Hey all,For people using homemade navigation units, how are guys getting airspeed? From google'ing, I've found that two pressure senors (MPX4115a), one static (inside the fuse) and one dynamic (attached to a pitot tube), could be the hardware. But I'm still a little fuzzy on how I'm going to get airspeed out of that. I know its going to be the difference and an equation or two, but does anyone know equation already?Thanks in advance, Keith.
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What you really want is the MPX5010DP, positive pressure port connected to the pitot tube, other port static. Then see section on measuring airspeed here:
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#define SEALEVEL_SOUND_KNOTS 661.4788
#define SEALEVEL_PRESSURE_PSI 14.6959465
float knots = SEALEVEL_SOUND_KNOTS * sqrt(5 * ((pow((psi0/SEALEVEL_PRESSURE_PSI)+1,(2.0/7.0))-1)));
psi0 comes from a differential pressure sensor which compares differential and static pressure in a pitot-static tube
http://www.auf.asn.au/groundschool/umodule2.html