> 3. I have a friend into model rockets - how high do they get?

    Almost everything that you can build @ home, including SMT, is too heavy
    to ride on all but the heaviest model rockets. However, the apogee can be
    read by a very small Tx that is actuated by a G-loss sensor (a switch that
    closes or opens when there is no gravity). The triangulation measurement
    relies on three ground stations. Contact your local Armed Forces for
    suitable equipment ;)

Huh?  Nonsense.  "low power" model rockets (motors up to a "D" - 20Ns) can
lift nearly a pound to reasonable altitudes.  "Mid power" (E to G motors -
up through about 120Ns (limitted by legal propellant mass)) can loft up to
3.3lbs before you begin to start worrying about low explosive issues and FAA
waivers.  "Easy Access" High power - requiring FAA waivers (not hard to get)
but (perhaps) not BATF Low Explosives User Permits (the central issue in a
current controversy) will get you up to a "small J" motor - which would be a
good 5-10lb liftoff weight.  High Power Model Rocketry - under codes similar
to low power, but requiring LEUP, FAA waivers, and BIG land areas (favorite
launch sites: idle farmland, dry lakebeds, and sod farms) will currently get
you up through M motors, capable of lofting perhaps 100lbs lift off mass.

Whoever said 0-5000ft was spot on.  A lot of the big motor activity seems to
be in launching heavier rockets, rather than small rockets higher.  People
who regularly launch higher than 5000ft are relatively uncommon.  (Of
course, part of the reason for that is that higher altitude flights are
harder to recover, since they tend to drift really far.  More and better
electronics would help.)

For most rocketry-related electronics projects, batteries are the heaviest
component.  I launched a rocket last fall containing a camera strobe (w 1 AA
alkaline battery) converted to repetitive operation on an A motor.  The
liftoff weight was under 4oz (which was the limit for that particular A
motor.  It didn't go very high (20 ft?))  Next time I'll be less
conservative and try the C motor...

BillW