Odd...I seem to recall the Germans did Quite well with a three winged aircraft....and the AN -2 is still earning an honest living.
Originally Posted by
Ascend Charlie
Hugely inefficient trying to lift a big machine with little props. Moving lots of air slowly with a big rotor, is far better than moving smaller amounts faster with a small rotor. Downwash, noise, power requirements.
Ring wings have been tried since the 20s, biplanes were dumped due to the interference between wings.