[GreenKeys] possible floater balloon launch tomorrow

[Nick]

Good luck guys and have lots of fun. I really enjoyed the video of your last balloon launch.

Nick  -  N0NCQ



Sent from my T-Mobile 4G LTE Device


-------- Original message --------
From: Gil Smith <gil at baudot.net>
Date: 12/2/17 10:08 PM (GMT-05:00)
To: GreenKeys at mailman.qth.net
Subject: [GreenKeys] possible floater balloon launch tomorrow

Hey folks:

My son and I are considering a possible balloon launch tomorrow, surface wind and winds-aloft permitting.  This will be our 6th launch, and the first one that we hope we NEVER get back.  That is, we want this one to be a "floater," and fly across a state or two or maybe more.

Our last five flights were normal recoveries (though we lost the second one over Eloy due to transmitter failure;  after that we ran two or three transmitters).

Last year's SB-1 flight got up to 108,000 feet:  https://www.youtube.com/watch?v=OAXS8cJj2lI
The previous AZHAL-1 flight was also pretty cool:  https://www.youtube.com/watch?v=9ZydHQspzJw

However, on this "floater" flight we will be flying a minimal-weight payload, and loading the balloon with just enough helium to barely get it off the ground.  There are many risks:
- it will only have one transmitter, so electrical failure will end tracking
- if it rises too quickly it will burst and not be a floater
- if it rises too slowly it may just crash early onto a mountain in its path
- the latex balloon degrades with UV from the sun, so may burst anyway
- the latex balloon leaks helium, so even if it floats, it may just come back down earlier that expected
- a low target ascent rate will be difficult to set properly, since the neck lift is so low

We will be flying a payload that only has a tracking transmitter. There will be no cameras, no geiger counter, and no data logger.

How far will it go?  It is a total crapshoot.  I will be happy if it at least gets out of Arizona.

The current plan:
- this will be flight SG-1, with tracking callsign AF7EZ-15
- transmitter will send updates about every four minutes
- payload will be about 100 to 150 grams
- balloon will be 1200g Kaymont
- float altitude predicted to be about 130,000 feet (40,000 meters)
- launch currently planned about 4pm MST on Sunday Dec 3, probably south of Maricopa, AZ
   (want the first part of flight to be at night to minimize UV from the sun)

Attached is a prediction that shows it going through New Mexico, Texas, Oklahoma, Arkansas, Tennessee, North Carolina, and ending in the middle of the Atlantic Ocean.  This is an early estimate.  Also, the actual ascent rate will be difficult to control, so we will need to run multiple predictions at different ascent rates -- after it is flying for a bit, we can calculate actual ascent rate, and will know which prediction is the most accurate.

Anyway, if you might be interested in tracking this flight, that would be cool.

If you are on the path of the balloon, and recover it, it is yours to keep.

This flight will use a new tracker transmitter of mine, which I think I will make available as an open-source project.  It uses an STM32F051 programmed with a free gcc toolchain.  It has a one-watt 2m transmitter module, with an output filter and a pmos switch to only turn it on as needed.  The gps is a ublox neo-6 (a few years old, but still awesome).  APRS/AX.25 tones are dac-generated then fed to an active filter that cleans 'em up and provides pre-emphasis.  It will use a dipole using 35-mil welding wire, and enclosed in a water bottle for some greenhouse heating.

This tracker board is one of a three-board HAB system I call Spyglass.  For a traditional HAB launch, a datalogger board mounts above the tracker.  A "sensor bay" board will mount outside the payload in a sun-shielded foamcore wind tunnel, which provides sensors and prototyping areas.  This floater flight only uses the tracker board.

I will update as launch gets closer, or if it cancelled due to unfavorable predictions.

gil, af7ez
(and alec, k7ezx)

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