T-Rudder

[wet feet]

The tip foil in the photograph is shown with it's leading edge facing the camera.The pencil lines on the top surface are parallel to the centre line.Your assessment of the different approaches we are using is absolutely correct and you have my sympathy for the size of the task ahead in making your templates.Have you looked at Profili?It will do most of the work for you if you just specify the chord,the section and the skin thickness.
I have looked at a few International 14 rudders and they do seem to add a bit to the speed of the boats in spite of the increase in wetted area they bring along.All of those I have seen have been carbon and all have had adjustable foils,also carbon.Quite a heavy financial commitment,but justified if it makes a difference.

[wet feet]

The attached file shows the tip foil bonded and filleted to the bottom of the rudder.All that remains is to cut two slots for the carbon joining webs and then sheathing and painting.The view is from the trailing edge.

[SuperPiper]

I'm not sure what you mean by the 2 slots and the carbon web. Post it as it happens.

I have 8 templates drawn and 4 more to go.

[SuperPiper]

The drawing shows 17 stations, but only 12 templates were drawn. A few were skipped in the top, more rectangular section. The drawing shows the profile and the topography of the core. The trailing edge will be solid glass & epoxy.

The bulb has a NACA0030 section when viewed from the side but is a truncated NACA0020 when viewed from below. This gives the bulb a beaver tail effect.

The question for you: should the front view of the bulb be elliptical with a square junction with the rudder; or, should the bulb be concave and filleted to the rudder?

[MalSmith]

Originally Posted by SuperPiper

The question for you: should the front view of the bulb be elliptical with a square junction with the rudder; or, should the bulb be concave and filleted to the rudder?

I would go for the filleted version as it has less frontal area (less form drag) and is probably just as strong as the ellipical version.

Mal.

[wet feet]

The attached files show the carbon joining webs and their installation.The carbon layup wasn't absolutely ideal but ought to be more than strong enough.Since the stuff doesn't grow on trees,I went with it.The glass sheathing and painting are conventional but tedious processes.

[SuperPiper]

Wet Feet, that is a clever idea. Your technique ties the 2 elements together.

You are well advanced of my project. Here are a couple of photos showing my status.

The laminated plywood has 2 layers of 6oz glass and epoxy between. The piece of 1-1/4" stainless steel angle will form the flange for the detachable foil. The core pattern is bizarrely different from the plan form of the rudder.