[OldLuke]

Here's some information about the portcullis that may help. Note all of these calculations are rough:

Mass: 21kg
Effective "Gravity": 1.0 m/sec^2 (22N/21kg ~ 1.0m/sec^2)

The implications for this is that the Portcullis will fall slowly, about 1.5sec from the top and land with a velocity of about 1.7m/sec. Also means that the Portcullis, will rise a little more slowly than expected as well.