Powered Parachutes - Risers

History of PPC Risers

Early Powered Parachute (PPC) manufacturers used cable systems to attach ram air parachutes to the outriggers on their vehicles. These cables were very heavy and bulky. Typically they consisted of two (2) main cables (left and right) thimbles at each end, two (2) safety cables (left and right) with thimbles at each end, four (4) Maillion #6 rapide links (one at the parachute end of each cable), and two (2) upper steering line guide rings connecting both the main and safety cable links. The parachute wing connector links
attached to both the main and safety links. This
heavy grouping of metal at the ends of the cables was analogous to tying rock on the end of a string.

Several problems emerged with cable riser clusters of metal. The heavy weight of the cable cluster needed to be lifted by the inflating parachute wing. As the cables rise, they would scratch or gouge the vehicle. The vehicle ends of the cables would twist in place causing excessive wear to the thimble. Sometimes links connecting the forward and aft cables would tangle with the suspension lines during initial inflation causing lower suspension line damage (and aborted take-offs).

Steering lines were often routed through a ring that connected to the rapide links from the main and safety cables. This connection restricted guide ring movement, adding to lower steering line abrasion. The guide ring, due to it's diameter and the angle at which the steering line threads through it, caused significant wear and additional steering (foot) pressure. Lower steering lines were wearing out quickly at the guide ring location. A better method of connecting the wing and the vehicle was desperately needed.

In 1998, Bill Gargano introduced webbing risers. The design was based on risers used for heavy military applications. This design helped eliminate many of the problems experienced with cables. The webbing reduced excessive gouging and scratching on the frame. Pulleys used to route the steering line, minimized wear from friction. The simplicity of the design reduced the risk of lines tangling in cable clusters during inflation.

Webbing risers are now used on most major manufacturer's vehicles. Webbing risers are built for specific wings on specific vehicles so be sure that you are using the correct risers for your vehicle/wing combination.

The evolution of webbing risers has continued. We are now producing risers with special stiffeners reducing the chance of prop strikes, Bridge Risers for 4 point attachment vehicles, a variety of pulley configurations, torque compensation adjustments and parachute attachment legs.

Technical Information

Riser webbing was chosen for its strength and moderate elongation.

The 6000-pound webbing is white or light in color and covered with darker material to minimize dirt abrasion and UV degradation. Damage is easy to identify since the light webbing can be seen through the darker outer sheath. (If you see a light color through a burn or tear in the outer protective cover, don't fly.)

The forward (main) and aft (safety) legs of the riser are built separately then joined down the middle. Joining the risers for most of there length allows the two risers to act as one with the combined load sharing strength of 12,000 pounds. At the parachute end, each connector link has its own riser loop for attachment. These separate attachment loops minimize link to link wear and provide a direct path for the load from each link to and through the riser to the vehicle.

The steering guide pulleys are mounted on short, flexible loops and positioned for specific vehicles. The pulleys are designed to allow the 5mm lower steering line cord to move freely, thereby reducing both wear and foot (steering) pressure.

Our risers come with clear vinyl tubing on the vehicle attachment ends. This tubing is to be slid over the link/eye bolt/riser junction to hold the link in position, to help prevent the barrel from loosening and to reduce wear to the riser. Additionally, our parachute wings come with surgical tubing on each connector link. This tubing is to be slid down over the link once attached to the riser. This tubing maintains the position of the lines (keeps them from sliding around the link and over the barrel), holds the orientation of the link to the riser and helps prevent the barrel of the link from loosening.

FAQ

Q: Are Webbing Risers strong?

A: Most stainless steel cables used for risers are rated 4,000 pounds when new. Each leg of the webbing is rated at 6,000 pounds. Since each side has 2 legs sewn together, you have 12,000 pounds per side or 24,000 pounds total strength. That far exceeds the connector link.

The structural integrity is further maintained by the use of proper strength thread, proper stitch pattern and use of a protective cover.

Q: How were the Webbing Risers Tested?

We performed a number of pull tests at 3 different testing facilities. Risers were pulled one leg at a time and the bottom of the main and the top of the safety.

This assured that in the unlikely event of one riser breaking the remaining riser will carry the load.

Q: Will the curve from the Maillion rapide link connector damage the webbing when under load?

A: All strength tests were performed pulling from the maillion rapide link since this best simulated the true application. When testing to destruction the connector link attachment points remained undamaged.

Q: How Do you Inspect Risers?

A: Each riser has a protective outer sheath. You should preflight your risers by feeling for stiffness due to excessive heat and looking for wear and tear on the outer sheath. Pay attention to the pulleys and make sure they rotate smoothly.

If you see the contrasting color of the light colored webbing you need to take a closer look. Try to slide the outer sheath up and down to look for discoloration, broken fibers or stiffness.

If you do see damage you need to investigate the cause.

Q: Can I use the same risers on different vehicles?

A: The distance between the hard point attachments on outriggers changes with each vehicle and the CG tube setting. In addition, different vehicles attach the risers at different angles. Risers can be interchanged on vehicles with matching attachment structures if they are within the proper tolerance for the distance between the hard point attachments.

Q: What is the difference between Nylon and Kevlar risers?

A: Nylon risers provide the elasticity we enjoy to dampen turbulence and soften inflation. Kevlar has very little elasticity but it is lighter given the same strength. Kevlar is extremely susceptible to UV degradation and dirt abrasion. These risers cannot be easily inspected for fiber damage so should be changed every 3 years or 300 hours.

Q: What is the "down side" of webbing risers?

A: Webbing risers are more susceptible to heat damage than cables.

Q: When do Webbing Risers need to be replaced?

A: If the risers do not show any obvious damage they should last 5 years or 500 flying hours.