R-DAS Magnetic Orientation Sensor

 The dual-axis magnetic orientation sensor is a high-precision device that uses the earth's magnetic field to measure a model rocket's instantaneous orientation angles (flight aspect and spin angles) during it's entire flight. The sensor can also be configured to work as a backup to your primary drogue parachute ejection system at apogee. A 14-pin connector allows the sensor to be attached to the expansion port on the R-DAS flight computer for data logging purposes. The unit draws it's power from the R-DAS expansion port connection, so an independent battery is typically not required to power the unit in this configuration. The sensor can also be powered with an external battery (any power supply between 9 and 12 V will do). The board size (48mm x 48mm) is identical to the R-DAS igniter expansion unit developed by AED.

This sensor has been extensively tested in the field on several Level 2 and Level 3 high-power model rocket projects. See link below for some recent flight results.

Check here to see some flight results of this magnetic orientation sensor.

The dual-axis magnetic orientation sensor has many useful features:

• Easy to use: The sensor comes assembled and ready-to-use as an R-DAS add-on board for magnetic orientation angle measurements. Just mount it in your high-power model rocket and connect to your R-DAS flight computer via the supplied interface cable. No batteries required -- the sensor shares the R-DAS power supply through the 14-pin expansion port. A buzzer sounds when the rocket "tips over" thus allowing the circuit to be easily tested at the launch pad (if the apogee detection option is being used, be sure to disarm all ejection charges when doing this, however!).

• Data logging: Magnetic orientation data from the sensor is fed back to R-DAS and sampled at three analog input channels: ADC3-5, and one digital input channel IO0. Information about the "spin-angle" of your rocket is captured on ADC3 and information about your rockets "flight aspect" (angle between the rocket's flight axis and the earth's magnetic field vector) is captured on ADC4. Channels ADC5 and IO0 provide binary-like information about the rockets flight angle, i.e. a "0" means the rocket is tipped upward and a "1" means the rocket is tipped downward. Users may use the R-DAS user interface software to view and export the raw data. A simple trigonometric formula with instructions is provided for converting the output voltage measurements into trajectory angles in degrees.

• Apogee detection: Users who wish to use the optional magnetic apogee detection output capability must solder a jumper wire and large blue capacitor to the circuit board. Parts and instructions are provided for modifying the circuit to use this option. The capacitor discharge output can be used for triggering flash bulbs or other low current igniters at apogee (works great with Daveyfire 28B e-matches). A calibration screw is accessible on the circuit board for users who wish to modify the flight angle at which the pyro output is activated.

Check out the instruction manual for further information about this sensor.

Determine your local geomagnetic fields via NOAA here:

http://www.ngdc.noaa.gov/geomagmodels/IGRFWMM.jsp