You've seen the video. You've built and flown either the ST-1 or the ST-2 to collect data, or perhaps you downloaded data from someone else's flight. Here's how to see and understand the data.
This project walks you through the steps to download and install a program to analyze rocket data collected from flying a SensorTag on a model rocket. You’ll find out the G forces on the rocket, how fast it went, how high it went, and see the rotation and air pressure during the flight.
Here’s a link to the Maker project to built the ST-2 rocket that carried the iPhone in the movie. Build this rocket to collect your own data to analyze following the steps in this project.
You don’t need to know how to program to follow this project. You get the complete source code, though, so if you do know a little programming, you can tinker with the analysis program to learn even more.
The picker lets you select from any available rocket data. It is showing four data files from our rocket flights. Tap a different flight to see its data.
The five buttons at the right let you show or hide the five available plots.
Tap on a plot to see the numeric value at any specific point.
Edit these lines near the start of the program to add your own data.
Change the value of count to the number of data files the program will list.
Add any new files by adding another line to set a value in the files$ array. Increment the number in parenthesis by one for each new file. Remember that file names are case-sensitive in iOS.
The raw data will have a lot of extraneous information, as well as some valuable calibration information.
Find the start and end of the rocket flight. Enter the times in the Flight time fields. The plot will expand to show just the rocket flight.
Improve the accuracy by calibrating the device.
Sitting on the pad, the accelerometer should measure 1G.
Select about 10 seconds of data before the launch. Enter the times in the Calibration time fields to mathematically calibrate the sensor to 1G.
Step #8:
There's a story behind the data, as well as some important caveats about errors. See the Rocket Data Analysis portion of this blog if you would like to learn more about how the calculations are done and how reliable they are.
See this blog if you would like to learn more about creating user interfaces in techBASIC. This is what you need to know to modify the controls you see in the program.
See this blog to learn more about using plots and graphics in techBASIC. This tells you how to change and create plots like the five used in this program.
See this blog to explore how data is actually collected from Bluetooth low energy devices like the Texas Instruments SensorTag.
