... Seems this is the season the the drop box.
There are a few pre-req's. The lighter weight the fabric is, the better. You want to weight the bottom of the fabric with either lead tape or weighted tape.
You need to make a box that is the width of the fabric that you want to drop and at least 8" wide and 8" tall. On the bottom, attach a door that is hinged on one side and held closed by a loose pin hinge in the center of the other side. Attach industrial-strength Velcro to the inside of the box and to the top of the fabric. By attach I mean staple and sew. This has to be done well. Fabricate a pin that you can have a tie line securely tied to it. The last trick is put an eye bolt in the box about 6" away from the loose pin hinge on the side of the box. Hang the box, consult someone that knows how to rig to do this. It needs to be hung properly, it actually takes some heavy load when the curtain is dropped. Run the line that is attached to the pin offstage through a sheave or something to that regard. Roll or accordion fold the curtain and attach it to the velcro loading it from the top. Pull the pin, the door on the bottom opens and the fabric falls out. The velcro should be strong enough to hold the top of the banner, but the fabric can be yanked down completely as desired.
In a perfect world, you would put a solenoid on the drop box instead of the loose pin hinge. This works and makes operation easier, but it does take a bit more engineering.
