Saturday, 4 July 2009

Raising my profile...........

With the blade now lofted out in 2D it was time to make it 3D, this involved putting in a number of profiling stations perpendicular to the shaft to create the blades shape and profile through the water.
Again keeping it simple i went with MDF and extruded polystyrene block (modelling foam) as i could put both through my bench saw without worry, this created the basic three dimensional shape before any shaping took place.

I got the profile for the new rudder by a combination of measuring the old one and looking at the nearest equivalent profile from NACA (National Advisory Committee on Aeronautics). This sounds technical and it is, basically these boffins came up with a family of symmetrical profiles for aircraft wings back in the day, that relate the thickness of the wings (or in our case rudder's) chord to its depth.

The nearest i got was NACA 0015 profile which in layman's terms means the rudders thickness at its widest point is 15% of the rudders depth........................Christ that reminded me why i never completed my yacht design degree, anyway that's the science bit done, it was then back to what i am good at, using my hands and eyes and you get something like this.

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