A Cracking Flight

This flight was for a BBC TV show to be aired around Easter next year, with the aim to educate and inspire children to learn to code and to perhaps take up programming as a profession. This is a very worthy cause, especially with the current situation where the quantity of students wishing to enter University to study computing is much lower than it used to be, and on average they have much less programming experience than used to be the case. The result of course is a shortage of programmers and engineers going into industry and that’s not good for the UK economy especially in this technological age.

This of course is the problem that the Raspberry Pi was conceived of to address, with the aim to recreate the environment in the 1980’s where a generation of programmers were brought up on the likes of the BBC micro. Computers of that era booted into BASIC so even if you bought one just to play Elite you probably ended up typing in a game from a listing printed in a magazine, and maybe then modified it a little, or took the step to learn enough to write something of your own design. Many of today’s engineers started in this way, perhaps around 8-11 years of age which is the range that this TV programme is aimed at.

My own experience is a little bit different, because I’m a little bit older so when I was that age “computer” meant “mainframe”. Instead I started playing with electronics, building radios from kits. The Apollo missions flew at around that time, and I remember wishing that I’d been A – old enough, and B – American enough to be a part of that. That of course began the frustration that ultimately got me into HABbing as a hobby! At around 17 with a career in electronics ahead of me, I decided that I should learn about software, on the basis that sooner or later I’d either use a software CAD to design electronics, or I’d design electronics that would end up in a computer. This was about the time that the CBM Pet came out, but for me the most accessible computer was attached to a Teletype at the other end of a bus ride! I soon began to enjoy software more than electronics (the results are far more immediate, and you don’t have to spend your pocket money on boxes of components), thus changing the direction of my career before it started. However in my mind there was a major disconnect between typing a program into a teletype and what was going on at the electronics level and I wanted to fill the gap. So I designed and built my own computer from a pile of bits – an experience that put be in good stead for my entire career and of course my current hobby which combine electronics, software, photography (another hobby) and of course gives me my own (near) space programme!

So, back to the flight. I was approached by a production company who asked if I was willing to take part in the programme, with a flight using the Raspberry Pi as a tracker. I was happy to help. Filming took place a few days ago, amazingly on the first date we aimed for (no need to delay because of a poor flight prediction!). Even the rain held off though it was overcast and a little bit windy. The morning was spent in my office recording interactions with the kids and demonstrations of the tracking and in particular the live image transmissions. Here I am looking at the camera equipment squeezed into my office:

For the flight I’d built a new payload box to house the Pi and webcam, plus batteries and voltage regulators. No second camera this time. I also built a pink-ball backup tracker, and fellow HABber Anthony Stirk brought a new solar-powered payload:

He decided in the end not to fly it, so the actual flight just had the Pi payload (PIE3) and Buzz (BUZZ12). First job at the launch site, after the arrival and unloading had been filmed, was to get both trackers running. Here I am gluing Buzz together:

Meanwhile Anthony filled a party balloon and tested the wind direction and strength:

He and Ali then tied the payload train together whilst I inflated the balloon. First problem – the filler assembly fell apart! I use a “universal” filler rented with the Helium cylinder, and fix the filler hose to that with some special Polyproylene glue and a hose clip. This time the glue had run out so I used super-glue, but it didn’t hold. So I re-tightened the hose clip and used liberal amounts of duct tape to hold it all together.

With the balloon inflated it was time to tie off the neck of the balloon. With the earlier panic I’d put the balloon neck a bit too far down on the filler tube (and it’s quite a short neck on this size of balloon) meaning there wasn’t really enough of the neck free to fit the cable tie over. So I stretched the neck and … it slipped and came right off the filler! Fortunately I had a good hold of it, and Anthony quickly put a two cable ties and and then connected the line that goes to the chute and payloads.

With that done, I checked the telemetry again and we all walked the balloon and payload train upwind to the far side of the field.

I started to let the balloon rise and initially it was almost straight above my head, but as I let the line out the wind got much stronger and the line ended up nearly horizontal! The Pi box was so close to the ground, and swinging about in the wind, that it even touched the ground a few times!

With that sort of angle even Usain Bolt would struggle to run fast enough to safely release the balloon. I waited a few minutes but the wind refused to die down, so I sent Anthony to fetch some rings and a long cord so we could use the “2-line technique”, where the launch line is separate from the payload line. After he returned I pulled the balloon down so we could tie in the rings, but when it was about half-way down the wind eased and the balloon crept up to be straight above my head. So, we had an opportunity to launch “normally”, and after a brief delay for the camera, I launched (I didn’t even need to run!):

With that all done, it was time to get into the chase car and set off. This took a few minutes, to get things packed and to have the car filmed as it left. I drove, and we took one cameraman in the passenger seat, plus Ali and Julie in the back. I was glad of the extra space compared to a regular car!

The landing spot was expected to be near Sudbury in Suffolk, not far from where my previous flight landed. So we again headed for the M4 west and then the M25. Julie monitored the map and incoming images, whilst Ali kept in touch with other enthusiasts via the IRC channel. Worryingly, the live landing predictor had the flight landing very close to the sea, if not actually in it. I checked the ascent rate which at that time was lower than planned, so I did expect a sea landing. Fortunately though as the ascent proceeded the landing spot pulled inland, and the ascent rate increased to what I’d calculated.

While this was going on, Julie watched the live images being downloaded, and they just got better and better. This was turning out to be a very good flight! Even the traffic was on our side with no delays on the M4, and even the slight blockage predicted on the M25 amounted to very little. So we made good progress though probably not enough to get to the landing site before the flight landed. Here’s the full flight path and the route the chase car took:

From the M25 we took the M11 and then the A120, passing within a couple of miles of last week’s landing site. By now the flight was descending, having burst on cue at a little over 30km altitude.

The descent rate was spot on too, showing that the parachute was fully open and not tied up with the balloon remnants. It started getting darker as we got closer, and we lost the telemetry with the balloon 300m or so up. However one other listener – Dave “number10” – lives only a few miles away from the landing spot and continued to receive telemetry after the flight had landed. That was a bonus!

We headed for the landing site using a postcode given to us via IRC, and with Ali giving guidance from the live tracking map. Up front I was watching my touchscreen display mounted on the passenger side of the dashboard, with that showing a compass pointing to the payload position. As we got close the compass pointed over to the right, showing us that the payload was in a field (as seen on the map). I had to pass the field to find a turning place, then parked up right next to the field.

As we were getting ready to walk over to the payload, Dave “number10” called in to ask where we were. As it turned out he was parked the other side of the road from us! He came over and together we walked across the field which, by now, was in darkness. Dave had his handheld sat nav loaded with OS maps, and we used that as a guide. I scanned the field for the payload using a large torch, and we soon spotted the main payload box adorned with hi viz tape. When we got there both payloads were in good condition and the balloon had burst cleanly, so we picked everything up, called “mission control” to let them know, and returned to the chase car. So, a very successful day!

The Pi was still recording, having taken enough images after landing for me to put together this little time-lapse video:

Finally, these are some of the best shots from the Pi:

Also see:

Full set of Pi images

Julie’s Photos

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4 Responses to “A Cracking Flight”

  1. Graham Tanner says:


    I’ve been waiting several months for a suitable ‘launch’ to happen (one that would happen when I wasn’t working, one that I had a reasonable chance to contribute …) and last Friday’s launch worked perfectly for me.

    I was watching on the ATV feed (somebody forgot to re-position the camera so we could see the launch!, but never mind), and once it was in the air I tuned-in on my Yupi 7100. I was quite stunned to hear signals almost immediately, and a few seconds later getting DL-FLDIGI to decode them was the icing on the cake. I was most proud an happy to see my callsign appear on the tracker screen showing that my decodes were being used in the tracking.
    Over on IRC I was reporting its position to you, and making suggestions whether to use the M11 or A12. As you neared the landing site I continued to relay directions to you, including “it’s in the field to your right …. now!”.

    I have to say, that was one of the most interesting and entertaining afternoons for a long time. I can’t wait for the next one(s). One day, I might even turn-up for the launch!

    Keep up the good work.

    Graham Tanner, G6SUQ.
    West London.

    • Hi Graham,

      Apologies for not rotating the camera round, the whole filming thing was pretty hectic, normally I rotate the camera but in this case we were having wind issues, child issues and camera battery issues. Thanks for taking the time to track and glad you enjoyed it.


      Anthony M0UPU

  2. David Crookes says:

    Hi Dave,

    Please could you drop me a line to discuss the project for a magazine I’m currently working on. We’re doing a top 10 of Raspberry Pi projects and would love to include you.


  3. […] You can read Dave’s blog post about the filming and the flight here. […]

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