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Issue
98, September 1998
Smart
Rockets - Data Acquisition in Model Rocketry
by
Tom Consi & Jim Bales
Model rockets
have always served as ideal vehicles for teaching physics
and engineering basics. With this new data-acquisition device,
Tom and Jim show how to trace the rocket’s acceleration
and store the entire flight and its data.
Start
• Introduction to Model
Rocketry
• Rocket Science 101
• Control & Data Logging •The
Accelerometer •
Software • Power
• System Construction •
Launch Control Box
• Results
• Future Developments
• Software
& Sources
Model rockets have inspired generations of students to pursue careers
in engineering and science. Indeed, many of you probably
went through a rocket phase in your formative years.
Model rockets are popular
with aspiring engineers for good reason. They’re
exciting, they’re fun to build and launch, and they
offer a number of significant engineering challenges that
can be tackled with simple tools and small budgets.
From an educational perspective,
model rockets introduce a number of fundamental concepts
in physics such as Newton’s laws, lift, and drag.
Inexpensive microcontrollers and solid-state sensors add
an exciting new dimension to model rocketry.
It’s now possible to
build tiny devices that can measure and record the performance
of a model rocket in flight. This article describes just
such a device that we designed, built, and flew as part
of our "Smart Rockets" seminar at MIT.
Our system measures just
one flight characteristic—acceleration—although
it could be easily modified to measure other aspects of
a rocket’s flight. We designed the system to fly
in a small, single-staged, model rocket that could be
launched in a relatively small area.
The entire system, including
battery, is 4¼? long, slightly under an inch wide, and
weighs about 1 oz. (32 g). Photo 1 shows a picture of
the system mounted in the rocket.
 
Photo 1a–Here’s our smart
rocket on the launch pad. Note the clear payload
compartment containing the data-acquisition system
and the copper contacts beneath the fins. The brown
streak down the right side of the rocket is one
of the two lines of conductive paint that bring
the trigger signal to the payload. b—In
this view of the data-acquisition system, you see
the modifications made to the payload compartment.
The brown patch on the rear bulkhead connector is
conductive paint that forms a sliding electrical
connection with the rocket body. To the left of
the circuit board is a model-rocket engine.
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Inside the payload compartment
is a small circuit board that contains an acceleration
sensor, power supply, microcontroller, and nonvolatile
memory chip. A pair of leads brought out of the payload
run down to the tips of two fins and touch corresponding
contacts on the launch pad. The launch-pad contacts attach
to a cable that leads to the launch control box.
When the launch button on
the control box is pressed, two things happen. First,
the leads brought out to the fins are shorted together,
triggering the data-acquisition system. Second (and electrically
isolated from the first), a current passes through the
igniter, starting the rocket’s engine and setting
the vehicle into flight.
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