Actually in teh begining of the last century many designers started building circular aircraft, and all teh reports indicated that the flying saucer had advantages as :

easy and slow to fly

almost impossible to stall

highly crash proof

cheap easy to manufacter

if you dont think that is efficieny then I dont know what it is

i read also in leonard G cramps books that during early wing tunnel tests
the standard wing were ""retricted to be tested with very limited AOA"" unlike the circular wings taht have been tested in extreme angles of attack without stall!!


well, it is been a little offtopic but lets take a look at this propeller I found and it is patented 2008

it is easy to contruct too

what do you think?

http://www.freepatentsonline.com/7396208.html
http://www.linkgrinder.com/Patents/D...r_7396208.html