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[RMF]

Hi,

Got a 56" Vosper in construction with a twin rudder set up.


I'm looking for advice on positioning the rudder servo in relation to the rudder posts and how to then link that to the tiller arms on the rudder and the rudder/rudder linkage to get an even throw in both directions. The rudder / arms are proprietary items from any model shop.


I've seen a few ways of potentially doing this, but don't want to build one particular way to find out it doesn't work as well as it could?.


My biggest concern is getting even movement in both directions.


Can anyone offer any advice?.


Thanks


Richard

[dougal99]

Use an L shaped arm on the rudder connected to the servo and a straight arm on the other rudder. One leg of the L and the other straight arm should be in line with the length of the hull. Obviously the other leg of the L will be in parallel to the beam. Connect the two legs that are in line together and the other leg of the L to the servo. All movement from the servo will be replicated in both rudders.


Hope that's clear. Easier to do than explain.

[Umi_Ryuzuki]

He means something like this...

 

[Neil]

the simple way is always the best and most effective..............keep the linkages as short and direct as possible and as close to the rudders as possible.......

here is the set up on my twin rudder'd and twin prop'd Flying Christine.

neil.

[Peter Fitness]

This is how I set up the twin rudder linkage in my Grand Banks pleasure cruiser. It's straight forward and very effective.


Peter.

[Neil]

hey peter...what are those two six inch nails port and starboard for

[Peter Fitness]

To hold the boat together Neil, what else?  


Actually they're the greasing tubes for the prop shafts, like the one below which I made for another boat.


Peter.

[Neil]

now that peter, is modelling to a greater level..............making caps to go over the tops of the tubes...............my hat's off to you sir............I can't even be bothered putting grease tubes on to mine........tried it once and being totally heavy handed drilled through both layers of the tube.........never again. lol...........

and how are you...........haven't spoken in  ages..........keeping well I hope. neil.

[Peter Fitness]

Neil you're too kind   I use a small pedestal drill which allows greater control over the depth, thus preventing drilling right through the tube. The slide on caps are the next size up which allows a snug fit, and a small piece of flat brass is soldered on for the top. I use a small syringe to put grease in the cap then slide it on thus pushing the grease into the prop tube. I generally silver solder the grease tube to the prop tube for greater strength.


I am keeping well thanks Neil, I've been busy since moving back to the farm, and loving it. I haven't been doing much modelling, other than maintenance on my boats, but I sail regularly at our club lake. We have been enjoying a spell of fabulous Autumn weather lately, and sailing has been an even greater pleasure than usual.


Peter.

[Neil]

good to here Peter, good to here.................am I right in thinking your farm is near Lismore.

had a friend from Lismore years ago who's father had a farm on the outskirts.....they were called Sullivan...............peter Sullivan was a mate of mine........we used to live in Canberra but ride our motorcycles to Lismore during the summer breaks from teaching......and enjoy the fun and life up there,....great times they were too. Take care.
neil.

[Tbone]

Have you considered running a dual servo setup?
I hadn't considered this option until I stripped the gears on my rudder servo last time out.  The boat in my example was a single kort mind you but it made me realize I'm going to dual servos on my dual steering models.  Getting the boat back to shore was interesting with the erratic operation of the steering.

[derekwarner]

Interesting concept Tbone.......would the two Kort steering servos be...

1. driven independently?
2. mechanically interlocked?
3. just for extra torque?
4. redundancy?
5. double trouble?
6. what is the max degree +/- of rotation of the Kort nozzle over a propeller?

Derek

[Tbone]

They will be on the same channel with a y-harness. The harness I have allows you to center each servo independently.
They will not be mechanically interlocked, one servo per rudder. I don't think it will cause problems just for redundancy.

Thinking about it though if you have independent control of each prop or a mixer setup it will steer ok without the rudders anyway so maybe not really necessary.....

My single kort tug will get a stronger servo and possibly a servo saver.

[derekwarner]

 .... my knowledge of electronics & black magic things is very limited      ....but I thought a Y -harness would reverse the angular direction of the second Kort nozzle

So thinking about this...would a 15 degree to port command not turn the port nozzle to 15 degrees to port ....and also turn the stdb nozzle the same 15 degrees but to stdb?

This could be good for straight line running  , draining the battery or going nowhere fast around corners

Please clarify where I am going wrong.... ...........Derek

[Tbone]

That depends on how you set it up. You can set up the linkage to do what you want or mirror it and use a reversing y-harness.
The main advantage of the y-harness I'm referring to is that it allows you to center each servo individually and then trim on the tx will adjust both together.

Not sure if this make sense.

[sparkey]

  Neil,regards drilling prop tubes I always put an old shaft in the tube stops you drilling right through,also stops solder getting into the tube,as for the rudder set up I have only one boat with twin rudders and that has the Y set up no and have no problems,Ray.  

[inertia]

.... my knowledge of electronics & black magic things is very limited      ....but I thought a Y -harness would reverse the angular direction of the second Kort nozzle
Please clarify where I am going wrong.... ...........Derek

Derek
A standard Y-lead will simply send an identical signal from the receiver to two servos. Thus if they are the same make and type then they will rotate in the same direction. If you want to reverse the rotation of one then you need an extra device between that servo and the connection to the Y lead e.g. a servo reverse lead. TBone's Y-harness sounds altogether a more sophisticated thing in that it allows centring of each servo. More details please, Tbone.
DM

[Tbone]

Try this link:
http://www.horizonhobby.com/products/y-harness-6-inch-reverser-standard-EXRA320


That's the reversing version but you get the idea.  It will run one servo directly from the receiver and the other will run reversed; it also includes the pot to adjust the centre of the second servo to match the first one. 

[derekwarner]

 ....Tbone....the functionality of the component link you have provided will just reverse the direction of the Korts tubes...... 

DM........thanks ........but I think I should stick with steam........ .....Derek

[inertia]

Derek

Please have a look at this (I drew it especially for you.... ):
 The standard Y-lead will move both servos in the same direction of rotation on a given stick command. There is no provision for adjusting the centres of either servo.
 The Reversing Y-lead will move the servos in opposing directions of rotation on a given stick command. There is provision to adjust the centre of one servo (to match the other). This would be used generally in model aircraft to operate two aileron servos (one in each wing).
 Nothing in the review you've shown contradicts this.
 Quite which lead would suit your Korts best depends on how you have mechanically connected the servos to the Kort steering arms.
 I can't explain it any simpler than that - and steam is way beyond being a black art to me! The stuff still keeps coming out even when you switch it off!!
 DM
 

[derekwarner]

OK & thanks DM  .......

1. actually fluids...steam, hydraulic oil or the like operate in the same way or principals in circuitry as do electrons
2. steam is silenced when shut off 
3. electricity is isolated when shut off 

Both have the potential to kill if not understood & respected

4. I will stick with my wood fired BBQ    ....& cooking for the grandkids........

PS....did I ever mention that I have a big bag full of Craig Talbots goodies that I have not commissioned yet?...so don't leave town....... ...Derek

[sparkey]

  That looks interesting all that action bits and bobs, what's are they going to end up in?

[derekwarner]

Hi sparkey....those ACTion bits are .....

1 x P56
1 x P29A
1 x P34A
2 x P79

Originally purchased for a twin motor electric drive's for a side paddle wheeler [but never used or connected] .......fell in love    with steam instead

Derek

[sparkey]

  I have got a "project pending" box with all bits of electronics in, trouble is it is getting rather large,you never when you might need them,getting back to the linkage problem I still prefer the Y system once set up right I have had no need to adjust it,also if you knock one rudder out of line turn receiver off and on and they go back to original setting bingo,Ray.

[John W E]

hi all
 
what about the closed loop system, which I use quite a lot this is the system I used on the Vosper RTTL - the only difference being the servo is mounted upside down - and unable to be seen are the two push rods connecting to the servo.   The ends of the pushrods are threaded so that you can fit a threaded clevice enabling to adjust the pushrods lengths to balance them out to ensure that you have equal throw on the rudders.
 
Have a look at the photograph to see the setup of the connections on the rudder posts and you will note that there is a connecting rod between the 2 rudders as well.
 
 http://www.modelboatmayhem.co.uk/forum/index.php/topic,15073.0.html


the link above comes from HMS York build and if you go and look at the photographs you can see the type of connections which are made to the servo end.
 
aye
john