Inboard Rudders Chapter four

I did decide that the bottom part of the rudder needed to be reinforced and so cut slots between the carbon sections and inserts carbon plates.  The result was that the bottom of the core became at least three times stiffer than it was. 

Next, I readied all the components I would need for the lay=up.  I ended up with the following lay up schedule.

one layer 9 ounce uni carbon, two layers of 5/7 ounce carbon and one layer of 6 ounce stand glass. The last was to have a sacrificial layer if needed during fairing.  For "peel ply" I used a layer of Tyvek.   Then I glued plywood to the wing beds to clamp everything together with.

The I clamped everything together and waited for the next day.  One immediate benefit to the additional of those carbon bits is that the core was very stable to lay up.  No wiggling all over like it would have if it was just a foam core.  And the final clamping was not really needed.

The rudder came out of the "mold"  very easily.  A quick rough trim and it was ready for weighing.  It hit the scales at 2 pounds 15 ounces.  Of that, the rudder shaft is 1 pound 4 ounces, leaving 1 pound 12 ounces for the rudder assembly. One mistake I did make was that I forgot about the hole in the wing beds from cutting the bore.  It lefty a lump in the rudder side.  It will sand out but still, next rudder I will be sure remember to close that hole up.

It is my goal to have the complete rudder cassette weigh no more than the original outboard rudders were going to.  It will be close.

This part of my rudder build can be used for any rudder or keel strut you may wish to make. Places like ACP Composites has production run carbon fiber tubes up to 5/8" for very low prices that would make a good core strut for an outboard rudder and I would use possible two for a keel strut or perhaps even use stainless.

The advantages of using this technic are a stiffer construction that does not rely on the foam core for it's stiffness and strength, it is supported for the lay-up process and the result will be lighter than many of the alternatives.

The next chapter will be on the cassette itself.