Probably some sort of aerodynamic test rig to gather pressure data in the flow field surrounding the propeller. The tape gives it away as a temporary setup. The vertical arm probably goes over the top of the prop to the top wing center section.
Franzkait, Don't tell me it is a mechanism to jettison the prop inflight in order to get glide information undisturbed by the propeller airflow? I was wondering why all the lines ended at the hub.