I strongly recommend against using any flag poles for a mega tree. generally these poles are only 0.8 to 1 mm aluminium wall thickness and are sectional and these will fail due to fatigue and the stresses applied from guy ropes. These will fail at the sectional joins which are the weakest point.
How do I know this, from experience.
It is better to get a full length 3mm wall aluminium pole or a 2.4mm Galvanised steel pole and the cost is about the same. Prices on transport can vary greatly from $10 to $88, but the price of a 3mm wall 50 OD aluminium 6.5 metre pole is $55 and the price for a 2.4mm wall 50mm OD 6.5 metre Galvanised pipe is $45
So in the end when you look at the price for a flag pole and its weaknesses compared to that of a single length decent walled 50mm OD aluminium or galvanised pole then it really is a no brainer to go with something that will work and not collapse due to fatigue because all it ever was designed for was to cary a flag.
So save yourself some heart ache and invest in something that will last instead of cheap thin wall aluminium flag poles that will be lucky to last any length of time in any strong winds.
While I mostly agree with FastEddy, if your buying get a real pole. However if you already have a flag pole you want to use it, plan on using many guy wires (I use 16 but others use less) and use rubber plumbing couplings to hold up the sections. This isn't fool proof but many people have had them last for years (4 years, 72 strings of minis).
The issue I have here is very strong gusty winds, and the pole coulnt handle sustained 100km+ winds we had the other day. Seems like we are getting a lot of wind this year and the constant battering has caused fatigue in the thin wall of the flag pole. My mistake was i only used 6 guy wires, 3 at 2 levels
I seen the photos of Beacys which folded in half last week
Mine is the same age and was put through 120kmh winds the last week of November for about 1 day solid. The WA boys will know how bad the conditions were then.
I have 4x Guy wires from the top to the base. Kept it from falling over. Tree stands at 4.6m
I outlined it in my ebay mega tree how to hen I first built it. I Think my hook head design helps a little to because that's what the guy wires hang off. The hook head gets raised up and then when it gets to the top I insert a pin through for it to come back down on.