We started the day with the planned tests of the wing simulators. The modified third generation Parachute Test Payload (PTP-3) had three possible configurations that we tested, with the goal of evaluating the effects of the different wing sizes on a payloads stability during ascent. With all of these tests we endeavored to keep the flight profile as identical as possible, with the goal of reducing any deviance between tests. All of these flights were preformed without any issues, and the data from these tests was then collected and analyzed.
These results showed that, as we had expected, increasing the surface area of the wings had a significant affect on the stability of the payload while ascending. Using the data from the Inertial Measurement Unit (IMU), we were able to graph this affect for two of the three tests. While the Parachute System Control Compute (PSCC) failed to record data for the final test with the large wing simulators, we were able to use ground observations to draw sufficient conclusions to achieve our objective.
The above graphs display the velocity of the payloads rotation in the x, y and z axes. When the results of the two tests are compared, it becomes apparent that the addition of the small wings significantly reduced the magnitude of the x axis rotation. This reduction was unexpected, and points to the conclusion that the addition of small wings has a positive effect on stability, at least when the stability considered is rotational in nature.
The acceleration graphs show the other half of the wings effect. Increasing the size of the wings caused a notable change in the z axis acceleration that the payload experienced, with notable peaks visible on the graph. This change was also apparent during the test, as the payload was no longer hanging directly below the Flight Test System (FTS), but was instead being ‘pushed’ to one side.
Despite a failure to record data during the large wing tests, we were able to use ground observations to determine that the results followed the trends we had observed during the earlier tests, namely the lateral acceleration increased further and began to have a notable negative effect on the FTS flight performance.
In summary, these tests pointed to a clear answer to our questions about the effects of wing size on payload stability. We had found that the addition of small fins significantly reduced the rotational motion or ‘spinning’ that the payload underwent during flight, and thus had a net positive effect on stability. Increasing the size further introduced a new lateral instability that proved to make flight control a challenge. The design implications of these results suggest that the addition of wings can enhance the stability of a payload, but only so long as the size of these wings are kept to a minimum.