A childhood belief about family

When I was a child, my father had a decorative airplane propeller that was hung on the wall. When I was very small I asked him what it was. He told me that it was the propeller for an airplane that he was building (this was made more credible by the fact that he was in the military). He said that he was collecting parts for the airplane, and when he had all the parts he needed, he would build the airplane in our garage. I was very excited that we were going to have an airplane; periodically I would ask my dad whether he was closer to building it. He would always tell me that he was still collecting parts. I believed this story for years; I think I was about 11 or 12 before it dawned on me that he was pulling my leg.