Thanks everyone. I found the post with photo I mentioned before. Click and scroll down to the 5th post if you want:

http://www.rcuniverse.com/forum/m_48...tm.htm#4839188

NMOSSON, I assume this uses the second type you mentioned.. the flexible fiberglass plate. I guess I could PM the owner and ask. At first glance, I just assumed it was metallic.

About the upper ring, I just thought it would be stronger mechanically, but yes it would make it almost completely stiff. It seems unnatural to mount a rotorblade by just one side. But if stiffness is a bad thing, I'll scrap that idea.

How long till the holes in the plate wallow out into an elongated shape?

EDIT: Would something like this be suitable?:

http://cgi.ebay.com/ebaymotors/4409-...spagenameZWD1V