back to article Raspberry Pi used as flight computer aboard black-sky balloon

A Brit amateur balloonist has pulled off two major achievements: getting his hands on a wallet-sized Raspberry Pi computer and then sending it heavenwards to 39,994m (131,200ft). Over the weekend, Dave Akerman's PIE1 payload was carried aloft into the stratosphere under a latex meteorological balloon, sending back live webcam …

COMMENTS

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  1. JimmyPage
    Thumb Up

    I just love this stuff ....

    that's all

  2. Anonymous Coward
    Joke

    Wind blows in wrong direction.....

    If that goes in the wrong direction it'll be shot down as a threat to the Olympics and Dave will be banged up as a dangerous subversive!

    1. Anonymous Coward
      Anonymous Coward

      Re: Wind blows in wrong direction.....

      Heh, I'm wondering how long before some enterprising young perv rigs up a similar bit of kit attached to a remote controlled blimp and starts floating it past people's bedroom windows...

    2. xperroni
      Paris Hilton

      Re: Wind blows in wrong direction.....

      Actually I have a serious question about this.

      Are we allowed to launch these hydrogen-filled balloons anywhere, without asking for permits or otherwise telling anyone? What if it gets in the way of a plane, lands on a factory or something like that?

      1. hplasm
        Meh

        Re: Wind blows in wrong direction.....

        Yeah- it might make a nasty POP!

      2. pixel
        Go

        Re: Wind blows in wrong direction.....

        You need CAA approval to launch anything above a certain weight and 2m diameter (I think). More info is on the UK High Altitude Society wiki: http://wiki.ukhas.org.uk/guides:faq

        1. LinkOfHyrule
          Joke

          UK High Altitude Society wiki - not what I expected

          Damn, I was getting them mixed up with the Mile High Club - I bet they get that a lot!

      3. daveake

        Re: Wind blows in wrong direction.....

        Any balloon that reaches a size of 2m or more in any direction (and that includes the payload) needs permission from the CAA.

        The balloon was filled with plenty enough hydrogen to ensure it would burst.

      4. balloonatic
        Facepalm

        Re: Wind blows in wrong direction.....

        Needless to say, of course not. This is not 'Nam, there are rules. ukra.org.uk for the UK rules.

  3. Graham Dawson Silver badge

    Now where's that anon who was pooh poohing the idea that the pi could or would be used for projects like this? I've got a special order of sour grapes just for him.

    1. Anonymous Coward
      Boffin

      Pi

      Dammit, I keep on meaning to buy a Pi but I've just seen a SD card adaptor for my BBC Master that caught my eye. I can only tinker so much at any one time!

      Decisions, decisions!

      1. Steve Evans

        Re: Pi

        You mean this one?

        http://www.adonald.btinternet.co.uk/MMCCard/BBCMicro.htm

        1. Anonymous Coward
          Anonymous Coward

          Re: Pi

          No. There's a guy selling ready assembled units on Ebay that include a special ROM that allows you to use disk images from the net as normal disks.

  4. Anonymous Coward
    Anonymous Coward

    Heatsinks

    I may be a bit "off" on this, but why has Dave fitted a heatsink to the Ethernet controller (just behind the USB ports), and not to the main CPU/GPU (SoC) in the middle?

    I wouldn't have thought the Ethernet would be used at 39,000m, but surely the CPU would?

    Cool achievement overall, though :-)

    1. brooxta
      Boffin

      Re: Heatsinks

      The ethernet circuitry is housed in the same chip as the USB stuff on the Pi. The webcam was USB, so the chip was in use, even if the ethernet wasn't plugged in. Interestingly on heat scans of the Pi when it's running the hottest part of the board is the ethernet/USB chip, not the CPU/RAM stack in the middle. Dave did his homework!

      PS. Please can we call them Pydrogen balloons now?

      1. daveake

        Re: Heatsinks

        Well, less home work and more "putting my finger on each chip to see which ones were warm", but yes, what you said!

        1. John Bailey

          Re: Heatsinks

          Hey.. That counts as a digital heat sensor..

      2. Anonymous Coward
        Anonymous Coward

        Re: Heatsinks

        You're quite right - I'd forgotten about the Ethernet and USB being on the same bus on the RasPi (slightly embarrassing, as I own one).

        As you said: thankfully, Dave did more homework than me... :-)

  5. spegru

    heatsink?

    I'd have thought that the lack of convection would have been offset but low temperature

    1. daveake

      Re: heatsink?

      Generally, no. I've flown other payloads before with a couple of cameras in them, and they can get quite warm.

      Also, after the thing lands, the outside warms up (though not that much in our "summer"!) and the inside can get very warm indeed till recovered. As mentioned in my blog I was hoping to use switching regulators but they didn't arrive in time, so when I opened the payload the linear regulator was very, very warm!

    2. Rich 11 Silver badge

      Re: heatsink?

      Convection normally takes away much more heat energy than a small device can manage by radiation or conduction, so a heat sink at higher altitudes will definitely help.

  6. JimmyPage
    Happy

    By the way - I also love the banner ....

    Anyone else notice ?

  7. Anonymous Coward
    Anonymous Coward

    silly questions...

    could anyone explain, whether this was tethered? Surely not, I can't imagine a 40 km long piece of string. How much would it weigh?

    and then, yes, hypothetically, if not attached, what happens when it pops? I mean, think of the children, for God's sake.

    Worse still, imagine one of our Masters, moving briskly between the limo and the door of the conference hall. Short distance, brisk pace, wide grin, but still... I dread to think of the mess on the street...

    1. JimmyPage

      Re: silly questions...

      Not so silly - it's what we need to teach kids to do more of.

      With what seems like man+dog launching stratospheric balloons (James May ????) I've vaguely wondered about this too. ISTR talk that you need to watchout for pylons

      Regarding the descent, the only thing I can think of is that statistically, it's so unlikely a falling weather balloon will hit someone, it's regarded as acceptable. However, that said, a few years ago, we (Dad & I) found a weather balloon plus payload tangled up in a tree at his garage yard, in Hounslow - and I would not want that hitting me on the head. ISTR it had a little inventory tag asking nicely to call the Met Office, who came and collected it. It did have a rather Heath Robinson appearance, and was spray painted silver.

    2. Graham Bartlett
      Holmes

      Re: silly questions...

      I believe you'll find there's this thing they call a "parachute". Chap called Leonardo Da Vinci invented it, so perhaps it's still a bit of a newfangled idea...

      1. Nigel 11

        Re: silly questions...

        Even without a parachute, the drag created by a burst weather balloon is fairly considerable. I expect that for the weight of payload that it can lift, packed into something without any sharp corners, the risk of causing serious injury is negligible even if it does land on someone's head at terminal velocity.

        The odds of hitting someone with an object dropped randomly on the earth's surface are very small. There are probably more meteorites dropping to earth every year than there are weather balloons, and even a small lump of nickel-iron at terminal velocity could do serious injury or worse.

    3. TeeCee Gold badge
      Coat

      Re: silly questions...

      No big.

      I'm sure that getting a pi in the mush somewhere between the limo and the hall is a recognised occupational hazard for anyone on the Mastery side of things.

    4. pixel

      Re: silly questions...

      The Met Office launch several of these each day...

    5. daveake

      Re: silly questions...

      Er, no, not tethered. 40km of nylon is going to weigh (rough guess) 40kg and the balloon had about 600g of free lift available.

      As mentioned in the article we use flight prediction software so we know roughly where it's going, and if that means in or close to a large populated area or airport for example then we wait for another day. We can also change the flight path a little (e.g. increasing the ascent rate by adding more gas).

      All flights in the UK have to carry parachutes, for obvious reasons.

      1. Anonymous Coward
        Anonymous Coward

        Re: silly questions...

        and what's the risk of a chance meeting with an airplane engine? Presumably also low enough, considering flight paths, etc? (no sarcasm, I'm really curious).

        1. Lester Haines (Written by Reg staff) Gold badge

          Re: Re: silly questions...

          Well...

          http://www.theregister.co.uk/2012/01/30/balloon_warning/

          1. Annihilator Silver badge
            Holmes

            Re: silly questions...

            Further "well" (relating to Lester's linked article) is that a balloon wouldn't "pop up" on an aircraft - its ascent rate (at that height) would mean it would be in the FOV of the aircraft for some time.

            Regardless, at the speeds the aircraft is traveling, it's more likely the balloon would be pushed around the craft (best case), or it hits the balloon (ruptures, little damage to plane, bearing in mind the hydrogen won't burn at that altitude) or in the very absolute worse case it gets sucked into the engine. It's for this infinitesimally tiny probability that a plane generally tends to have at least two engines.

  8. jake Silver badge

    Old news ...

    We were doing that in the early 1980s.

    Much more fun, in the late 1960s we were drifting fused aluminum-foil draped oxy-acetylene balloons over Moffett Field when the weather conditions were right ... Watching the Phantom jets scramble was a hoot ;-)

    The balloon "boom" wasn't quite as nice as the sonic boom of the Phantoms ...

    1. Nigel 11
      Boffin

      Re: Old news ...

      Nice story but the physics is wrong. Oxygen and Acetylene gases are both denser than air. Such a balloon wouldn't get off the ground.

      1. jake Silver badge

        @ Nigel 11 (was: Re: Old news ...)

        As usual, I'm not providing details when it comes to this kind of thing ... The Oxy-acetylene was the "boom" balloon ... how it was drifted, without undue static, is left as an exercise for the reader ;-)

      2. Anonymous Coward
        Anonymous Coward

        @Nigel Re: Old news ...

        Hush! You're letting facts get in the way of fantasy

  9. Anonymous Coward
    Anonymous Coward

    surely the most important question, which many Pi owners are struggling with, is what did you power it with? and did the usb devices draw their power through the Pi or have separate power source?

    1. Nigel 11

      Batteries?

      Presumably the lightest possible batteries that pack enough charge for the duration of the flight. I'd guess non-rechargeable Lithium cells. Obviously one would check that the voltage and current needed are maintained at low temperatures (or weight-budget for enough thermal insulation to prevent them getting too cold).

      1. Anonymous Coward
        Anonymous Coward

        Re: Batteries?

        I've read his blog post now, you're right Lithiums, and shorted the poly fuses to get enough power through the USB sockets.

    2. Andy Gates
      Thumb Up

      4XAA works okay

      Any of those common 4x AA - to - USB portable power packs has enough grunt to work my Pi on the ground. Fancy batteries would be lighter, of course!

    3. daveake

      6 AA Lithium Energizers into a linear regulator, then that was connected to 0V and 5V test points on the Pi.

      I left the on-board 3.3V in place for this flight, but for next time it and the external regulator will both be replaced by switched-mode versions.

      The webcam powered from the USB port, but I shorted out the USB thermal fuse on the board. Webcam current peaks at about 250mA and the fuse is rated at 140mA. The 5V to the webcam drops quite considerably with the fuse in place. In tests I could take low-res photos OK but it all locked up when trying to take hires photos.

  10. stu 4
    Holmes

    flight computer ?

    Struggling to see how this is in any way a 'flight computer'.

    it ain't controlling the flight in any way at all.

  11. andy gibson

    I stopped reading....

    ... when I saw the first picture and that bloke's T-shirt with one of those oh-so-funny "keep calm" phrases on.

    1. James Hughes 1

      Re: I stopped reading....

      that would be your loss then....

  12. Dodgy Geezer Silver badge
    Meh

    As a matter of interest...

    "..Doubtless this will renew efforts by inflammable gas experts to convince us to use hydrogen for our Low Orbit Helium Assisted Navigator (LOHAN) mission, but we're sticking with cigarette-friendly helium, thanks very much..."

    Would there be ANYTHING which would convince you to use hydrogen?

    1. Lester Haines (Written by Reg staff) Gold badge

      Re: As a matter of interest...

      A large suitcase stuffed with cash.

      1. JimmyPage

        Re: As a matter of interest...

        Maybe ask Barclays to sponsor you ?

  13. Robin Szemeti
    Coat

    Amazing acheivment

    Truly stunning ... I'm impressed.

    Wait, not at the ballon altitude or the assembling of the various perpipherals. Frankly lofting a camera to 143,000 feet is not that much of an achievement compared to actually gettign hold of a Rapsberry Pi. It's the stuff of legends .. there are people who claim to know people who have seen one, but, when these leads are followed up, they turn out to be dead ends. Rarer than olympic guards and dodo eggs, the RaspberryPi is the stuff of dreams.

    I'll get my coat, its the one with an Arduino in the pocket.

    1. daveake

      Re: Amazing acheivment

      I got two of them. I bet you're really impressed now!

  14. Robin Szemeti

    LiPo suction

    The best energy/weight density of any current battery (current, geddit?) is probably LiPo

    1. Anonymous Coward
      Anonymous Coward

      Re: LiPo suction

      LiPo will not perform well in the cold, might even damage the cells. Maybe LiFePO4 could cope, but even that is usually only rated to -20C.

    2. balloonatic

      Re: LiPo suction

      Rechargeable battery, maybe. But LiPo's do not have the power density of some lithium primary cell chemistries. Also the temp performance is very very poor, as someone else mentioned.

  15. Chris Evans

    switching regulators

    Hi Dave great work. Do you have the make and part no.s for the switching regulators to hand?

    1. daveake

      Re: switching regulators

      Some modules on ebay. Currently on a slow boat from China.

  16. Anonymous Coward
    Anonymous Coward

    I'm interested in knowing if @daveake ever considered using an old, cheap, mobile phone for this purpose?

    Seems to me he would get a nice camera, working GPS (which was reported not to work here due to interference from the Pi or webcam), lightweight power supply and built-in protection without much of the bulk. Plus how cool would it be to have it text back it's coordinates after landing? Telemetry could be done over a USB-serial converter for example (or jailbroken iDevice TTL serial pins)

    Don't get me wrong, I can appreciate the fun in sending what is effectively a media player design up into near space and can think of other similar fun things to send up there. Just curious on opinions if a mobile would also work.

    1. daveake

      I did this just because it seemed a cool thing to do with my Pi that was sat on my desk waiting for something to do.

      The phone idea is interesting, but I'd be very surprised if the GPS works at high altitudes. Most deliberately crap out at 18km. Very few (the Lassen is one) correctly follow the rule of "stop working above 18km and 1000mph". Most do "or" not "and".

  17. A J Stiles
    Pint

    39994

    Just six metres shy of a nice round figure. That has got to be a sickener!

    Have one of these to make up for it .....

    1. daveake

      Re: 39994

      The 39994 was reported by another payload on the same balloon, 10 metres below :-)

      Dave

  18. Matt Piechota

    "LiPo will not perform well in the cold, might even damage the cells. Maybe LiFePO4 could cope, but even that is usually only rated to -20C."

    Use the batteries as part of the heat sink. ;-)

  19. TRT Silver badge

    You didn't title the article...

    Pi in the sky. I'm disappointed.

  20. xerocred

    do you need a licence or anything this?

    Seeing as you're not allowed to even fly a kite above 200' or close to an airport etc.

    and the transmitter frequency?

    Just curious... And think this is great stuff.

    1. daveake

      Re: do you need a licence or anything this?

      Yes, you have to apply to the CAA for permission. If it's granted (which it normally is if you're not close to an airport or other restricted area) then you get a permission sheet and they issue a NOTAM (NOtice To Airmen). These cover the launch site and surrounding area for the duration you asked for (II normally request a few hours on a Saturday and Sunday). I quite often then get calls from private pilots asking if it's OK to fly through the zone.

      The transmitter frequency is in an unlicensed band for which airborne use is allowed, though only at very low power (so we use very sensitive receivers).

  21. Jess--

    @Daveake

    I wonder if you could provide a little more info on the software used for the sstv on the Pi

  22. This post has been deleted by its author

  23. Anonymous Coward
    Anonymous Coward

    Daft Question Time

    Yes I know this may sound like a daft question but.....

    I have just looked into getting one if these raspberry thingies and it would seem that when you buy one, you don't get a SD card with the OS on it as part of the package.

    Now, unless I am wrong about that, this seems a bit daft to me - you wouldn't buy a PC without a hard disk would you and this seems to be the case here.

    Correct me if i am wrong (and I don't mean comments like 'the SD card is really cheap' because that is just so much bullshit.

    1. UglyMike
      Boffin

      Re: Daft Question Time

      Indeed, several things are 'missing' from the Pi if one wants to be pedantic. There is no input/output device included, there is no storage provided, not even for the boot image (ie the SD card), the Pi doesn't even come with a power supply etc.

      However that is more or less by design. The object was to get a functional computer out there at a ridiculous low price point for the education market. Yes, you have to provide a keyboard/mouse and a micro usb power adaptor at the minimum (we'll assume you have a TV...) but these things are very easy to get from a number of sources, if you don't have them already. Most people will likely already have them. As for the SD card, if they'd include the SD card, they would probably have to offer several packages with different sizes and classes, included the one YOU want or you'd be peed at having to buy an SD card not to your likeing Now you can get exactly the one you want (which, yes, costs extra). Of course , if you want the full blown system with Rasberry Pi + case, large and fast SD card, powered hub, Wifi dongle, wireless keyboard/mouse, separate power adapter, hell even an external USB drive (and all this kit new of course) and have it shipped to your doorstep, then yes, you'll be pay quite a bit more than the 35$ bare pcb board. However, with a second-hand keyboard/mouse, a TV/monitor, a wired ethernet connection, an old/dual use phone charger and a basic 2gig SD card (most of which will be already present or are dirt-cheap), the 35$ bare pcb (+shipping & VAT) will do very well for its target audience. That audience might not include you however.

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