Dear Gary and Peter.
All of the early GRP sailplanes were built using balsa as meat in the sandwich. The penny should have dropped, when the balsa sheets began to show during winter, that the structure was not water proof and the balsa was not hermitically sealed. When water ballast was used in these sailplanes it was contained in bags – with the exception of the Cirrus – that were made from waterproof material that could not be securely bonded. My LS3 was delivered with bags made from plastic shower curtain material. Those bags were replaced – at minimal cost by LS. They were made from sheets of fabric re-enforced rubber which had vulcanised seams which never failed but after about three years during a form2 inspection when laid out on the lawn applying the pressure they resembled monstrous soaker hoses. The internal rubber had perished. The next bags “Guaranteed not to leak” didn’t even get into the wings. They leaked more than the previous ones. The last pair I fitted were made by Clipper Plastics. They were much better made and welded. I sold Vixen to TC. How did they stand up Terry? While the use of water ballast can cause serious issues sometimes it creates humorous events. Some years ago – at the Mildura Mini Comps – TT arrived with his crew and newly purchased Kestrel XC. Mildura had no running water and a tanker supplied water for the competitors who filled up their 25l containers from it and then ballasted their sailplanes before briefing was held and because they were so heavy generally put a tip on the ground held down by a tyre. After briefing the TT team headed off to tow XC to the launch point. TT driving the ute, XC on tow and Fairlie on his tip. As the tow rope became taught TT noticed Fairlie trying to lift Charlies tip. Now Fairlie – in her prime – could lift and carry a small horse but try as she could, the tip of Charlie would not leave the ground. In a fit of ‘something’ TT leapt out of the ute and threw himself across the top wing tip. His weight nearly bent Charlies tip to the ground before their combined effort raised his stbd. wing so he rotated around his wheel and the port tip impacted with the ground. The shock of that was sufficient to flick Fairlie off and she landed flat on her back – seriously winded – near the edge of the scrub. The arrival of Charlies port wing on the also ground resulted in another remarkable spectacle. As TT lay across Charlies tip an audible rumble was heard which increased in intensity and then a cylinder of water appeared from Charlies stbd. wing bag hole and erupted into his luggage locker, then into his cockpit until it was entirely filled. A lot of truly remarkable events occurred at the Mini Comps. A lot more available. How to derig a Nimbus with full ballast. Stealing a tug. Aero tow retrieves, six-shooter ants etc.. Do you want to read about them? Regards Noel. From: Gary Stevenson [ <mailto:[email protected]> mailto:[email protected]] Sent: Tuesday, August 29, 2017 9:35 PM To: 'Peter Champness' Cc: 'Gliding Australia Forum' Subject: [gfaforum] RE: Water bags and GFA forum Hi Peter, ‘Fraid I can’t help you with you perceived communication problem. I have received your general posts quite OK in the past. Tim Shirley is the GFA IT manager. Re gliders with tanks as opposed to bags, NR has given you the answer in a nutshell, buy please see my comment below about bags. Bags can perish and let go inside the wing too! Regardless, In both cases the ballast system must be checked for integrity, at each Form 2 inspection, and if the system does not pass the test – there will be a leak, as shown by failure of a pressure test - then it is a matter of determining the location of the leak, and fixing it – for integral tanks this could in many cases prove to be very difficult – or simply not flying with water. Noel mentioned foam, but some early gliders used balsa (eg Libelle), but regardless, ingress of water into this core part of the structure is not good, and the end result is exactly the same. In the case of the Libelle, at survey (as opposed to annual), inspection, a 50 m diameter core is cut from a specified location in the underside of the wing and examined. Then regardless of the inspection outcome, a repair must be done to fix the hole. In passing, I need to add here that Libelle’s use bags. What is interesting with the Libelle, is the question of where the NEXT hole should be cut, say 1000 hours down the track, at the following survey. I suggest that for obvious (to me), reasons this next core should be taken from a (slightly??), different location, but this is NOT specified. Would maintenance guru’s like to make comment here? Regards, Gary From: Peter Champness [ <mailto:[email protected]> mailto:[email protected]] Sent: Tuesday, 29 August 2017 8:38 PM To: Gary Stevenson Subject: Water bags and GFA forum Gary, Can you help here? It seems that I can receive some the Aus Soaring emails but I am not able post to the group. Who should I talk to? Also do you know why most the gliders without waterbags are now banned from carrying water? Thanks Peter Champness <http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=emailclient> Image removed by sender. Virus-free. <http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=emailclient> www.avg.com -- You received this message because you are subscribed to the Google Groups "Gliding Australia Forum" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. 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