Hello...

First of all, this isn't homework as I haven't had math homework in over 20 years! This is just a math problem that my grandfather gave me before he died 10 years ago that I have not been able to solve. I have asked several people who are much more math-smart than me, but get different answers every time! So...here it is. I don't have the answer, so if you post hoping for your answer to be confirmed, you will be disappointed. Good luck to whoever solves it!

There is a flagpole that is 20ft high. It is 5 inches in diameter at the base and 3 inches in diameter at the top.

There is a rope that is one inch in diameter that is wound around the pole, coil upon coil (each of the coils are touching).

There is a bird who flies to the top of the pole and he is going to fly around the pole and unwind the rope (he will fly so that the rope is perpendicular to the pole). If he keeps the rope taut during his flight and completely unwinds the rope from the pole, how far will he have flown?