Windshield wiper question

[agnes the dog]

I have a 59 Apache and have only had it for a couple of months. When I got it, the wiper blades looked like a hula skirt, so I got a replacement set from rockauto. They came and I installed them and it didn't rain for a while. When I finally turned them on, they were really floppy. On each pass, the wiper arm kinda climbed over to the other side of the blade and dragged it across. I was unhappy and got another 12" set from autozone. That set is doing the same thing, though not as bad. I realize I'm using 50+ year old technology. Do I just have to accept that the wipers are going to suck or am I doing something wrong? It almost seems like the wipers are too tall. Sorry, don't have pics at the moment. Can post some tomorrow.