[kach22i]

http://people.clarkson.edu/~space/VALPG1.html



http://www.codeonemagazine.com/archives/2001/articles/arp_01/xplanes/xplane_x22.html



http://www.gdsys.net/WWWmembers/unicorn/DUCTED_FAN/ducted_fan.htm



"Ring-Wing"
http://www.piasecki.com/pa-2c.htm



http://www.steerprop.fi/productsfeat05.htm



http://avdil.gtri.gatech.edu/RCM/RCM/DroneProject.html



http://adg.stanford.edu/aa241/propulsion/propulsionintro.html


http://www.bridgingworlds.com/raspet.htm


http://www.sdsefi.com/air41.htm