My dad is letting me borrow a very nice DLP projector and the backyard for the night. I am going to run the movies and sound from my laptop and a set of 5.1 speakers. I am thinking about using a white painter's canvas dropcloth for the screen.
Hi Hobbes, welcome to the forums!
I was in the local farm store yesterday and they were doing something in the middle of the store that they didn't want people to see. Some sort of remodeling. They had used the clothesline approach except they stretched 1/4" steel cable and hung tarps with zip ties from that cable. It looked like a tarp wall. Perfecty straight across the top and every tarp was hanging (near) perfecly flat.
What I'm getting at is a couple eyelets screwed into the house with a cable between them to suspent the tarp screen from. There are right and wrong ways to do that, (and your dad my say something similar to; there is NO right way to do that on my house) so that may not be an option for you.
If not, then you'll need a stand and simply use the house as a windbreak.
Bottom line, if you put this together, you're going to want to do it again -- soon. So do it by your dads rules, get him involved, and he may plaster the whole backside of the house with projection screen.