Emergency Quadrotor
My UAV needs to be quite big to stabley carry a payload of 1-2Kg. This thing weighs 8-10Kg and can carry another 4-6Kg!
Unfortunately it does seem to have some slight design flaws in that the fans all rotate in the same direction. Really you want opposing pairs in order to cancel out the gyroscopic rotation effect. Plus I think that you can get more thrust if the fans are below the motors rather than blowing across them.
Also I personally prefer the term quadracoptor to quadrotor.
Emergency Quadrotor via Hackaday - One really big quadcopter that is following in the steps of the Spruce Goose