More details would be great, but I can see uses for this in fast pilon racers and clipped wing arobatic planes were prop torque can be a problem.

That and the cool factor would be great. I for one would use a 4 bladed prop if all I needed was more blade or more clearance. anytime you add more mechanicle parts, you lose some efficancy, but if torque was a problem, this would be the perfect solution.

Actualy, someday I plan to build The Bugatti 100p, and will need a setup like this.