Wind shear

[billvon 2,476]

Had an interesting wind shear incident yesterday at Perris. After a 4-way I set up my usual 90 degree front riser turn. I come out of it, the canopy starts to recover as it does normally - then it stops recovering at about 20 feet. I add brake - nothing. I go to 3/4 brakes, and the canopy is still descending at the same rate. I set up for a PLF, and hit feet-thighs-ass . . .

The canopy picks that moment to start flying again, and I pop up a few feet, get it leveled out, and land on my feet. Another jumper looks at me with a "what the hell was that?" look. Behind me I see another jumper pound in, apparently caught by the same effect I saw.

The winds had been the usual nuts Perris winds at around 1pm, but this was around 5pm and the winds had calmed down a bit. They were pretty steady (8-10) out of the north. Looking back at it, it's pretty clear that I had hit a lull where the winds dropped near zero, or the tail of a dust devil that reversed the wind direction for a split second as I passed through it.

So the question is - was carrying more speed a good thing or a bad thing? Had I not been carrying the extra speed, I wouldn't have been descending as fast, and there may have been less speed to deal with PLFing out of when I lost lift. On the other hand, the canopy might not have had as much airspeed to work with when the winds changed, and I might have hit even harder. The guy in front of me hit the same shear, but he hit it just slightly higher, and his canopy started flying again a few feet above the ground - he landed normally.

[AggieDave 6]

Firstly, Bill, I'm glad you're ok.

This is a good question and presents a few issues. For starters, I don't believe there is truely a singularly hard and fast answer, since wind conditions will never be the same at different times, even at the same place. However, I do know that personally, I stay off my dive loops when wind conditions are bad.

A little about my gear, my approach and why I tend to not do high-performance when the conditions aren't right.

I jump a Crossfire2 149 loaded at (roughly) 1.9:1 and 9 times out of 10 I toss out a 270 for my approach.

Although I can't fully explain why or how, its truely just a "feeling" I get from my canopy, what my canopy is translating to my body and mind when trying to do a highperformance landing in bad wind conditions is that I am wrong, this is dangerous. This is from all inputs, the feeling from the harness, the feeling of the pressure on the front risers, rear risers during the swoop and toggles.

I've found that I've had plenty enough speed to "cut through bad wind" and keep my canopy flying with a basic straight in approach during unfavorable wind conditions. However, I am at a higher wingloading, so that most likely plays a significant effect.

Oh, at the end of the day, I feel more comfy under a Sigma 370 with a heavy passenger in "odd winds" then I do under my sport canopy. Even though the wingloading isn't (obviously) nearly as high, with all of the mass of myself and my student, the canopy flies quite nice through "bad wind."

--"When I die, may I be surrounded by scattered chrome and burning gasoline."

[GravityGirl 0]

We had a pretty traumatic incident at Byron last year due to a wind sheer.

Three canopies flew through the same "funk". A fairly highly loaded velocity with induced speed. A Sabre 135 loaded at 1.25 and finally a Silhouette 150 very lightly loaded.

The velocity cracked and flew through it. The Sabre had a moment of partial collapse and sudden reinflation as it passed through it. The Silhouette unfortunately got picked up spun around and the pilot landed face first at a high rate of speed. (She is fully recoverd and has been back in the air.)

My thoughts are that I would like the extra speed. Not from a snapping hook turn as much as from the canopy I fly.

I've been thinking about this a lot lately as the winds begin their funky dance when the heat comes up.

I'll be interested to see what others experience and thoughts are here.

~~~~~~~~~~~~~~~~~
Peace and Blue Skies!
Bonnie ==>Gravity Gear!

[D22369 0]

Had an interesting wind shear incident yesterday ***

I have witnessed windshear first hand .... and that makes your post one of the most understated posts on this forum................

I caught one recently that as I was setting up my left 270, it turned my canopy 90 degrees to the right, upon which I aborted my usual landing in favor of survival....

***So the question is - was carrying more speed a good thing or a bad thing***

> who knows?, more airspeed, more lift - usually........ or slower airspeed = more time.... 6 of one 1/2 dozen of another....

I dont know if mine was the edge of a dust devil or windshear either.....

But I am glad you came through your incident intact.......aint adrenaline great

Roy

They say I suffer from insanity.... But I actually enjoy it.

[crutch 0]

We have a similar effect when jumping into the stadium if there are any winds at all. I personally like to front riser down through it so I have a little extra speed, but as you have found out, the toggles don't have the desired effect through the windshear. Then again, we jump larger canopies into the stadium (the grass is a lot softer too) to try and protect ourselves as much as possible (loading 1:1 or less). I do agree with Dave though, my Sigma canopy tends to fly through the shears better than the other canopies I jump. Why, hell beats me, it just does.

blue skies,

art