the knozzle leading edge and is directly in line with the prop rotation plane. It is a treat to see a landing craft almost turn in its own length.

The second one is about 2 1/2" in diameter and made from a discarded laser printer drum. This is on the MicroGlass 1:16 Army ST Tug and although it is not in the water yet, I expect to get pretty good rudder "control authority" with it.

Regards,

Dr. Spiff

texmac1

The problem with the Amsterdam is fitting a steerable Kort nozzle into the keel frame for the rudder and prop.
with out a major modification to the hull. when I get the brass prop fitted I will take a photo and post it.