Blue Bus has cracked Question Time #90 by stumbling across the answer as Oscar Stielau's Star Bee Gyros Gyrobee ZK-RDA.
The original photo that I cropped was looking up under the tailplane with the rotor blade behind. Unfortunately in cropping the image, the original image has been lost in the ether of my computer, so I will post another photo taken shortly after. This photo shows Oscar doing his "Look Mum - No Hands (or Feet!)" routine.