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Motor Failure and RF Success

A project log for High Power Experimental Rocket Platform

Experimental high power rocket with active stabilization, live telemetry, autonomous GPS guided recovery and HD video

j-m-hopkinsJ. M. Hopkins 02/21/2016 at 00:300 Comments

The EX-003 flew today on a I-530 6 grain 1-1/4" motor. This flight was a test for RF transceiver and data path validation.

Regrettably the flight was cut short due to a motor failure at around 500ft. Apogee was reached at 730ft. The motor failure was deemed to have been caused by a new propellant grain separation o-ring being used in this iteration of testing which when ejected from the casing became an obstruction to the nozzle causing an over pressure event.

The picture above shows a sudden darkening of the exhaust plume just before the failure. This is indicative of a large amount of rubber being burned. The likely cause, as stated earlier, is an o-ring partially obstructing the nozzle, drastically reducing the nozzle throat area and causing pressure to climb rapidly.

Analysis post burn shows an engorged burnt and melted o-ring, certainly capable of obstructing a nozzle.

Following the failure the drogue parachute was ejected at speeds between mach 1.2 and mach 1.3. This high velocity did damage to the drogue, as seen in the next picture.

The shroud lines were separated from the bottom seam to over half way to the top before the depowering of the parachute halted increased damage. All the gore seams stayed intact.

The drogue took the brunt of the deceleration, and after apogee the main deployed without issue.

On the plus side a limited test of the transceiver was completed and data was sent back via the serial link in real-time to the ground station.

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