That incident is almost a qualifier for the Darwin Awards!! (see: http://www.darwinawards.com/)
ROSS ____________________________________________________________________________ _____________ At 11:12 PM 4/25/2016, you wrote: One should be careful on this matter. Please think again. I seem to recollect a case in America with an FRP sailplane years ago where the vents on the wing surface to the water tanks were taped over and a flight in wave conditions was undertaken. Also the tank outlets were closed and so the tanks were thus sealed . This did not present any problems on ascent to some serious altitude (something like 15 to 20,000 feet). On ascent the excess higher pressure in the tanks caused the tape at the vents to lift sufficient to bleed the air out of the tanks via the vents progressively. The problem came on long descent from high altitude where the air pressure differential at the vents pushed the tape hard to the surface and prevented partly or wholly the air flowing back into the tank. The result was that towards the end of the descent both wing tanks, leading edge to spar, collapsed due to the large and crushing pressure differential. Many sailplanes have wing undersurface tank outlets where a tapered plug sits into a tapered seat built into the wing shell. Higher interior air pressure as compared to exterior pressure, such as in the long descent situation above, will push the plug into the taper improving the seal. There is a good argument for duplicated vents to each tank with the vent outlets in different locations, given that a vent may become blocked say due to mud wasps. The vents are there for a reason, because venting unwanted pressure differential is good. Regards, Roger Druce On 23/04/2016 8:15 PM, Justin Couch wrote: On 23/04/2016 2:30 AM, Jim Staniforth wrote: Can a pilot tape over the dump holes to reduce noise, or is that a breach of contract? I'm pretty sure some tape over the holes would be fine - plenty of gliders with underwing dump valves have a little mylar or rubber flap over them for fairing purposes - our club DG1000 does. I've seen tape plenty of times over the Jantar dump outlet too for the same reason. I can't say for 100% coverage, but the flight manuals of gliders that I've read state that the tanks should be left open if flying without water. Obvious reason for this is to prevent the pressure change splitting the wing open at altitude. A bit of tape won't hold much pressure behind it so the manufacturers instructions are still being obeyed anyway. _______________________________________________ Aus-soaring mailing list [email protected] http://lists.base64.com.au/listinfo/aus-soaring Borgelt Instruments - design & manufacture of quality soaring instrumentation since 1978 www.borgeltinstruments.com <http://www.borgeltinstruments.com/> tel: 07 4635 5784 overseas: int+61-7-4635 5784 mob: 042835 5784 : int+61-42835 5784 P O Box 4607, Toowoomba East, QLD 4350, Australia
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