The 3D flight path is normally drawn using a combination of the barometric altitude data and the GPS data for north-south/east-west location. But none of the Arless flights include GPS data files, so, for this visualization, I approximated the 3-D flight trajectory by assuming the rocket is traveling in the direction it is pointed, i.e., its angle-of-attack is zero. This is a good approximation for most of the flight when the rocket is traveling the fastest, and so is a good approximation of the flight path. It does not work at the end of the flight when the rocket velocity is close to zero, so the flight trajectory visualization ends just ahead of the first ejection event.
The two Excel spreadsheets that contain the data from the GWiz altimeter and the Rocket Logger for the flight used for the video above are available here:
Here is the link to the Arliss flight visualization video. Click the picture at the left to enlarge a snapshot of the completed visualization.
The spin rate of the rocket increases and decreases directly with the velocity of the rocket, reaching a peak of almost 2 revolutions per second. A spin rate that is proportional to velocity is due to a cant angle on the fins.
The tops-down view of the rockets orientation leaves a trail from the tip of the nosecone. As the rocket spins, the cross-coupling between the axes causes a small nutation, or looping motion of the rocket, that can be seen as the trail traces the path of the tip of the nosecone.
The wild gyration of the rocket at the end of the flight occurs after the nosecone/payload has been ejected. The first ejection event can be seen in the spike in the accelerometer data.
Copyright © Thomas Fetter
ARLISS Flight Visualization
At the end of 2014, I purchased an RAF AL-016 High Speed Data Logger board. The first opportunity I was going to have to fly the Data Logger would be at the Tripoli Central Dairy Aire launch in May of 2015 (that launch was canceled due to rain and I flew th Data Logger at the TCC 2015 October Skies launch). In the mean time, I wanted to test the Python visualization program that I had written. Fortunately, there are a number of Data Logger data files posted on the RAF web site from ARLISS flights where they flew the Data Logger. Some of those flights also have altimeter data available.
I chose the Tokyo Institute of Technology flight flown by Bob Feretich on 9/8/2014. This flight has a link to the Data Logger and G-Wiz altimeter data files.