Dudek Snake, User Manual

24

change of pressure & trimming of the aerofoil, resulting with rapid collapse.

At slower trim settings both the sink and steering forces are reduced, so that 
effective thermalling becomes possible. 
Please study pictures illustrating trimmers and speed-system operation on the 
next page. They explain the influence of various settings on the profile shape.

Remember:

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Trimmer setting is another thing to include in your pre-flight check list!

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If the setting is not symmetrical, the paraglider will turn in flight. And if you 
inadvertently release the trimmers, reflex profile of the Snake XX will keep 
your wing level, so after hitting the gas you will descend with increased 
speed instead of intended climbing.

Released trims without brakes 

Typical setting for fast and safe flying. Center of 
pressure of the aerofoil moves forward, practically 
excluding collapses. Pitching moment induced by 
the reflex aerofoil increases angle of attack.

Released trims with brakes applied 

Even slight brakes application (especially on full 
speed bar) shifts the center of pressure back, and 
due to lack of reflex on trailing edge, pitching 
moment now decreases angle of attack. 
Additionally turbulence behind the wing occurs. In 
some circumstances this can lead to a collapse. 
Using the brakes can be sometimes necessary for 
heading corrections, still you should keep your 
brakes free when flying ahead, otherwise the reflex 
feature doesn't work.

Closed trims

In this configuration brakes are the normal and 
prescribed steering system. Slow trim is used for 
launching & landing in nil wind, as well as 
thermalling. Due to decreased speed of the 
paraglider its steering characteristics remain similar 
to classic profile paragliders (with increased tuck 
resistance). 

center of pressure

lift

speed

sink

pitching moment

Influence of classic steering on the reflex profile

Pilots used to classic paragliders tend to fly "active" style, with their brakes constantly tensioned. 
Flying a reflex wing like that is ineffective and can possibly be dangerous.
 Basic rule of reflex paramotoring says: 

the more turbulent it is, the more trims should be 

released and classic steering should be limited, especially with speed system engaged

.

In such moments paraglider is much more effectively steered by TST or ALC systems, designed 
specifically for that reason.
Problem is illustrated by following drawings: