Each flight log entry usually
represents a launch or test day, and describes the
events that took place.
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Day 17 - Flight
Computer Successful Flights.
Getting Frankovka III ready for launch. A
bit of voodoo always helps.
... and launch ...I don't know ... kids
today ... packet of chips in one hand, rocket
release in the other.
Inflight images from Frankovka III. You can
see the rocket shadow here.
Standard view of the oval.
looking south towards the city on the
I just like the green colour of this image.
On the way down, the Air Command team await
the rockets' return.
Frankovka III on twin parachute.
Making sure the range is clear befor launch.
Frankovka III with FC.
Setting the time delay on the FC.
FC's maiden ...ummm ... water plume...
On one of the flights the rocket ended up
Last week we scouted out a new launch site
with plenty of clearance.
Clear skies with warm temperatures and a
An older rocket that survives
most impacts without a parachute.
2 x 1.25
This is a 2 bottle rocket joined
at the base, with a parachute
recovery system. The rocket remained
in the same configuration since the
last launch day.
This is an older rocket designed to
carry a video camera and a flight
computer. On this day, it was flown
with the camera on one flight and
the flight computer prototype
but no video camera on all other
consists of 2 x 2L bottles.
PK, GK, Paul K and John K.
of launches: 8
On this day we flight tested the flight
computer (FC) for the first time. It has
been about 3 weeks since the last launch day
because the weather was either too rainy or
windy to fly. The FC is designed to provide
a more reliable parachute deployment system,
as well as provide other functionality. Full
design details of the FC are available
Flight Day Events
First off the launch pad was a newly
rebuilt Frankovka III rocket because on the last
launch day it was quite heavily damaged.
The top bottle and payload section had to
be rebuilt. On this first flight the video
camera was fitted but no flight computer.
The rocket took off at a bit of an angle,
but flew fairly straight. We fitted twin
parachutes to slow it down even more in order to try
and stabilise the
video footage. This was reasonably
successful, but the two parachutes tangled
around each other and so were effectively one
This flight used the nosecone-off-at-apogee parachute deployment system, and as
has happened on numerous occasions the
parachutes deployed a little too early. Luckily we
have much stronger main chute lines now so
there is little risk of breaking them.
After this flight, we removed the
nosecone and payload section from the
rocket and replaced it with the prototype
FC controlled parachute deployment
nosecone. Since this was the maiden flight
we opted to not include the video camera
just in case ... well you know.
We filled the rocket, packed the chute,
and turned on the computer. I worked out from previous
video footage of this rocket that the time
to apogee was about 5.5 seconds. While
on the launch pad we set this time delay
on the FC. (The flight
computer can set the time delay in 1/4
We launched it and the flight profile was
similar to the previous flight, angled
slightly on take off, but then flew
straight again. The rocket went through
apogee, but the parachute deployed perhaps
1 to 2 seconds after that. The parachute
deployed well and the rocket landed well
We only used one parachute for these
We refilled the rocket with water, re-packed the chute and the rocket was ready
to go. There was no fussing with balancing
the nosecone or anything. You just turn on
the computer, set the delay, arm it
On each subsequent flight we reduced the
deploy time by 0.5 second. With the final
setting set at 3.5 seconds deployed the
parachute at the point we wanted. Although
the rocket reached apogee at around the 5
second mark, due to the parachute being
tightly packed it was taking about 1.5
seconds to fully open. This allowed the
parachute to fully open at apogee. We
simply roll up the canopy and lines when
we pack the chute, however, there are
much better ways to pack a parachute for
faster opening. We may do that on future
We were really pleased with the
ability to finely adjust the parachute
deployment. The rocket was launched at 120
psi on virtually all flights. For testing
we wanted a slightly lower pressure so
that the flights were more consistent.
This rocket has flown at 140 psi on a
number of occasions.
We believe the strengthening breeze
had a lot to do with the angling of rocket
on take off. We observed this behaviour on
previous breezy days.
On one flight the rocket got stuck in
a tree, but luckily it was within reach
and was easy to bring down. That led me to
think that perhaps the rocket should have
a parachute line cutter so that should the
rocket get caught in a tree by the
parachute, then say after 30 minutes if
the computer is not turned off it could
cut the line.
Last week we investigated a possible
new launch site that is free of trees and
has at least 300m radius of clearance,
although in one direction it is about 2
km. When we build bigger rockets we will
have to go to this site (assuming the
owners will give us permission) as the
park where we are is getting too small. On
the last flight of the day the rocket
drifted down range about 130 meters.
This was a good
flight with the video camera getting
fairly good stable footage. This
flight wasn't as high as others but
the twin parachutes opened a tad
Had to launch this
one for the kids while Frankovka III was
being re-fitted with the FC
nosecone. This one went up fast and
Our good old OO had
a good flight although on the way up
it spun and wobbled a little bit, it
looked like the nosecone wasn't
sitting properly. The parachute
deployed well near apogee.
time 22.5 seconds
The FC maiden
flight. The deploy time was set to
5.5 seconds. The parachute deployed
well past apogee and the rocket landed well.
The rocket again took off at an
Flight time: 22.4 seconds
Similar flight to
above with delay set to 5 seconds.
The chute again opened past apogee.
Flight time 20.6 seconds
Again similar flight
as above with delay set to 4.5
seconds. The chute was still
deploying past apogee but was
getting closer. The rocket drifted
down range so far it got stuck in a
Flight time: 22.1 seconds
Good flight again
with time set to 4 seconds. This was
fairly close after apogee. Again the
rocket landed well.
At slightly higher
pressure and deploy setting set to
3.5 seconds the parachute opened
about where we wanted it. The rocket
also drifted down range the
Flight time: 26.4
seconds (130 meters down range)
Design and Development
Here is a video with a description
showing a close up of
the FC parachute deployment mechanism.
Next on the drawing board for the FC
is to give it the ability to record air
speed sensor data. This will mean also
writing a bit of code to allow the FC to
transfer its data to a computer for later