Hi all,
I have been playing around with the doppler speed program for about a week and have had pretty good success measuring speed and in-flight rpm at our field. Comparing my figures with a radar gun on the same planes generally agreed within 2 mph, as long as the flight path was straight and level (not coming out of a dive, etc), and people weren't running up their loud planes in the pits behind me (those unmuffled YS 91 4 strokes on 30% nitro are LOUD!)
I had some fun today downloading audio files of the 1999 Unlimited Gold Reno race (you can find them here:
http://www.pylon1.com/multimedia/reno99/ ) This particular file was of Dreadnaught, Dago Red and Strega passing by on lap 2. I don't know what order they passed, but the doppler analysis gave me 482.8 mph @2894 rpm, 496.1 mph @ 2827 rpm and 467.6 mph @ 2764 rpm for the first 3 planes to pass the microphone. I wonder if these figures are representative of these unlimited racers (considering that the Rare Bear speed record is 532 mph running 2900+ rpm).
I would be curious if anyone can replicate these numbers. I made the assumption that the air temp at Reno on Sept 19, 1999 was approx 30 C and I used a correction factor of 2 for the microphone placement (seemed to give most realistic speeds).
I have been trying to figure out how to load all the software onto my Compaq IPAQ 5455 pocket PC and record thru the built-in mic and then analyze the files while still standing on the flight line! However, the few spectrum analyzer demos available for the PocketPC2002 platform and are too frustrating to use to measure the approaching and departing freq shifts. Does anyone know of a good spectrum analyzer for the IPAQ's?
Darwin