Yo !
>Glide ratio for an aircraft, for a canopy, for a
>paraglider, etc., is by definition "the best flight
>capability of that particular wing" which depends
>only by its geometry (which consequently affects
>its aerodynamc properties) and is a unique number.
This is true for a fixed wing aircraft. On a ram-air parachute flying straing you have to change the wing shape and/or trim in order to change the airspeed and the angle of attack. We change the wing shape with brakes input and both the shape and the trim with
risers. Therefore, you could define "the best flight capability of that particular canopy", but not the wing - it will be a different wing for the different flight modes.
>Now, from the flight corresponding to the "glide
>ratio" trajectory (=zero brakes), you can move on
>and apply brakes, make turns, and so on. Of
>course, doing so you "worsen" your "theoretical"
>glide ratio flight path (i.e., straight in approach on
A major disagreement: full flight mode does not give you the best glide ratio on a majority of the
canopies.
For a fixed wing, there is a minimum descent speed and a maximum glide ratio speed. To achieve and keep them you use controls outside of the wing itself.
For a given ram-air canopy, you still have these 2 speed values but they are associated with different wing shapes and trims. They are generally slower than a full-flight speed, and achieved by applying some brakes and/or rear risers. Ram-air in a full flight can be compared to a fixed-wing glider in a dive ;-) The best glide ratio for most base canopies i have flown is achieved with a bit of rear riser input, or a combination of rear risers and some brakes.
bsbd!
Yuri.