Free fall of hatch with a frictional hinge

Hi people!
I have a real life problem that i can't solve....Im trying to figure out the tangencial speed or angular velocity of a hatch at the moment it is about to close (initially it was closed). The hatch has been accelerating due to gravity. It looks much as a pendulum to me. But, it gets more complicated when you add the fact that the hinge of this hatch, has friction that can't be ignored.

- Can i calculate this friction?

- Can anybody help me to get a mathamatical model of this system? (maybe just doing energy balance).

- And the main question...How can i calculate the angular velocity at the moment of the impact with the frame?

Imagine something like this (http://www.getprice.com.au/images/up...etal_hatch.jpg)

Thanks.