Audible Feedback

This is a complete jump with the Prodigy 2 and FlySight.

The FlySight audio track comes from the jumper being filmed. The audio was reconstructed afterward, using information recorded during the jump, and then overlaid on the original video. The reconstructed audio track was produced by a FlySight, and recorded directly from its audio output, in order to make the reconstruction as authentic as possible. Synchronization was accomplished using the FlySight's LED, so the audio is as close as possible to real time.

The FlySight was in glide ratio mode with a maximum of 1.5:1. On this particular jump we had a significant headwind, but you can see that the tones produced by the FlySight still clearly identify changes in glide ratio resulting from slightly different body positions.

Andrew Levson is the man behind the camera. The jumper being filmed is Michael Cooper.

Logged Data

FlySight handles the dynamics of freefall exceptionally well. FlySight can be turned on a few minutes before exit, and begins providing audible feedback immediately after exit.

Here, we discuss a sample data set from a jump using the Prodigy 2 (not the same jump as the video above). The log file itself can be downloaded here:

Log file

For this flight, there was a moderate wind from the west. The flight line went west about 1.25 km, then north 0.75 km, then 2 km east.

On the right, you can see a plot of glide ratio for this flight. To determine glide ratio, FlySight uses velocities provided directly by the u-blox receiver. For real-time feedback, this is enormously superior to a method based on differences in position, because the receiver's velocities are accurate to 0.1 m/s.

As expected, the glide ratio going west is slightly worse than on the return flight, because of the wind. One of the remarkable things about FlySight's real-time feedback is that the precise value of the glide ratio is not important. What is most clearly perceived is the change in glide ratio due to changes in body position.

glide ratio and elevation

glide ratio and vertical speed

To the left is a plot showing glide ratio compared with vertical speed.

Low vertical speed sometimes indicates high glide ratio, but you can see from this plot that the two are not quite the same. For example, early in the jump, vertical speed climbs while glide ratio levels out.

Although it is not completely clear in this data set, there are hints that minimizing vertical speed will not necessarily maximize glide ratio. In future jumps, we hope to record data which explores this relationship further—for example, by demonstrating increasing glide ratio with increasing vertical speed.