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minutes-2011-10-25

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    Attendance:

    • Bob
    • Micah
    • Jesse
    • Alex
    • Isaac
    • Mike
    • Brett

    Discussion:

    Micah: “I’m thinking make balloon explode” Others: arming it might be dangerous.
    Jesse: “for plausible deniability, I’m thinking you shouldn’t be here, Chris.” (Chris is the head of Sector67)

    we need to order:

    • foam
    • balloon
    • string
    • hydrogen

    Micah: the foam should absorb plenty of energy. (Showed a graph of energy absorption at various levels of force for the foam). The foam we want to buy is $10, and that’s for 3x what we need.

    Discussion: what happens at 60k feet? Isaac wanted to know what would happen to the GPS chip and if it would cut out or just stop reporting. We decided to do our test run up to 70k feet just to see what would happen.

    tmobile – $3 a day no limited data, no-contract sim for $7, but reception might be a problem outside of area if we land outside of city limits. Still, it appears to be the best option for cell plans. verizon phones are cdma and so won’t work with tmobile plans. need to be careful about that.Boost Mobile might be an option, too: the unlimited data plan for this phone costs 35 cents per day.

    we could also do it all sms and not use a data plan. That would be good as a backup option, especially if we don’t have a data connection or plan.

    instamapper sends data to their online service. we could look at the api and see about using that. there’s also an android app that integrates with the service already, so that could be a backup plan.

    fcc requires two release mechanisms, but the balloon popping counts as 1. Bob and Isaac vote against having any ignition source near the balloon at any time.

    When acquiring a balloon, we need to find one that is accessible to everyone. Surplus stores are great, but not a reliable option.

    What should the timing be for capturing video/photos? Need to come up with a flight plan for capturing video/photos.

    Hanging it sideways would be the way to go to see yourself on the ascent. Horizontal up, then vertical down. That way you get two sets of images that look completely different with no effort. Some worry about whether we’d be able to get the image of the curvature with the uncertainty of the orientation during falling. In low atmosphere, there wouldn’t be a lot to keep the dart vertically centered so it could tumble.

    Still examining the parachute option and whether it’s necessary or not. Hopefully not, but still need to test the impact velocity.

    To keep the window from fogging up, we can put dessicant inside the window.

    With a 7′ balloon and such a small package, we’d get to altitude in 30 minutes. We can consider having a smaller balloon. If we want the balloon to burst at a certain altitude, then we need to match the amount of hydrogen.

    CHECK UNITS – we’re running into problems already with metric vs. imperial. We should only do metric.

    let’s go over 60k feet. We need to know what the GPS unit will do, and we don’t know if 60k is enough to get the curvature.

    Names:
    helloworld – taken
    helloworldballoon – available
    helloearth – taken
    hellospace – taken
    goodbyeworld – taken
    wheresmydroid – copyright issues?
    icqmobile – dumb

    Progress report:

    • Lift/Balloon – Adam & Alex
    • Hydrogen – Alex & Mike
      • need to know our max load: 60grams for the dart, 180 grams for the phone, release mechanism, string, balloon, reflector, fins, waterproofing, adhesives, etc. Total weight will be about 1 pound.
      • need to do calculations to figure out amount of hydrogen needed and balloon size required.
    • Filling/release mechanism – Alex
      • release trigger – isaac says he has the software programmed to wait for a text message before starting data collection.
      • mechanically we have a tether we can yank to release the balloon
      • filling is taken care of (HOW was not specified)
    • Line/tether – Adam
      • micah will look it up. longer is good for stability, shorter is better for weight. have to account for some force of wind.
    • balloon re-entry module release mechanism – Micah
      • Micah doesn’t have a good idea. perhaps a solenoid, but those are heavy. thinking a mouse trap sort of thing with a spring activation.
    • electronics – Micah & Mike
      • headphones only? if it bypasses the speaker we might need a separate audio source
      • we have the headphone jack option
      • possibly the ioio board – we could get speakers back and have lots of ports – better for expanded platform
      • play a wav file, test the output, possibly get 4 channels with a diode so you use + and – on each channel.
    • optional parachute – Bob & Jesse
      • We’re not even going to bother yet until after our drop tests.
      • cage/foam insulation/window and testing – Jesse & Micah
      • foam is on its way.
      • could do two colors of paint; black for cage for energy, bright orange for shaft for recovery.
      • need a way to know if the machine is functioning.
      • we could make a clear case for waterproofing
      • Alex will look into waterproof cases
      • only need a window by camera
      • micah wants a low altitude test in a couple weeks.
    • fins/reflector – Jesse
      • we don’t know how big they need to be until we have some tests.
    • impact/crash zone/retro rockets. – Jesse & Micah
      • retro rockets are out
      • two weeks from now will be testing
      • an initial design exists that should offer stability and crash zone
    • decoration/bumper stickers – Everyone
    • heat
      • brett will bring in nitrogen next week for cold testing
    • phone acquisition – isaac
      • seems like it’s not a problem. at least two devices are available.
      • for cold test let’s use a blackberry/test device
    • app – Bob & Isaac
      • Isaac will get it up on github
      • waits for text message, records data to log now, but to database later.
      • could build a zip that puts it all together, then uploads to the app
    • wiki/web site – Bob
      • wiki and site is up, though we still need a name.
    • Register with hackersinspace
      • done

    Things to schedule:

    • need hydrogen
    • hydrogen explosion test in two weeks? maybe just skip it and link to the other videos of the similar experiment.
    • cold test next week – tuesday
      • we can use dry ice because it has a more appropriate temperature than nitrogen and is more easily accessible.
      • Jesse must get a capsule ready
      • Isaac needs to make a version of app that takes pictures and collects temp.
    • 300 foot impact test – tuesday after that
      • we could use adam’s balloon

    To get chris to order:

    • need two real balloons
    • tether
    • 300′ line
    • dry ice – brett will get it
    • we should be good on electronics
    • hydrogen
    • foam
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