It's not a parade, Dick.

But, back to the subject at hand, the "test prop" for this little idea will be two 3-bladed mejzlik props bolted in tandem to this adapter hub. Any slippage at either the hub or at the joint between the two props, will be problematic at best, and might cause severe damage to the props or engine. Therefore, this 6-bolt hub idea is especially helpful in proving, once and for all, whether it is the compression of the props from the bolts, and associated friction against the hub, or if the bolts are actually the last word in what prevents the propellors from spinning on the output shaft.

Please study the photos closely. There is no reinforcing CF or fiberglass at the hubs joint, only a thin layer of thick CA between the two props to hold them in alignment until the bolts and center stud are fully tight. After that, it's up to the bolts to prevent the props from getting out of phase and remain properly centered.