Basic Information
Name	Xi-40
Launch date:	30 November 2024
Rocket description	- 3”/ 76.2 aluminum airframe (0.035”/0.89mm) - 4 fins, 2024 aluminum (0.065”/1.65mm) - 3D printed PLA tangent-ogive nosecone - 3D printed PLA boattail fairing/motor retainer - 3D printed PLA aft-mid body coupler - 3D printed PLA aft smoke system support - 3D printed PLA on-board camera bracket & fairing - 3D printed PLA NFB - 42 inch ellipsoidal "Fruity Chutes" parachute
Payload	- Blue Raven flight computer (primary role) - Blue Raven flight computer for backup apogee separation – EggTimer Quark altimeter as 2nd apogee backup and backup main deploy - BRB900 GPS transmitter - Liftoff-activated and apogee-activated smoke trackers with Legendary formulation. - SJCAM C100 on-board video camera
Liftoff mass	3.254 kg.
Stability Margin (minimum)	1.84
Flight objectives	- Assess cold-weather performance of new avionics.

Motor details
Motor name	APM-E.14.3 (38mm)
Propellant	AXP-AP4.7 (Ammonium Perchlorate 65.8% /Epoxy (New Classic) 24%/Aluminum 10% /Lampblack 0.2%)
Grain mass	346.7 grams
Estimated Impulse	677 N-sec. (est.)
Class	J

Additional information

- The rocket is largely the same as that for Xi-39, except parachute is new white/orange 42” ellipsoidal.

- The launch clip attachment was modified. Now attached by redundant means to the airframe with epoxy adhesive and a #2-56 machine screw.

Weather conditions
Temperature	-14°C (7°F)
Wind	NW 15 km/hr (ground level)
Sky	Partial Sun with thin stratus clouds overhead
Other	-22° wind chill
Ceiling	unlimited

Launch Event Description

This was the first cold-weather test of the new avionics – the pair of Blue Ravens and the Quark flight computers. The Raven-3 flight computer, used on earlier winter flights, had been functionally tested at -20°C, exhibiting no ill effects. Although the Blue Raven appeared to be of very similar design (with the exception of the Blue Tooth feature), I had not performed any cold weather testing on the unit. The Quark, likewise, was also not tested for its cold-weather functionality. As such, as a precaution, the AvBay was wrapped with a pair of chemical hand-warmers and insulation blanket, which was removed just prior to loading the rocket onto the launch rail. The nosecone, housing the BRB unit, was likewise wrapped.

All went smoothly during setup of the rocket and launch equipment, although it took longer than usual due to the cold (bare hands became stiff and painful after a minute or so and required frequent warming) . Following our checklist as usual, we proceeded to set up the launch rail assembly and the rocket. No glitches were encountered. Once the launcher was set up, the BRB transmitter and receiver were activated and verified that a good GPS signal was obtained. The two Blue Raven units were activated and verified to be functioning nominally. The Blue Tooth feature worked fine in the cold, providing status to the Featherweight app on my cell phone. The Quark was activated and, likewise, worked fine and was verified to be ‘ready for launch’ by its chirping. The lift-off activated smoke charge was powered-up and armed. Finally, the on-board camera was powered-up, set to record mode, and installed in the mid section of the rocket. The final step was to install the aerodynamic fairing that fits over the protruding portion of the on-board camera.

As usual, for filming the flight, I used my Sony HDR-CX240 Handycam fitted with scope tube. It was kept in a warmed and insulated box until just prior to launch.

We headed to where the Launch Firing Box was located, 275 feet south of the pad. After verifying the sky was clear, the countdown proceeded. At the zero mark, the ignition button was pressed. A puff of smoke, followed by a bright flash signified motor ignition. The rocket soared skyward with a loud roar, accelerating at a sufficiently slow pace that allowed me to follow its ascent with my camera. The motor burned for an estimated three seconds. We lost sight of the rocket after burnout, but were able to follow the smoke trail from the lift-off actuated smoke grain until it disappeared as the rocket climbed ever higher. We searched for sign of the apogee-activated smoke trail but none was visible, likely due to the thin clouds overhead. After a short while, we heard a faint ‘pop’ sound of the apogee pyro. We did not make visual contact until more than a minute later when the parachute pyro charge was heard firing. We immediately spotted the fully-inflated parachute to our left, at a distance estimated to be about a 1000 feet (300m.) away. The rocket gently descended and touched down near the frozen ditch that runs the length of the site.

We programmed the GPS coordinates received from the BRB transmitter into the hand-held Garmin GPS unit. Indicated distance was 0.2 miles (320 m.). We trekked to the touchdown site and as we approached, we noticed that the rocket had landed in the middle of the ditch (at this location, the ditch was at least 30 feet wide). Fortunately, the water was frozen, although the thickness of the ice was not enough to walk on safely. In fact, as I approached the ditch, the ice beneath my boot fractured, resulting in a rather unpleasant bootful. We decided the safest option would be to go back to the parked car and get a rope and grapple, which I conveniently carry in my car trunk. The round trip to the car and back took about a half-hour (we took advantage of the oportunity to warm ourselves in the heated car). When we approached the landing site, we noticed, to our surprise, that the wind had blown the parachute all the way to the shore of the ditch. The rope was not needed, as I was able to gingerly approach the parachute, using it to pull the rocket to safety. I then checked my Raven app, and it displayed an apogee of 4600 feet. The Quark was beeping its coded apogee value of 4542 feet. The rocket parts appeared to be in pristine condition.

Flight Analysis
Event:	Time (sec)	feet	metres
Apogee*	15.8	4105	1251
Separation*	16.3	4102	1250
Chute deployment	67.6	544	166
Touchdown	104	-	-
Range	-	1196	365
Max. velocity	625 fps	190 m/sec.	-
Descent rates:	ft./sec.	m/sec.
Free-fall	79	24.1
Parachute	19.6	6.0

* Corrected for non-standard base temperature.

Post-flight analysis and comments:

Post-flight examination of the flight data indicated that the operation of the two Blue Raven units was fully nominal, with a reported apogee of 4600 feet and 4595 feet. The Eggtimer Quark also performed nominally with a reported apogee of 4542 feet (all reported altitudes not corrected for base temperature). As such, the reported apogees for the three units were within 1.3%. All three flight computers fired their pyros nominally. Maximum reported acceleration of the rocket during motor burn was 13G’s.

Operation of the BRB (GPS) unit was fully nominal. GPS-based apogee was 4199 feet (1280m.), which is within 2% of the corrected Raven apogee..

Examination of the Raven axial acceleration data indicated that the APM-E.14.3 motor had a fully nominal burn that matched static test results. Burn time was 2.0 seconds.

Both smoke systems burnt nominally.

The on-board video camera worked nominally, providing good footage of the entire flight.

Examination of the rocket components verified all were in pristine condition. As such, this was a fully nominal flight despite the cold conditions. It was particularly satisfying that all the electronics worked as expected.

Misc photos:

Propellant segments for E.14.3 motor Xi-40\DSCF7701.JPG

E.14.3 motor Xi-40\DSCF7702.JPG

AvBay ready for flight Xi-40\DSCF7705.JPG

Blue Raven:

Barometric altitude plot Xi-40\Xi-40-Raven2-alt.jpg

Axial acceleration plot Xi-40\Xi-40-Raven2-accel.jpg

Big Red Bee GPS:

Flight path projected onto terrain Xi-40\brb-mapped1.jpg

Google Earth projection of flight path Xi-40\brb-mapped4.jpg

Launch photos:

Author with Xi-40 rocket Xi-40\DSCN0788.JPG