From: bdaniels@ssf-sys.DHL.COM (Ben Daniels)
Subject: Tracking - was Spotting and Ground Speed
Organization: DHL Systems, Inc.
Date: Fri, 16 Oct 1992 03:41:30 GMT

(warning: topic drift alert)

Timing and wind velocity and airspeed are too complicated to work with
in the heat of the action. (Especially in the days before calculators.
I can just see me standing there on jump run with a sly drool trying to...)

But if I take the trajectory of the group in front of me and displace the
whole thing top to bottom 1000 ft in the direction of the jump run, that's
my trajectory. And it's easy to do.

When they go, I look out at the horizon - eyes level - mind level. Drop
my eyes straight down. Right. They got out over the farm house so I'll
wait until we are across the road and about that far into the next field
before I go. Basically when they go I just keep spotting.

Of course when the uppers are really screaming it's a perfect time to
forget about close in relative work and do some large scale RW with the
whole planet.

Pope Valley had probably the best uppers. At a certain time of the year
the DC3 would hardly penetrate and it was hard to stay in the plane long
enough to get far enough up wind even for a regular spot.

I would take a small group and go way way WAY up wind and then track back.
It was great. Deliciously awesome and scary surfing the big wind. I always
felt very small and science fictiony being blown across the surface of a
planet like that.

Tracking was always a thing of mine anyway. I practiced it a lot and tried
all kinds of positions. Looking in the movies at people wearing smoke it
seems clear that there is no smooth air flow. It is all turbulence above.

That means it is all air deflection - no lift like a wing. That means I
want the greatest frontal area and the best shape for scooping the air
and sending it back towards my feet.

Now my center of mass is higher than my center of area. So for a while I
was trying positions with my hands up around my head in various ways, but
the position I finally settled on was pretty similar to the standard
track.

First of all very stiff. At the end of a 60 second track my legs would be
trembling. From the solar plexus to the toes was straight. From the solar
plexus up was kind of a curved scoop made out of chest, shoulders and
head. My shoulders would be hunched up around my head but kept as wide
as possible and my head would be part of the overall shape.

My legs would be no more than an inch apart. Working together they seemed
to catch more air than spread apart. I would leave a very small gap with
the idea that maybe the turbulence in between would give me another couple
inches of effective area, but I was never sure about this. Similary for
the arms along the body.

The final refinement, which really seemed to make a lot of difference, was
to turn my hands over and fly palms up.

I discovered this in 1975 when I was getting my gear in perfect shape so
I could go on one of BJ's incredible journey's and I wanted to be able
to focus on just the skydives.

I had put on my gear and jumpsuit and was looking in the mirror trying out
various shapes and thinking about how to scoop the most air and send it
backward. When I turned my hands palms up my arms and shoulders made a
much better shape.

It felt kind of funny the first couple times I tried it, but I kept in mind
that all the air sees is my overall shape. There are two "scoops". One is
the chest/shoulders/head and the other is the arm/torso/arm. The arms are
slightly below the torso like stabilizers on a canopy. The backs of my
hands were even with the fronts of my thighs.

If you get in front of a mirror and try various shapes with the "maximum
air scooping idea" you'll see what I mean and discover your own position.

As for angle of the whole body relative to the air (ie how much head down)
the only way I can describe it is to imagine Niagra Falls frozen in the
winter and you are balanced right on the edge in your tracking position.

You want to be head down just enough that you start over the edge and then
hunch your shoulders yet another millimeter higher and stretch your neck
to keep from going. That's how it felt to me. I was always about two
feet taller at the end of a long track.

Skratch

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email:  bdaniels@ssf-sys.DHL.COM