When I saw "50 seconds of weightlessness" (see quote below) I made a very rough estimate based on 45 degrees nose-up to 45 degrees nose-down Reduced Gravity Flight centered at about 35,000 feet where the speed of sound is about 295 m/s, and an airspeed of mach 0.85 at that altitude:
t = 2 * 0.707 * 0.85 * 295 (m/s) / 9.8 (m/s^2)
which gives about 36 seconds.
The article left me somewhat upside-down and confused, asking myself "How many seconds of near-zero gravity are practical on a Reduced Gravity flight?" as well as "Do they do things like this on the ISS when the cameras are off?"
The article states:
Kulash: We also came up with a system for doing a single take over eight parabolas. In each flight you have 15 parabolas and in each parabola you have 20 seconds of double gravity, then 50 seconds of weightlessness and few minutes of setting it all up again. So to make it one take, we took eight of these in a row over 40-45 minutes.
Sie: We also we slowed our playback of the song down a bit (28.5 percent, to be exact) and performed each portion of the dance a little slower. This way, the 21 seconds of song fit neatly into the 27 seconds of weightlessness. The pilots — there are 10 OF THEM flying the plane at the same time, by the way — pull out of the parabola when the plane has enough downward speed and momentum in order to "scoop" itself up out of the downward acceleration.
The bold highlight is mine. In the first quote - perhaps the numbers are reversed and it's 50 seconds of >1G and 20 seconds of weightlessness, which would then be more consistent with this article, which also supports the 27 seconds in the second quote.
So my question: "How many seconds of near-zero gravity are practical on a Reduced Gravity flight?"
I count seven "parabolas" instead of eight, but between 02:00 and 02:31 it looks like partial gravity - not a typical parablola.
video time - they are clearly modulating frame rate to reduce the high G periods begins ends 00:26 01:04 01:06 01:24 (normal walking) 01:26 01:42 (normal walking) 01:48 02:05 02:07 02:12 weak gravity? 02:27 stronger gravity? 02:31 02:47 02:51 03:08