Friday, November 16, 2007

wind, wind, go away

Ok yeah it's supposed to be rain - but our launch date just got scrubbed due to wind :( Note the projected path has the balloon landing in the Atlantic. Hrm, it's a bit chilly to be swimming.

Thanks to project SABLE folks who pointed out that our GPS was one that would not work above 60000 feet (oops). We ordered a new Garmin GPS (see parts list) to replace the Byonics GPS. Here is the list we found for GPS receivers that work at >60k ft.

We had another 2 crammed work days: setup up new GPS; soldered the new power connection to a DB-9 connector (for connecting GPS to RF transmitter); bought and setup a 2nd RF scanner; setup a 2nd laptop for 2nd chase vehicle; setup a spreadsheet to do all our math calculations (helium needed, ascent rate, burst altitude); tied ropes to connect parachute to cooler; punched holes through the cooler for the camera lens, antenna, and the GPS receiver; setup styrofoam shipping wedges to hold the camera in place in the cooler; created S- hooks with 90 degree turns to attach the ropes to the threaded rods on the cooler; and we've run a lot of simulations on ballon track with our spreadsheat numbers to decide if we should launch this saturday or not (tomorrow). For now we've scrubbed the launch. I suddenly have a lot more sympathy for why NASA is always moving the shuttle launches.

We've also decided that in hindsight, the parachute is too large. We don't need it to land like a feather - we just need the cooler and camera to survive. Our current payload estimate is 3lbs and our chute was rated for 3.5-8lbs (R7). We'll try to exchange the chute for a smaller one - maybe something in the 1.5-2.5lb (R3 or R4) range. Thanks to the folks at Rocketman for their advice here.


Igor said...

What is your time lapse between photos ?

For information, our parameters were as follows:

- a canon s3 is
- when switched on, we would have the optical full on at 12 X
- photos were taken every 23 seconds.

the results were

the actual photos are here:

Your camera seems to be able to do 4 X optical or 3 times less than ours.

With a 12 X, we had a resolution close to the high end of google maps:

You guys have a good flight,


Igor said...


Daniel said...

We're going to use the CHDK software on our camera to run a script that will tell the camera when to take a picture. This way we can take a picture once every few minutes at low altitudes and once every few seconds at high altitudes. Hopefully we'll be able to get a couple of videos at high altitude too.

As for the optical zoom, I don't think we'll be zooming in much as we're mainly trying to get a cool picture of the curve of the earth.

You guys have some cool pics. Good luck on your project.

Igor said...

By the way, thank you guys for putting out all the technical information.

If you are taking photos sideways (in order to get the curvature shot), you might want to find ways to have a way for the payload to rotate so that you can get a 360 panorama.

Good luck on your flight and Happy Thanksgving,


Lobster said...

Thx for the Software Recap, specifically AGWPE & AGW Tracker. I have a MicroTrak 8000 for my primary transmitter. Fired it up then went to the APRS sites... nothing. I have no repeaters anywhere around me.

Saw your doco on the AGW tools... so I dug out an ancient scanner, picked up a 1/8 to 1/8 stereo cable at RadioShack, and hooked it all up to my laptop. Ta da! I can see my packets and my loc on the maps. So thx again for all your detailed doco... we hope to launch in the next 3-4 weeks.

Using a Nikon S1 (tiny, light, has an intervalometer built in), but may add a Canon with CHDK, owing to your success with it. I would like to use CHDK to do movies at intervals.

Best regards,

Daniel said...

One gotcha we found with CHDK is that it can only switch back and forth from picture mode to video mode if your camera has a button dedicated for taking movies. For instance a Canon Powershot S2IS has a dedicated "record" button for taking a video from any of the camera's modes (P, Tv, M, etc). The Canon Powershot A610 (what we bought) doesn't have a movie button though, you have to manually turn the mode dial to the "Video" setting then press the shutter button. So as of right now it doesn't look like we'll be able to capture any videos with our A610 :(

I'm glad you were able to find some useful info on our blog :) We've been trying to document everything fairly well so others can use our blog as a ballooning reference.