Wing Blowers
I’ve got a secret to share, it’ll make a lot of people happy and a handful of people, not so happy. Are you a glass glider owner (with tanks, not bladders) that is experiencing shrinkage of the spar? Are you seeing ripples or deformations in your wing profile? Some manufacturers are more prone to this or well known for it, fortunately, there’s a cheap fix that doesn’t include a full wing refinish – hence the handful of people not being so pleased about it, the glider workshops… The other people that will apply this little gliding secret, are the people like me, who like to split hairs and get every advantage that I can get my hands on. You might think it’ll do nothing, that it does nothing, but every little bit helps, and from my experience in Australia, this works.
Water Ballast
So what is the secret? Those who fly XC typically fill our gliders with water, it allows us to fly faster with the same sink rate, effectively shifting the polar curve of the glider to the right. What does this water do to the structure though? Nothing when it’s in the wings and you’re flying, but what about when you dump the water, pack up after flying and leave the glider for a few weeks before you’re able to glide again? The tanks remain ‘wet’, often the wing tank plugs are left in and all there is to vent out the moisture is the tiny vent holes produced by the manufacturer. I believe that the moisture (often many liters) that is left in the wing from the flight before, seeps into the structure somehow, along with the atmospheric heat of the day, causing the wings to deform ever so slightly. Not immediately, but over the course of a couple of years with some well-known manufacturers & over 10yrs with others, spar and wing root shrinkage soon appear. Extremely frustrating, considering that a refinish costs AU $1500 (USD $1000) per meter of wingspan!
Dry Water Tanks
Ok, here comes the secret, sorry for taking so long to get there! I have a friend here in Australia who was about to book his 18m glider (you know what type, I just don’t want to say it!) in for its third refinish to remove the spar bump. I suggested to him that he open his dump valves, then connect his glider up to a wing blower system, blow air through it 24/7 for a month, over the whole three months of the winter break if you can, then let me know the results. The call came through, “Woolley, it worked, the spar bump has disappeared and my profile looks true to the eye”!
Blower System
What’s the wing blower system? I use an Ozito wet/dry blower vacuum cleaner hooked up to a greywater pipe with a fitting to fit snuggly into my filler ports. The blowing rate should be close to 150kph to dry the wings out overnight (which I do after every flight), or for long-term blowing as suggested above can be around 115kph. I have a competition set up too, which is using a Ryobi one+ workshop blower, soon I’ll be converting to a high-powered 12v blower system so I can run it for longer.
I hope by reading this article, I’ve saved you USD $15,000 :D
Banner photo by John Absolon, 'Got that shot' Images
Adam Woolley was born into the gliding world, being the 3rd generation in his family. Going solo at 15, his thirst for efficiency in soaring flight & quest for a world championship title to his name has never wavered. One big passion is sharing his experiences & joy with other glider pilots all around the world. Adam is an airline pilot in Japan on the B767 & spends his off time chasing summer around the globe. He has now won 7 national Championships & represented Australia at 5 WGC's & 1 EGC.
