Lately I've been spending most of my time outside of my day job working on the propellers.  The picture above shows the current progress of the 4 propellers for Goliath.  From left to right, there is the foam core with the birch plywood stiffeners inserted.  Next is the first clockwise (CW) propeller done being milled.  Second from the right is the second counter clockwise (CCW) propeller with a few layers of fiberglass tack in placed and almost ready to have resin applied.  On the far right, is the first CCW propeller with the resin cured and currently being sanded and trimmed.  It'll get a few coats of primer and a finish coat before it's done.

The birch stiffeners seem to work well, and the propeller core is stiff enough now to handle the weight of the fiberglass and resin during the layup process.  Another improvement to the layup process was tacking the fiberglass layers in place with spray adhesive, just the minimum amount to hold them in place.  This made dealing with the multiple layers and overlaps a lot easier.

Previously I had done a propeller layup that ended up twisting on side of the propeller, but the other side was still good.  This was used to do some rudimentary load testing.

I incrementally placed weights at the 75% span location to test out the loading.  While this doesn't match exactly what the blade will see in flight, it's close.  Shown above is 30 lbs loaded on the single blade which translates to 240 lbs for the entire vehicle and the currently the target hover thrust.  There was about an 1.25" deflection at the tip.  I did test the blade to 35 lbs, still without any failure, but I couldn't keep the weights from tipping over and take a picture at the same time.

Hopefully in a few more weeks the the set of propellers will be complete and some initial hover testing can take place.