3 rudders is plenty with a single trim wing. Trim wing is helpful in
some cases even with only 22 hp for thrust that I use in my setup.
My pulleys are 6.25" & 12" and with a 54-50 prop I get around 3450
static rpm, and as much as 3700 at speed. I'll try to remember to
measure the length & width of my rudders & trim wing when I go to my
shop this evening.
Marquis
Ken Roberts wrote:
> On Aug 2, 9:48 am, jas...@[EMAIL PROTECTED]
wrote:
>> I have removed my direct drive set up (42 inch prop) from my UH13pt,
>> and rebuilding it as a belt reduction, with a 54 inch prop, powered by
>> a 23hp Briggs. (Thanks Marquis for your input).
>>
>> If 6.25 / 12 pulleys - is that the pulley diameter ratio?
>> How many rudders should I use?
>> How tall and wide are the rudders?
>> Is a trim wing needed?
>>
>> Jim
>> Rochester, MN
>
> Jim,
>
> You'll be running on the Zumbro with Ben, right?
>
> In that case, I'm going to say 5 rudders. Make them 14" to 18" wide
> (all the same) and make sure they deflect about 45 degrees each way.
>
> I suspect you'll want a trim wing or two on that thing. A 13p with a
> 54" duct gets a lot of down force on the nose from the high thrust
> line. Not sure if a single wing will be noticeable on a craft with
> that small an engine, though. Marquis will be able to tell you that
> one. I drove his craft, but only once.
>
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