“Adam Van Renssen is a highly qualified, and very capable Aeronautical Engineer who finished top of his class at the University of Pretoria. His frustration with the current testing and repair methods have lead him to design, develop and custom build a unique system to measure lines within a 0.8mm tolerance. His work speaks volumes, and as one watches the process unfold it is akin to watching a master musician. He is able to “see the numbers” and knows almost immediately what the profile of the wing is from looking at the numbers.
I am constantly in awe of his technical genius and am exceptionally proud to have him as partner in Attitude4Altitude. This division of our business has opened my eyes to so much. Suddenly the numbers mean something, truth is the modern wings we fly become out of trim after a certain number of hours. I am old school, we never really tested much until something “felt wrong” – nowadays paragliders have to be trimmed after their first settling 25hrs to 40hrs and then again at least every 100hrs.” – Tracey King (Chief Instructor)
SAHPA regulations recommended that a paraglider is inspected annually, or as per manufacturers’ recommendation, to ensure your aircraft – on which your life depends – remains in an airworthy state.
There are so many wings in the market that are not tested before they are sold. This is a uniquely South African state of affairs. In Europe, the seller is obliged to have the wing tested and certified safe for use before selling it. Most wings on the overseas market are sold with a recent (within a couple of months) test report. When considering purchasing a new wing, please make sure that you are fully aware of the condition of the paraglider, a maintenance inspection is a good way to determine the condition of the wing and suggest what type of life the paraglider might have had prior to purchase.
You can expect to receive a full test report, for future reference, on Glider Inspection and Trim work completed.
Glider Inspection and Porosity Check
Your paraglider is firstly inspected for any defects, damage to the risers, lines, pulleys, canopy fabric and stitching. Defects are noted and addressed.
The air permeability, or porosity, is measured next. This is a measure of how much air can bleed through the fabric of your paraglider, potentially affecting the airflow over the wing. High porosity can cause inflation difficulties on launch or after a deflation, and can even cause the paraglider to enter a parachutal stall.
Your paraglider’s porosity is measured on five places on both the top and bottom surfaces, to ensure the whole wing is in airworthy condition.
We use the latest JDC MK 2 porosity meter. The JCD porosity meters are the most accurate and most frequently used porosity meter in the paragliding industry.
BOOKING Lead Time: 2 weeks. Turn Around Time: 1 week
The JDC MK 2 measures the time necessary for 0.25 litres of air under 4hPa pressure to go through 38.5 cm2 of cloth. The glider’s canopy is measured for porosity in several different areas of the top and bottom surface.
We provide 5 measurements on the top surface and 5 on the under-surface. The measurements are made 20 – 30 cm inboard from the leading edge in the approximate positions indicated in the diagram. The lowest accepted average value for the top and bottom surface is 10-15 seconds as recorded by a JDC porosity meter.
Using the industry standard formula, see the table used to interpret the results, the wing was found to be in: “See Highlighted Cell” in Yellow Formula —> 5400 / time in seconds displayed on the MK2.
Glider Trimming
Paraglider lines change dimensions over time due to a number of reasons, including age, load, flying style, materials that it is made of, heat, UV, etc.
This causes the airfoil shape of the paraglider to deform, or go out of trim. An out of trim paraglider can potentially stop performing according to its test specifications and may have adverse behavior in collapse recovery.
An out of trim glider will also handle differently, and performance will also be inhibited.
With a re-trim, your glider is measured using state-of-the-art laser telemetry equipment with very fine tolerances to accurately determine the line lengths. Using sophisticated software the trim state of your glider is determined and line length changes required are calculated to bring your glider back into trim, as per EN 926 standards.
The glider is then re-trimmed and remeasured to ensure that it is within tolerance of the EN standards, and that performance of your wing is restored to its factory setting.
