Lu,. .. .Thanks. I found 29 patents that involved Coanda effect and rotor blades. They are interesting ideas, but if Coanda cannot provide enough force to offset rotor torque it probably will not give enough force for lift. . .. .Time will tell.. .______________. .. .RW-1. .. .Here's some more interesting ideas: . .<a href="http://www.vtol.org/uavpaper/NavyUAV.htm" target="_blank">VTOL UAVs Come of Age</a>. .. .The Bell Eagle Eye would make for a nice personal vehicle. <img border="0" title="" alt="[Cool]" src="cool.gif" />