Tail wind on 0-1 sec. delays?

[Rod]

Is there such thing as too much tail wind on short delays. And I'm not talking about hurricane force winds here, but maybe something in the range of 20-30 mph tail winds. Obviously a strong tail wind on the ground will make for a fast downwind landing if you don't get it turned around in time.

I'm more concerned about the strong tail wind during the deployment sequence. i.e., heading, inflation, PC entanglement?

Just curious as to what are other people's limits on winds , and why? Does it all depend on the object your jumping, how much delay your taking, the object height?

Rod

[d-dog]

I've been taught that the biggest risk of a higher tailwind with a short delay is PC enganglement when going stowed. More specifically, the wind blows the PC under your shoulder/arm on deployment, thereby routing the bridle up your chest and out around your shoulder. At the least, this would result in a severe PC hessie.

Without a tailgate, a big tailwind can cause line-overs but I believe the tailgate pretty much eliminates this even in a fairly strong wind.

There's a big difference between a true tailwind of, say, 30 mph (which might be pretty safe with the right gear and canopy control skills) and a gusty wind of 20 mph. The latter can cause squirrely deployments, downdrafts, and broken limbs on landing even if the jumper does everything right. Basically, that's simply a roll of the dice.

Practically speaking, the thing that scares me most in high-wind jumps from low objects is losing control of the PC while prepping it for handheld. This could easily result in a fatality, and I'm triple cautious when doing this if the winds are strong.

Be safe out there!

Peace and happy holidays,

D-d0g
ddog@wrinko.com
www.wrinko.com

[guest]

A friend of mine jumped in a 27mph tailwind from about 800', short delay, and had a 2-3 second down plane.
Eye witneses said he had a fully inflated canopy. It just happed to be straight out in front of him.

"He got out of that one..."

c-ya

:o

[FFC1]

>I've been taught that the biggest risk of a
>higher tailwind with a short delay is PC
>enganglement when going stowed. More
>specifically, the wind blows the PC under your
>shoulder/arm on deployment, thereby routing the
>bridle up your chest and out around your
>shoulder. At the least, this would result in a
>severe PC hessie.
----------------------------

From personal experience, I can verify this account. I left the object (400 foot A) with a 2 second delay reached back and tossed the PC. The Bridle went under my arm in front of my shoulder. Basically I swam out of it. Right arm in back as if grabbing the left side of my helmut then pushing the bridle away. The rest was uneventful. I learned with a tail wind and going stowed, that I pull the PC out and toss it up and behind me rather than just the side. Freaky $hit. Also if the elbow pads were outside my shirt that day, the bridle would have had a seriously potential snag point.
I've reconsidered going hand held off this object.

[Rod]

Thanks for your input guys. This is the kinda info I was after. ;-)

Rod

[imported_Tom Aiello]

>A friend of mine jumped in a 27mph tailwind...and had a 2-3 second down plane.

It sounds to me like this might have been a deployment stall. Since a wing needs to fly forward (relative to the air around it) to generate lift, a canopy deployed in a tailwind can open in a stall (no lift generation). To recover, the canopy nose dives (in front of the jumper) creating this downplane phenomenon.

This is pretty much the same thing that will happen if you set your brakes too deep for your wingloading. I've got good video of this happening to me when I jumped a canopy with brakes set for bps (who outweighs me) in a very moderate tailwind.

Obviously, an opening stall and resultant diving canopy (downplane) will be very negative on a low deployment, where you may not have sufficient altitude to recover, and therefore end up diving into the ground.

How ver, to more directly address Rod's situation, I don't think that a deployment stall will result in high speed ground impact after a 1 second delay from 320 feet, as the canopy will likely have time to recover in his case.

--Tom Aiello
tbaiello@mac.com

[david]

Been jumping off my favorite tower (350 ft) with 15mph to 27mph tail winds the past three months. 27 mph being the highest. I would say 22-23mph being average. I have a Kestrel 1000 wind meter just to keep track of winds and their effects. Haven't had any problems yet. I have noticed the higher the wind the worse my on heading preformance gets. I would asume that your chance for line twist does increase also. Just make sure the higher winds don't blow you past your landing area. And as stated in the other reply's, do not go stowed and make sure you have control of your pilotchute at all times! But I guess the best rule is only jump what you feel comfortable with. Some jumpers don't have any problem jumping in high wind. I've climbed down more than once because of winds. This is only my opinion.

Stay Safe