thoughts about X-winds

[Mac]

I have recently spoken to a couple of people that had openings they did not expect with Cross winds.

My thoughts are that if you have a right to left cross wind, your PC may go out toward the left, but the canopy will infact try and open toward the right (towards the wind direction),

Their feelings were that they expected to turn left off heading due to the PC pull.

I have read through older posts, and it seems that people still have varying results with cross winds, so as this subject has not been discussed for awhile I thought I would bring it up, and get some other opinions and experiences on this......

I remember sometime ago a post by Dwain on the physics attached to the theories on bridle direction pull and wind direction, using a teabag analogy, but have been unable to locate it, i only found a post about vented PC's when i searched also stating that the PC coming off at an angle is not in itself the reason for off headings - if someone could find that post it would be cool..............

I have myself experienced both right and left off headings with a right to left cross wind, but the left off headings I could actually put down to things like a dropped shoulder or head low exit and bad body position so could not really say why it happened - but generally I would expect a right off heading with a pure X wind and everything else being stable.

Is the fact a canopy comes off at an angle and perhaps loads the risers unevenly also going to effect the reasons that the off headings occur in a certain direction? Does perhaps the fact you have a deep container effect the way this off heading occurs?

Any further thoughts on winds, directions and openings? Experiences and thoughts most welcome - most people see to think they "know" what is going to happen, but I bet there is so much more experience out there that disproves everyone elses theories!! hehe

I would appreciate it if anyone had the Dwain post on directions and openings - as I last read it about a year or so ago, and cant remember the content exactly.

Thanks

Michael

edit: I am taling about freefalls in the 1-3 sec region as I assume that static lines and PCA's would act differently to freefalling due to fixed bridle points - maybe you could add your experiences with these too if your a SL lover?!

[Faber]

most of the offheadings i had in x winds turned the canopy up against the wind(oppersit site as the pc goes),i dont know if the Multi in that point can make it vorse(i jump the multi),but i guess soo.

I love SL but never really had a great offheading(max 90 off if i rember correct)

[Mac]

actually thats something I did not think about, the use of the multi and its effect on off headings in winds. I dont jump a multi, so I think this would also be an interesting area whether the multi helps / hinders / on heading performance due to the way it pulls the canopy out.

Anyone with multi / single attachment deployments that can comment?

Thanks

Michael

[jason]

Is the fact a canopy comes off at an angle and perhaps loads the risers unevenly also going to effect the reasons that the off headings occur in a certain direction?

[...]

I am taling about freefalls in the 1-3 sec region as I assume that static lines and PCA's would act differently to freefalling due to fixed bridle points - maybe you could add your experiences with these too if your a SL lover?!

My experience, and if I recall correctly this is in line with the general agreement, is that the riser loading is the most important factor. If you're jumping crosswinds in a short freefall, the PC and canopy (which are less dense than you are) blow downwind. The upwind riser is loaded first, as a result, and the canopy turns upwind. If you're SL'ing or PCA'ing a crosswind, *you* drift downwind (since your PC is fixed). The downwind riser is loaded first, and as a result the canopy turns downwind.

SL's, in my experience, are quite sensitive to this. A person can, for instance, step 8 inches to the left of the attachment point and be nearly guaranteed a ~20 degree offheading to the left. My experience with short freefalls in crosswind is more limited.

[space]

Thoughts posted,

[space]

In my experience, whether FF-ing, PCA-ing, DB-ing or
watch-ing, this is what I have observed.
It is very dependent on the wind velocity. Somewhere
there is a switch where ones "shoulders parallel to
the Horizon". In a low speed crosswind, it creates a
shoulder low scenario to the relative wind ((Situation
#1)turning one´s canopy into the wind), in this
premise, one affects the canopy riser loading. The
switch comes in what I consider moderate to more than
moderate winds. Situation #1 you affect the canopy
because of your weight. In (situation #2) moderate to
plus winds, The canopy takes you! Jerking you
shoulders parallel to the the bottomskin of the
canopy. This will put one in a banking turn (downwind)
that will not stop until one is under the canopy cg.
DB´s and FF´s are very prone to this scenario IMHO.
Less affected is the PCA in this aspect, but this
brings on a new set of factors which I can´t begin to
contemplate, which is the nose and tail being blown
downwind of the PC attachment point with an upthrust
of wind.
My best advice would be for one to always jump with
the shoulders as perpendicular to the wind vector at
deployment time for FF´s, and DB´s as possible. How
one can acheive close to that is only a guess. I
really hate smokestack jumps for this very reason.
Have fun,
take care,
space