Repair of Dudek Nemo paraglider wing after a strike from the propeller

Hi there all,

We were feeling like shooting some photos today, so we got some great images of our careful attention to fiber alignment.  I've been meaning to shoot this for years, but only recently did my brother-in-law give me the gadget that does macro so well.  While we repair these sensitive paragliding wings we all love, we see a lot of fine details.  I have long felt that looking closely at ripped edges is a fascinating education on the forensics of fabric failure.  We can almost always tell how and where the failure started.  Sometimes you can even see oxidation on the ends of fibers which tells you they were damaged before the current failure, like rust on a dent in a car panel.

Here we see a Dudek Nemo paraglider that was hit by the propeller.  We see and repair this a lot, and we take great care that the shape is undisturbed, and the restoration is total.

Above we see the rather brutal prop strike that ripped the fabric across two cells.

This is the part that even after all the years of sewing, we still find pleasing to do.  We talk elsewhere on our site about fiber-for-fiber alignment for our fabric wing repairs, and this is what we mean here.  Every part of a rip in fabric has a unique key that you can plainly see.  If you look carefully enough, and you have the patients to pay attention, the edges can be aligned within less than 1 mm .  For us, that is still a bit of fun, and it makes for results as near to perfect as we can figure.

The grid pattern of the "ripstop cloth" in these shots is 4mm square.  The individual fibers fit into the ridge of a fingerprint.  This rip was a particularly good example of the "keying" that happens when fabric of this type fails.

These after shots are here on our studio floor at WindFire Designs.  We will try to get some shots of this wing when it's back in the sky.

The shot below shows our repair as it meets a main seam between paraglider wing cells.  This repair was done internally, so the pressure in the cell pushes against the patch in the correct direction. It also means the cosmetics of the wing are impacted very little.  It has the advantage that the edges of the patch won't be exposed to snagging on objects that might lift up the edge and start collecting debris.  Our stitching is the triple-step zigzag.  If one were to cheat here, and jump the patch over the seam, it wouldn't look nearly so nice, and it would change how the fabric acts at that seam.  We like rebuilding the seams just the way the factory does.

paraglider repair

Since we started doing kite repair we've also been getting a fair few paraglider repairs in. Now we do paraglider repair officially. Here is a pro designs wing with a lot of damage to a few cells. Most of the repairs can be completed internally. We used a very clever method to repair these right against the seams without having to disassemble the fabric. This preserves factory alignment and strength.

Another powered paraglider repair

Recently we've been doing quite a few paraglider repairs. This one is a Dudek 27 meter. Apparently it was damaged because of the motor and prop. One cell needed to be completely rebuilt. All of our work was done internally so there was almost no change to the color of the wing.

Paraglider Repair - keep track of the dribs!

This nice looking wing is a Mac Para Eden 3 Paraglider. This one was sent to us by a long-time kite repair customer of ours, Brian Haupt. Thanks Brian. The cells had pesky damage on the lower skin that also effected the bridle attachment point. This first shot shows some of the damage and the disassembly that was necessary to properly repair this area. In my opinion, this wing is very nicely made. The blue tape in this shot is my way of keeping every stitch hole lined up on the dribs, the bridle point, and the rib they attach to while the skins are being healed up and repaired.

Below you can see the spread of the damage over several cells. It seemed that the wing smeared across a blunt object to cause these small and distributed lacerations.


I also noticed that there are two thread gauges used to make this wing. Of course they were easy to match, but it was interesting to see where the factory decided to use each gauge. Smaller gauge thread seems to lay a bit smoother in the final seam and it also makes your bobbins last longer between refills. Larger gauge thread doesn't always mean the stitch is stronger. If you sew onto an area that can keep up with the strength of the larger thread then it might be a good choice. But on thin cloth, large thread displaces the fibers of the cloth more drastically with larger holes and thus makes it weaker. This factory was smart, as you have to be when a life hangs from your wing.

I have done a lot of work with ram-air foils. I have designed and built them, three sizes in total. I have also taken one of my favorite buggy kites [the quadrifoil competition C2] completely apart, stitch by stitch, to see what made it tick. Recently we've been repairing paragliders here. They are very complex wings internally. Not only do they have dribs, but they are also tediously built with small details all over that are not to be taken for granted. I always imagine the people sewing them from scratch. Like anything that is sewn, if you look closely you can see the human behind the machine. Paragliders are reasonably easy to work on, as long as you pay absolute attention to detail. These wings are a product of many many design decisions and there are no accidents in the way they are built.