By Brian Germain
The stall is one of the least explored and most
feared aspects of flying. Avoidance of this flight
mode causes many canopy pilots to be uncomfortable
with flying slowly, and unpracticed in this important
art. This article will discuss the governing variables
relating to the stall, in hopes that this knowledge
will help parachute pilots to become less afraid
of this essential aspect of the flying experience.
First we must explore what a stall is. The assumption
made by most canopy pilots is that the stall is
caused by slow speed flight. This is not true. It
is correlated with low speed flight, but a wing
can stall at high speed too. A stall is caused by
an excessive angle of attack. When the relative
wind flows over an airfoil, it is bent in the general
direction of down. This causes an opposite force
called “Lift”. When the orientation
of the airfoil is changed to a higher angle with
respect to the relative wind, it is said to have
an increased angle of attack.
Air is quite cooperative. It is willing to be redirected
and still flow in a fairly organized manner…up
to a point. At a specific angle, all airfoils fail
to bend the air into submission. This discrete angle
of attack is referred to as a stall. It is coupled
with a sudden drop in lift, and thus a significant
increase in decent rate. Whether you are flying
an F-16 or a Lotus 190, recovery from a stall is
always the same: the pilot must reduce the angle
of attack. On an airplane this requires forward
pressure on the yolk or stick. On a parachute, we
are simply required to let off the downward pressure
on the toggles or rear risers that has increased
the angle of attack in the first place.
Each parachute stalls and recovers differently.
Depending on several governing variables, some parachutes
will recovery nicely from a stalled configuration
no matter what the recovery technique, while others
will require very careful execution. Let’s
take a look at these issues one by one.
The characteristics of a stall on any ram air canopy
are based on two main variables, and several lower
order variables. The most significant governing
variable is the flight mode when the stall is reached.
If the canopy is in a sink, rather than level flight
(zero decent surf), it will tend to stall in a more
forgiving and docile manner. The second primary
variable is the attitude about the roll axis when
the stall is reached. In other words, if there is
any bank angle when the stall precipitates, it will
cause the lower wing to stall first, resulting in
significant yaw energy, which can result in line
There are several other things to consider when
testing the stall of a canopy, including: canopy
design, density altitude, wing-loading, aggressiveness
of the control input, and most importantly, recovery
technique. This will be discussed next.
If the wing is allowed back into forward flight
quickly, it will dive aggressively toward the ground,
causing a drop in the angle of attack, as well as
the lift and therefore the overall line tension.
This may allow the wing to surge below the suspended
weight (you), and possibly cause a jumper/canopy
entanglement. Further, if the release of the brakes
is asymmetrical, the lack of line tension can allow
the wing to surge unevenly about the yaw axis, causing
The key to stalling any wing is to enter the stalled
configuration in a sink, with the wing level and
static about the roll axis. As soon as the stall
is reached, the toggles (or rear risers) should
be released only a few inches to allow for only
a slight drop in the angle of attack. As soon as
the brakes are released, the jumper should be prepared
for a sudden increase in toggle pressure, as the
tail of the parachute is about to get hit with a
pulse of relative wind. If the pilot is unprepared
for this, the toggles will usually be pulled upward
and in an uneven manner, often resulting in an aggressive
stall recovery that may result in line twists.
When the brakes are released quickly to the full
flight position, the wing doesn’t have much
drag. This means that there is very little to prevent
it from surging forward in the window. When the
brakes are released slowly, and then held down,
just above the stall point, the wing has a great
deal of drag. You have two big barn doors at the
back of the wing helping to prevent and aggressive
Further, as you become more familiar with the stall
and recovery characteristics of your wing, you may
begin to fly “actively” with respect
to the recovery process. In other words, as soon
as the wing begins to fly forward in the window,
the pilot jerks on the brakes to dampen the forward
surge. It is important to do this minimally enough
to prevent re-stalling the wing. A well-timed reapplication
of the brakes during the recovery process will significantly
reduce the amount of altitude lost in the stall.
This can be very useful in the event of a low altitude
stall. This maneuver can be practiced in relative
proximity to another canopy in deep brakes. Be sure
to keep your distance when you do this. By definition,
a stall is a loss of control of the wing.
Rear risers stalls tend to be sharper at the onset,
but quicker on the recovery. Therefore it is advisable
to stall the parachute on the rear risers first
before attempting to stall it on the brakes. Further,
such maneuvers should always be performed at an
altitude that will allow for a safe cutaway.
With all of these concerns, one must ask "Why
should I stall my parachute in the first place".
There are several valid reasons why each jumper
should rehearse stalls at altitude.
1) In high angle of attack approaches, such as
may be necessary in a tight landing area, stalls
can happen inadvertently while maneuvering. This
is why it is also important to practice slow flight
maneuvering by lifting the toggle on the outside
of the turn, rather than depressing the one on the
inside of the turn.
2) In order to reach a (near) zero ground-speed
on a no-wind day, the pilot must have full "Toggle
Authority". In other words, if the toggles
are set too long, the pilot will be unable to access
the slowest possible airspeed, and therefore will
be forced to land with more ground-speed without
the advantage of a headwind. Being able to finish
the flare completely and then let up after landing
to prevent the stall from pulling you onto your
heels in an essential part of any no wind landing.
When you decide to practice stalls, I suggest taking
the process step by step. Simply honking your brakes
down with your eyes squinting in negative expectation
usually results in a wild ride, and sometimes a
cutaway. Try hanging out in slow flight for a while.
Bring your toggles down to a bit more than half
brakes and leave them there. If you are above the
stall point, it isn’t going to just stall
all by itself. Watching people fly in deep brakes
is usually similar to watching them light a firecracker.
Your parachute isn’t going to explode…promise.
When you get your canopy into the deep brake mode,
take a deep breath in and let it out slowly. Relax
your muscles. Let your legs hang limp. I find that
nervous pilots can’t connect with their parachute
because it isn’t touching their bones. If
you soften your muscles, your will allow the leg
straps to sink into you so that you can feel what
is happening with this new part of your body. By
truly relaxing under canopy, we begin to sober up
from the adrenalin that is blurring our vision and
skewing our perspective toward the negative.
Stalls are an essential part of flight. If you
are to be fully in control over the wing, you must
explore all aspects of your parachute's performance
envelope. Ultimately, flying slowly is the most
important aspect of flight because we land in slow
flight. The more comfortable you are with your slow
flight skills, the better your touchdown will be.
Remember, the definition of a good flight is one
that ends well.