[aprssig] Balloon warmth

Bruce bruce.coates at sasktel.net
Wed Mar 24 14:57:23 EDT 2010

Ok, now you got me interested.  I've been wondering what I was going to do 
with the two unused ADC inputs on my SMT OpenTracker and now I know.  On our 
May 8th flight I hope to include an experiment to measure the effect of 
solar heating.  I'll have two identical Styrofoam blocks suspended outside 
the payload box.  Each will contain an LM335Z temperature sensor.  One will 
be painted black (or whatever I find that absorbs IR) and the other will be 
unpainted white Styrofoam.  The 335s will provide a wee bit of self heating 
which might simulate the heat radiated by devices in a normal payload.  I 
could also move the bias resistor out there for a wee bit more heating.  The 
biggest trick will be not getting them knocked off during post burst.  ;-)

Should be interesting.

73, Bruce - VE5BNC
SABRE Balloon Project

From: "Steve Noskowicz" <noskosteve at yahoo.com>
Sent: Wednesday, March 24, 2010 9:02 AM
To: "TAPR APRS Mailing List" <aprssig at tapr.org>
Subject: Re: [aprssig] Balloon warmth

> The sealed plastic pouch versions don't use air.  It is a reversible 
> exothermic chemical reaction.  This is the ones with the metal popple 
> disk.
> I think they have a super saturated solution of an acetate salt, perhaps 
> sodium acetate.  There's several YouTube videos showing the process - ad 
> nausium...
> at fractions of an inch of mercury the Iron compound versions will die.
> -- 73, Steve, K9DCI
> --- On Wed, 3/24/10, Scott Miller <scott at opentrac.org> wrote:
>> About a dozen people have suggested
>> this, but I'm not convinced the oxygen level is
>> sufficient.  I do happen to have a vacuum chamber in
>> the shop, so once I get a functioning payload again I'll
>> have to throw a few of those in there and compare the heat
>> generated to a control at 1 atmosphere.
>> Scott
>> N1VG
>> AD4BL wrote:
>> > An alternative to keeping equipment warm on a balloon
>> flight is to use the hand warmers.   They
>> last about
>> > 8 hours and provide enough heat to keep equipment
>> operating in a cold environment.
>> >
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