Dad- Here are a selection of images with my comments.
This is the window through which we'll move the boxes. There's nothing below it except the baseboard heater and that phone line jack to the right, neither of which should present a problem.
Here is a view of the sill. I've put a 2x4 in there to show you how we can protect the 1" high plastic wall. However, there is nothing to keep that 2x4 in place. We need a solution for this. Perhaps we can place a heavy blanket or similar over the entire sill and slide boxes over that. Did you keep the rubber floor mats from the VW?
This is the floor of the fire escape. There's some surface rust, but everything seems structurally sound. There is 38" x 52" of usable space. The largest box I have is 20" x 20", so there will be enough room for one of us to stand out here and position the box on the platform.
This is the vertical post to which we will affix the pole. While it would be ideal to nestle the pole into the channel of this angle iron, the railing at the top of this post prevents perfect alignment.
This is a second look at the post.
This is an elevated look at the top of the post.
This is a close up of the foot of the post. The angle iron down here is 2 1/2" wide. In contrast, the railing that bolts to the top of the post is only 1 1/2" wide.
This is a view looking down on the sidewalk. The guy at the bottom will need to pull the platform away from the basement entrance and trash can house to the right as the platform descends. Note also the power line in the left side of the shot: It is the black line that is not part of the sidewalk channel grid. It shouldn't be difficult to avoid this.
I see two issues still to resolve: 1. I need to find a way to keep both the upper and lower sashes as close the ceiling as possible so we have as much room to work as possible. 2. It seems that the pole will have to lean back slightly to accommodate the top railing. This isn't a problem per se, but it isn't ideal. We'll need to affix or otherwise lash the pole to the post very securely, because it will want to wiggle out of position as we place weight on the pulley at the top.
One more thing: We need to keep the box located on the platform as we lower it. If you can screw eyes near opposing edges of the platform, we can use a couple of bungee cords to meet this need.
The heaviest box I have is probably around 70 pounds, but I'd like to use this system to get the piano down as well, which weighs around 100 pounds. My bookcases will likely have to go down the stairs, as will the couch, mattress, coffee table, and box spring.
Let me know your thoughts. Talk to you soon!