In reading about other flights, it appears a fairly common practice is to run the packed-up capsule in a freezer with the aprs and camera and everything else running until power is exhausted or some other problem occurs. You monitor telemetry the whole time, checking signal strength and so on. If you have something in the freezer for the camera to shoot, you also check the pics to ensure they come out okay.

If we intend to do this a number of times, would it be worth the effort of building a small vacuum chamber we can shove in a freezer?

One flight I read about lost telemetry because as the batteries ran down the camera power supply adjusted and began emitting RF that screwed with the telemetry electronics. That would be uncovered in a battery-exhaustion preflight checkout. I think in that same flight the camera got goofed on reentry because the membrane-covered buttons were all depressed by increasing air pressure. The vacuum of space had removed the air under the membrane on the way up, and on the way down the atmosphere literally pressed every button at once and held them all down for more than a day before air seeped back under the membrane.

Just wondering.

If you want to use the SPOT on an iPhone, you can get the SPOT iPhone app for $2.99. That will display the lat/longs, plus the speed the SPOT is traveling at, and the distance it is from your current iPhone GPS location.

Completely aside from the particular mobile platform (iPhone, Blackberry, Android) I argue that you can't rely on mobile internet in rural areas; in nearly any chase and recovery, we traverse rural areas. I know how many of us have smart phones; I have a HTC Evo, wow works great in central Raleigh, 4G and all. But, I argue we could build a much stronger chase and recovery team if we elect to have one dedicated team member at a stationary, grounded, perfect internet connection, with the phone number of the team members, etc.

iPhone SPOT app:
http://itunes.apple.com/us/app/shared-page-mobile/id346524744?mt=8

Jonathan

I have a Kestral 4000 which will log barometric pressure, altitude, temperature, humidity, and a bunch of calculated values (density altitude, windchill, dew point, wet bulb, heat index).

It will also record wind speed via a little impeller.....but wind speed is zero for a balloon-- we move with the wind! There is no relative wind.

You can log as frequently as once per second, or 'zoom' way out. For our use, I would think once per minute would be cool.

There are some limitations. It "only" goes down to -49 fahrenheit, and 10mb. Ok, 10milibar is wicked high, maybe 100,000 feet. So, that is pretty cool. http://www.nkhome.com/kestrel/kestrel-4000/features.php

It runs on AAA, so we could use lithium for their low-temperature performance.

I have been hesitant to fly it because of the cost ($350), and I was afraid of losing it.

For GPS data, we could put a handheld GPS in the capsule (e.g. an eTrex Vista, or another handheld) and pull the data off at recovery. That will give us GPS altitude and a track; some (like the Vista) have a barometric altitude as well.

Just ideas!

Thank you~

Jonathan

I have 2 GoPros and if we had redundant trackers a Canon G9 we could potentially fly.. Have a underwater case for it, wonder if that would help or hurt?

"Redundancy" doesn't have to be expensive. Some of the things I'm thinking of are:

making sure that all connectors two means of making sure that they say connected,

- screws on Dx- type connectors
- zip ties
- Yes I'll say it Duct Tape!

Take it apart, find the contacts, remove the switch and solder in a relay or similar and have a micro-controller programed to 'push' the button every interval. Probably methods to hack the spot to do the same thing, but.....

Question if this would violate some Terms&Conditions somewhere though..

I'm a fan having both: a fixed person at a reliable internet connection, and having the spot send out SMS.

I'm working on a script to pull down data from the SPOT shared page and pull out the lat/long. There is a 'timeInGMTSecond' elemet as part of each ping. I will isolate that, and if it is newer than the last one I pulled down, then I'll parse out the lat/long and send it out by e-mail / SMS to whatever team members want to get updates. I'll cron the script to pull once-per-minute during launches, so within about 60 seconds of a new ping reaching the SPOT website, the lat/long will go out by SMS to the chase phones.

But, a person at home still helps a lot in coordinating, and also looking at the lat/long in google maps-- "the capsule is behind the Lowes!"

Jonathan

First, I think temperature testing is an excellent idea. However, your average freezer is not cold enough to provide accurate simulation. I recommend an insulated box and dry ice instead. Also, the lowered pressure makes almost zero difference to thermal behavior until you get way past 100 kft altitudes. (Basically it doesn't matter until you're talking about thermos-bottle quality vacuums.)

I understand the recovery from the tree was a bit of an adventure. Some things I've learned recovering (a modest number of) rockets:

Long shock cords. If there's 100 feet of cord between chute and payload, you're likely to have one or the other on the ground.

Put a loud sonic beeper in the payload. It can be really easy to be nearly under the payload and not be able to see it. Having a loud beeper helps.

My recovery kit includes a number of things you might not think about. FRS or similar radios: you won't always have cell coverage, and being able to coordinate anyway is helpful. Pruning snips: if you have to get through 20 feet of brambles to get to the payload, you'll be glad you brought them. Gardening gloves and bug repellent also make it in.

I have a slingshot, fishing weights, and line to snag those long cords and haul things out of trees. I use a braided line (I think called "spider wire" or something), sold as fishing line, attached to a 1 oz fishing weight. It doesn't curl up as much or tangle as much as monofilament. I then use the lightweight line to drag a piece of heavier cord, and pull with that. Note that you'll want plenty of excess fishing line, and more than double the amount of cord for the highest point you're recovering from. For an 80' tree, I'd want something like 200' each of line and cord.

I have a long pole, with a piece of wire pointed backwards (a barbed hook), and a retractable razor knife in the corner at the top. (Think tree pruning saw, but sharper angle, and a razor blade in the corner.) It's perfect for cutting shock cords to release things tangled in trees. (Of course, once you start cutting cords, you're probably giving up on the parachute, but those are fairly cheap.)

I have a friend that has a physically hacked SPOT. I talked to him, and was able to go upstream to the source of the hack, to the electrical engineer that made the mod.

By soldering in a Pic12C629 (via 4 solder points) that is running some software he has written it will make a SPOT1 turn itself on, send a message, and then turn itself off. (Well, there is still some minor power drain for the PIC, but not much: 3uA draw in sleep mode, between PowerUp/Ping/PowerDown cycles.) This means it will run for a long time: estimated 9 days on a pair of AA lithium. The SPOT 'Tracking' mode, by contrast, ends after 24-hours.

Once modded, the device becomes a ping-monster, with no other functions. Literally, if the batteries are installed, it will just power cycle, ping, sleep--- until the power fails. There is *no* user interaction-- you start the thing by putting in batteries. You turn it off by taking the batteries back out.

He has offered to solder in his PIC for us, if we wanted to mod a SPOT1.

Advantage: turns a SPOT1 into an auto-pinging machine that will auto-push out SMS messages to our phones.

Disadvantages: We need a SPOT1 to mod; we're limited to 10 e-mail/phones to send the messages to (by the SPOT website.)

Anybody interested in modding a SPOT1? If so, want our group to solder the PIC, or send it off for soldering/testing by our EE-Hack-Me-Spot friend?

Thanks!

Jonathan

Rick, you've refered to the 'RSS' feed; can you point me to exactly what you're talking about?

If you mean the XML page, as I wrote above, we already have a script that pulls that down, parses it, and sends out notification to as many devices (by SMS and by e-mail) as we want. So, put the SPOT in track mode, and we're now pushing lat/long out to as many phones as we want, by SMS, no internet required, no problem.

But, the XML page is not updated as frequently as the Tracking website. You've said RSS-- but as far as I see, the functionality is just taking that same XML data source, and feeding it into some other tool, like Yahoo Pipes, to create an RSS feed. The source is still the same: the XML page, which we are already pulling down, parsing, and sending out. No sense in pushing that into an RSS feed; we already have a script to pull in that data; we can do whatever we want with that data-- push it out, log it, etc.

On a separate note, the unmodified SPOT only runs in TRACK mode for 24-hours. For long duration, one may want the device to keep going until the batteries are depleted. That's another thing the physically modded SPOT does: runs for about 9 days 'pushing' messages out, all on one set of lithium batteries. That modded SPOT is essentially pushing the notification button, and sleeping; the notification button pushes near real-time alerts out, but it is limited to 10 e-mal addresses or phones. (We could, of course, parse out the XML--- but then you’re back to a data source that isn’t as fresh, and isn't near real-time.) For the physically modded SPOT1, an e-mail distribution list would, of course, solve the 10 e-mail / SMS limit.

Jonathan

That depends on whether we're doing a simple up and down flight, or if we're going for distance. For example: https://secure.wikimedia.org/wikipedia/en/wiki/Spirit_of_Knoxville

Okay, that sounds like a lot of fun, and something I had not even considered. So ignoring the cost of the electronics, what would be a reasonable cost for the balloon + gas for a trip like that?

For our normal up and down flights, I still don't think we need more than 24 hours, but I can certainly see the need for something like this on long duration flights. Of course, for that flight, we will need a small computer on board for telemetry, dumping balast, etc in addition to the tracking.

Count me in as being very interested in that attempt.

I had run across the youtube video earlier and was amazed at just how big the payload was - much larger than our very small payload as it had very different goals when constructed.

But you mention you already have the balloon - awesome! About how heavy would the payload (including the necessary ballast) can we lift with the balloon you have - and how much helium would it take?