Powered Parachutes - Articles - Misconceptions about PPC Wings
by Betty Pfeiffer and Bill Gargano

There is much misinformation going around the powered parachute community. Some of this information is extremely dangerous to both novice and advanced PPC pilots. The purpose of this article is to dispel the most dangerous myths and provide a foundation for a more educated understanding of this wonderful form or aviation.

Fallacy: Powered Parachutes cannot stall.

Background: It is very difficult to stall a current generation powered parachute especially if it is being flown in calm conditions.

Truth: Anything that flies, given the right conditions, can stall. Problems with incorrect rigging or use of steering lines, getting caught in inappropriate weather conditions or turbulence can exasperate a small problem and push you to a stall.

Powered parachute designs trying to maximize the performance can get caught going just over the edge and experiencing stalls that can’t recover. This can happen while in a climb while initiating a gentle turn.

Fallacy: Wings will maintain their performance for the life of the vehicle.

Truth: As you fly your powered parachute, the material in the wing stretches. With some materials this can cause an increase in permeability over time. When the material becomes highly permeable it can cause problems with inflation and increase your rate of descent. The Ultra Violet (UV) exposure of the parachute to the sun will adversely affect the strength of both the parachute and the lines. Obviously we see the upper surface most affected by the UV exposure.

Dirt, stones or other debris trapped inside the parachute cells will adversely affect the longevity of your wing.

Parachute lines over time and use will stretch and wear out. This effects the manufactured suspension line trim/flight angle of your parachute and therefore the flight performance.

Your vehicle will likely outlive the service life of your wing. Depending on the materials used and your flying conditions, you can expect your parachute to last anywhere from 150 to 2000 hours. Consult your manufacturer for details.

Fallacy: Anyone can safely fly a Powered Parachute

Truth: To fly safely you must have a basic understanding of flight and micro-meteorology, adequate reaction times, altitude awareness, a level headed approach, and the ability to make good decisions. Physically you must have control of the vehicle. Anyone who experiences panic reactions should not fly.

Fallacy: All powered parachute wings of the equal size perform the same.

Truth: With the use of CAD programs, high tech fabrics, high tech materials and better testing equipment, parachute designers have been able to shape their wings to take advantage of desired performance requirements. This has given parachute designers more leeway in developing the characteristics they like into the wing.

Two wings, both with 500 square feet, can be designed in different ways to optimize different flight characteristics.

Each design decision is a trade-off. If you want a better climb you will sacrifice a higher speed range. If you want a better gliding parachute, you may sacrifice quick turn response. Anyone claiming to "have the best of everything" is not objectively viewing their product.

Fallacy: Most repairs on the wing can be done at home.

Truth: Although many temporary field repairs can be done at home, they may end up in ultimately intensifying the damage.

For example: You have a hole in your parachute and chose to patch it with sticky back tape. In time, dirt works into the edges of the patch. The dirt causes abrasion on the material and you end up with a hole in your parachute the size of your patch.

Or

You sew a patch onto the parachute with your home machine. If the stitches are too small you will weaken the fabric around the patch. If you use cotton thread, the thread may not be strong enough for the loads required in that area of the parachute and the thread will break, or the thread will suffer the effects of mildew.

Or

You over sew the patch and go into the parachute fabric. This is in an area of high stress. The stitching under tension caused a small hole in the fabric. The small hole starts to tear. The tear turns into a rip.

Bottom line: It is far safer to leave repairs up to the professionals.

Fallacy: If the manufacturer repairs your PPC everything will be perfect.

Truth: Manufacturers are people and people sometimes make mistakes. As a pilot it is your responsibility to double check all work done on your PPC. You are your own final inspector.

Fallacy: You can interchange powered parachute wings with vehicles from a different manufacturer.

Truth: Factors that affect the shape and performance of your parachute include the distance between your hard point connections on your vehicle frame, the length of your cables or webbing risers, the amount of stroke available on your foot pedals, the length of steering line needed.

Differences in any of these measurements will affect the shape and performance of the wing. Interchanging wings built for different vehicles can put you in a very unpleasant compromising position. Note: Some vehicles from the same manufacturer can have different measurements. You need to consult the manufacturer on the interchangeability of wings.

Fallacy: You can always use your same wing for solo and Tandem flight.

Truth: Safe flight is directly related to wing loading and density altitude. If you are too light on a vehicle you can be bounced around even in mild turbulence. If you are too heavy on a wing, your take off distance, climb rate and landing distance will be adversely affected. If you are way too heavy on a wing, the safety margin for structural integrity of the parachute may be in question.

Fallacy: PPC are completely safe because you are always under a parachute.

Truth: A PPC wing is a NON-RIGID wing made of soft fabric, tapes and suspension line. The wing is affected by moving air. From the time you inflate it, until you deflate it, your PPC wing is always in a state of flux. The parachute shape thus can change and become unpredictable.

Fallacy: Emergency reserve parachutes for PPC systems are a good idea.

Truth: There are many problems with the use of an emergency reserve parachute with a PPC. The most compelling issue is this: Once you have deployed your emergency parachute what happens to your wing?

We have learned from the paragliding industry that once a round emergency parachute is deployed the paraglider will often reinflate. At that point the pilot is essentially under two parachutes. The square "parachute" wants to fly in front of the suspended weight while the round parachute needs to drag behind the suspended weight.

The pilot must look at the relationship between the parachutes to decide the appropriate response. Often the paraglider will down plane i.e. fly in front and below the pilot. In this situation the pilot must disable the paraglider.

In a powered parachute we have additional considerations. What if the prop will not turn off? How will the pilot disable the PPC? If you will compress your vertebrae by landing in a seated position at 16 feet per second, how large must the parachute be to descend slow enough? Where should the parachute be attached to the vehicle to assure a favorable impact position? What are the entanglement issues?

Most PPC accidents happen very close to the ground. Most problems are a result of hitting power lines, fences or other obstacles.

Fallacy: One wing is good for all wind conditions.

Truth: Stronger wind conditions, i.e.: 10 mph plus, will have a greater negative affect on a lighter system than a heavier one. What we are really talking about here is wing loading. A lighter pilot will have a lower wind limit than a heavier pilot, because the heavier pilot has additional wing loading to help penetrate the wind. The lighter pilot is more easily pushed around by the wind.

Fallacy: If a line breaks just tie it together.

Truth:

Fallacy: If a line breaks just tie it together.

Truth: All of the suspension lines on your PPC wing are specific lengths. Changes in these lengths greater than one inch will adversely affect flight performance. Tying even one line together can alter the designed flight trim of your wing to a trim that will not work in all flight modes. This is dangerous.

Knotting anything significantly reduces it’s strength by 45 to 60 percent.

Fallacy: The old wings are as good as the new wings.

Truth: Most of the older wings were designed for speed. Most contemporary wings have been designed for lift. All older wings used materials that wear and degrade faster than contemporary materials.

Fallacy: Suspension lines will never change their length.

Truth: Every time you fly your PPC, the wing is loaded. The load is not constant. There are peak loads during inflation, dynamic maneuvers, and recoveries from maneuvers. This load is transferred to the vehicle through the suspension lines. The suspension lines carry the load from all portions of the wing, but the wing is not evenly loaded. Some lines carry more load more often then others. Those lines will stretch over use and thereby change the designed flight trim angle and performance. A PPC wing in this condition should have the lines adjusted by the manufacturer.

Fallacy: Connector links never need replacing.

Truth: Connector links distort from use, the barrels become tight. Over-tightening can cause microscopic cracks.

Fallacy: Seat belts never need inspecting.

Truth: The Seatbelt is the only thing holding you to the vehicle. UV damage, nicks, scraps, wear and tear, all contribute to degrading the seatbelt(s). Hardware damage caused by dragging it on the ground compounds webbing abuse.

Fallacy: You can safely take off cross wind because you have a motor.

Truth: The vehicle and the parachute do not become a system until you are airborne. A vehicle on the ground only dominates the direction of the cart. As the wing inflates it wants to go downwind and take the cart with it.

Fallacy: Trim tabs are meant to trim your wing.

Truth: The word trim has many meanings in Powered Parachuting. It can mean the default flight mode dependant on how you secured your steering lines, the cross-country in-flight adjustment tab, or the flight angle designed into the parachute.

The biggest Fallacy of all: Powered Parachutes are absolutely safe.

Background: Powered Parachutes have enjoyed a tremendous safety record due to a relatively short history and a lot of luck.

Truth: Every form of aviation is dangerous. A lack of understanding of weather conditions, parachute and vehicle maintenance, ground obstacles, and the pilot’s mental and physical conditions can increase the risk of something going wrong.

Powered Parachutes have their own unique dangers including exposed propellers, limited safe flying conditions, limited seat belt/chest strap arrangements in the event of a roll over, extreme parachute sensitivity to cross winds and gusts on takeoff and landing, and a very short training period for new pilots.

Powered Parachuting offers a fun easy way to enjoy flight but is not without risk. We have touched upon a few of the most dangerous myths in this article. We hope that this article stimulates thoughts and conversations that promote safer and more educated power parachte pilots.

Fly Safely,
Betty Pfeiffer Bill Gargano
High Energy Sports, Inc. Quantum Parachutes Inc.

Bill Gargano is one of the leading Powered Parachute designers in the field. He has been working with powered parachutes since the early 1980’s.

Betty Pfeiffer has been building hang gliding harnesses and parachutes for hang gliding and paragliding since 1982. During the past year she has become intimately involved with powered parachute wings and powered parachute safety.