Member Since: June 17, 2007

Country: United Kingdom

  • I'm not sure that's true. I think it would only be a problem if you:

    a) Live in the US. Which 95% of people don't, and - b) then tried to export it.

  • Because it is simply a chip that takes the 1.5GHz GPS satellite signals and then converts them to a baseband binary output, it never does any kind of actual GPS engine stuff - finding the satellite signals in the data, tracking them, decoding their data and calculating a position. That's all an exercise for the student.

    So, if you need to have GPS on something moving at 515+m/s and feel up to the maths/code of GPS decoding, this is the thing for you.

  • I think there's an element of the human brain's weakness risk perception here.
    You can mess around with a few grammes of something nasty in a flimsy but complex model aeroplane, or you can put 1.5 tonnes of fertiliser in the back of a pick-up truck and ram into something at 60mph.
    I know which one is the more dangerous to security both at home and abroad, but I bet you're not leaving blog comments about how we must restrict the export of pick-up trucks.
    I've just rad some similarly hysterical comments on Hack-a-day about someone why tried to stabilise a tiny model rocket with some servo-powered fins. The reactions are understandable (if you're willing to accept that many people can't see the wood for the trees), but depressing.

  • Yes - it's quite easy (in that lots of people do it as a hobby) but please be safe. Find your local Tripoli approved (assuming you're in the US) High Power Rocketry group and go along to one of their launches to see how it's done. Ask lots of questions!

  • Sorry to double post, I thought I'd add a couple of lessons learned from a few dozen flights:
    - Mechanical Connectors (rather than soldered joints) are the root of all evil - minimise the number of mechanical connections. A huge number of the issues we've experienced can be traced to connections.
    Where you do have connections, make them decent locking connections (more so than the standard 0.1" polarized molex), solder the spades (not just crimp), add some heat-shrink and stress relief. Some of these payloads hit the ground pretty hard (say the balloon remains tangle with the 'chute), and it's so easy for a battery to be shaken loose or a connector to pop off. Spring terminals can be easier to work with than screw terminals, especially once you factor in the thermal contraction of screw terminals at altitude.
    Basically, if you're not happy about throwing your payload down a flight of stairs, you should probably reconsider launching it!
    - Cable-ties (zip-ties) become brittle at -60 degrees celcius. Don't use them for anything load-bearing. (You can guess we learned this one the hard way)
    - Make sure the payload is fully on and working before you start inflating the balloon - if you inflate the balloon before initialising the payload, murphy will ensure it refuses to get a gps lock.
    - Always have a spare roll of duct tape.

  • Can I also plug the CU Spaceflight hourly predictor?
    It gives you the locus of landing spots if you were to launch each hour for the next 5 days - it's basically a 'week at a glance' view to help you see when the winds might be on your side. Being so close to the North Sea, we find it very useful to see what days could give us a dry landing.
    CU Spaceflight

  • You highly doubt Wikipedia is incorrect? How Ridiculous! Just do the maths! To trust a block of text written by some random guy over the compelling simplicity of some basic sums is astonishing. Shame on you!
    I did note rate you negative either, I didn't even realise such a feature existed. However maybe I should because you're putting your faith in Wikipedia.

  • Why is there a picture of a kalman filter for this news item?

  • You have featured several high altitude balloon projects over the years, they're popular and fun.
    A lot of the GPS receivers cut out at 18,000ft. It would be very useful to know whether or not your receivers work up at balloon altitudes.
    To start the ball rolling:
    Lassen IQ's work as high as we have tested them (33km+)
    Anything SirfIII-based cuts out at 24km.
    Ublox-based stuff (eg GS406) works up to 50km altitude if you set the correct mode with the UBX protocol.

  • I fly these in Europe (the UK) as a member of CU Spaceflight
    You don't need permission before each flight in a strict sense, but the CAA will allow you a NOTAM (notice to airmen) to launch with, and you just phone up the local control tower before launches to inform them that you're going to launch.
    The biggest latex weather balloons commonly used (3kg) have a Burst Diameter of 13m. they are maybe ~2m on the ground. I am not sure where you got your numbers from, but if a balloon is 4m dia on the ground, and 20m dia at 10km, that is a volume increase of 5^3 = 125 times. This implies the atmospheric pressure at 10km is ~1/125th sea-level pressure. This is completely incorrect - it is more like 1/4 sea-level pressure.

No public wish lists :(