Model Boat Mayhem

Mess Deck: General Section => Beginners start here...! => Topic started by: XV Pilot on July 10, 2012, 08:38:07 pm

Title: Calculating rudder size?
Post by: XV Pilot on July 10, 2012, 08:38:07 pm

Hello.

The title says it all really. How do I go about working out the right size for my rudder?

The boat in question is a knock-off of the Graupner B-24 "Bat Boat" which  measures 655mm by 235mm, and will be (under)powered by a pair of 380-size motirs of dubious origin.

The rudder recommended by Graupner for their model is the G2322, but I don't see how I am meant to mount that to the transom and still have space for the servo horn to move without cutting a big hole in the transom for it.

I would prefer to use something like the G2332 which looks like it will stick out far enough to leave space for me to run a pushrod to the horn through a small bellows-sealed hole in the transom, but the sizes are confusing me a bit.

These are the rudders I am considering: http://www.cornwallmodelboats.co.uk/acatalog/race-rudders.html (http://www.cornwallmodelboats.co.uk/acatalog/race-rudders.html)

Thanks!

Title: Re: Calculating rudder size?
Post by: essex2visuvesi on July 11, 2012, 07:12:04 am

I would go for the 2393.2 or 3
http://www.cornwallmodelboats.co.uk/cgi-bin/sh000001.pl?REFPAGE=http%3a%2f%2fwww.cornwallmodelboats.co.uk%2facatalog%2fadmiralty_paints_water.html&WD=g2322&PN=graupner_rudders.html%23aG2322#aG2322

This kills 2 birds with one stone as it addresses the cooling issue in your other thread as well

Title: Re: Calculating rudder size?
Post by: Manfjourde on July 21, 2012, 05:07:37 am

I kind of have the same question. I have a Sea Nymph and Commander and Swordsman on the way. Any recommendations on rudders for those and where is the best place to get them in the US?

Title: Re: Calculating rudder size?
Post by: HS93 (RIP) on July 21, 2012, 07:33:07 am

http://www.cornwallmodelboats.co.uk/acatalog/boat_rudders.html

I would use the mini 40x26 on the Nymph

and the medium or large depending on how fast you are going if fast go for the smaller   55x36 or 60 x 41 on the commander remember if you get the larger you can cut them down with snips or a Junior hacksaw

the medium on the Swordsman 55x36 as that will be going quicker, again you may have to trim a small amount off the front edge to aid fast sailing
keep them nice and light and they will perform great, I have built all the originals many years ago and these where the type of rudder suplied by model shops at the time, (but with brass outer tubes)

Peter

Title: Re: Calculating rudder size?
Post by: surfs up on July 21, 2012, 01:04:28 pm

I would forget rudders and use a mixer and two esc.

Title: Re: Calculating rudder size?
Post by: Manfjourde on July 21, 2012, 04:55:10 pm

Peter, thanks for the info and link!