Basic Information

Name

Z-33

Launch date:

6 September, 2017

Rocket description

- 63.5mm aluminum airframe

- 4 fins, aluminum, increased span

- birch elliptical nosecone

- 3 ft. ellipsoidal "Fruity Chutes" parachute, modified shroud lines

- ultra-low-power pyros

Payload

- Raven3 altimeter

- BRB900 GPS transmitter

- Smoke charge (activated by Raven at 2175 ft. level)

- Apogee Backup Timer

Liftoff mass

2.375 kg.

Stability Margin (initial)

2.59

Flight objectives

Test of:

1)      modified chute for improved reliability

2)      KNSB made with surfactant

Motor details

Motor name

Impulser

Propellant

KNSB-S.1

Grain mass

301 grams

Nominal impulse

354 N-sec

Class

I

Additional information

-Due to Flight Z-32 failure of parachute to inflate, analysis indicated the problem was due to the shroud lines being too heavy. The "Fruity Chutes" parachute comes fitted with braided nylon lines rated at 225 lbf (1000 N.) break strength. With 12 shroud lines, this is overkill for the Zeta rocket. Physically, the lines are nearly the same mass as the canopy. This could lead to a collapsed canopy that fails to “catch air”. The shroud lines were replaced with lighter gauge braided-nylon lines, proof-tested to a force of 100 lbf (450 N.).

-KNSB propellant was made using 0.1% Sodium Laureth Sulphate” surfactant added to the melted slurry to reduce viscosity to aid casting. Deemed KNSB-S.1, this is the 1^st flight using this propellant.

Weather conditions

Temperature

19°C

Wind

SW 4 km/hr

Sky

Mainly clear

Other

RH 45%

Ceiling

14k ft.

Launch Event Description

Setup of the rocket proceeded smoothly with no glitches. Raven checkout beeped nine times for voltage and gave 4 positive indications for the 4 pyros. Backup timer was then tested and confirmed to be operating nominally. For videotaping the flight, I used the hand-held camcorder (with scope tube).

After verifying the sky was clear, the countdown proceeded. Immediately after ignition switch was closed, motor ignited and rocket accelerated rapidly skyward, veering approximately 5 degrees to the right as it climbed toward apogee. The motor burned for approximately 2 seconds. Rocket disappeared from sight around 2 seconds after burnout. About 12 seconds later we spotted a smoke cloud, then heard a ‘pop’ of the pyro firing shortly afterward. A second smoke cloud appeared and then a smoke trail was spotted from the Smoke Charge. Owing to the smoke trail and sun glinting off the rocket’s chrome bands as it tumbled, the descent was easy to follow. The parachute charge was then seen to fire and the chute was seen to immediately deploy and fully inflate.  The rocket descended in a stable manner, with the smoke charge burning-out some seconds later. The rocket landed downwind roughly 700 feet distant.

We programmed the BRB GPS coordinates of the landing site into the Garmin hand-held GPS unit. The distance was indicated as 0.13 miles away. When we arrived at the landing site, the rocket appeared to be in perfect condition. Raven beeped out an apogee of 2534 feet (763 m.).

Flight Analysis

Event:

Time (sec)

feet

metres

Apogee

12.9

2536

773

Separation

14.0

2523

769

Main deployment

40.9

700

213

Touchdown

76.5

-

-

Range

-

703

214

Descent rates:

ft./sec.

m/sec.

Free-fall

71.4

21.8

Main parachute

18.0

5.48

Post-flight analysis and comments:

A good video of the entire flight was taken with the hand-held camera, which clearly captured the smoke clouds from all the pyro charges. From the video, the smoke charge was seen to burn for 30 seconds, which matched expectation.

Post-flight examination confirmed that the rocket was in perfect condition. The flight was fully nominal.

The rework of the parachute shroud lines appears to have been a positive improvement, leading the rapid inflation of the chute canopy.

Based on the performance of the rocket, the addition of a small amount of surfactant does not appear to have a noticeable effect on burn rate or impulse.