how about measuring different glue 2 thermistors to 2 resistors put the two resistors in series on a constant current source (constant output heater) put the one pair in the airflow the other pair inside the plane measure resistance of both thermistors the heatloss from airspeed should be a good indication of airspeed (needs small mass so reaction speed is sufficient) use the pair inside the plane to compensate for air temperature use a 2 dimensional lookup table for windspeed Peter -----Original Message----- From: Adam Bryant To: PICLIST@MITVMA.MIT.EDU Date: Tuesday, May 04, 1999 7:19 PM Subject: Re: pitot tubes >Andy, >I have thought about this too. The only feasible idea I came up with was >a small paddle wheel mounted inside the fuselage or wing with half the >paddles sticking out into the airflow. Count the RPM's over a period of >time and calculate airspeed based on the circumference of the paddles. >Placement would be important, and thinking about it, you probably >wouldn't want it on the fuselage so you don't have the effect of the prop >blast throwing off your readings. It might be kind of draggy depending >on the install, but should give you a reasonable approximation of the >speed. > >On Tue, 4 May 1999 11:50:14 -0400 Andy Kunz >writes: >> At 04:06 PM 4/15/99 -0700, you wrote: >> >Hi Andy, >> > >> >http://www.dwyer-inst.com/index.html >> > >> >Pitot tubes in there somewhere. Unless the OT sturmtruppen >> >decide you don't need to know, of course. >> > >> >Jack >> > >> >Andy Kunz wrote: >> >> >> >> Anybody know of small (3-5mm dia) pitot tubes for a PIC-based >> project? >> >> They have pitot tubes alright, but I'm looking for small ones in the >> 2-3" >> long range. I would like to mount it to a model airplane to >> determine >> airspeed. >> >> Does anybody have an alternative idea? >> >> Thanks. >> >> Andy >> >> >> ================================================================== >> Montana Design Tech Support - http://www.montanadesign.com >> ================================================================== >> > >Adam Bryant (age 0x23) >abryant@peaktech.com (work) >adamdb@juno.com (home) >Parker, CO, USA >Robotics, RC Airplanes, anything using a PIC > >___________________________________________________________________ >You don't need to buy Internet access to use free Internet e-mail. >Get completely free e-mail from Juno at http://www.juno.com/getjuno.html >or call Juno at (800) 654-JUNO [654-5866]