This ad ran in a lot of magazines in the early 1980s (maybe earlier as well). Of course, being obsessed with UFOs at the time, I wanted to try it out. This was another one of those send-aways that my Mom prevented me from getting. She was convinced they were all junk, which they probably were. She was also convinced that even if this worked a little that I would either get it caught in power lines and electrocute myself or that it would go high enough to get into trouble with our local airports.
I have my doubts this thing would have ever gotten off the ground, but her fear-based tactics worked and the money for my Giant Solar Powered UFO Airship, stayed safely in my pocket. Until I blew it on pizza, candy and video games.
I have learned in recent years, that thing was actually pretty large and on a warm day could actually get some altitude. That would have been truly thrilling as a kid, even if their was the risk of electrocution and aviation police.
Turns out you can still get these magnificent beast. ThinkGeek has them (and you can see how large they are) for just $17.99.