How much difference does temperature really make in terms of canopy speed?

[grue 1]

Is a 100° day really a lot faster than a 60° day, or is it a one of those "significant in terms of numbers, but real-world flying isn't affected too much" sort of thing?

cavete terrae.

[PhreeZone 15]

Do some research on Density Altitude. Quade's page pulls up as #3 on Google. http://futurecam.com/densityAltitude.html

Yesterday is history
And tomorrow is a mystery

Parachutemanuals.com

[pchapman 262]

Rough approximations for equivalent atmospheric effects, for the altitudes and temps we deal with:

+10 C ( +18 F)
= + 1200 ft altitude
= + 1.8% airspeed (or just call it 2% roughly)
= 3.6% reduction in canopy size
or a need for 3.6% increase in canopy size to counteract the effect

So, ignoring any humidity differences which have a small effect, 100F vs 60 F gives about the same as an 8% size reduction on a canopy, which in many cases is a little bit less than one full size reduction. (Eg, a 150 canopy minus 8% = 138, while the next size down might be a 135.)

A little more advanced:
Some forget that the standard temperature depends on altitude. So they might be at 5000' in Colorado on a 15C day, and think that the temperature is "standard" and not adding any density altitude above the 5000' where they are standing.

But the standard is not "15 C", it is 15C minus 1.98 C / 1000 ft. So at 5000' and 15C the temp is already about 10 C above the standard, making the density altitude even higher.

Yes there's lots of aviation literature out there on the effects of temperature and altitude.

[MakeItHappen 15]

Quote

Is a 100° day really a lot faster than a 60° day, or is it a one of those "significant in terms of numbers, but real-world flying isn't affected too much" sort of thing?

See also Density Altitude - Wing Loading Converter and links at the bottom.

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Parachute History
DiveMaker

[Lindsey 0]

Yeah. A 100 degree day is a lot faster than a 60 degree day.

:)
linz

--
A conservative is just a liberal who's been mugged. A liberal is just a conservative who's been to jail

[Tonto 1]

In practical terms, the effect is huge.

Our DZ is 5000ft AMSL, and often 100 deg + in the summer.

Some days the post impact gymnastics from the 200 - 600 range jumpers is just amazing. It doesn't seem to affect me much, so maybe I have some "feel" dialed in and read it subconciously on the decent, and it doesn't seem to affect the students and very low time jumpers as their more conservative wing loading cushions them somewhat... but the inters who downsize mid summer? They are interesting to watch.

t

It's the year of the Pig.

[Brumby 0]

Well, where im from (in the cld parts of North East England) We dont notice the difference because its always damn cold lol

[EddieJ710 0]

by jumping and experiencing the effects of warm vs. cold weather..and being an Aerospace engineering student and actually seeing the numbers.....yes.....there is quite a bit of difference which you can see on paper as well as feel in the air.

[Calvin19 0]

pilots look at it in the efect density altitude. an airport at an MSL elevation of 3000', with a temperature of 100'F, would have a density altitude of something more like 5000', so, your parachute would fly as fast as it would if you were 2000' higher.