On Thu, 4 Jun 2009 20:30:31 -0700 (PDT), Frogwatch
wrote:

Hmmmm, I found a web site where you can buy shotgun shells that fire
everyhting from slugs to pyrotechnics. So, why not a corner cube
unfolding radar reflector launched from a 12 guage flare gun for day
use? Give it a parachute and it'd fall slowly enough to be maybe
seen..

hmmmm. Doubt you'll get enough air time.
But how about this?
Life raft kit RADAR reflecting kite.
Might already be a patent.
If not, it's yours.
I'll just think of something else.

--Vic