12- Fin Fairing

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I’m sure that everyone’s composite moldings will be slightly different, but when I test fitted my Fin fairing, it wasn’t quite high enough … in other words the top didn’t line up with the rudder top fairing.

I played around with different options to solve the issue, but since the flange depth on this fin fairing is 5/8″ rather than 1/2″ on the others, I decided to it fit slightly raised in order to compensate, as can be seen in the picture.

The rear edges have to be trimmed to match the rudder and leave a minimum of a 1/8″ gap.

Also I added a flox mix inside the front top edge to allow adjustment of the front profile to match the fin leading edge.

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It takes careful adjustment to make sure the fairing is aligned correctly in all plains.

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Once satisfied it is sitting correctly, it’s match drilled as usual.

Then the layup for the rear face is resined/floxed in place.

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When adding the flox & cloth to the inside, I added some flox mix inside the front top to give more material for trimming the front profile as required.

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I also added some micro balloon mix to the rear top, again to allow adjustment to match the rudder profile.

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I used NAS1149FN416P washers on the holes to give extra strength to the countersunk holes for the pop rivets.

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Actually, the other benefit of the washers is that they provide secure centering for the countersink bit pilot.

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So here it is attached, showing the amount I raised the rear in an attempt to improve the fin/rudder profile match.

I guess this is only possible if you are intending to fill & blend the join.

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A micro balloon mix soon covered up the join!

You can also spot in the picture where I had to adjust the front profile slightly to match the fin … hence the flox addition.

The micro balloon fill at the rear top would have been much larger had I not raised the whole fairing slightly at the back.

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