Model Forum / General / Rockets / August 2009

I'd look at using either a Basic Stamp (or similar product) from
Parallax (http://www.parallax.com/) or a pic microcontroller from
Microchip (http://www.microchip.com).  Some of the Basic Stamp
controllers are based on propriatary pic controllers.  The Basic
Stamps are easiest to use and learn, by design, but are also more
limited and take up more square footage.  The pic controllers offer a
wider range of products, but you need a development kit (hardware and
software) to program them.  There are free versions of the software,
and I think you can find schematics/plans on the web for building your
own programmer.

There are two basic ways to measure altitude: accelleration, and
pressure (you could also use GPS but that's harder and the antenna
takes up room).  You can get free samples of accellerometers from
Analog Devices (http://www.analog.com/en/sensors/inertial-sensors/
products/overview/CU_over_Inertial_sensing_technology_products/
fca.html).  Simple pressure sensors are easy to find (ie: digital tire
gauge), but take interface circuitry to make them work.

The timing on this is interesting because I'm looking at designing/
building an accelleration logger for hobby/sport rockets.  How many
G's will a rocket see, and for how long?

I looked into this quite a while back.
I found some sensors and could write the progs but it became obvious that I
could not construct anything for less money than what was already available.
I did design a poor mans apogee release,. Barometric capsule that would
trigger a microswitch when pressure started going back up.
Good Luck,
Tom