Made an attempt at this today with reasonable success. Separating the blades from the main craft works to generate lift but was having the same problems as @K^2 where they would escape their cages when spinning fast enough. Building a cage the entire length of the blade and a few struts made it much more stable, enough to get up to 1km on Kerbin and could've gone higher.
The center blades are attached to a structural panel that's trapped as tightly as possible by a cube of panels. The top and bottom wings are attached to the main craft and strutted together.
I believe the vertical speed from that clip is from the engines - not the wings. With gimbal and SAS on the engines point slightly downwards trying to correct for the spin, generating enough thrust to take off.
https://i.imgur.com/dt2OTwZ.mp4
