Neil Anderson Flies EasyMega to 118k' At BALLS 23
Altus Metrum would like to congratulate Neil Anderson and Steve Cutonilli on the success the two stage rocket, “A Money Pit”, which flew on Saturday the 20th of September on an N5800 booster followed by an N1560 sustainer.
Safely Staged After a 7 Second Coast
After the booster burned out, the rocket coasted for 7 seconds to 250m/s, at which point EasyMega was programmed to light the sustainer. As a back-up, a timer was set to light the sustainer 8 seconds after the booster burn-out. In both cases, the sustainer ignition would have been inhibited if the rocket had tilted more than 20° from vertical. During the coast, the rocket flew from 736m to 3151m, with speed going from 422m/s down to 250m/s.
Apogee Determined by Accelerometer
Above 100k', the MS5607 barometric sensor is out of range. However, as you can see from the graph, the barometric sensor continued to return useful data. EasyMega doesn't expect that to work, and automatically switched to accelerometer-only apogee determination mode.
Because off-vertical flight will under-estimate the time to apogee when using only an accelerometer, the EasyMega boards were programmed to wait for 10 seconds after apogee before deploying the drogue parachute. That turned out to be just about right; the graph shows the barometric data leveling off right as the apogee charges fired.
Fast Descent in Thin Air
Even with the drogue safely fired at apogee, the descent rate rose to over 200m/s in the rarefied air of the upper atmosphere. With increasing air density, the airframe slowed to 30m/s when the main parachute charge fired at 2000m. The larger main chute slowed the descent further to about 16m/s for landing.