Great info! Thanks!

I've been thinking about this for a few hours tonight (this is what my Friday nights have come to?!?). I see this needing discussion on the following fronts:

Goals

1. 100,000 feet (?)
2. Record/recover still photos and/or video
3. Record/recover altitude data
4. Record/recover flight path data
5. < 4lbs

Vehicle/Fuel

1. Need scientific/sounding balloon (source: Kaymount)
   i. size? 600g yields 30.8km burst altitude requiring 1.5 m^3 volume at release (1.5m^3 of helium?)
2. Gas (Helium, probably… Duke? Party shop?)
   i. quantity?
3. Parachute (size? material? purchase/make ourselves?) (parachute: http://www.the-rocketman.com/recovery.html)
4. Vehicle structure: styrofoam seems pretty good insulation for temp. & impact
5. Radar reflection (might as well try…); Al foil wrapping vehicle
6. Reflective/neon body for recovery?

Payload

1. Camera(s) (suggest 1-2 HD video and 1-2 still w/ intervalometer) (I'm volunteering this stuff… may rent a couple GoPro HD 1080p high-impact cameras for a couple days and rig some Canon cams w/ CHDK)
2. Altimeter (peak record only? data logging progress device?)
3. GPS Beacon (cellphone w/ Accutrack software = cheap. Does someone own a Spot tracker? http://findmespot.com/en/index.php?cid=102)
4. Insulation (thermal & impact), suggest fiberglass attic insulation

Planning/Scientific

1. Trajectory forecasting: http://weather.uwyo.edu/polar/balloon_traj.html
2. Release location
3. FAA Contact
4. Project/team name
5. Budget
6. Launch date
7. Coordinate with schools? (Durham Central Park School good candidate)

Recovery

1. Pre-mapped fall radius based on trajectory forecast
2. GPS beacon / real-time (Boost Mobile phone or similar)
3. If not GPS, homing FM radio beacon? Tune in the beep on our car radio? LOL!
4. Beeper and/or flashing light beacon
5. Note with phone number(s) / reward

The accutrack uses GPS and assisted GPS depending on the phone. The most solid player seems to be the Spot but it's pretty pricey.

I have no problem with taking it easy on the first launch... old camera and recovery is fine by me, honestly. I figured that most people helping would want altitude data, etc.

So lets build us a cooler payload, grab a 350g balloon, go to the party store, and rock out next week! :-)

I haven't come across any off-the-shelf units that record altitude at that height. Justin Hamel (an awesome resource and great guy) uses a standard Garmin GPS as an altimeter but I can't find confirmation of its range. It's also $200! http://justinhamel.com/2010/04/17/near-space-adventure-flight-5/

The people at Spot specify that their ceiling for location reporting is just under 30,000 feet. Maybe that's inherent in the GPS tech?

Does anyone have one of these supported Accutrack phones and not using it, possibly left over from an upgrade? If so, would you be willing to donate it to the balloon launch?

Btw, Accutrack provides the following data: Location, speed, heading and altitude

It will not work to high altitudes, due to ITAR restrictions (previous post), but we can get a good estimated projection of maximum altitude based on altitude and velocity reports on the way up, followed by picture data to let us know the moment of maximum altitude.

Supported models include:

Motorola iDEN Phones (by Boost Mobile, Sprint/Nextel): i265, i290, i296, i335, i355, i415, i425, i450, i455, i465, i560, i570, i576, i580, i605, i670, i680, i710, i730, i733, i736, i760, i776, i830, i833, i835, i836, i850, i855, i860, i870, i875, i880. Other recently released ixxx phones with GPS might also work. They are being added to this list after we test them or users confirm working.

Blackberry Phones with Built-in GPS: 7520, 7100i, 8110/8130 (Pearl), 8310/8330/8330m/8530/8900 (Curve), 8350i, 8800, 8820, 8830, 9000 (Bold), 9500 (Storm), 9520 (Storm2), 9530 (Storm), 9550 (Storm2), 9630(Tour), 9700 (Bold). Also possible on 7130e, 8703e. Blackberry Phones with Bluetooth GPS: AccuTracking also works on Blackberries with external Bluetooth GPS provided that the Blackberry phone firmware version is v4.2 or later

(Note: BlackBerry Pearl has 4 different models: 8100, 8110, 8120, 8130, of which only 8110 and 8130 have built-in GPS. BlackBerry Curve also has different models: 8300, 8310, 8320, 8330, 8830m, 8520, 8530, 8900, of which only 8310, 8330, 8830m, 8530, 8900 have built-in GPS. Other models need external Bluetooth GPS)

Windows Mobile Phones: HP hw6915, hw6925, hw6945, HTC Touch Pro, HTC Tilt 8925, HTC Mogul/XV6800/PPC6800/P4000/P6500, Moto Q9 series, BlackJack II (SGH-i617). Also possible on: HTC Touch, HTC 5800/Fusion/S720, Moto Q# seriers with built-in GPS, Palm Treo 700w/700wx, UTStarcom PPC-6700/XV-6700/HTC Apache.

@RodneyRadford ...sorry--somehow I saw the accutrack post and missed the ITAR one.

cheers,

--me

I have not heard this - do you have any reference we can consult to find out which GPS manufactures interpret the ITAR restrictions that way, or which GPS devices are best?

Would love to hear if there's a "right" GPS for this. Though then too, the 'ideal' GPS is one that will give us altitude reports AND has built in/easily added a means of reporting the current information back... guess we'll see what we can come up with for the first time, though.

I can look into whether the CO2 vendor at a shop with which I'm affiliated can get helium through their Airgas contract, or whether I just have to go to the store front like everybody else and pay the regular price. I doubt I'll be able to swing anything, but it'd be worth asking. Actual cu. ft. TBD; looks like a full 4 lb. payload would take something like 60 cu. ft. of helium.

it's a shame hydrogen is such a bad idea--it's so cheap! (:

depending on what sort of balloon we built, I could imagine a hot-air variety working reasonably well--but we can't exactly fit a heater in a latex weather balloon, either, which at a quick glance seems to be our cheapest/easiest shot at the balloon itself.

Does anybody have any thoughts on safety? How big a payload vehicle do we need to have to make sure it's not overly dangerous when it's plummeting in from the stratosphere? For that matter--how fast is dangerous? Or what impulse? Or--what units are we trying to keep below a threshold, even? This is the part that's starting to concern me most. The technical challenges of getting it /up there/ seem pretty straightforward at this point--we just need to be responsible about it.

--cpg

Well, by the end of the meeting, I think all we decided for certain was that we had a lot of things to figure out.

Somebody had mentioned a wiki entry... here's a link: http://wiki.techshoprdu.com/index.php?title=High_Altitude_Balloon

We've got major subsystems:

Balloon: skin + gas. Unless we come up with a better idea, something like this for the balloon: http://www.scientificsales.com/8237-Weather-Balloon-300-Grams-Natural-p/...

Based on a table I found ( http://www.chem.hawaii.edu/uham/lift.html ) , it looks like a 5 ft. diameter balloon will lift 4.19 lbs. Somebody mentioned Airgas selling helium for $1.20/cu. ft.; that'd be about 65 cu. ft., or about $78. I don't know that I saw that they sell it by the cu. ft. though, but rather by the tank--so researching the purchase of helium is an open question. I do suspect "balloon grade" helium is probably fine; unless somebody can tell me otherwise, I don't think it's that they "cut" it, just that they don't refine it to the 99.-whatever percent that some applications need.

Parachute: Canopy, cord, mount, deployment

Canopy: was it you, Rodney, that had mentioned having a parachute size calculator that came up with a 4 ft. dia. for a 4 lb. payload? We'd need to purchase the 'chute from somewhere. Also need cord.

Open question for the parachute: How do we deploy? Do we attach the peak of the canopy to the base of the balloon to keep it 'upright'? how do we keep the 'chute from getting tangled with the balloon cable?

Payload: box, camera, batteries, insulation/heater, altimeter

Altimeter is an open question, but low priority. Accepting ideas for this one. Best so far is a second, downward-facing camera; in addition to cool aerial photography, we can compare features in successive frames to estimate our difference in altitude between each frame. This'd give us a very rough approximation of peak altitude. But that means we have to spring for another camera and chip, and that's not the lightest of instruments anyways. I am happy to launch without an altimeter if we don't come up with a good solution that's under weight and under budget.

Primary camera: We want black sky and limb curvature; we need an instrument which points horizontally. Open question: camera type? If anybody has a Canon PowerShot, we (Who? Tanner?) think we can rig the software to take pictures every N seconds.

Battery: What kind of life expectancy do we have at low temperature? Do lithium cells work best? Do we need an active heater? How much current does *that* take?

Box: Have we decided on a styrofoam cooler, then? $1.59 sounds like the sort of thing I am ALL ABOUT!

Recovery: Kevin mentioned APRS; this would take care of location data and reporting without problems with the cellular network. How much is this going to run us?

Remember: The goal is still $250 and 4 lbs. The FAA is the authority on the 4 lb. rule, so there's no slack there. $250 would be the contest max--and bluntly, I don't want to pay more than that anyways...

You want industrial grade helium; that's the cheap stuff that's almost all helium, but not medical / specialty gas purity levels. I may well be completely mistaken about balloon helium dilution, I've never used the stuff.

National Welders (or any other source) sells it by the tank, but there are a wide variety of tank sizes, and pricing is by the cubic foot, almost independent of tank size. And assuming you end up doing multiple launches, budgeting by the cubic foot makes sense.

Also, Techshop buys welding gases from National Welders on occasion -- we could pick up the helium from there if someone lets us know what you want and pays for it. You'll want to check out tank and regulator purchase / rental as well.

This table has a good list of GPS receivers that can operate above 60k feet.

http://showcase.netins.net/web/wallio/GPSrcvrsvs60kft.htm

I think that's the same one, then. "High pressure" N2 regs for me are in contrast to the lower-pressure CO2 regs (...both nominally for beer, "high pressure" for a kitchen, though it's the same tanks whether it's for food or industrial use). I'll make sure it's CGA 580.

how big do we have to buy if we need 65 ft3 of industrial helium gas?

thanks,

--me

fill to 5 ft. diameter, bursts at 11 ft.; I don't know what the difference in altitude will be, but our flight will realize its operational ceiling and begin its descent whenever the balloon bursts.

I disagree with this assessment. If we have to buy 5x (for example) more helium than we actually use for the one launch, I don't see a problem in listing our cost as just the helium we used - not the price of the entire tank.

Look at this page by rocketman that lists the descent rate for various weights:

http://www.the-rocketman.com/recovery.html

The relevant lines to us are 4', 3lb or 5', 4.7lb for a 12mph descent rate, or 3', 2.8lb or 4', 5lb at a 17mph descent rate. So if we choose the 4' parachute, our descent rate ranges from 12mph for a 3lb payload to 17mph for a 5lb payload (which is larger than legally allowed), so I think 4' will be large enough.

If we go with the rocketman parachutes, we can attach it to the top of the parachute which puts the balloon remnants out of the way as the parachute is being deployed. Thanks to John for pointing that out as I did not realize they had a loop in the top of the parachute (hence my incorrect diagram of attaching the chute and balloon to the payload)

For the first launch, I say we ignore it and just use the GPS data we get, along with the frame number of the camera pictures to determine our ascent rate - and calculate our altitude from that.

I like the idea someone posed about advertising on Craigslist for camera donors for "we put your camera in near-space, and give you a photo in return if successful". We still have to list the realistic cost of the camera (can't put $0) for the contest, but it allows us multiple cameras as fall-back if we have a catastrophic failure and lose our only camera for future launches.

Hopefully, no on an active heater as that would definitely suck up battery capacity. As for will it work - my first thought was to just buy some lithium batteries, put them on a current drain, and throw them in the freezer to test them.

However, a google search showed that a comparable flight (30km!!), the temperatures got down to -45C (now that is COLD!):

http://www.natrium42.com/halo/flight2/#data

They used LiSO2 (lithium sulphur dioxide) batteries which are not cheap! Btw, take a look at the other data/pictures/notes on that launch - definitely a more high tech approach and something we could consider after launch 1.

If we truly have chute failure, there is not anything we can really do as it will come in very hard (over 100mph), so we have to make sure the chute is clear of obstructions and is firmly attached to the payload box to eliminate that as a possibility.

We just pick an area that minimizes that likelihood, which is why I was suggesting SW of the triangle to minimize impact on airspace, military land, large bodies of water, swampy area, etc. It is very likely it will land on private land, and we play that by ear - if it is something we can easily get to, without problem, we do that - else we ask. I am more concerned that it gets caught in a tall tree and we can see it, but not recover it.

Yes, I will contact them this week and report back.

That is fine, but seems like if we can get Scott, or someone else, to drive the Techshop truck in for the launch (and recovery) we could get a few good pictures of it with the balloon and, if (when) we are successful, that will be good advertisement for Techshop... perhaps they can split in with us as an equal partner.

Agreed - I think there was too much over-engineering time in the meeting last night. I say we go with the parachute from Rocketman, balloon from whatever reasonable site (there are several - yours is fine), check on helium prices through Techshop and party dealers and get that ordered, locate a camera (I will post on Craigslist later today to see if I can find a few donors), and that leaves one main question - APRS or cellphone. I like the simplicity of the cellphone, but believe the APRS is a better solution, so as long as someone else knows the APRS technology and can get everything to us quickly (say next 2 weeks), that sounds good. If not available in 2 weeks, we go with the cellphone.

Either way, the goal is to stop asking so many questions and start building... ;-)

If we meet only once per week, and spend most of the time discussing over complicated solutions, the month will run out and we have not started building anything.

So if you (cpgorski) agree to look in to the helium issue, and I check with the FAA, we need a volunteer to step forward to assist with the camera prep, and someone to stop forward to assist with the APRS or cellphone (or both to start), and someone to just start collecting the necessary items.

And, with all the other low priority items mentioned above, I forgot one high priority item (ahem) - what do we call ourselves? We need a team name to register....

Amber got their blessing to register but did not yet register us. IS THERE ANY REASON ANYBODY CAN THINK OF *NOT* TO COMPETE, or are we all on board? If we are--I'll go ahead and register us!

--me

Event Board & Judges
• Judges are members of each hackerspace, and will be submitted to the Event Board. They will ensure all rules are
followed.
• One person from each hackerspace will be on the Event Board. The Event Board will oversee the event, judge each
applicant, and declare winners.

This is unclear to me - do we judge ourselves, or does each team have a judge and we swap judges between teams (ie: grade each other mentality), etc?

And is there any chance we can meet before next Sunday - say mid this week?

Perhaps we should send a couple of questions to them about cost, specifically:

* If no receipts are available for a used item, can we use eBay sold prices as a measure of it's cost?
* Can we only 'charge' for the cost of just the helium used, and not the cost of the regulator, tank rental, unused helium, etc? Seems that makes sense to me to only charge that which was sent up
* What about items already lying around? Several items had a $0 cost on them for the $150 MIT launch because they already had it on hand. Since that is the 'ruler' for this competition, seems reasonable to do the same for items such as tape, aluminum foil, wire, rope, etc
* What if we put a $40 award on the size of the box for safe return and someone finds it and requires us to pay up - does that cost count in as well? I would assume not.

Also questions about the judging - how that works, who will be here, availability of judge, etc

Regarding team name - "Team Tech Shop" is good. An alternative is "Techshop Gearheads" based on the gear in the logo, but I am okay with anything (but it would be nice if we could use the same name next year if we compete again, although not a requirement). Either way, just get us registered with something...

yeah, losing a hunnert bucks up front and still needing to buy the radio is not reasonable for us for this one.

I'd still love to see a Phase II wherein we put as much awesome stuff as we can scare up and squeeze into a 4-lb package onto a balloon; maybe that one gets APRS (and altimeter, thermometer, barometric pressure, scanning cameras, rocket launcher, and a crew of four... no, wait--scratch that last one). For now though I'm betting accutrack is the way to go.

Matt Santelli says he has several of those phones he can donate; I'll find out the model and we can determine an 'estimated price'. That'll save us the time and suffering of trying to order one online, at least.

Will see if I can find out if the MIT team did anything special to avoid cellular tower problems.

...Kevin and Tanner, if you gents have found a way to do APRS for dirt cheap, now's the time--!

--me

My comment about the cost of APRS was less about the up-front cost, or the possibility of losing it - but it was so we could stay within the $250 limit (and hopefully well below so we can get a few bonus points).

Once we get beyond this launch, I would like to see us stretch in two different areas - one how much can we cram in a 4lb box (APRS + microcontroller + lots of sensors + panning camera, etc - for the spirit of we are hackers, less have fun) and one how cheaply can we make this (can we replace the camera and phone with something we make cheaper, could we make our own parachute or balloon, etc - all for the spirit of the competition).

For now, though, if we can just replicate MIT's project, that would be a good start...

Yeah, absolutely on the APRS price thing. If our radio experts know of a way to purchase APRS gear for much cheaper than a quick Google tells us, then perhaps that's still in--otherwise it's probably accutrack for us, which reminds me, I need to email both Matt and the MIT team. The latter remarked that you shouldn't have the phone transmitting while at altitude, but I don't know how they had it not-transmitting at altitude and then cut in at ground level.

I am reluctant to pick up known-busted hardware, especially with descriptions like "the shutter won't stay open"... "stay"? are we sure we're even talking about the shutter and not the little retracting lens cap? ...who even knows? If it's the lens cap and you want to pick it up for a song, that's probably fine, but I'd definitely check on what it is that's busted before I gave anybody any money...

--me

Hey guys.... just found this discussion thread. You may be interested in the following web site from a group that conducts similar experiments for the HAM radio community. This appears to be their knowledge base of 'lessons learned' from 150+ launches! The information should be useful - although they are launching 6+ lb payloads.

http://www.eoss.org/pubs/faqloon.htm

-great info on balloon size, helium tanks / regulators, coordination with FAA, and tracking electronics and camera control based on a BASIC Stamp processor (time constraints probably make the last item impractical).

Wish I could help, but my priority at the moment is completion of the TechShop kitchen cabinets in the woodshop.

Good Luck!
Dick

If it's not too late, can we have the name be "TechShop RDU" and not "TechShop Raleigh" since those of us who live in Durham, Chapel Hill or Carborro would like to participate too. :-) Thanks.