[Discuss] Near-space balloon: Foam ball located and purchased

James Hukill EMAIL HIDDEN
Tue Nov 1 18:07:39 PDT 2011


Ok so I dug in my pile of parts.. much less due to the great purge of
Feb.11, to the Jawa Table at work..  This was before the Eugene Maker
Space, I will not repeat this mistake.
..and I do not have the external GPS antennas any longer.
I am sorry..
Does not mean we can't do something like
this<http://www.gartrip.de/antenna.htm>..and
$5.00 antenna <http://www.amazon.com/Powerful-External-Amplified-Antenna-Receiver/dp/B000ZKUR1W/ref=sr_1_4?ie=UTF8&qid=1320195956&sr=8-4>
?



On Tue, Nov 1, 2011 at 9:09 AM, James Hukill <EMAIL HIDDEN> wrote:

> I might... MIGHT.. have an antenna for it.. So I will go digging..
>
>
> On Tue, Nov 1, 2011 at 9:01 AM, Laura Harris <EMAIL HIDDEN> wrote:
>
>> Thanks for all the input, everyone. Ben and I will go over the various
>> approaches and make some design decisions.
>>
>> We'll need a pair of simple cradles to hold the halves on the workbench
>> during construction and assembly- these can be as simple as a pair of
>> sturdy cardboard boxes with 8" dia holes cut in one side, and edging the
>> openings of the holes with something cushy like thin craft foam. If someone
>> wants to fab those up and have them at the shop no later than next Sunday,
>> that would be great. Otherwise, we'll throw something together on Sunday. I
>> expect the ball to arrive in the next couple days so construction will be
>> able to start this next weekend.
>>
>> I'll build a little enclosure to test the impact that gold mylar has on
>> GPS performance- will have it at the shop next Sunday.
>>
>> Does anyone have any epoxy resin- not the glue, but the stuff used for
>> fiberglassing? West Systems 105 is the material of choice but it's spendy-
>> $45 for a quart of resin and the fast hardener + whatever shipping costs.
>>
>>
>> L
>>
>> ------------------------------
>> *From:* Thomas A Ramsey <EMAIL HIDDEN>
>> *To:* EMAIL HIDDEN
>> *Sent:* Monday, October 31, 2011 7:11 PM
>>
>> *Subject:* Re: [Discuss] Near-space balloon: Foam ball located and
>> purchased
>>
>> I'm liking the nylon all-thread idea but I am a little concerned with
>> it's strength. If we only have the one all-thread and it breaks our strips
>> we lose the bottom half on the rig. I also don't trust velcro AT ALL. If it
>> becomes wet or consistently stressed it will disconnect. Zip ties are great
>> but difficult to reuse (they can in fact be reused). If we decide against
>> zip ties I propose using multiple all-threads. Perhaps three or four; one
>> down the center then the others at 45 degrees from the top center straight
>> (nearly so to avoid each other) through. Nylon to keep weight down. I know
>> it may make for more supports to work around but we should be able to
>> handle it.
>>
>> I really like the strobe ideas as well. If we do have a separate strobe
>> rig I think it may need to be insulated as well. I've read temperatures as
>> low as -60 to -70 Celsius at the altitude we expect to go and most consumer
>> grade electronics like leds are only rated about -20.
>>
>> -Tom
>>
>> On Mon, 31 Oct 2011 14:35:59 -0700 (PDT), Laura Harris wrote:
>> > We can use nylon all-thread for the central support rod, if we go that
>> > route. Long velcro-enabled straps would be reusable and strong though
>> > a bit heavier that zipties (but not by much). If we used a net, we'd
>> > still want to secure the halves together (unless you were thinking of
>> > drawing the net up into a tight neck at the top . . .). I'm leaning
>> > towards the nylon all thread center support rod approach, personally.
>> >
>> > As for the interior construction, the interior walls, floors, and
>> > ribbing are 5mm foam-core. I was thinking of using gold mylar film for
>> > the reflective insulation, but we can go without it and fill dead
>> > areas with extra foam.
>> >
>> > Reasoning behind a partial hard-shell was assuming the ball will land
>> > bottom down so a full shell could be avoided to save weight. Still, it
>> > would definitely make it a tougher rig- more likely to survive for
>> > reuse. I was thinking of using fiberglass with epoxy resin for the
>> > hard shell.
>> >
>> > Idea for paint scheme: paint the bottom 3rd black and the rest red.
>> > Black so it is easier to see on the way up (against the sky) and red
>> > so it stands out on the ground. Also, a fluorescent colored parachute.
>> >
>> >
>> > We can use 1-watt LEDs for strobes. With the short duty cycle a strobe
>> > requires, we won't need heat-sinks for the LEDs and they are bright
>> > enough to be easily seen in daylight. A simple 555 timer driving a FET
>> > switch is all we'd need for a driver. Another thing we can do is hang
>> > a strobe from the tether. That way its weight is not considered part
>> > of the 6lb payload limit (if I understand the FAA regs correctly). One
>> > of those little waterproof xenon strobes doesn't weigh much, either.
>> >
>> > -------------------------
>> > FROM: Rick Osgood
>> > TO: Laura Harris
>> > CC: Ben Hallert ; "EMAIL HIDDEN"
>> > SENT: Monday, October 31, 2011 1:58 PM
>> > SUBJECT: Re: [Discuss] Near-space balloon: Foam ball located and
>> > purchased
>> >
>> > I just had another thought about the design of the chassis that we
>> > didn't bring up at our meeting yesterday. We need to be careful about
>> > the material the payload is made of as well as the GPS placement. The
>> > eTrex doesn't have an external antenna so we need to make sure it can
>> > get an accurate GPS lock from inside the payload. So any metal above
>> > it would be a bad idea. So the chassis needs to be insulated but with
>> > material that the GPS radio signals can get through.
>> >
>> > On Mon, Oct 31, 2011 at 1:51 PM, Rick Osgood  wrote:
>> >
>> >> Ben, so your idea would be to have the cord come through the sphere
>> >> via a hole in the top and then attach to the inside of the bottom
>> >> half? I want to make sure I understand your idea correctly. That
>> >> sounds like it could definitely work and I like that it would remove
>> >> the requirement for extra reinforcement on the top half. Only
>> >> downside would be having the rope going through the payload where it
>> >> could get in the way of the electronics.
>> >>
>> >> Laura, I think the zip ties idea could be cheap, simple, and
>> >> effective. It would be nice to have something that didn't require
>> >> cutting and replacing the zip ties every time we open and close it
>> >> though.
>> >>
>> >> The last balloon I did, we just had a threaded rod going all the way
>> >> through the center of the payload vertically. There was a washer and
>> >> a nut on each side to hold the two pieces tightly together. Then a
>> >> small horizontal hole was drilled through the threaded rod at the
>> >> top so we could stick a sort of hook through it where the line was
>> >> attached. The threaded rod was nice and strong but it will add more
>> >> weight and then you have a metal rod going all the way through the
>> >> center of the payload which can make the inside electronics layout
>> >> more difficult. You can see it in some of the photos from this site:
>> >> http://www.toddfun.com/2011/02/20/high-altitude-balloon-launch-2/
>> >> [17] . Here is one example photo:
>> >>
>> >> On Mon, Oct 31, 2011 at 1:29 PM, Laura Harris wrote:
>> >>
>> >>> Ohh- that looks good, Ben.
>> >>>
>> >>> One idea for holding the halves together is to use a pair of
>> >>> extra-long nylon zip ties running longitudinally at 90 degrees to
>> >>> each other- grooves formed in the surface would keep them from
>> >>> sliding off. They're strong and light and they avoid the need for
>> >>> any hardware.
>> >>>
>> >>> -------------------------
>> >>> FROM: Ben Hallert
>> >>> TO: Laura Harris
>> >>> CC: Rick Osgood ;
>> >>> "EMAIL HIDDEN [4]"
>> >>> SENT: Monday, October 31, 2011 1:12 PM
>> >>>
>> >>> SUBJECT: Re: [Discuss] Near-space balloon: Foam ball located and
>> >>> purchased
>> >>>
>> >>> May I suggest that instead of attaching the cord to the top, we
>> >>> run it
>> >>> down and attach it to where the battery bay is? This way the whole
>> >>> thing is 'sitting' on the cord and we can cut any weight created
>> >>> by
>> >>> reinforcements that would reach to the top of the sphere. Namely,
>> >>> the
>> >>> only 'strength' needed would be at the bottom where it's already
>> >>> planned to exist. This also reduces risk of retrieving just the
>> >>> top
>> >>> of the sphere. :) I've attached a modified version of the
>> >>> drawing.
>> >>>
>> >>> - Ben
>> >>>
>> >>> On Mon, Oct 31, 2011 at 12:51 P.M, Laura Harris wrote:
>> >>> > The ball comes split in half so it's just a matter of holding
>> >>> it together in
>> >>>> flight. I've attached a pic of a sketch showing a preliminary
>> >>> idea for
>> >>>> construction.
>> >>>>
>> >>>> ________________________________
>> >>> > From: Rick Osgood
>> >>>> To: Laura Harris
>> >>>> Cc: "EMAIL HIDDEN [9]"
>> >>> >
>> >>>> Sent: Monday, October 31, 2011 10:54 AM
>> >>>> Subject: Re: [Discuss] Near-space balloon: Foam ball located and
>> >>> purchased
>> >>> >
>> >>>> Sweet! Do you plan to mold something around the sphere? I'm
>> >>> curious to see
>> >>>> your final design and how we will be able to open it up and
>> >>> mount
>> >>>> everything.
>> >>>>
>> >>>> On Mon, Oct 31, 2011 at 9:53 AM, Laura Harris wrote:
>> >>>>
>> >>>> I found a 12" dia hollow polystyrene foam ball and purchased
>> >>> one. Should be
>> >>> > here in a few days. This is it:
>> >>>> http://www.plasteelcorp.com/mm5/merchant.mvc [12]?
>> >>>> This dramatically accelerates the build progress. :)
>> >>> > L
>> >>>>
>> >>>>
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>> >
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>> >
>> >
>> >
>> > Links:
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>> > [17] http://www.toddfun.com/2011/02/20/high-altitude-balloon-launch-2/
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