[aprssig] Tracker3 9600 baud balloon tracker beta offer

Matti Aarnio oh2mqk at sral.fi
Thu Dec 19 08:47:14 CST 2013

On Wed, Dec 18, 2013 at 06:50:19PM -0800, Scott Miller wrote:
> The test flight had deliberately very low lift and it drifted around
> for about two hours before it finally froze after sunset.  A
> fast-rising balloon in daylight would probably be fine, but I'd
> still recommend more than the 1/2 inch foam that we used for
> insulation.

Thermal conditions up there are dominated by radiative transfer because
air pressure is so low that convection will not be moving much.

Commercial weather balloon sondes these days have a thin plastic box,
and underneath it a highly reflective thin metal case.  Add a clip-on
Li primary battery, and the thing is flight ready.  (Thin = low weight.)

Thermal radiation out of that brightly reflective metal is much lower,
than out of black epoxy of chips, and standard circuit boards.
Thermally a metal box open towards earth is probably best compromise.
Space is so damn cold...

> 73,
> Scott
> N1VG

73, Matti OH2MQK

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