Rudder foil

 In the last few days, I vacuum bagged the rudder foil.  I built this in a very similar fashion to the spreaders I made a while ago.


I started with foam inserts from Flying Foam.  I ordered a tapered insert for the bottom 2/3's of the foil and a straight section for the top part that will contact the rudder cassette.  The maximum chord (front to back distance) is 10", but I trimmed a bit off of the trailing edge since it would just get distorted during the fabrication since the edge was so fine.  


I split the foam inserts length-wise and then glued them back together around a piece of 1/4" Hydrotech which acts as a spar of sorts.  The plywood is really just intended to keep the outer skins of the foil from separating from the foam inserts.  

The foil started with an interior layer of CF sleeve.  I used an 8" sleeve which easily conformed to the foil (which varies from 10" at top to 6" at the bottom).  I then added three layers of unidirectional CF which taper from the top to the bottom so that at the bottom only a small section of one layer of uni is used, and then covered the whole thing up with an outside layer of the CF sleeve. 


The photo above shows all of that being vacuum bagged.  And the photo to the left shows the result afger I trimmed the ends.


A little bit of fairing, and then I'll use the foil as the mold for the rudder cassette.


There have been a bunch of broken rudders on i550's.  Hopefully, this one is strong enough to hold up.




A bit of an add-on to the original post:

The foam that I used was not stiff enough to insure that the process of vacuum bagging wouldn't distort the foil, so the first layer of CF sleeve was not bagged.  Instead, I used the same technique that I used to create the spreaders, using the female foam sections that came from Flying Foam to provide pressure on the wetted-out CF sleeve.  The picture to the right shows the result.  You can just barely see the plywood "spar" at the bottom of the picture.  I also shaped the foam to round the leading edge using a surform tool.  Once the initial sleeve hardened, the foil was plenty stiff enough to vacuum bag.  Of course for all layers I used release cloth and absorber cloth.