Hydro Gravity Roller

[vineet_kiran]

 
@Airstriker

Nice diagram.   Releasing the latch at maximum potential energy is a good idea.   
But in that diagram just imagine the force acting due to balloon.  A  hydrogen balloon always tries to move in upward direction perpendicular to the ground  and not in the direction of  shaft axis carrying the weight.  This upward force of the balloon acts on the bearing and tries to slow down the momentum of  shaft falling down along with weight.   The upward force of the balloon will be maximum when the rotating shaft comes to horizontal position.    At this point the balloon trying to move upwards perpendicular to the ground will greatly reduce the momentum of  falling weight.  Hence this may come to equilibrium at some point or the other end will not have enough momentum to stick on to a latch.
Anyway it is difficult to imagine and as I said we have to build and see.
Regards,
Vineet.K.