Value of a Test Flight
by Jérôme Daoust
Some familiar sayings after a paraglider test flight…
pilot flew a wing with a higher certification level than his normal wing,
lands with big smile saying "Not even a small collapse, it's
great" and is ready to buy it.
pilot lands and says "That's a scary wing, it moves around a lot. Collapses
must get really ugly".
So how much value is there in a test flight, and what are
appropriate conclusions we can gather from it?
First, what we can not
conclude from one day of flying:
- From how "nervous" it feels
overhead, you cannot predict:
- The collapse recovery behavior (and general
- When I changed from a Gin/Oasis (DHV
1-2) to the Nova/Aeron (DHV 2) I was surprised that the DHV 2 wing was
so dampened overhead (maybe more than the Oasis) and rarely collapsed,
but was consistent with DHV 2 recovery behavior when it did. Then when I
switched from the Aeron to a Nova/Tattoo (same DHV 2 class) the increased
requirement for active piloting was striking from the first flight, but
it recovered noticeably better from collapses (trim and accelerated). I
flew an Advance/Omega 6 (DHV 2-3) that felt less "nervous"
than the Tattoo (DHV 2) I had at the time. My current Nova/Ra (DHV 2) is
nervous in pitch and yaw (but much dampened in
roll) yet is the most relaxing DHV 2 wing I have tested when recovering
from accelerated collapses (even rated 1-2 on frontal at max speed).
- There are wings of a lesser DHV class
which require more active piloting than some of the class above, yet a
pilot should not assume that he automatically has the skills to manage
the collapse scenarios of the higher DHV class wing. Chances are you can
test fly a competition wing and land with a big smile.
wing's collapse resistance.
- Wings which are less dampened and move
more overhead as a whole, do not necessarily
get more asymmetric or frontal collapses. Rapid adaptation to the
changing air mass is not necessarily a bad thing, and you do get a sense
of the air's "texture" so you may actually be more on you
grads to prevent collapse than a more dampened wing.
cannot predict fully accelerated collapse behavior from tests at trim or ½
- Most pilots will not dare test fully
accelerated collapses to get a taste of what will likely happen to them
later during ownership, so they try to extrapolate the behavior from
their observations at trim or ½ speedbar. But the reactions of a wing
follow the square of the airspeed prior to a collapse, so good-natured
collapse recovery lesser speeds is no guarantee of full-speedbar
- Thinking that full speedbar collapse
recovery is not important, is fooling yourself.
The next time you need full speedbar to penetrate, you will be at risk
and entering uncharted territory.
cannot predict a wing's collapse resistance after a few hours airtime.
- It requires about 40 hours before a
sense of how collapse-resistant a wing is. Before that the sampling time
is insufficient. There have been days where I though the air was nasty to
me and a friend thought it was fine, while the reverse happened just as
well. Collapse-inducing air is location and time specific.
- Some judge how good their wing is by
how big/thick/rigid specific components (fabric, risers, pulleys,
leading/trailing edge reinforcements) are. Real longevity is difficult to
What we can get an idea of:
- If you
are OK with the level of active flying
we said above that a "nervous" a wing is no indication of poor
recovery behavior or low collapse resistance, and that there are benefits
to feeling the air, it remains that such a wing will require more input
from you, making the ride less relaxing and drawing some of your focus
away from other flight goals. Be aware that after about 10 hours with a
new wing, you will have developed new reflexes (maybe from new neural
connections established during sleep) and you will start feeling significantly
more at ease with it.
- First you need to locate the amount of
safe/usable brake pull for minimizing the sink rate.
- L/D at
trim at accelerated.
- Difficult to measure or get a sense of
unless there is a significant (at least 0.5) difference. Comparisons with
friends flying at your side can be spoiled by many variables like: Wing
loading, model size (a larger size of the same wing typically has 0.25
better L/D), amount of drag at the pilot level, how each wing reacts to
- Some wings dissipate more energy than
other during constant turns or change of directions.
of typical worst-case scenarios.
- One cannot predict the worst thing that
can happen to him. But some bad scenarios are more common than others,
for example stall are not as likely as a
collapse while fully accelerated. Some say they solve the issue by
avoiding to use their speed system but they will
still end up using it to avoid being blown back and often close to terrain,
which is not the time to test recovery skill if needed. I like to do 2 (to
avoid getting off easy on the first one) of each of these (with lots of
altitude) and feel that if I'm not willing to do it in relatively safe
conditions, I should not be flying this wing:
Limit yourself to
How to be
comfortable flying full speedbar on your new wing?
of arm fatigue on long flights.
- Arm fatigue sets in more quickly if you
elbow can not be kept under your hand (hand often needs to be at/below
your shoulder), and compounded by the brake line tension for your
favorite airspeed. Wings with higher certification levels (DHV 2 and
above) are often easier on the arms.
What we can get a true sense of:
response to brake input.
- It is when you just switched to a
different wing that you are most aware of this, as your muscle memory of
your previous wing is most fresh.
- You can measure it. But be aware that
it is significantly dependant on altitude: The rule-of-thumb is that each
1000 m increment gives you at least 2 km/h more.
- You can compare with a friend flying at
your side (if you are at a similar ratio into your respective weight
of inflation and kiting.
- But most recent wings do that well.
- If the
accelerator system is easy and smooth to fully use. Some require more
- If the
rucksack that comes with the wing is big enough for all your gear.
testing and demo-ing.