AltimeterTwo Version 4.0 Enhances Ejection Detection

AltimeterTwo is great for automatically analyzing rocket flights. But there have been situations where it mistakenly thought that parachute ejection occurred right as the motor stopped firing.

For most rockets, this situation was not encountered. But if your rocket naturally decelerates very rapidly after burnout—because of the right combination of large diameter, high drag, or light weight—then you might have seen this situation. It was repeatably seen in Crayon rockets, for instance, since they are relatively thick and light and can fly on smaller motors. The result would be a very negative Apogee-to-Ejection number (because Ejection was detected before apogee) that was almost the opposite of the Coast-to-Apogee figure (which would have still been calculated correctly). The ejection altitude would also have been very low (near where the motor stopped firing).

Version 4.0 of AltimeterTwo was developed to better judge ejection detection in these situations. It is a little more picky about the kinds of shock that define ejection. Hopefully it won’t miss gentle ejections. We’ll keep our eye on that.

If you have an AltimeterTwo prior to version 4.0 and would like to upgrade your firmware, just mail it to us. We’ll flash it with new firmware (you’ll lose your recorded flights) and send it right back to you.


Jolly Logic
231 Daylight Pl
Danville, CA 94526

Be sure to include your name and return address!