I recently discovered that the hub of a PT carbon fiber prop ( http://www.f3aunlimited.com/pt-model...ic-carbon-prop ) is different enough than a Falcon carbon fiber prop to prevent it from seating properly on the backplate of a Falcon CF spinner ( http://www.f3aunlimited.com/falcon-8...th-cnc-cooling )

The PT hub interferes/rides up on the raised features of the Falcon backplate.

A potential fix was found at a local Home Depot.
By installing a 5/16 x 1 1/4" neoprene washer on the backplate before installing the prop, the interference is no longer present. The neoprene washer is thin enough so there is no need to modify the CF spinner cutouts in any way and allows either a PT or Falcon prop to be used. The 5/16 cutout fits an 8mm motor hub perfectly and as far as I can measure, there is no issue with balance. The neorpene also 'grabs' the back of the prop and the serrations on the spinner backplate so there appears to be no issue with the prop 'slipping'. The 1 1/4" diameter fits the prop hub perfectly without any overlap that might possibly interfere with cooling.

The Home Depot part number is http://www.homedepot.com/p/5-16-in-x...9358/202210309
Model # 89358

Internet # 202210309

Store SKU # 597862