articles: fury of a dust devil video,
Attending a Maneuvers Clinic,
Collapse Accident with video and diagram, and
one of the most-often cited fears of inquiring minds. "But can't that
paraglider wing collapse?" they ask. Of course it can. But it turns out that the
dreaded collapse has more bark than bite and most are easily avoidable. Even
when it happens it's rarely more than a surprising sight. There
are, of course, exceptions.
Gaining a mastery of the wing can
dramatically reduce the chances of a collapse in the first place. But
that mastery comes through sound training and experience. Not just
experience boating around in smooth air, but exposing yourself to lower
levels of turbulence and maneuvering. Don't think you can read about this
here, in the Bible, or anywhere else and just go do it, either. Steep
maneuvering in a paraglider is risky beyond its appearances, especially for
those who tend to jump ahead of their capabilities.
Some good news: the wing is built to open and fly. Quickly. So even if part of
it does fold down, once it's reloaded, normal lift returns pronto. Higher
performance wings are notorious for getting their long, skinny tips caught
in the lines (a cravat) and can be more challenging to recover.
What's surprising is how easily most wings can be controlled with up to
half of their area folded up. In most cases, if the pilot minimizes brake
pull, lets the remaining wing accelerate briefly and then steer, it's quite
flyable, even landable like that.
Two rules should followed by new pilots:
- Rule 1. Never have NO brake pressure, always have about pressure 2
or what many instructors call quarter brakes (about the weight of your
arms). The wing is far more collapse resistant with some brake pressure
but, beyond about pressure 3, the benefit goes away since you lose brake
authority by being too slow.
- Rule 2. if you feel something unusual, do the default action:
reduce brakes, reduce power, then steer. Risk and reward has the
refrain "Hands Up, Power Off" which means "Reduce Brakes, Reduce Power".
You're cruising along when bumps begin—how much brakes to pull? First,
briefly go hands nearly full up then go pressure 2. If something unusual
happens, reduce brakes a bit reduce power a bit, then steer. Remember, the vast
majority of complications from collapses are not the fold itself,
but rather the pilot's abrupt and excessive reaction to it.
the Bump Scale for a standard
reference to turbulence strength.
Here is a complete article
more than meets the eye but the skill is primal for those who want to
really be able to master their craft. It's much more than riding the
brakes and must be learned over time.
I've seen numerous accidents and collapses that were aggravated by
the pilot's attempt at using brakes when the best action would have been
simply reducing brake pressure to about pressure 2 (see brake pressures) and concentrating on
You can do a lot to
avoid collapses in the first place. Staying out of turbulence is the best
prevention. Keeping the wing from going forward too much is the next
best thing. The further forward your wing goes, the more likely a collapse
Free flyers in strong thermal conditions get collapses a lot,
relatively speaking, so avoid such conditions. A good start is to only fly
in the first 3 and last 3 hours of the day. Don't fly in rotors—downwind
of obstructions and remember that stronger wind means stronger mechanical turbulence.
fly too slow. Speed is life especially once you're already in
turbulence. If you're getting bounced around a lot hold pressure 2, as
mentioned above, but reduce it if you feel the airflow on your face decrease
or the wing goes back. One you give up too much speed, those brakes are nearly worthless. Except for
heavily reflexed wings, have the trimmers set to slow and do not use the
speedbar. Flying faster can dramatically aggravate a fold since the extra airspeed
will tend to pull it under farther.
As an aside,
cruising along in turbulence under power leaves you more susceptible to going parachutal—a
rarity in free flight but more common in motoring, and another reason to remember "reduce
brakes, reduce power, then steer" if you feel something unusual.
You are most
susceptible to collapses when 1) lightly loaded, 2) accelerated, 3) hands up, 4) descending power off.
High Performance vs Reflex
High performance wings (higher than DHV 1-2 or equivalent), especially
when lightly loaded, will behave the worst during large folds—they are more susceptible and less likely to recover
cleanly. Their higher certification, in fact, comes significantly from how long they
take to recover from various upsets. These long, skinny wings are favored
by cross-country pilots for their great glide at the expense of higher
risk. Don't think that skill alone will make them safe—it will make a difference but
pilots have died in the thermic cauldron called "big-air." Small
folds, less than 50%, seem to affect higher performance wings less
than lower performance wings.
Having said the above, realize that any wing, when confronted with a
sufficiently strong vertical gust will fold. A heavily loaded wing
will be the most resistant but it's recovery will be sportier. A highly
skilled pilot flying a small, moderate performance wing actively is quite
resistant but only with appropriate active piloting.
A reflex wing, trimmed so the reflex is engaged (trimmed fast) with
speedbar applied will have the greatest resistance to collapse. I have
experience with these unusual wings since I found their claims a bit hard
to swallow. So I did some experimentation and back-to-back comparison with
existing wings. It was enlightening. Eventually, that experience will be
included in another article. Note that if one does collapse at such high
speed, all bets are off.
Many instructors prefer
calling them wing folds or asymmetric tip folds or asymmetric wing folds.
Turbulence means a downward
vertical gust that causes all or part of the leading edge to fold under.
It then blows back and lift is lost. Depending on severity, the glider
will turn towards the folded portion since the open part is lifting.
If the whole leading edge
folds under, it's called a frontal collapse. If a tip folds it's called an
asymmetric collapse or asymmetric tip fold.
the fast half of a slow/fast task at the 2005 USPPA competition, at about
1.5 meters high, I hit turbulence. 40% of the left wing folded as my left
side brake went limp. It only took a couple inches of brake with my right
hand to steer and keep it tracking down the lane. This technique allowed
me to keep from hitting the ground and within the 5 meter wide lane.
important response to turbulence is to get off the speedbar. I didn't
since I had no idea how bad it was! It happened while nearly fully accelerated, trimmers
at 3/4 out in moderately turbulent air: a very, very, VERY susceptible condition.
Photo by fellow
competition pilot Stan Kasica.
A Reflex style wing
wings load the A's and B's very heavily with the trimmers set to fast.
They are less prone to collapse in that condition because the leading edge
is less subject to "blow down," where relative wind aggravates
the collapse as the leading edge is blown down and back, taking more of
the wing as it goes. The effect is seen in all three of these pictures and
the video below.
any wing, going real fast, will be wilder on the recovery. So even the
reflex wings will frequently earn (or deserve) a DHV 2 or performance rating at their faster settings.
For most collapses, here is
the best bet for recovering.
1. Let it fly first by
reducing brake pressure slightly for a second. The good side will
2. Add the least amount of
pressure required to steer your course straight. The hand on the collapsed
side will be loose, there is no point pumping it in most cases. However,
one large pump can sometimes clear things up AFTER some speed is gained.
But always use pressure—as the pressure builds in the collapsed side you MUST let that hand go up.
3. For smaller collapses, weight
shift away from the turn, if able. Don't waste time with it, though, during a large collapse,
unless you can do it instinctively.
4. React to pressure. If you
feel the pressure build, in most cases it is best to let your hands up to
allow the wing to accelerate.
5. React to fore/aft swing. If
you're pointed at the ground, you may need FULL brakes. As soon as you
start swinging back under though, you must get off the brakes. More
advanced techniques exist for dissipating the energy resulting from such a
dive but you certainly won't remember that from a one-time read here. That
requires expert instruction and practice.
6. In a severe collapse there
are many potential complications that may defy correction. Each situation
is different, that is why avoidance is so important. There are thermals
and windshears and rotors out there that no amount of pilot technique will
counter. A good SIV (maneuver/safety) course will help prepare you
but, even then, without rehearsal it's doubtful you'll be that much more
prepared for the most severe deformations.
Realize that these maladies
are incredibly rare. Most paramotor pilots have never even experienced a
significant collapse (less than 30% is almost un-noticable) but that
doesn't mean you shouldn't be prepared. What has happened is pilots
over-reacting with too much brake input too quickly. That has
caused a number of crashes!
pilot was about 200 yards inland from the the Salton Sea which exhibits
calming on-shore winds like an ocean beach. He was descending on speedbar
which is a more vulnerable condition.
had been reporting only light thermal activity and wake turbulence did not
appear to be a factor. This was a fluke.
he was a very competent pilot who managed this properly, keeping his cool
and using the minimum brake pressure required to recover which he did with about a
30 foot altitude loss. This was on a DHV 1-2 wing.
by Jim Farrell
Shift (skip this if time is important)
Conventional wisdom suggests
weight shifting to steer during a collapse and, to the extent possible, I
agree. During smaller collapses it is quite beneficial—I've demonstrated
turning away from a 50% collapse using weight shift alone on the Spice.
However, experience and observation suggest that for large collapses it's
impractical and even contrary (because of time wasted trying) to a rapid
recovery. Here's why.
In a truly large collapse
your body will fall towards the folded side. A turbulence induced
collapse is quite different than an intentional one. When you induce it,
usually by pulling the A's down on one side, you know it's coming and will
likely start weight shifting immediately if not a hair in advance.
Plus, just hanging on those A's gives some support and you won't fall
as much, if at all.
The surprise version will
give neither support nor warning. You won't prepare and will likely
fall towards the down side making it harder to move back up for
effective weight shift.
When the wing initially
folds, in most cases your body will actually swing briefly away from
the fold and then you'll fall towards it. It can be quite
confusing. A simple procedure, such as "reduce brake pressure for a second then steer
with the least input required," will yield more consistent results
until you've gained experience with the requisite timing. More
steering inputs may certainly be required in some cases, but in most
cases, they are way overdone.
Weight shift works by
differentially moving the risers. Cool foot crossing and body
contorting may impress the babes, but if the risers don't move,
neither will the
wing. In a large collapse, the collapse-side riser is barely
in play, if at all.
Most motors don't have
enough weight shift capacity to make a huge difference. Even those
that do are probably half as effective as free flight harnesses.
I've never been able to induce
a collapse as bad as what nature has. Even pulling down one side as fast and hard
as possible has never done more than about 60%. While that was
attention-getting and turn-inducing, it was not as bad as what Mother
Nature's turbulence served up. So we shouldn't think that just because we
can handle self-inflicted versions, we'll easily tame natures fury.
Prevention is still the best medicine.
In the 3 major asymmetric collapses that I've experienced, two during
thermal free flight and one while motoring, I fell immediately to the down
side and recovered from that position mostly using the above technique.
One was from launch at Marshal. Alan Chuculate, launching behind me,
described that event as a 70% collapse. Another, also at Marshal,
cascaded. That is, one side folded then the other. Airspeed dropped and I
was successively falling to each side. That side would load and the other
side collapsed. After 3 repetitions I dropped out of the harness into the
landing configuration to prevent weight shifting and the cascading
stopped. Scary. In that case eliminating the possibility for weight
shift allowed a recovery. Of many dozens that I've induced, mother nature
took the cake for collapse severity.
My advice: don't mess with mom.
shifting here would likely be worthless since there is no load on the
collapsed side. This is a 70% fold and there is no cure but to use just
enough brake on the good side to let it accelerate and inflate the left
I am just starting to induce a 50% collapse and steering with only weight shift
(the other hand is operating the camera). My right hand is pulling
down the entire right A riser (on the left side of the picture). A hard,
fast pull can induce over 50% which will be sporty. If done accelerated it will
probably be violent with a lot of turn. Don't try this unless you're ready
for a wild ride!