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Tiny Digital Altimeter
 Winged Shadow Systems
produces a tiny electronic barometric altimeter called the How High that is about the size of a
penny and weighs just a shade over 2 grams. Though designed for model
aircraft use, It will fit tubes slightly smaller than BT-20 and if you use a
"button" Li-ion cell you can build a sub-1/4-ounce altimeter that fits in an
18mm nose cone. It "self zeros" and records in 1 foot increments up to 7000
feet above launch altitude. It will operate on 3.2 to 12 volts at about 1
milliamp. Winged Shadow Systems also produces a similar
stamp-sized modules called the How Fast for reading airspeed and data logging (recording the
data from the speed and altitude modules through the whole flight for later
ground-based analysis. both units can interface with the key-fob See
How data reader and storage device that can wirelessly read the data
stored in the "How" modules for up to 10 flights and display the results
digitally (no flash counting). Check it all out at
www.wingedshadow.com .
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Though this isn't the smallest nor
the most sophisticated of devices that you might use to measure the
altitude your models reach, it does strike a practical balance. It comes
as a complete unit. You don't have to add switches or wires, especially
if your model contains any standard RC gear...it will plug into any free
channel on an RC receiver for its power (there is also a trick that it
can do when plugged into such a receiver...see the
Winged Shadow site for more clues) or you can simply
purchase a very small RC battery pack and just plug it into that. Of
course, you can "custom wire" it if you like.
It's incredibly easy to use. It takes
advantage of the photo-switch ability of LEDs to activate its readout
function. It has a practical altitude range for any model rocket and
most high power rockets.
Used together with the How Fast
unit and you can do some pretty serious research work and investigation
into drag, weight, and other performance variables and how they affect
model rocket speed and weight.
For a scale modeler like me,
adding one or both of these units to a scale model for either the NAR
Sport Scale or Scale events and you can tack on a few "special effects"
or payload points that may not only help you win but help you learn
something from the experience, too.
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