Basic Information
Name	Xi-12
Launch date:	6 June 2019
Rocket description	- 76.2/63.5mm aluminum airframe - 4 fins, 2024 aluminum - delrin conical nosecone - 3 ft. ellipsoidal "Fruity Chutes" parachute
Payload	- Raven3 altimeter (primary role) - Eggtimer Classic altimeter for backup apogee separation and backup main deploy - BREO-N flight computer (2^nd backup, apogee only) - BRB900 GPS transmitter - Smoke tracker with Legendary smoke formulation
Liftoff mass	3.150 kg.
Stability Margin (initial)	3.69
Flight objectives	- 2nd flight of JEM rocket motor

Motor details
Motor name	JEM
Propellant	KNDX
Grain mass	438 grams
Nominal impulse	548 N-sec
Class	I

Additional information

The propellant grain design for the JEM motor was modified as a result of the anomalous behavior during the 1^st flight. The grain core was increased in diameter from 7/16 in. (11.1mm) to ½ in. (12.7mm). The goal of this change is to assure that the flow of combustion products occurs solely through the core, avoiding flow around the exterior of the grain, which leads to inhibitor destruction. The motor for this flight is loaded with 14% less propellant than was utilized in the previous flight.

Weather conditions
Temperature	26°C (79°F)
Wind	NE 10-15 km/hr
Sky	Sunny, clear
Other	R.H. 37%
Ceiling	30k ft.

Launch Event Description

With the arrival of warm weather, we used our launch-wagon to haul the supplies. The weather conditions were near-ideal for a launch. Once we arrived at the site, setup of the rocket went smoothly, with no glitches. Followed checklist as usual. The BRB transmitter and receiver were activated and verified that a good GPS signal was obtained. After installing rocket on pad, the BREO-N, Eggtimer, and then Raven were activated. Raven beeped nine times for voltage and gave 3 positive indications for the 3 active pyros. For videotaping the flight, I used the hand-held Sony camcorder (fitted with scope tube).

After verifying the sky was clear, the countdown proceeded. At the zero mark, the motor immediately ignited with a cloud of smoke appearing at the base of the rocket. Less than a second later the rocket climbed skyward. Ascent was largely vertical with a slight veer to the right. Burn time was around two seconds, which was the expected duration for a nominal burn. Visual contact was lost shortly after burnout. After about a dozen seconds, we heard a faint ‘pop’ sound of the apogee charge and then spotted the twin smoke clouds of the primary and backup apogee charges. Shortly after we noticed a glint from the rocket and saw the beginning of a smoke trail. We were able to follow the tumbling descent very well, thanks to both the smoke trail and the sun glinting occasionally off the rocket’s chrome bands. After descending for over ½ minute, the parachute deployment charge was seen to fire and the chute immediately blossomed. The rocket drifted gently earthward, coming ever closer to where we were located. The rocket gently touched down in a nearby field roughly 100 feet away.

Despite the close proximity, we nevertheless programmed the landing site GPS coordinates into the Garmin hand-held unit. Indicated distance from where we were located was 119 feet (36 metres). The rocket was found to be in pristine condition. Raven failed to beep out a peak altitude. It appeared that the Raven has switched off at some point. We noted that all the pyros had fired and confirmed that the smoke charge had fully burned.

Flight Analysis
Event:	Time (sec)	feet	metres
Apogee	14.8	3365	1026
Separation	15.7	3352	1021
Main deployment	50.1	887	270
Touchdown	87	-	-
Range	-	339	103
Descent rates:	ft./sec.	m/sec.
Free-fall	74.6	22.7
Main parachute	21.3	6.5

Post-flight analysis and comments:

Post-flight examination of the rocket and data confirmed that the flight was fully successful. The operation of the EggTimer, BREO and BRB were fully nominal. The Raven data indicated an anomaly -- data recording ceased shortly after chute deployment. It was determined that a large shock load associated with the deployment event caused the toggle switch which controlled power to the Raven had “toggled” to the off position. Replacing the toggle switch with a rotary switch (such as that now used for the BREO) will be considered. The peak altitude readings reported by the Raven, Eggtimer and BREO all agreed to within 0.2%.

The JEM rocket motor performance was fully nominal. The rocket acceleration curve provided by the Raven indicated a burn that matched the expected performance and closely matched that of the static test. Tear-down of the motor revealed that the grain casting tubes, which serve as burn inhibitors, were fully intact except for the ends which are expected to burn away. For the next JEM flight, a full propellant load will be used. This will hopefully confirm that the enlargement of the grain cores resolves the anomalous burning issue seen in the previous flight.

Raven data:

Barometric and axial acceleration data Xi-12\Xi-12_Raven_basic.gif

Acceleration curve, boost phase Xi-12\Xi-12_Raven_accel.gif

Eggtimer data:

Altitude versus flight time Xi-12\Xi-12_ET.gif

BREO-N data:

Altitude versus flight time Xi-12\Xi-12_BREO.gif

BRB:

Flight path, mapped Xi-12\Xi-12_BRB-track.jpg

JEM motor:

Propellant grain segments Xi-12\DSCF5830.JPG

Grain segments, primed Xi-12\DSCF5831.JPG