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[asimmd]

Hi Guys

I have nearly assembled all the parts needed to start building my Hermann Marwede Radio
Conversion.

I have the 2mm shafts,and the 20mm brass props as recommended,but the rudders I have
are Robbe No 1479,size 20 X 25 X 32mm,which are the smallest ones I can get.

My question is,do these rudders need to be made smaller,and if so what size should they be?

Many thanks

Alan

[triumphjon]

how big were they on the original model ? i normally make my own rudders in brass , using k&s tubing and bar stock , with some flat sheet for the blade , i solder the blade into a slot cut into one end of the bar , use an intermediate fitting tube for the post , and buy an 8g tiller arm ! i can normally get about four posts from a length of tube ! jon

[tigertiger]

Sorry if I am trying to teach you to suck eggs.

If you convert a scale model you will need to use bigger rudders. This is because water does not scale.

On my boats of about 1/15 scale I use rudders that are about 1.5-2 times bigger than scale.

[asimmd]

Thanks for the replies.

I am tempted to use the rudders that come in the kit but they seem a bit small,hence the question.

I will probably use the old modellers adage of - if it looks right - it is right,and if I need to I will use
1/16 rod to make up the connection to the tiller arms.

Alan

[Bunkerbarge]

I personally like to remain scale so when I converted my Revell U-Boat I used the kit rudders but changed the stocks for brass tube.  I actually expected it to be difficult to steer but I was very surprised when I discovered that it manoeuvered very well on the water.

Dealing with scale effects at this size can be a very inexact science as so many other things come into it.  I'm sure that a very small difference in propeller size will have quite an effect on rudder performace as well as the speed at which they rotate.

I would suggest that you use the kit rudders, with a strengthened stock and try it.  If it isn't as effective as you want then maybe nothing more than a bit of clear acetate sheet stuck to the face of the rudder with an overlap around the edges may give you enough without it looking out of place.

[asimmd]

Well,not being one to take my own advice,I have made a pair of rudders for the Marwede.

The Robbe set I had were far to big and didn't look right,the ones in the kit are very thin and again
did not look right so nothing else for it,I made them from the Robbe set I had.

Careful filing and sanding has produced a pair that look the part,I am so glad I had a go.

Thanks to everyone for the advice.

Alan