Wet canopy -- landing incident

[katzurki 0]

On first load of the day the jumper flew through heavy rain, getting the canopy and lines thoroughly wet. This changed flare characteristics of the canopy significantly enough that the jumper received a bad case of sprain / ligament tear on landing. Jumper said she flared like normal, but nothing seemed to happen. Dacron / F-111 combo may possibly have contributed (as opposed to microline / ZP--it probably wouldn't matter so much with the fabric, but dacron seems quite likely to adsorb some water). Wingload well under 1, 30 previous jumps. She said her mistake was not practicing flare after flying through the rain.

[darkwing 5]

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... Jumper said she flared like normal, but nothing seemed to happen.

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I do not think the problem was related to the wet canopy. If anything, I would argue that an old f-111 canopy would have lower porosity when wet, and flare better. The problem is much more likely to be due to turbulence, or inexperience, or a combination of both. I have flown wet F-111 canopies many times over the years, and have noticed no significant differences.

I'm not sure if there is a significant dimensional change in dacron lines when wet, but even if so, it would scale, and not be a big factor.

I will gladly retract my comments if there is authoritative info to the contrary.

-- Jeff
My Skydiving History

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[JohnMitchell 16]

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I have flown wet F-111 canopies many times over the years, and have noticed no significant differences.

I'm with him on this one. I've landed a bunch of wet F-111 canopies and noticed nothing different.

[Tonto 1]

I've landed plenty wet F-111 type canopies at 0.8 wingload. Never noticed any negatives.

t

It's the year of the Pig.

[mjosparky 4]

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I'm not sure if there is a significant dimensional change in dacron lines when wet, but even if so, it would scale, and not be a big factor.

Dacron lines or any line for that matter is not going to absorb much water when under tension. Putting under tension after it is already wet will squeeze any water out of it.

And you are correct; getting F-111 type material wet will lower the porosity.

My idea of a fair fight is clubbing baby seals

[FrogNog 1]

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Dacron lines or any line for that matter is not going to absorb much water when under tension.

I'm not saying I think Dacron lines (or any lines) do or do not absorb much water.

But are the lines really under that much tension during flight? Isn't the per-line tension in regular flight around 10 pounds each below the cascades, and 5 pounds each above? (For a 200 lb OtD jumper flying 9 cells.)

-=-=-=-=-
Pull.

[mjosparky 4]

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Dacron lines or any line for that matter is not going to absorb much water when under tension.

I'm not saying I think Dacron lines (or any lines) do or do not absorb much water.

But are the lines really under that much tension during flight? Isn't the per-line tension in regular flight around 10 pounds each below the cascades, and 5 pounds each above? (For a 200 lb OtD jumper flying 9 cells.)

Next time you are under canopy reach up and strum one of your lines. 10 pounds is enough to play a tune.

My idea of a fair fight is clubbing baby seals

[riggerrob 643]

I have landed a few wet F-111 canopies and never noticed a difference in flare characteristics.

Thunderstorms can emit really nasty wind shifts, wind shears, wind gusts, down drafts, micro bursts, etc. That is probably what slammed your friend.

Cold fronts also produce rain and "slightly" milder wind gusts.