1 bladed prop?!

interesting.

Here's a picture of a single blader sold by Mejzlik usually for specialist control line speed events. I think Bolly list some as well but you have to sort out your own counter weight with theirs

This Mejzlik is sold as a blank and has to have the final shape applied by the user

single bladed props were often used on Wakefield rubber powerd contest models, but I must say I have never seen them used on an engine powerd plane interesting.

https://www.youtube.com/watch?v=4vAw1CC4A3g

Note the single blade prop, the asymmetric wing and the engine speed once it gets up to full revs.
You can see these at the Nats