Basic
Information
|
Name
|
Z-7
|
Launch date:
|
2 January, 2015
|
Rocket description
|
63.5mm aluminum airframe
4 fins, birch plywood
aluminum conical nosecone
3 ft. ellipsoidal parachute
|
Payload
|
Raven altimeter
Mini camcorder (set to 640x380 resolution)
|
Liftoff mass
|
2.254 kg.
|
Flight objectives
|
- Main deploy set at higher altitude (576 ft.) to visually track
descent
|
Motor
details
|
Motor name
|
Impulser
|
Propellant
|
KNSB
|
Grain mass
|
281 grams
|
Nominal impulse
|
330 N-sec
|
Class
|
H
|
Weather
conditions
|
Temperature
|
-16°C
|
Wind
|
SE 5 km/hr
|
Sky
|
Light overcast
|
Other
|
-
|
Launch
Event Description
|
Despite cold weather, setup went smoothly. Raven and on-board
camcorder powered up, followed by sky check, countdown and liftoff. Rocket
soared skyward leaving a nice smoke trail, which aided visually tracking the
rocket well past burn out. Disappeared from view. Nothing was heard, which
caused some concern, as apogee charge should have fired after about 15
seconds. Several seconds later a reassuring ‘pop’ sound was heard, which was
followed by an odd “twanging” sound. The rocket was not sighted and after a
minute or so, it was decided that the rocket must have reached the ground,
and we began a visual search of the area. After a few minutes of visually
scanning the surrounding area, a black object was spotted in a snow covered
field, roughly a thousand feet away. We proceeded toward the object and it
soon became clear that this was indeed the rocket. From a distance, the
rocket appeared to be in good condition, with the parachute lying on the
ground next to the recovery section. It was odd, however, that the aft
fuselage was apparently stuck in the ground with the fins facing upward. Upon
reaching the site, the rocket was indeed in basically good condition, but was
clear that the parachute did not unfurl, despite clearly being deployed from
its compartment.
|
Flight
Analysis
|
Event:
|
Time (sec)
|
feet
|
metres
|
Apogee
|
12.9
|
2728
|
831
|
Separation
|
20.7
|
1688
|
517
|
Main deployment
|
32.1
|
562
|
171
|
Touchdown
|
40.2
|
|
|
Range
|
|
990
|
302
|
Descent rates:
|
ft/sec.
|
m/sec.
|
|
Free-fall
|
76.3
|
23.3
|
|
Main parachute
|
70.3
|
21.4
|
|
Post-flight
analysis and comments:
|
The aft section of the rocket was packed with frozen mud,
clearly indicating it hit the ground at a significant velocity (70 fps per Raven data). There was
some damage to the coupler and camcorder due to hard landing. The Raven was
undamaged, as was the rest of the rocket. The camcorder was tested and found
to be in working condition (requiring minor repairs) and good on-board
footage was obtained. Analysis of the Raven data indicated that the primary
apogee charge fired, but separation of the rocket sections had not taken place. Separation occurred
well after apogee as a result of the backup
apogee charge firing. Parachute ejection occurred as expected (this was
confirmed by the on-board video footage) at an altitude of 562 feet. For
reasons unknown, the parachute failed to unfurl, and the descent continued in
a free-fall manner, at a slightly retarded speed. It was initially thought
that the cold temperature caused a stiffening of the nylon material of the
parachute canopy. Subsequent cold-weather testing (@ -25C) later discounted this as the cause.
The reason for the primary apogee charge to fail to initiate separation was
traced to the Crimson Powder (CP). For this flight, the CP was more finely
ground than previous and was packed more tightly in the charge holder. This
resulted in slower combustion of the charge, and combined with the cold
ambient temperature, the pressure generated was insufficient to break the
tape seal securing the separation joint. For future flights, CP particle size will be
carefully controlled, using a granular form of mesh size range of #10-#60.
|
Raven baro and accelerometer graph:
Z-7\Z-7_raven.jpg
Photos:
My brother Blair setting up
launch pad Z-7\DSCF3384b.JPG
Rocket on pad Z-7\DSCF3383a.JPG
Liftoff (capture from videos) Z-7\launch_capture_1a.jpg
Z-7\launch_capture_2.jpg
Z-7\capture_camera_2_no.2b.jpg
Landing in snow-covered field Z-7\DSC00024b.JPG
Z-7\DSC00025b.JPG
On-board video capture, showing
forward section of rocket Z-7\Image3.jpg
On-board capture, showing some
tangling of lines Z-7\Image26.jpg
Parachute is visible in this
capture Z-7\Image19.jpg
View shortly before landing Z-7\Image17.jpg
Videos:
Launch (camera 2) Z-7\Flight_Z-7_camera2.mp4
Flight (camera 1) Z-7\Flight_Z-7_camera1.mp4
On-board video Z-7\Z-7_on-board_camera.WMV