4 ms·

IMO (skydiving instructor, world record holder with ~800 jumps), it doesn't necessarily contradict the definition of freefall...and was in keeping with Kittinge

IMO (skydiving instructor, world record holder with ~800 jumps), it doesn't necessarily contradict the definition of freefall...and was in keeping with Kittinger's mission (which was to test whether a Mercury astronaut with no skydiving experience could exit their spacecraft safely in the event of an emergency during the ascent). The jump on which the 1960 record was set was Joe Kittinger's 34th jump. Regardless, tandem skydiving rigs traditionally use drogues to stabilize and slow the freefall. So while they do provide drag, and semantically one could say that it's not "terminal velocity", ask anyone who's made a tandem jump: 120mph is freefall. I'd say if a drogue is landable, you could call it a parachute. Most drogues are ~2 feet in diameter and only slow you down by, say, 20mph...not exactly landable. Definitely an interesting question, though.

genwin 14y ago
Maybe the skydiving community has its own definition of free fall? My books say there can't be any force on you except gravity, which seem to rule out any apparatus intended to slow the fall.
- xymostech 14y ago
  But there's obviously air resistance, otherwise you wouldn't ever slow down. And the drogue is just providing more air resistance. I tend to agree with you, that I don't think that should count as free fall, but gravity is certainly not the only force being exerted.
- lloyddobbler 14y ago
  As @xymostech mentioned, any time you're in the atmosphere, there's obviously air resistance (i.e., drag) as a factor. So according to most physicists, true freefall would only exist in a vacuum. If you don't consider air resistance to be a "force besides gravity," then it becomes a somewhat semantical question of where you draw the line of "apparatus intended to slow the fall." In your statement above, what does "you" mean? Even without a drogue, your vertical speed can be influenced by such subtleties as what you're wearing. If I wear a zero-porosity nylon jumpsuit and fly on my belly, I'll fall at roughly 120mph. If I fly in baggier clothes, or throw on a sweatshirt over that jumpsuit, I can slow to 115mph. If I'm wearing a heavier rig with a bigger parachute in it, my rate of speed will increase. You get the idea. So again, semantically, if we ignore the fact that air resistance is a force besides gravity, would the only way to achieve freefall be to jump from an aircraft naked, wearing no parachute? Ultimately, no matter what you're wearing, terminal velocity is different for every person or object falling through the atmosphere. It's the sum total of gravity and drag, semantics or not. :)
  - genwin 14y ago
    Yes, free fall can be fuzzy due to clothes and whatnot. But someone who didn't use a drogue chute should be able to have a shorter free fall time yet still be eligible to claim the record for longest free fall time, all else being equal.

genwin 14y ago

Maybe the skydiving community has its own definition of free fall? My books say there can't be any force on you except gravity, which seem to rule out any apparatus intended to slow the fall.

xymostech 14y ago
But there's obviously air resistance, otherwise you wouldn't ever slow down. And the drogue is just providing more air resistance. I tend to agree with you, that I don't think that should count as free fall, but gravity is certainly not the only force being exerted.
lloyddobbler 14y ago
As @xymostech mentioned, any time you're in the atmosphere, there's obviously air resistance (i.e., drag) as a factor. So according to most physicists, true freefall would only exist in a vacuum. If you don't consider air resistance to be a "force besides gravity," then it becomes a somewhat semantical question of where you draw the line of "apparatus intended to slow the fall." In your statement above, what does "you" mean? Even without a drogue, your vertical speed can be influenced by such subtleties as what you're wearing. If I wear a zero-porosity nylon jumpsuit and fly on my belly, I'll fall at roughly 120mph. If I fly in baggier clothes, or throw on a sweatshirt over that jumpsuit, I can slow to 115mph. If I'm wearing a heavier rig with a bigger parachute in it, my rate of speed will increase. You get the idea. So again, semantically, if we ignore the fact that air resistance is a force besides gravity, would the only way to achieve freefall be to jump from an aircraft naked, wearing no parachute? Ultimately, no matter what you're wearing, terminal velocity is different for every person or object falling through the atmosphere. It's the sum total of gravity and drag, semantics or not. :)
- genwin 14y ago
  Yes, free fall can be fuzzy due to clothes and whatnot. But someone who didn't use a drogue chute should be able to have a shorter free fall time yet still be eligible to claim the record for longest free fall time, all else being equal.