Hang Gliding - FAQ - What's needed?
Serous maintenance for any hang glider should be done only by experienced HG shops and recognized experts in HG repair work. Here are a few notes on ways to improve and maintain your glider.
Basetube Safety Cable:
I mentioned a Basetube Safety Cable, earlier. If you ever find a hang glider without one, advise the owner of the glider to go here:
http://user.xmission.com/~red/BaseTubeCable.htm
It's an easy, invisible mod, and hopefully never needed, but it's not expensive. Unless the basetube is formed and solid composite, such as an airfoil basetube, I see no reason for a glider to lack this simple backup for the standard HG basetube. Any decent cable-maker tech can do the work for you, if needed. Wheels are great on any low-time pilot's glider, but wheels can put stress on a basetube, and that should be no cause to worry. The Basetube Safety Cable is important for any glider, and more so, if it has wheels.
A remedy for Sail Flutter:
Sometimes a glider develops a sail flutter between the
ribs, at the trailing edges. It may happen at slow airspeeds, or only at
higher airspeeds. A sail flutter is not dangeraous, but it can be more
than annoying. Sail futtering can even ruin the sail, at the trailing edge
of that panel. The sail there can become porous and soft, (like a bedsheet),
with no "calendar" stiffness left. Try this:
The local hobby shops can
sell you carbon fiber, pre-formed, as rigid blades or rods. The blades will be
rectangular, like miniature pine planks, in various widths. The rods may be
round or square. I like the round rods, here. Find (or make) a tiny hole near
the rib at one end of the trailing edge of the fluttering panel, Insert a CF
blade or rod through the trailing edge, between the sail layers. The CF stick
should be almost as long as the space between ribs there. If the hem is large
enough, a blade may fit between the sail layers, between the stitching and the
trailing edge fold. If the hem is too small for a blade there, insert a round
rod between the sail layers there, or in the space between the zig-zag stitch
holes. Use the largest rod that fits inside the stitching. You can slightly
taper one end of the CF sticks with fine sandpaper, to make installation easier.
CF is usually black or gray, but it will not be seen at all, once it is inside
the sail. A few hand stitches at the installation end of the CF rod, using
UV-proof upholstery thread and an ordinary sewing needle, will keep the CF in
place. Fabric shops sell upholstery thread, but ask for the outdoors variety.
zig-zag stitches- /\/\/\/\/\/\/\/\/\/<==========CF rod.
You
will need to take a little extra care when packing up the glider, with these new
stiffeners in the trailing edge. Still, that issue would be even
worse, if you would have added any extra "speed ribs" instead.
Sail Stitching:
In the normal wear-and-tear of everyday flying, sooner or later you will find some sail stitching has been damaged, during set-up or tear-down.
Rub the nearby stitching between two flat hands, above and below the sailcloth, to "inspect" the nearby stitching for damage. Sail stitches should not come apart under this inspection. Now twenty or thirty blown stitches here would be a serious cause for alarm, but a few bad stitches would be normal, and easy to fix. If a lot of stitching fails under the rubbing pressure of your two hands, something has gone very wrong here, and you will need some professional advice. A whole new sail may be needed, and if you can't get one for a good price, you may need to retire this glider, permanently.
It's a simple thing to fix some damaged stitches, but you want to do it correctly, so the problem stays fixed. Click on this link below, then hit the Refresh (or Reload) button, to get the latest version on that page.
http://user.xmission.com/~red/SailStitching.htm
Sail Cleaning:
Sailcloth may get dirty, but don't panic. Most stains and dust may look bad, but they really do not harm the structural strength of the sail. Do not weaken the sail material, just trying to make it look new again. You prefer that sailcloth to be strong, rather than pretty. Keeping a sail clean is a much better strategy than ever trying to clean it, later. Wingtip cover-bags are a great help in keeping a sail clean, during set-up and dis-assembly. An old pair of blue jeans will provide two good wingtip covers; just cut off each leg at the thigh, and sew the cuff closed. You needed a "new" pair of old cut-off jeans anyway, right? :-)
Water conservation is NO part of the following procedures. If you are not planning to use extravagant quantities of gently flowing water in the rinse process, it is probably better to fly with a dirty sail. Soap will become concentrated in a poorly rinsed sail, and may attack the fabric, or the stitching. Dampness, in the future, could renew that attack, so plan to rinse, rinse, and rinse again.
If you do decide on a sail-cleaning event, set the glider up in a shady place, with a good source of clean flowing water. The most harmful dirt (like sand or grit) can easily be hosed off, using a gentle, solid steam of water. The trick is to flow the water across the sailcloth, and not to point the water stream into the material. Flowing water carries dirt away; water impacting the surface just drives the dirt deeper. If all of the dirt is on one side of the cloth, you could use this "impact" technique to your advantage; wash only from the "clean" side; do this only if flowing water does not remove the dirt, first.
I do not recommend high-pressure sprays, as they might make the sail weaker, and more porous to the air. The only chemical "cleaner" that I like on sailcloth is Simple Green, and then only when diluted. This cleaner is for "spot-cleaning" the sail only, and you should immediately rinse this cleaner AWAY from the aluminum airframe. Do not get this cleaner (or most cleaners) on your aluminum, even as a mist. Remove the sail from the airframe (if you have experienced help for the project), if the dirt is where the aluminum is. Try various dilutions in easy stages, first 10% chemical cleaner with 90% water, then 25% cleaner, then 50%, et c. Use the weakest solution of cleaner that does the job. Apply the cleaner with a trigger-spray bottle, set for "spray" and not "stream". With water flowing across a problem area, use the softest-bristled of paint brushes (like a wide artist's brush) to coax out the dirt. Do not use sponges or wash cloths on the sail, if you can avoid it. They usually just smear the dirt around, cutting nearby undamaged sail fibers, and may drive the dirt deeper into the sail. On the most extreme dirt, such as black oil, try "Extreme Simple Green Motorsports Cleaner & Degreaser" (www.simplegreen.com). Use two very soft sponges, gently, one on each side of the material, and "scrub" very gently in tiny circular motions. Apply fresh cleaner often, and rinse the area clean with generously flowing water after each attempt. Wash the sponges vigorously after each attempt, so you do not compound the problem. You can not expect to get all possible dirt off a sail; just get it clean enough to live with, without degrading the material's structural strength.
Rinse the sail thoroughly and repeatedly, when you are satisfied with the cleaning process. Leave the glider set up in a shady, airy (but not breezy) place to dry completely. Make sure that the VG is fully relaxed, if your glider has a VG. Insert the ribs, but do not put the full rib tension on each rib. Put a heavy rubber band on the end of the rib, then stretch it through the sail tensioner, maybe making a few turns that way. Loop the free end of the rubber band back on to the end of the rib. You want the sail pulled smooth at each rib, to avoid wrinkles, but not at full sail tension. Leave all of the rubber bands in place, on each rib end, until the sail is fully dry.
You might wish to hurry the drying process. You can do that, to some extent, if you are careful. Do NOT use a commercial heat gun, anywhere on the glider. Those things get *far* too hot. A commercial heat gun can usually melt plumbing solder, and there is NO way to be "careful" with that much energy, near your sail. A hair dryer can get too hot, also. You CAN use the warm air exhaust, from an old vacuum cleaner, and that will be safe, for your tubing and your sail. The old vacuum hose will be full of dirt, so do not use that. You can usually find clear plastic hose (of the correct size) to fit the vacuum cleaner exhaust opening at home-improvement or hardware stores. This new, clean hose can be used to direct warm (not hot) air at structural junctions, sleeving, and hardware. If you remove the end caps from each end of the main airframe tubing, you can direct warm air from the vacuum cleaner through the length of each tube, to assist the drying process; ten or twenty minutes for each tube should be sufficient. Be sure that everything is completely dry, before you pack the glider for storage.
This last section is not very relevant to regular Hang Gliding these days, but if you are the rugged individualist
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