We are still waiting for “official” approval from CASA. Though we are fairly confident it will be approved. We are proceeding with the final stage of the project, leading up to the launch. We have:-
Confirmed availability of Helium gas and what the latest date is that we can order/purchase it
Sorted out where we will stay on the Friday night (day before the launch). We are fortunate in that it is the ‘quiet’ season and so we can book this accommodation ~ 2 weeks out.
We have found a place that can hire out the Satellite phones at a reasonable price are happy to make the satellite phone booking “tentative”. We will up later to confirm that we require it.
Organised a “pre-flight” meeting.
Confirmed availability of all the crew who will help make the launch possible!!
I have decided to do up a small “simplified” picture of all the communication links. It neglects the fact that there is a separate Spot satellite and there are obviously servers where information is stored, but it should be helpful.
There was much thought and time spent trying to find a suitable design/construction procedure for a radar reflector. There are several ones on the Internet, e.g. Instructables one, but they did not seem that practical/suitable. This post describes how our Radar Reflector was built.
The requirements of a reflector are:-
It is light weight
It is able to perform its function regardless of the orientation
It is strong (rigid)
It is easy to construct and not overly expensive.
For materials I decided to use core-flute material (Sold at companies that create signs) and Aluminium tape (50mm x 5metre) from Jaycar and two cable ties.
The construction is best illustrated I think using some photos. Please see below:-
Measuring up – 3 squares – each with side of 250mm
Cut out the squares using a blade. Dark lines indicate where we need to create incisions later on
Incisions are made. Incisions are just a little narrower than the width of the Coreflute
Assemble the three squares. Cables ties later connect two ‘right-angle’ pieces together.Apply Aluminium tape to all faces. Weight is 250grams
We will drill a hole later on in a corner for the thread. Will re-enforce this hole with additional Aluminium tape.
It became obvious that there are probably some ways to make the build process a lot easier. Possibly putting tape on initially before cutting and putting together.
I do also wonder if we “really” need to have Aluminium tape on both sides of the Coreflute; but decided in the end to apply it to both anyhow.
But it is strong/rigid, light, not too difficult to make and inexpensive.
The Balloon can in some cases travel quite far distances and so tracking the balloon needs to be as easy as possible. Much useful data, like GPS co-ordinates, speed and direction are already gathered. We also calculate and display the distance between the ground station and the payload. A graphical representation of the trek of the balloon and the position of the groundstation – a map – would be most helpful. This post describes the steps to accomplish this.
OpenStreetMap (http://wiki.openstreetmap.org/wiki/OpenStreetView) is a very good “free” mapping software that can be installed on a LINUX based system. First we needed to assess this piece of software and its suitability. It was initially installed on a Debian machine using a map that encompasses a fairly large area of the Cairns region, where all balloon trajectories are within. Initial testing suggested it should meet the requirements – it was highly functional and showed the main roads that would be traveled and the API DEV interface is well documented.
The installation process was replicated on a Beaglebone Black. Angstrom Linux was ditched in favour of Debian Linux. Additional space was required, so an 8GB microSD was inserted, formatted and mounted. I had to go through the whole slow process of compiling support for the RTC_DS3232 module and get wireless etc going. Because a lot of additional packages were required, many unrequired packages had to be removed.
The result, a map that can be viewed offline and show all the waypoints of the balloon and the position of the groundstation when using a phone/pad device with built-in GPS. Below is a screenshot of it.
Example waypoints of imaginary balloon
Here is an example with predicted flight path in red.
The interface has been written to show only way points for the current day. Red way points are for the balloon, except for the Green one which is the beginning one. A Blue point indicates the vehicle (when we have a GPS enabled device, e.g. an iPhone). Red path is the predicted flight path and can be generated by uploading a CSV file created on http://habhub.org/predict.
NOTE: We don’t have the blue icon here because this was done from a browser without a GPS device.
A line separates each balloon way-point and time/position are recorded against each way-point.
It can be a little slow at times, but when a map is generated and cached, when it is later recalled, things work relatively quickly. Definitely suitable for what we need it to do.
