Precision Antenna Launching

To describe the effort as “Precision” is a bit hyperbolic, but David (WB6TOU) did do his very best this week to calculate a suitable pressure value for his homemade antenna launcher in preparation for Winter Field Day this Saturday. The goal: shoot an EFHW (end-fed halfwave) over a tall tree while keeping the landing zone within walking distance.

Above all, David believes in the scientific method, but that didn’t stop him from having a little fun first. A “failure” test at 100 psi seemed like a good idea. He and the equipment survived intact. Scientific conclusion: we don’t have trees that tall in California.

That suggested the need to run several more test launches to associate that which he knew with the things he didn’t know. The graph below are the results of eighteen such tests at increasing pressure values. Counting the number of seconds from a vertical blast off to the thud of an earth impact, and applying a little high school math, David derived the following graph for a 60 degree launch angle.

David is our Club’s technical director. That makes him really smart. We’ll see just how smart this Saturday morning (January 25, 2025) during Winter Field Day at the Hogan Dam Observation Point. We’re all rooting for you Dave. Don’t let us down. Everyone is invited.

(Email Keith-N7DXC at kcolgan@softcom.net with inquiries)