NORB makes its maiden flight!
After establishing a name which we could use for our cause, it was soon decided that the name NORB would be given to our first ever high altitude balloon flight...
After recently taking up an interest in the high altitude ballooning hobby and meeting some fantastic people from the UKHAS, I thought it'd be a good idea to try a flight for myself. With very little programming knowledge and a Raspberry Pi I got for christmas, I didn't realise exactly what I was getting into!
My first task was to make some sort of tracker that would retrieve, parse, and send the telemetry back down to earth alongside my Raspberry Pi. After much research, I found that a few bits and pieces from Anthony Stirk's HAB Supplies store would do the trick. Armed with my new components and having researched how to operate them, I was ready to go, so I shoved it all on a nice piece of veroboard. Here it is...
The veroboard consisted of the following components:
- NTX2 Radio Transmitter
- 2 Switchmode regulators
- A Ublox Max 6 breakout board
- SMA connector for antenna
Despite the whole thing looking really "professional," it never flew... After requiring repairs, I subjected it to the mercy of the Royal Mail and after putting no return address, and the incorrect delivery address anyway, I doubt that they ever flew it on a HAB somehow.
It was July 2012 - only weeks away from the scheduled launch date down in Cambridge and all I had was a Pi and a pretty shabby box (of course now without the veroboard tracker...)
But we were in luck. The famous David Akerman, master of Pi HABs and teddy bears, had a spare PCB which he'd left for me at the HAB supplies store. The PCB was pretty much what I had before on veroboard, but much nicer and probably much less likely to fail. It consisted of the same components, but it didn't have any on board power regulation. This was fine because I could just wire it with a couple of JST cables to my *spare* switchmode regulator. Not the best image but there it is...
The next task was to construct some form of box. We'd already settled on 25mm thick styrofoam as that seemed to be the popular choice for HAB. This is because it's very lightweight, quite tough and waterproof. After considering all the ways we could make the box we settled on having only two pieces of foam, a bottom and a top. This would involve moulding cutouts in the foam for the components to sit in so that they were snug and couldn't move.
As well as the box, the avove photo also shows our self-constructed 1/4 wave antenna. This was made from 4 pieces of single core circuit wire and some RG174 coax cable which you can get from many places such as Maplin or B&Q. The main element (the part extending towards the floor with outer shielding removed) had to be cut to an exact length of 164mm. The coax I used already had an SMA connector crimped on the end that connected to my Pi N Chips circuit board previously shown. Some people like to solder the coax directly to the RF pins on the transmitter as some RF is lost to the connector but that part's up to you.
The 26 pin header was a lifesaver as it meant I could use a simple GPIO ribbon cable to connect it straight to my Pi. After spending quite a while sorting out some Python code, the whole thing was working perfectly. To test out the antenna I built was up to scratch, we took a quick trip up a big hill as Mike Stirling a few miles away tried to decode my payload, which was sort of a success:
Before we knew it, we were driving down the M1 fighting with the horrendous rain as it tried to blur our vision and our chances of flying. Our 7-seater Ford S-MAX had become barely a smart car as we travelled down with a huge supply of eqiupment. As luck had it, the weather gradually became clearer and there we were waiting patiently for our launch guide, Steve Randall...
During the wait, I suggested we solder the two wires on our backup tracker to enable the flow of current. This involves plugging in a £7 soldering iron from Maplins in a dodgy chinese mains adapter in the boot of our car. It heated up surpirsingly quickly, but I think this may be the reason why the car is currently in service for a failing battery...
Below is an image of our backup tracker for the flight provided by Anthony Stirk at HAB Supplies (go buy from him). The ball simply consists of an AVR-based tracker called a "Pava" which does basically what my Pi was doing, but he knew it wouldn't fail...
After soldering everything together and accidentally burning my Dad, Steve arrived. We probably spent in all less than an hour setting everything up. We had to tie the payload and backup tracker to some nylon chord which then went up to a parachute which then went up to a 1200g Hwoyee balloon. While filling, I tried to contain my laughter as a gust of wind blew the balloon around which engulfed steve as he continued to fill it with Helium. At the time, I was useless at tying knots, so my Dad kindly assisted Steve while I observed...
The time had come. Months of arduous preparation, much investment and dedication from a multitude of people, it was ready. Steve begun slackening the nylon chord to allow the balloon to accend in a controlled manner. When he reached the bottom of the chord, he handed control to me. From the backup tracker to the balloon itself, the distance was incredible. I could just about see the huge balloon as a small object, eagerly awaiting my release as it floated above the tree line.
I let go. Up it went at around 5 m/s on its journey to the edge of the stratosphere. After packing everything away, we legged it back to our trusty S-MAX, and away we went.
In all honesty, it felt surreal to be actually in contact with the payload as I decoded it from the little vertical magmount on the top of our car and the ancient laptop on my knees. It continued to report back altitudes of around 28KM, before the NORB tracker failed. Sure enough, I could see that there was still a tone coming from the transmitter, but no data. We hastily reverted to the backup tracker which was working away beautifully as we saw our HAB peak at a higher than predicted altitude of 35.5KM (116,000ft)!
As it begun its decent, my Dad and I in the chase vehicle began wondering where to go to retrieve it upon landing. After a few arguments as to whether to turn left, right, reverse, we settled on a farmer's field. To our surprise, the payload was tracked down to 200m above sea level by some local trackers and the area was quite a bit above sea level anyhow. Unbelieveably, it landed in the field just next to the field we were waiting in.
We got out our trusty 10 element Yagi antenna (courtesy of Anthony Stirk from HAB Supplies). I was soon introudced to the sheer power of the Yagi when it instantly without me even needing to point it, brought back a green decode of data. We had a position, in that almost ready to harvest wheat field...
Rather than trample all over the crops, we took the decision to go and knock on the farmer's door. A man came to the door and my Dad began to explain what had happened. Then before I knew it, I was in the back of the farmer's Land Rover Defender as he drove us through his crops in search of the missing payload.
We reached the point where the Land Rover couldn't pass so we travelled the rest of the way on foot. My jeans were saturated as we waded through the metre-high wheat in search of NORB. It looked like everything had gone to pot, when suddenly the farmer called: "parachute! I see an orange parachute!" I'm afraid I'm not quite sure how to rotate this image:
It was one of the most exciting moments I'd ever had. I was so pleased, I started to sprint through the wheat in excitement, loosing both my shoes in the process (which took longer to find than the actual payload).
NORB had made it. Fully in-tact, Pi-Cam still flashing away. Our very first HAB flight, NORB, had been a raging success!