Dec 28, 2012, 8:14 PM
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Re: [Shredex] Hot/Cold Air vs. Fallrate
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I would imagine most people would see an increase in fallrate when it's colder. We tend to bulk up with winter clothing under jumpsuits, making them tighter and reducing drag, so I'd think that would be a much larger effect than air temperature itself. That's just coming out of my ass, though; that whole "science" thing is hard.
Dec 29, 2012, 2:20 PM
Post #11 of 21
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Re: [Shredex] Hot/Cold Air vs. Fallrate
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Assuming EVERYTHING is constant except for air temperature, you will fall faster in hot air and slower in cold air because the drag force will decrease with a decrease in air density, and air density will decrease with a decrease in air temperature.
Force of drag = 0.5 X density of fluid (in this case air) X velocity^2 X Cd (drag coefficient) X A (reference area)
Dec 29, 2012, 4:07 PM
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Re: [dream2fly] Hot/Cold Air vs. Fallrate
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The reasoning I ask, is because normally in a track I can get to a good 82mph vertical speed with the lowest being 79 and an average of 86. But last weekend it was a very cold day and I had one heck of a tailwind pushing me along and yet I couldn't fall slower then 95mph. It confused me...still is...
Dec 30, 2012, 9:57 AM
Post #14 of 21
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Re: [Shredex] Hot/Cold Air vs. Fallrate
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The reasoning I ask, is because normally in a track I can get to a good 82mph vertical speed with the lowest being 79 and an average of 86. But last weekend it was a very cold day and I had one heck of a tailwind pushing me along and yet I couldn't fall slower then 95mph. It confused me...still is...
How was the fall rate measured? GPS or barometric altimeter? That could have an influence on a cold day.
Dec 31, 2012, 5:00 AM
Post #16 of 21
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Re: [Shredex] Hot/Cold Air vs. Fallrate
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Alti-Track was used.
I wouldn't consider that a very reliable form of measurement.
To answer your previous question, I fall at the same speed, just seems MUCH longer when it's fucking freezing.
billvon (D 16479)
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Jan 2, 2013, 9:29 AM
Post #17 of 21
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Re: [almeister112] Hot/Cold Air vs. Fallrate
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>I would imagine most people would see an increase in fallrate when it's colder. We >tend to bulk up with winter clothing under jumpsuits, making them tighter and reducing >drag . . .
?? More clothing increases drag. It's pretty common to have bigway fallrate problems on the first dive of the day when people add sweaters and thermals. Cold air is also more dense, and this decreases fall rate BUT it decreases fall rate for everyone and thus is not a factor for relative work.
Jan 2, 2013, 11:35 AM
Post #19 of 21
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Re: [skyjumpenfool] Hot/Cold Air vs. Fallrate
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I tend to notice the difference more when landing my canopy's.
it also seems easier to absorb air through my skin on hotter days (for breathing in freefall)
this question is one about the variability of a very minor factor in freefall speeds - the first question should really be "does the variability in air density even have enough effect to overcome the natural variability of freefall speeds"
- i.e., colder air = more resistance = slower terminal v with all other things held constant - which they aren't normally. But is it really even noticable when you realize that all other things aren't held constant from jump to jump, let alone on completely different temperature days?
(This post was edited by rehmwa on Jan 2, 2013, 11:35 AM)
