Design, Mechanics, and Terminology

A speedwing consists of 3 main parts; the aerofoil, the lines, and the risers.

As you know from Aerofoil Aerodynamics, the aerofoil creates lift. The lines attach the aerofoil to the risers, while the risers attach to your harness, and give you flight controls.

The front of the aerofoil is called the leading edge, while the rear is called the trailing edge.

The risers and lines on most modern speedwings are split into 3 groups; A, B, C. Group A is located toward the leading edge, while group C is located toward the trailing edge. Behind group C are your brake lines and brake toggles, attached to the trailing edge. Both the left and right sides of the glider have separate line sets and risers.

It is crucial to be aware of the type of glider you are flying, and piloting appropriately for the given air conditions.

Pitch

Pitch is the rotation of the glider about its lateral axis (side-to-side).

Roll

Roll is the rotation of the glider about its longitudinal axis (font-to-back).

Yaw

Yaw is the rotation of the aerofoil about its vertical axis (top-to-bottom). In paragliding, a glider exhibits yaw movement during a spin.

Line Length

Paragliders tend to have significantly longer lines than speedwings, with a few exceptions, such as the Bantam.

The line length affects the handling characteristics of the glider in the following ways:

• Longer lines give the glider more dive, as the recovery arc is lengthened.
• Longer lines result in the pilot experiencing more G-force during roll and pitch movements.
• Shorter lines increase the roll-rate of the glider, leading to more responsive handling. This is an important consideration for newer pilots, as gliders with a high roll-rate are more sensitive to weight-shift and brake input.

Aspect Ratio

Both speedwings and paragliders alike are designed with an aspect ratio appropriate for their intended use-case and pilot ability.

Gliders with a higher aspect ratio have better glide performance, at the cost of passive safety. Gliders with a higher aspect ratio typically have more cells, and therefore less pressure in each cell. This reduction in cell pressure makes the glider more susceptible to asymmetric collapse.

Conversely, gliders with a lower aspect ratio have greater stability and therefore passive safety, at the cost of glide performance.

Pitch Control (Speed System)

Conventional paragliders, mini-wings, and speedwings typically either a speedbar, a trim system, or the FLARE system to control the pitch of the glider.

Paragliders, with the exception of tandems, use a speedbar design. A speedbar design consists of a pulley on the A-risers, connected by a cord running through the harness, to a bar operated by the pilot's feet.

Conventional speedwings and tandem paragliders use a trim system, normally connected to the rear risers. The trim system consists of webbing running through a cam. When the cam is released, the load on the C-risers causes the webbing to run through the cam. This lengthens the C-risers, and to a lesser degree the B-risers, relative to the A-risers.

The combined speed system is a much newer design, pioneered by the brand FLARE. This design combines a trim system consisting of two pulleys with the brake lines, connected at the brake toggles. This combined approach allows a pilot to simultaneously control trim and brake input.

Additionally, some gliders, such as the Little Cloud Puffin, use a riser design with both a speedbar and trim system.

It is exceptionally important to be aware of the manufacturer recommendations and warnings for proper use of these riser designs.

These designs come with trade-offs:

• During a collapse, a speedbar should be released immediately, whereas a trim system cannot be adjusted in such short time. This makes asymmetric collapses with speedwings even more dangerous when trimmed with reduced angle of attack.
• Trim systems free the pilot from operating a speedbar with their legs. This allows the pilot to adopt a greater range of body positions.
• FLARE's combined system simplifies the brake and trim system by combining them. This makes the piloting very intuitive.
• FLARE's combined system greatly reduces the pilot's ability to control speed separately from pitch. This makes it more challenging to land precisely by shortening the flare with brake input.

Directional Control

When a pilot pulls the brake on one side, it creates an asymmetry in lift and drag forces that causes the glider to roll and turn:

1. The brake deflects the trailing edge down on that side of the wing. This increases the camber (curvature) of the aerofoil, which increases the lift generated on that side.
2. However, the lift force acts perpendicular to the wing surface. Since the wing tips are angled downward, the increased lift on the braked side generates a sideways force component pulling the wing in that direction.
3. This sideways force creates a rolling moment around the center of gravity (pilot's body) because it acts above the CG with a sizeable lever arm. The paraglider begins to roll toward the braked side.
4. The increased lift and drag on the braked side also create a yawing moment, causing the glider to yaw in the direction of the turn. This yaw helps to further establish the bank angle.
5. As the glider banks, the total lift force tilts in the direction of the turn. The sideways component of the tilted lift provides the centripetal force needed to make the glider follow a curved flight path.
6. The banked wing is like an "overloaded" wing - it needs to generate more lift to oppose the pilot's weight, so it flies at a higher airspeed and has a faster descent rate in the turn.

In summary, the initial rolling motion is caused by the sideways force from the asymmetric lift acting above the centre of gravity. The yaw rotation helps stabilize the bank angle, and the tilted lift force sustains the turn. The pilot's pendulum motion under the wing is a result of the turn, not the primary cause of it.