Sunday, December 14, 2008

Uni-directional carbon fiber in the rudder blade (updated)

There are a number of steps involved in getting the basic foam core re-inforced properly.  After the wrapped high density core is inserted,  some unidirectional carbon fiber tape has to be laid down on top of it.

Here are the pieces of tape cut to length and ready for application.  I used a 9 oz. weight carbon fiber  tape.  I can never get the tape trimmed as perfect as the plans show it.   You can also see the rebate around the high density core.  I tried to tailor the depth of the rebate down the length of the blade but I am sure some fairing putty will be required to get the profile shape back.  I'm always slightly phobic about making the rebate deep enough (is the high density core too thick?, is it mounted properly?), but I just stick to the dimensions indicated in the plans.

First I filled up the gaps around the rounded corners of the high density core with some high density putty.

And while still wet applied the layers of carbon tape.  The epoxy saturated  carbon uni-directional material really needs to be compressed and using a plastic sheet to squeeze out the excess resin really does minimize the overall thickness, which I think is what you really want.  

Everthing looks good and when it's cured I will apply the fairing putty to the trailing edge of the blade and recover the profile shape over all this carbon fiber.  Then turn the blade over and do the other side.

Updated December 23rd

Work has slowed a bit with Christmas and other projects but I have made a bit of progress in finishing off the one side of the rudder blade.

The above picture shows the trailing edge cut away to the centre and is ready for the lightweight putty fill.  The original layer of 6 oz fiberglass cloth really helps here to cut away one side of the blade at a time.

Here is the blade (port side) with the putty applied and sanded down close to a point that is almost ready for carbon fiber cloth sheathing.  I will now turn the blade over and finish the other side but  I have run low on carbon fiber and will have to visit Noah's or Canada Composites soon. ( A trip to the other side of Toronto).   I want to make sure I have enough material to finish the blade and rudder case.  This will be my last post of the year so merry Christmas and a happy new year to all.  2009 should be interesting. 

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