- Conduct repeat flight of Zeta rocket with A-100M motor.
W 15 km/hr
launched 40 min. prior to sunset
Setup went well with no glitches. Clear sky confirmed, countdown
commenced, and shortly after zero count, smoke seen at base of rocket, then
rapidly rose skyward. Shortly after burn-out, parachute was seen to eject and
blossom. Raven beep-out of apogee not noted.
analysis and comments:
Parachute deployed prematurely. Backup apogee charge did
not fire. Raven baro data exhibited highly
anomalous pattern. Discussion of anomaly with Adrian Adamson solved the
mystery of premature deployment of Z-1 and Z-3, and explained the anomalous baro data. The source of the anomaly was a result of the
rocket basic design, utilizing a common compartment for the Raven and for the
parachute. Under sufficiently high acceleration, the parachute will slide
“downward” and act like a piston, generating a positive pressure spike in the
“avbay” containing the Raven. The Raven interprets
this increase in pressure as beginning of descent, and thereby triggers
apogee deployment. A simple fix was implemented for the next flight. A two
second time delay was added to the required condition of apogee deployment.
This problem presumably did not manifest itself with Z-2 because the Impulser
motor generates a more gentle acceleration than the A-100M.