Basic Information
Name	Xi-27
Launch date:	11 December 2021
Rocket description	- 76.2 aluminum airframe - 4 fins, 2024 aluminum - 3D printed tangent-ogive PLA nosecone - 40 inch 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 - Liftoff-activated and apogee-activated smoke trackers with Legendary formulation. - SQ11 micro-camcorder, aft-facing
Liftoff mass	3.128 kg.
Stability Margin (minimum)	2.34
Flight objectives	- 1^st flight powered by APM-E.3 motor with AXP-AP2.4 propellant.

Motor details
Motor name	APM-E.3
Propellant	AXP-AP2.4 (68% ammonium perchlorate/25% epoxy/7% iron powder)
Grain mass	375 grams
Nominal impulse	682 N-sec.
Class	I

Additional information

- The APM-E.3 motor is a five-grain version of the four-grain APM-E.2 motor flown on Xi-25. Due to the length of the motor, a 3D printed PLA boat-tail was added to the aft end of the rocket. A thermal-break feature consisting of an o-ring and silicone gasket was incorporated to prevent melting of the plastic boat-tail body.

- A new larger parachute (40 in. versus 36 in. previously used) to accommodate the growing mass of the Xi rocket.

- New tangent-ogive nosecone designed to reduce drag at near-mach velocities anticipated for future Xi flights.

- A new launcher was designed and built utilizing aluminum tee-slot rail, which replaces 5/8 in. diameter steel rod. The rod was found to be too flexible under windy conditions. In addition, smaller launch lugs can be used with the tee-slot rail.

Weather conditions
Temperature	-7°C (19°F)
Wind	SW 15-20 km/hr
Sky	Clear with bright sun
Other	-13°C windchill
Ceiling	unlimited

Launch Event Description

Following our checklist, we proceeded to set up the new launch rail system and the rocket. A few glitches were encounted with the new system, but these were quickly overcome. The BRB transmitter and receiver were activated and verified that a good GPS signal was obtained. The BREO and EggTimer unit were activated and verified to be functioning nominally. However, when the Raven unit was activated, it beeped out code indicating that the main (parachute) pyro was not functioning. Our launch rules allow the launch to proceed if a single parachute pyro system is operating. As the EggTimer activated nominally, the decision to “go for launch” was made. The on-board camera was then powered up followed by the lift-off activated smoke charge.

For videotaping the flight, I used my Sony HDR-CX240 Handycam fitted with scope tube.

After verifying the sky was clear, the countdown proceeded. At the zero mark, the ignition button was pressed, the igniter fired immediately. The rocket then accelerated off the pad, climbing straight and true. A black smoke trail made it easy to follow the rocket during its initial ascent. The motor burned for approximately three seconds. We lost sight of the rocket following burnout. It was apparent that the lift-off activated smoke tracker failed to operate. After approximately 15 seconds, a tiny smoke cloud was seen, indicating that the apogee pyro charge had fired. A second (backup pyro) smoke cloud was then spotted. Some seconds later a faint smoke trail was seen as the apogee smoke charge began to burn. We were able to visually follow the tumbling rocket, and lost sight of it about 20 seconds later as the smoke trail became too faint due to downrange distance. A short while later, a ‘pop’ sound was heard as the main pyro fired, and the rocket was immediately sighted drifting earthward under a fully-blossomed red-and-black parachute. Less than ½ minute later, the rocket gently landed over the crest of the nearby embankment.

We programmed the GPS coordinates of the touchdown site into the Garmin GPS unit. Indicated distance was 0.4 miles (0.64 km). Checking a map of the surrounding area, we determined that the predicated landing site was near a sideroad, which allowed us to drive to the location. We found the rocket exactly where indicated by the GPS coordinates, near the edge of the sideroad. The rocket appeared to be in perfect condition. Upon closer inspection, we did notice that the on-board camera had broken away from the rocket on landing. The camera was found nearby. Raven beeped out an apogee of 3903 feet.

Flight Analysis
Event:	Time (sec)	feet	metres
Apogee*	15.1	3601	1098
Separation*	16.1	3593	1095
Main deployment	56	593	181
Touchdown	86	-	-
Range	-	2101	640
Descent rates:	ft./sec.	m/sec.
Free-fall	86	26.2
Main parachute	17.5	5.3

* Corrected for non-standard base temperature.

Post-flight analysis and comments:

Post-flight examination of the rocket and data indicated that the operation of the EggTimer was fully nominal. The BREO unit stopped recording at the 57 second mark, coinciding with chute deployment. The same thing happened on Flight Xi-25. The cause is currently being investigated. The Raven, EggTimer and BREO each gave apogee readings within 1%.

The reason why the Raven gave a negative indication for the main (parachute) pyro channel is currently being investigated. The pyro device was tested and found to be fully functional.

Examination of the Raven flight computer data, and post-inspection of the rocket motor, showed that the APM-E.3 motor had a fully nominal burn with the acceleration curve closely matching the static test thrust curve.

Althought the BRB transmitter did perform nominally during the flight, the unit did not record any flight data. Discussion of this issue with Greg Clark (BRB creator) narrowed the problem down to defective flash memory. The unit has been sent to Greg for repair.

Post-flight examination of the lift-off activated smoke tracker confirmed that the smoke grain had not burned. Both igniters were found to have fired. It is likely that the cold temperature of the smoke grain was at least partly responsible for the anomaly. For future cold-weather flights, the igniter design will be modified to generate greater heating, and/or the grain will be coated with an ignition primer.

The on-board SQ11 micro-camera did not record any flight footage. The recording stopped while the camera was being installed in the rocket. It is believed that I may have inadvertently toggled the record button (stopping recording) during installation. In the future, greater care will be exercised during this operation.

Raven data:

Barometric and axial acceleration curves Xi-27\Xi-27_Raven_basic.gif

Axial acceleration curve Xi-27\Xi-27_Raven_accel.gif

Eggtimer data:

Altitude versus flight time Xi-27\Xi-27_ET.gif

BREO data:

Altitude versus flight time Xi-27\Xi-27_BREO.gif

Miscellaneous photos:

APM-E.3 motor Xi-27\DSCF6693.JPG

AXP-AP2.4 propellant grains Xi-27\DSCF6666.JPG

Igniter clip installed Xi-27\DSCF6669.JPG

3D printed PLA boat-tail Xi-27\DSCF6691.JPG