Excellent vid (and build!).
Good find TD👍
😎

Martin555,
You are most welcome. I was glad to help. BTY, my own curiosity forced me to do it. I had always assumed( not a good thing to do as this case shows)
that the three rudders worked together at the same time. I have been educated.
Jonathan

Hi ToraDog,
Thank you for posting the video it made it a lot easer to understand the explanation of the effect and the rudder setup.

Martin555

I found a nice YouTube video of an Italeri r/c conversion. At about the 2:10 mark he shows the rudder arrangement. It is worth looking at.

Hi ToraDog,
I first heard of this effect when working on a Lürssen T45 FAC, which had basically the same hull as the S Boot. But the principle is explained in the link you posted😉-
"These rudders force the water under the hull outward, lifting the stern, thus reducing drag, and lowering the wake height, which “requires less energy, allowing the vessel to go faster."

"The effect was noticed at speeds above 25 knots, by swinging the "effect" rudders outboard by 30°. Once attained, the effect rudders could be swung back to 17° outboard, and the speed could be reduced to as little as 20kn while still maintaining the benefits of the effect."

"During test runs with S-2, the first boat from series production, it was accidentally discovered that the boat stopped responding to the rudder at high speed and full rudder positions but started to display the effects described above. When investigating what caused this behaviour, the basic principles of the Lürssen effect were discovered. Starting with S-2, the following boats were then equipped with the two small rudders on either side of the main rudder which could be angled outboard up to 30°.
A wedge was added under the rear of the hull from S-18. The wedge further added to the effect of helping the craft to stay level at high speed."

Alles klar Herr Kapitän?
Cheers, Doug 😎

Doug,
That is interesting. When were the outboard "rudders" used and what activated the movement? It sounds like they were moved at specific times and to specific points, rather than proportionally. If so then a computer radio should work well to activate them using a mixer function, which could be set up to just about any parameter. I would do it,, but I gave away my E-boat hull. LOL

I too had been pondering the application in a model TD👍
It means actually having two control channels!
The outboard rudders are not used for steering and in fact should NOT be linked to the main rudder, only to each other! But not directly as they work in opposite directions.
Maybe they should be referred to as 'vanes' rather than rudders?
A second servo and control channel would be needed to swing them out by 30 or 17°.
I wonder if the Lürssen Effect would be measurable on a model!
Whose up to try it?😉
Cheers, Doug 😎

The e-boats used the Lurssen effect very well. I would be interesting to try it on your built. It is explained here: https://en.wikipedia.org/wiki/L%C3%BCrssen_effect

thanks prob will

Just happy to help Phil.
I also agree with Doug a Schnellboot build log would be good.

Martin555.

Phill.
You are welcome.
Don’t be afraid to ask for anymore help or pictures.
Regards Bill 👍🍷🍷

wow thanks for the pic helps a lot

thanks bud helps a lot

Me three.

"PS.Be good if you could do a blog on this.I for one would be interested 👍 "
Me too Phil👍
Cheers, Doug 😎

Great minds think alike Martin.
Regards Bill 👍

Hi Phill.
Martin and I are on the same wavelength here.
I attach (hopefully) six pictures of the set up I used in my Schnellboat.
I used the rudders from the kit and made the tubes and posts on the lathe.
I find that the turning circle is adequate for my needs,but I have made an attachable rudder that I put over the centre main rudder.To be honest I don’t use it as it really doesn’t make any great difference.
If you check out my boat harbour there are more pictures on that.
Also,I have built her so that the front and rear guns rotate.
If this is something you were thinking of then I am happy to share pictures of the set up.
Just let me know.
Regards Bill

PS.Be good if you could do a blog on this.I for one would be interested 👍

Thanks Martin.
Weird! Some odd things have been happening with pics lately🤔

BTW I much prefer the method in your sketch👍
The method in the photos looks more difficult to set up, and the movement looks very restricted.
Cheers, Doug 😎

Very strange Doug.
I don't know what happened there.

Martin555.

Odd! Your pics suddenly vanished Martin!
Can you repost them?
Doug 😎

Hi Phil,
Here is a very rough sketch of one way of doing it.

Pushrod from servo goes to "L" shape rudder horn.
1 x 'L' shape rudder horn
2 x straight rudder horns.
1 x link pushrod
1 x servo pushrod.
4 x linkage stoppers

Connect the three rudders using 3 x linkage stoppers and a long pushrod.

Connect the servo pushrod to the "L" shape rudder horn using 1 x linkage stopper or clevis.
(See sketch)

[Edit] also some photos of a similar method.

Hope this makes sense.

Martin555.