[PSUBS-MAILIST] Determining the size of a rudder

[leifur@hafmynd.is (Leifur Thor Leifsson)]

Hi.

My name is Leifur Thor Leifsson and I'm developing an AUV. The AUV is
torpedo shaped and is around 1.3 m in length, 0.2 m in diameter and weighs
around 34 kg.  

Now I'm trying to redesign my rudders and elevators because I think they
are too large. Both the rudders and elevators are made from a flat aluminum
plate which is 2 mm thick. 

I am thinking about using a "reverse" airplane wing for the elevators of
the form NACA 4412. The elevator is supposed to overcome the buoyancy of
the vehicle, enabling it to dive. I have determined the neccessary size of
it by using information about lift for this specific wing section.

For the rudders I am going to use a symmetrical wing section of the form
NACA 0018. Now the question is; how do I determine the size of the rudders
so they will work efficiently in all cases (giving enough force to
manoeuvre the vehicle for various speeds, etc.)? 

Leifur Thor.