On Thu, 11 May 2000 08:50:42 -0700 Jim Ham writes: > Yah, the root routine is brute force. But in its defense I have to > say it > works. It usually converges in 6 or 7 iterations. Maybe someone on > the list > will extend Scott's algorithm to 24 and 32 bits. > > What I ment to post, and where my interest is, is the conversion > from A/D > pitot pressure counts to velocity. Somewhere I'm getting this 20% > error. It > looks like pure physics to me - the calculation is trivial once > you've > looked up all the constants. So where is the error comming from? > > I'd expect it to also be "pure physics." With a uniform speed, there would be no airflow in the line from the opening to the pressure transducer, so it seems to me that nothing can happen in that line. It must just be how the wind is hitting the opening. Are there some special requirements related to shape, size, or whatever? To determine the windspeed, can I just stick a little pipe (pointed forward) out the top of a car and run it down to a pressure gauge? (and watch it fill with rain...). I still wonder about just having a short rod (cellular phone antenna?) sticking out the top of the vehicle and measuring the forces on it to determine windspeed. Harold FCC Rules Online at http://hallikainen.com/FccRules Lighting control for theatre and television at http://www.dovesystems.com ________________________________________________________________ YOU'RE PAYING TOO MUCH FOR THE INTERNET! Juno now offers FREE Internet Access! Try it today - there's no risk! For your FREE software, visit: http://dl.www.juno.com/get/tagj.