This is my Horten Parabola flying wing that is one of my favourite models. I have a fairly light outrunner set up in it so it is quiet enough for parkflying and is capable of thermalling too. I managed to source a pusher folding prop for it and have a lot of fun ridge soaring it.
The model is actually a Sif designed by the great Jupp Wimmer in Germany. Pic of him below with some of his followers. Also in that pic is a microlight version of the Sif. He has designed a whole range of models based on the crescent wing format.