P A R A C H U T I N G ' S N E W S M A G A Z I N E
Ask the Editor
Contents of Batch 17:
How do I pick the best
canopy after graduating from student training?
How can I tell if my
steering lines are too long?
How do I practice for my
tandem rating?
The following questions were submitted by visitors to our Web site and answered by the editor of Skydiving magazine. .
To ask a question of your own, click here.
How do I pick the best canopy after graduating from student training?
Q. I’ve
just completed my AFF training. I’ve used mainly
9-cell canopies (buses) but want to progress to faster
canopies. What would be the best size canopy to convert
to without jeopardizing safety?
A. Picking a canopy just by its size
isn’t the best way to go.
A better way is to first
determine what "wing loading" is best for you
and then calculate the canopy size that will give you
that wing loading.
Wing loading is calculated by dividing the jumper’s
"exit weight" by the surface area of a canopy.
(Exit weight is the jumper’s weight plus all
clothing and equipment.) If you weigh 170 pounds and wear
a 25-pound rig and 5 pounds of clothing, then your exit
weight is 200 pounds.)
Most canopy manufacturers as well as some more
forward-thinking associations have established
recommended exit weights for jumpers of various
experience levels and ambient conditions. Students, for
instance, generally jump canopies that are sized to give
them a wing loading of 0.65 to 0.85.
Again: Your Exit Weight / Canopy Surface Area = Canopy
Wing Loading.
As an example, our 170-pound jumper (200-pound exit
weight) under a 170 sq.ft. canopy would give it a loading
of about 1.2 (200/170 = 1.2). That’s a little too
high for a newer jumper; a larger canopy would be better.
Although, this number might vary depending on your
training, abilities and flying preferences - and where
you jump (high or low altitudes, tight or open landing
area, nearby obstacles, that sort of thing).
You can obviously rearrange the variables to compute what
canopy is right for you. Your Exit Weight / Recommended
Wing Loading = Recommended Surface Area.
Thus, if the recommended wing loading for the canopy you
intend to jump (for someone with your experience and
particular situation - such as field elevation) is 0.9
and you weigh 200 pounds at exit, then the canopy should
be 222 sq.ft. or there about (200/0.9 = 222).
Different canopies have different recommended wing
loadings because some canopies are designed to be
"loaded" heavily. The manufacturers publish
recommended loading ranges in their owner’s manuals.
(Most owner’s manuals are a great source of useful
information about the canopy.)
Having said all this, the best way to transition to
smaller canopies is under the direct supervision of an
instructor who knows how to teach modern canopy flying.
(Many instructors are good at teaching exits and freefall
maneuvers, but they know beans about teaching canopy
control. It’s not really their fault; canopy
technology is advancing faster than USPA and other
associations can keep up.)
A competent instructor can help you transition to smaller
canopies in only a few jumps. (This doesn’t mean you
should then try to make an impromptu demo into a swimming
pool, however.) A good instructor will have a
canopy-training syllabus and will use methods such as
follow-the-leader training and ground-based video to make
learning fast, fun and relatively safe.
This isn’t quite the answer you’re looking for.
But it’s a better approach than grabbing a rig off
the rental rack and hoping you can handle what’s
packed inside.
How can I tell if my
steering lines are too long?
Q.
I’m a student skydiver with 18 jumps. I purchased
gear when I graduated AFF; the main is a Triathlon 220
7-cell. Everyone says this is a good canopy for me - I
weigh 210 pounds - but I have a big problem landing. I
have already sustained a few minor injuries hitting the
ground. I watch others land and I don’t see why
I’m having such a problem. I have been talked down
by radio, listened to experienced skydivers, and nothing
seems to work. The man I bought my gear from was tall
with very long arms. I’m concerned my steering lines
are too long, preventing me from achieving a full flare.
How do you determine if the toggles are tied to the right
place on the steering lines to achieve an optimum flare?
A. There are two ways: On the ground, by
measuring the steering lines, and in the air, by stalling
the canopy at altitude.
While descending under canopy, let the toggles go all the
way up to their keepers. Look at the control lines as
they extend up to the trailing edge of the canopy. They
should be slightly bowed by the airstream, and the
trailing edge of the canopy shouldn’t be pulled down
at all.
Then gently pull one toggle down a couple of inches. You
should feel only a little tension on the steering line,
and the canopy should begin a very, very gradual turn.
Sometimes the steering lines are too tight because the
toggles are tied too closely to the canopy. If they are,
the canopy’s performance is being hampered and it
won’t flare as well.
I like a canopy with about an inch of slack in the
steering lines. That way, I know the canopy is in full
flight when the toggles are up. Other jumpers, however,
want the canopy to begin turning as soon as the toggle
moves.
But steering lines can be too loose, too, meaning the
toggles are tied too far down. In full flight, the
steering lines will have a significant bow in them.
You’ll feel the slack when you start slowly pulling
a toggle down; there will be little tension until you
start deforming the canopy’s trailing edge. If any
"slop" exists, it will be quite noticeable.
If the toggles are too loose, then the canopy might not
give you the flare authority you need when it’s time
to land, especially if your arms or your risers are
relatively short.
Check this by flaring your canopy at altitude as if you
were landing. From full flight, pull both toggles down in
one smooth, slow motion. The canopy should stall briskly
at or before the bottom of the stroke. If it
doesn’t, then it’s likely the toggles need to
be moved up the lines a couple of inches, or the keepers
need to be moved up the risers, or both.
A canopy’s steering configuration can be checked on
the ground, too. Many owner’s manuals include
line-length specifications, and it’s not hard to see
if your canopy meets those specifications. If the data
isn’t in the manual, or if you don’t have a
copy, contact the manufacturer. Manufacturers gladly
supply this information; they want their canopies
configured correctly. Aerodyne Re- search is a
particularly responsive company.
The length of the risers and the location of the
steering-line guide ring also play important roles in a
canopy’s control system. The industry has set some
standard specifications for risers, but a lot of
variation exists.
A steering line configuration that works well with one
jumper might not be right for another, especially if the
jumpers are of different weights.
Smaller, higher performance canopies have shorter control
ranges (the distance the toggles must move from full
flight to stall) than larger, "boxier"
canopies. But all can be rigged so a jumper has the full
range of control available to him.
The canopy you have will land you very well if it’s
rigged and flown properly, in spite of its rather high
wing loading. Check the canopy’s steering system,
and get a little training. You might also decide you need
a larger canopy — at least until you gain a little
more experience (see the question about wing loading
above.)
How do I practice for my
tandem rating?
Q. Is
there anywhere I could rent a tandem rig for a month or
two? I have taken the class twice and, although I did
pretty well, I did not pass the class. No one will sell
me a tandem rig without a tandem license, so how am I
supposed to practice for the class if I don’t have a
tandem rig? I am a pretty good skydiver, and think I
would make a good tandem master.
Tandem instructor and examiner T.K. Donle, who runs
the tandem program of the Relative Workshop, responds:
A. Tandem jumping requires certain
skills and abilities that go beyond normal skydiving.
Just look at the fatalities that have occurred worldwide
on all brands of tandem systems since 1985. Out of 34
tandem accidents, 31 students and 31 instructors have
lost their lives. No other instructional role is as
dangerous as tandem. And when you look at the nature of
these fatalities, you’ll quickly realize that, in
most cases, it was the instructor that failed to perform.
I don’t want to sound negative because I don’t
know your specific circumstances. But if you’ve
already taken the class twice and failed, this is a prime
indicator that either you don’t have enough
experience yet to easily handle the rigors of a
certification course. Or, the demands of performing a
tandem jump are overwhelming you.
Keep in mind, during your tandem courses, you’ve
only taken experienced jumpers as passengers who are
usually playing "good students." How will you
react to the stress when you perform jumps with
problematic "first jump" students?
Your tandem examiner is obviously concerned about your
abilities. A tandem rating is not a right that
all skydivers are given. You must earn the privilege
of obtaining a tandem rating through acceptable
performance during a tandem certification course.
The only time you can "practice" tandem jumping
is under the direct supervision of a properly rated
tandem instructor/examiner. Because the FAA controls
tandem jumping in the U.S., most manufacturers are very
strict about how their certifications are carried out.
You cannot go back to your home DZ and practice tandem
jumping if you failed to pass your certification. Your
examiner has already determined that you do not possess
the necessary skills to perform safe tandem jumps or use
a tandem rig at this particular time.
If you are able to borrow a tandem system for the purpose
of "practicing," you and the individual who
loaned you the system are both in violation of federal
law. In addition, the tandem system could be legally
confiscated from the owner by the manufacturer. So please
don’t go that route.
Another important point you should realize is that even
while jumping a tandem system in the solo mode, you can
still experience every tandem malfunction except
passenger interference. And please be aware that there
are 10 different drogue malfunctions on top of all the
others. This sole difference is exactly what has caught
so many tandem instructors by surprise.
(We disagree that making a solo jump using a tandem
rig without the manufacturer’s approval would
violate federal law, since the jumper would meet the
FAA’s requirement of wearing a TSOed "single
harness dual parachute pack." That doesn’t mean
it’s a good idea to jump such a complicated system
without the proper training. The Relative Workshop could
also pull the equipment’s owner’s tandem rating
and possibly confiscate the equipment. - Ed)
If you would like to improve your chances of successfully
passing your next course, I would suggest skydiving as
much as you can to develop whatever skills you may be
lacking. Sometimes just having more air time can help
build your confidence and get you through those stumbling
blocks that you came across during your last
certification course. Continue to study your Tandem
Owner’s Manual so standard procedures as well as
emergency procedures are fresh in your mind. It’s
possible that you may be able to attend a future
certification course for retesting. That would be up to
your examiner, with input from the tandem manufacturer.
I realize this may not be easy for you to swallow, but
the simple fact is many jumpers do not have the
"right stuff" to be safe tandem instructors. If
you look at the fatality figures, we know of at least 28
who couldn’t quite hack it.
My office is always available for counseling and
technical advice. Please give me a call, send an email or
fax and I’d be glad to discuss your future in tandem
jumping.
(T.K. Donle is the director of the Relative
Workshop’s Vector tandem program. He can be reached
at 386-736-7589, fax 734-7537, or email tk@relativeworkshop.com)
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