Issue 98, September 1998
Smart Rockets - Data Acquisition in Model Rocketry

FUTURE DEVELOPMENTS

There are many ways to improve and expand this system. It could be miniaturized further by using a PCB with surface-mount components.

Earlier, we mentioned our decision to use a wire link to the rocket to trigger the data acquisition as opposed to using a threshold acceleration to trigger the system. Two of our students managed to implement this idea and got it to work quite nicely. Other triggering schemes could use optical or radio signals as wireless triggers.

Also, more sensors could be added. An old model-rocket trick for measuring roll rate is to install a photosensor in the side of the model. As long as the model doesn’t fly directly into the sun, there will be asymmetric illumination around the vehicle, causing a periodic signal from the photosensor as the rocket rolls. The PIC could easily measure the frequency of this signal.

A number of other sensors could be added—thermistors, pressure sensors, and even tiny gyroscopes. Another class of sensors consists of devices that indicate when critical events occur during the flight of the model.

For example, a fine wire could be placed across the nozzle of the rocket engine. When the engine ignites, the wire burns through and signals the PIC, which logs the exact time of ignition. You can imagine similar sensors that indicate when the rocket leaves the pad, when it clears the launch rod, and when the ejection charge occurs.

Additional sensor data could easily exceed our system’s capacity. Greater memory can be obtained via high-capacity serial flash-memory modules (discussed by Tom Cantrell in "Serial Flash Busts Bit Barrier," INK 85).

We’ve only scratched the surface of the many possibilities for smart model rockets. We hope to explore some of these avenues in another course. This time we were more than satisfied that all of the students got to fly their rockets and collect real data.

Jim Bales is a research engineer with the MIT Sea Grant College Program. He received his Ph.D. in solid-state physics from MIT in 1991. His research interests include sensors for underwater robotics and power systems for autonomous platforms. You may reach him at bales@mit.edu.