Powered Parachute Flying Handbook
 

Chapter 3 — Components and Systems

The Steering Bars

The steering bars are located just aft of the nosewheel and mounted on each side of the aircraft; they move forward and aft when the pilot applies foot pressure. [Figure 3-8] The steering lines from the trailing edge of the wing are attached to the outer ends of the steering bars. (Some manufacturers have developed a steering pedal system on their airframes, although the steering lines function in the same manner.) The main steering lines divide into various smaller lines, which attach to multiple points on the trialing edge of the wing. Pushing on either one of the steering bars causes the steering lines to pull down the corresponding surface of the trailing edge on the wing, creating drag. This in turn slows that side of the wing and banks the PPC into a turn.

Pushing both steering bars simultaneously causes the steering lines to pull down equally on the trailing edge, which causes two things to happen: it decreases the powered parachute’s forward speed by increasing the drag and it changes the shape of the wing, increasing angle of attack which increases lift. This procedure, called “flaring” or “braking the wing” allows the pilot to touch down at a slower rate of speed and descent, thus creating a smoother landing, which results in less wear and tear on the aircraft as a whole. [Figure 3-9]

Wings and Components

The powered parachute wing is unique, as compared to a fabric wing on an airplane, in that when it is not inflated it loses its ability to produce lift. When a powered parachute wing is inflated or pressurized, it becomes semi-rigid and is capable of producing lift and supporting a load. Rather than being bolted to the fuselage like an airplane, the parachute wing is attached to the cart by lines and cables which are known as risers.

The wings are manufactured by attaching an upper and lower section of skin to ribs. [Figure 3-10] The ribs of the wing determine the airfoil shape. [Figure 3-11] The shape of a powered parachute wing will change slightly when faced with different gross weights, air pressures, and environmental conditions such as moisture, air temperature and wind.

    

Different wing manufacturers use different fabric treatments to render the fabric airtight, so the air that enters the wing cannot escape through the fabric surface. The top surface of the wing is generally treated to help protect it from ultraviolet light and the elements. Keeping the powered parachute wing out of direct sunlight will increase its useful life.

If the fabric degrades and air is allowed to escape through pores of the cloth, the overall flight performance of the wing is greatly reduced. If your powered parachute wing should become too porous, more groundspeed may be needed to pressurize the wing, takeoff distance may increase, more RPM may be required to hold altitude, and fuel consumption may increase.

At first sight, the suspension lines on the powered parachute wing might appear like an unorganized wad of strings. On the contrary, each line has a distinct purpose and each line has distinct properties. The suspension lines are sometimes designated A through D and differ between manufacturers; check your POH to know the line labels for your PPC. [Figure 3-12] The front suspension lines are located at the leading edge and the steering lines connect to the trailing edge. The

suspension lines come together at a point where they connect with the riser. (The risers are the connection between the suspension lines and the cart.) Many manufacturers color-code the wing suspension lines to assist the pilot in their preflight inspection and layout of the wing prior to inflation. [Figure 3-12]

Suspension lines must be constructed of very strong materials, yet remain very small in profile to reduce parasite drag. The most commonly used materials are polyaramid and polyethelene, which are both carbon based.

Kevlar® is a common polyaramid used for suspension lines. Its properties render it extremely strong, as well as resistant to stretching or shrinking, and it is not susceptible to temperature changes. However, one critical drawback of polyaramids is that they tend to kink or knot when looped around. When polyaramids are used to construct suspension lines, they are encased in a skin of a terylene product, like Dacron® or a product with similar properties. Polyethelene materials, such as Spectra®, Dyneema® or Technora®, are very strong as well as more flexible than polyaramids, which makes them more durable under hard use. However, polyethelene materials are more likely to stretch or shrink, and they are more susceptible to temperature changes. If your wing is equipped with polyethelene suspension lines, it is imperative you do not store your equipment in a place that might experience extreme temperatures. The POH or owner manual provided by the chute manufacturer will specify limits for temperature and storage.

Every line on the powered parachute wing is precisely measured and fitted to a specific location. Therefore, it is imperative to inspect the wing during preflight, in addition to having the wing and its lines inspected periodically by qualified technicians. The technician will conduct strength tests as well as look for wear and compromised attachment points; refer to your wing manufacturer’s specifications for inspection parameters. Under no circumstances should powered parachute suspension lines be spliced or tied if severed! Each line’s length and strength is specifically calibrated. If you tie a knot in the line you will change the specifically-engineered flight characteristics of the wing, rendering it unairworthy.

 
 
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