I number my planes in the order in which they're flown, not built. Some planes have taken a few hours to build, others a few months.

In fact I've built a few more planes that do not appear on my list, they were never flown, scrapped for any number of reasons before finishing. For example, here's my Scaled Composites White Knight and Space Ship One I built around 2005. It never flew, so it's not in my list.

There have been a few rare occasions in the past that I've bought a plane from someone, these also are not in my list because I didn't build them.

I also maintain an Excel spreadsheet that records details and measurements of all my planes.