Richard Nakka's Experimental Rocketry Web Site



Flights Z-3


 

Basic Information

Name

Z-3

Launch date:

25 October, 2014

Rocket description

63.5mm airframe (plastic)

4 fins, birch plywood

aluminum conical nosecone

2 ft. circular parachute

Payload

Raven altimeter

Liftoff mass

3.84 lb (1.74 kg)

Flight objectives

- Conduct repeat flight of Zeta rocket with A-100M motor.

 

Motor details

Motor name

A-100M

Propellant

KNSB-RIO

Grain mass

122 grams

Nominal impulse

144 N-sec

Class

G

 

Weather conditions

Temperature

10°C

Wind

W 15 km/hr

Sky

Clear

Other

launched 40 min. prior to sunset

 

Launch Event Description

Setup went well with no glitches. Clear sky confirmed, countdown commenced, and shortly after zero count, smoke seen at base of rocket, then rapidly rose skyward. Shortly after burn-out, parachute was seen to eject and blossom. Raven beep-out of apogee not noted.

 

Flight Analysis

Event:

Time (sec)

feet

metres

Apogee

-

-

-

Separation

-

-

-

Main deployment

-

-

-

Touchdown

15.1

-

-

Range

 

300

90

Descent rates:

ft/sec.

m/sec.

 

Free-fall

-

-

 

Main parachute

-

-

 

 

Post-flight analysis and comments:

Parachute deployed prematurely. Backup apogee charge did not fire. Raven baro data exhibited highly anomalous pattern. Discussion of anomaly with Adrian Adamson solved the mystery of premature deployment of Z-1 and Z-3, and explained the anomalous baro data. The source of the anomaly was a result of the rocket basic design, utilizing a common compartment for the Raven and for the parachute. Under sufficiently high acceleration, the parachute will slide “downward” and act like a piston, generating a positive pressure spike in the “avbay” containing the Raven. The Raven interprets this increase in pressure as beginning of descent, and thereby triggers apogee deployment. A simple fix was implemented for the next flight. A two second time delay was added to the required condition of apogee deployment. This problem presumably did not manifest itself with Z-2 because the Impulser motor generates a more gentle acceleration than the A-100M.

 

Raven baro and accelerometer graph:                                                   Z-3\Z-3_raven.jpg

 

Photos:

Rocket for Flight Z-3 on pad prior to launch                                          Z-3\DSC00010.JPG

Eric Nickel examining Zeta-3 after touchdown                                     Z-3\DSC00013.JPG

 

Videos:                                                                                                          Z-3\Flight Z-3.mp4

 


Last updated

Last updated March 3, 2015

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