Thanks for the information. I’m amazed that more people aren’t aware of this very handy navigational aid. It is especially useful when having a “who’s plane is fastest” race between yourself and a friend flying identical iron. You both agree upon an rpm and manifold setting and then sit back and see whose bird is fastest from your home base to were ever your going for dinner that day. I used to pull out every trick I knew like moving the seats back and making the passengers sit in the baggage compartment, holding trim and navigating by pressure rather then radio, to get every last bit of speed out of my bird. The other guy could never figure out why his plane was so much slower. The longer the flight, the more effective this type of navigation is. The down side is that your not able to fly a strait ground track so it might be more difficult to find the pieces should something expensive happed along the way.