> > The magnetic field vector is (at least for low altitude flights) to > > be considered constant in terms of both magnitude and direction. > > Measuring and recording the time history of the magnetic field from > > a 3-axix magnetometer will allow You to figure out the rocket > > pitches and rolls with respect to the (fixed) earth magnetic field > > vector. Converting to a coordinate system of Your own liking may be > > done either by measureing the earth magnetic field vector in that > > particular coordinate system, or simply by offsetting the initial > > conditions. Could you acheive the same thing by using a couple of ADXL accelerometers? (Each chip can have 2 axis). Haven't used one myself yet but they look really cool and I'm just dying for an application to come along. Brent Brown Electronic Design Solutions 16 English Street Hamilton, New Zealand Ph/fax: +64 7 849 0069 Mobile/text: 025 334 069 eMail: brent.brown@clear.net.nz -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.