I want to design a 6 foot cylindrical staff for performance twirling and sparring that would be virtually indestructible for a single man without mechanical help.

These are the requirements I have in mind:

1) outside diameter <= 1", preferable .6 or .7 for easier manipulation and lower air resistance

2) yield strength >= 250 lbs from the center

3) weight <= 5 lbs, lighter is significantly better

First, is this possible or even close to possible?

I understand that tubing has higher strength / weight than solid rod, but how can I choose an optimal outside diameter and wall thickness.

A local metalworking professional suggested that filling an aluminum pipe with a rod of some hard, light, composite plastic would greatly improve its strength. But again, I need at least a rough calculation of how much stronger it would be. Are there any proven applications of this kind of design? Can anyone suggest a good fill material?

For the tube, I’d rather use titanium than aluminum, since it seems like the obvious material for high strength / weight. The sparse information I’ve found seems to indicate that grade 5 (6Al-4V) appears to be notably stronger than other common grades. Unfortunately, all the titanium tubing I've seen is grade 2 or 9. Any idea why? What to do?

I would VERY much appreciate any suggestions at all.