Basic Information

Name

Xi-29

Launch date:

29 July 2022

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

3.180kg.

Stability Margin (minimum)

2.40

Flight objectives

- Stretched Impulser motor with KNSB.

Motor details

Motor name

Impulser.1

Propellant

Cast Potassium Nitrate/Sorbitol (KNSB)

Grain mass

318 grams

Nominal impulse

395 N-sec.

Class

I

Additional information

-          Impulser.1 is a stretched version of the Impulser motor which holds 6% more propellant.

Weather conditions

Temperature

24°C  (75°F)

Wind

SW 20-25 km/hr

Sky

Clear with bright sun

Other

Scattered clouds

Ceiling

unlimited

Launch Event Description

Following our checklist, we proceeded to set up the launch rail system and the rocket. The BRB transmitter and receiver were activated and verified that a good GPS signal was obtained. The BREO, EggTimer and Raven units were activated and verified to be functioning nominally. It was then noticed that the forward launch lug had partially disbonded and was loose. We carefully removed the rocket from the launch rail, then reinstalled the rocket, having switched to the alternate set of launch lugs.

The on-board camera was then powered up followed by the electrically triggered 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, and the igniter fired. The rocket immediately  accelerated off the pad, climbing straight vertical initially, then veering about 10 degrees into the wind. The motor burned for approximately one second. As the rocket coasted toward apogee, we did not see the expected smoke trail. We soon spotted the distinct white smoke cloud forming as the primary apogee pyro fired as the rocket arced into the wind at apogee. A few seconds later the backup smoke charge cloud appeared, followed by an audible ‘pop’ sound some seconds later.

A thin smoke trail then appeared, as the apogee-activated smoke charge began to burn. The rocket tumbled earthward, its descent path clearly seen by the trail of smoke and the sun glinting off the rocket. Less than a half-minute later, the parachute ejection pyro was seen to fire and nearly immediately the chute fully inflated. The rocket gently drifted downward, carried by the wind in a north-east direction. The rocket touched down relatively close to the launch pad.

We programmed the GPS coordinates of the touchdown site into the Garmin GPS unit. Indicated distance was 0.15 miles (240 m.). We headed toward the touchdown site and soon spotted the parachute resting atop some tall alfalfa. The rocket appeared to be in pristine condition. The Raven unit beeped out a peak apogee of 1890 feet.

Flight Analysis

Event:

Time (sec)

feet

metres

Apogee*

11.5

1968

600

Separation*

12.2

1856

566

Chute deployment

28.4

664

202

Touchdown

58

-

-

Range

-

574

175

Max. velocity

458 ft/sec.

140 m/sec.

mach 0.43

Descent rates:

ft./sec.

m/sec.

Free-fall

82

25

Parachute

18.0

5.5

Post-flight analysis and comments:

Post-flight examination of the flight data indicated that the operation of the Raven, EggTimer and BREO was fully nominal for each. The reported apogee for the three units was within 0.5%. The GPS based apogee reading obtained from the BRB unit was 1788 feet (545 m.), which is 4% lower than the corrected barometric altitudes.

Examination of the Raven flight computer acceleration data indicated the the Impulser.1 motor had a fully nominal burn with the acceleration curve closely matching the theoretical thrust curve.

Post-flight examination of the lift-off activated smoke tracker confirmed that the smoke grain had not burned. Both igniters had fired. However, closer examination of the igniter pyrolant suggested that the pyrolant had not combusted fully. The pyrolant/residue was wet, suggesting that the pyrolant had absorbed moisture in the duration between installation and launch, which was about a week (moisture absorption is known to be problematic in summer). For the next flight, the pyrolant will be changed to a composition that is less prone to moisture absorption and extra care will be taken to isolate the igniters from ambient air.

The on-board SQ11 micro-camera did not record any flight footage. The recording stopped shortly after the camera was installed in the rocket. This is the same thing that happened in the previous launch. It was thought at the time that the cold weather was responsible. However, it is now apparent that the camera is faulty and will be discarded.

The launch lug that detached suffered adhesive failure at the surface of the PLA lug material. The adhesive used for the bond was a different type of silicone than usual. The lug will be rebonded with J-B Weld adhesive, making sure the surface has been roughened and cleaned.

When reviewing the video footage of the flight, it was discovered that recording had stopped during descent of the rocket. I recalled that I had accidently bumped the spring-loaded hinged LCD screen at that moment and the screen closed. This shuts off the camera (not a good design on the part of Sony).