[aprssig] Tracker3 9600 baud balloon tracker beta offer
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
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, Matti OH2MQK
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