control input variations

[superstu 0]

Does the way you move your control inputs effect the way your parachute flies? specifically, does pulling your rears out, down, or back effect the canopy any differently then if you were to push them forward (toward your fronts)? would this effect efficiency?

Slip Stream Air Sports
Do not go softly, do not go quietly, never back down

[skygod7777 0]

i've tried pulling straight down, pushing out, and pushing forward, and can not tell any difference, other than when you push forward it looks like your not flaring, so it kind of looks cool.

later

[edid 0]

I figure pushing out has to give the best performance advantage; albeit small perhaps. Spreading the rears flatens out the canopy and a flatter wing is a more efficient wing yeiding a better glide. What do you do when you want to get back from a long spot? Most everyone spreads their rears (except Velo pilots it seems who seem to be able to hang up there better in brakes).

[BrianSGermain 1]

Yes, it does make a difference.

Here is a section from The Parachute and its Pilot that may be helpful.

There are other considerations when attempting to improve the glide angle of your parachute. The front view of ram-air canopies is bowed, with the wingtips lower than the center cell. This is because the lines are roughly the same length across the canopy. Referred to as “Anhedral” wings, airplanes are rarely shaped this way. The lift vector at the wingtip presents at an angle to gravity, thereby reducing the net lift produced by the wing. Furthermore, Anhedral wings tend to have less roll axis stability than those with “Dihedral” designs (curved upward).

Unfortunately, parachutes rigged to fly completely flat do not open, nor are they terribly stable. So we are therefore stuck with two partial hemispheres, described from the center points of our connector links at the top of our risers. We can, however, improve this shape in flight.

Consider that ram air canopies are, in a frontal view, two partial circles, separated and limited by the span of the tops of our risers(see fig). If we were to allow the risers to spread further apart from each other, our glide would improve somewhat. The first step in accomplishing this goal is to bring the slider down to the bottom of the risers, and loosen the chest strap. This allows the canopy to “expand out” and flatten more, and in fact grow in surface area. The effects of this are more pronounced on smaller canopies, particularly ones with heavy wing loading. Another positive side effect of this reduced Anhedral wing shape is an increased ability to save yourself from a low turn, and a general dampening of oscillatory tendencies on the roll axis.

The second method of reducing the Anhedral wing shape is to push the rear risers apart, as you pull them down. This further flattens the wing, and increases the glide of the canopy beyond rear risers alone. It also reduces the chances of stalling due to excessive application. Best of all, if you lean forward in the harness as you do this, you will find that you can hold this position much longer and with less effort than merely pulling the rears straight down. Keep in mind that pushing the rear risers apart will accomplish little or nothing if you have not pulled your slider down.

Hope this is helpful!

Brian

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