Barometric pressure sensor for HABs?

Michael Hojnowski
 

Heya,

I've been using GPS for altitude on my balloons, but I'm working with a student who's interested in trying a barometric pressure sensor attached to an arduino with my next HAB flight.   I've got a pile of BMP180s laying around, but  they only seem to be rated for 9,000m.  It looks like the BMP280 has the same issue.  I'm expecting 36,000 meters or so.  So, two questions.

1) Is there a better series of devices to use?
2) The last time I screwed with the BMP180, the altitude formulas I found didn't seem to work.  It was thousands of feet off, just at ground level.  If there is a "defacto" subroutine to use for calculating altitude from a pressure sensor that everyone's using for HABs, I'd love a pointer.

Thanks for any tips!
Mike / KD2EAT

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