Newshound Posted May 9, 2012 Report Share Posted May 9, 2012 My ship has developed all of the sudden a loud whisling noise only when I am ascending, same with engine on or engine off in a strong thermal and at...More... Quote Link to comment Share on other sites More sharing options...
Newshound Posted May 9, 2012 Author Report Share Posted May 9, 2012 My ship has developed all of the sudden a loud whisling noise only when I am ascending, same with engine on or engine off in a strong thermal and at...More... Quote Link to comment Share on other sites More sharing options...
Thermalseeker Posted May 9, 2012 Report Share Posted May 9, 2012 In addition to the canopy seal, take a look at your wing root tape and also the alignment rivet on the wing hinge fairings. I've noticed mine whistles if I don't keep a piece of tape over the alignment rivet. It will also whistle if a tear develops in the tape along the wing root, particularly at the leading edge. It's kinda tricky to get the tape to wrap neatly up front at the leading edge-fuselage junction. So, I use 3 pieces of tape. One on top, one on bottom and a banana shaped curved piece about 5" long, cut from 2" tape, right at the leading edge. I do the same on the horizontal at the front where it meets the vertical. I had some vinyl circles made at the local sign shop that fit over the inspection covers to seal them up, and I tape up the wing fairings, too. FWIW, when I bought my Ximango the gear door alignment was terrible. The main gear door on the left side was down about 3/4" on the front side (effectively acting like a scoop) The first winter I had mine up on jacks for about a month, opening and closing the gear, reshaping and adjusting the doors and getting them to close and seal properly. I had a dang hurricane coming in through the center console until I fixed the doors. You can also do a "bellows" seal on the wing root rib where the aileron push-pull tube passes through to stop air infiltration. This type root rib seal is very common on racing sailplanes. We use parachute cloth for the seal. Contact me off list and I'll show you how we do it. I like Mike Bolus' "Maxi Tape" ( 614-783-6912 or usoar@juno.com for ordering) for wing root taping. It's stretchy, fairly easy to bend around corners and doesn't leave much adhesive. What adhesive it does leave will come off easily with a rag dampened with acetone. Tessa tape (available from Wings and Wheels, among others) is the preferred tape for safety taping Mylar. It's thinner, but doesn't stretch. Fine for straight application, but getting Tesa tape to bend around a curve is an exercise in futility.The canopy seal is a fairly easy fix. We see this fairly often on racing sailplanes, particularly in cold weather. We use sticky-backed open cell foam weatherstrip (1/4" works great). You can test the canopy seal by sticking a strip of paper on the joint and close the canopy. Pull on the strip. If it comes out easy, i.e., with no resistance, your canopy seal is probably leaking. You can repeat this around the perimeter of the canopy and find exactly where it's leaking, or you can just put it on the underside of the canopy rail (out of sight) all around for a quicker fix. Wipe the existing seal with denatured alcohol to remove wax/grease that might be on the seal so the foam will stick better. Be sure that you use open cell foam or your canopy might not close properly. I also use 1/4" open cell foam weatherstrip on my gear doors and fuel drain access doors to seal them up. The gray urethane stuff seems to handle the UV better than the tan stuff. Hope it helps!Regards,John LawtonWhitwell, TN (TN89)Ximango #135 Quote Link to comment Share on other sites More sharing options...
Thermalseeker Posted May 9, 2012 Report Share Posted May 9, 2012 In addition to the canopy seal, take a look at your wing root tape and also the alignment rivet on the wing hinge fairings. I've noticed mine whistles if I don't keep a piece of tape over the alignment rivet. It will also whistle if a tear develops in the tape along the wing root, particularly at the leading edge. It's kinda tricky to get the tape to wrap neatly up front at the leading edge-fuselage junction. So, I use 3 pieces of tape. One on top, one on bottom and a banana shaped curved piece about 5" long, cut from 2" tape, right at the leading edge. I do the same on the horizontal at the front where it meets the vertical. I had some vinyl circles made at the local sign shop that fit over the inspection covers to seal them up, and I tape up the wing fairings, too. FWIW, when I bought my Ximango the gear door alignment was terrible. The main gear door on the left side was down about 3/4" on the front side (effectively acting like a scoop) The first winter I had mine up on jacks for about a month, opening and closing the gear, reshaping and adjusting the doors and getting them to close and seal properly. I had a dang hurricane coming in through the center console until I fixed the doors. You can also do a "bellows" seal on the wing root rib where the aileron push-pull tube passes through to stop air infiltration. This type root rib seal is very common on racing sailplanes. We use parachute cloth for the seal. Contact me off list and I'll show you how we do it. I like Mike Bolus' "Maxi Tape" ( 614-783-6912 or usoar@juno.com for ordering) for wing root taping. It's stretchy, fairly easy to bend around corners and doesn't leave much adhesive. What adhesive it does leave will come off easily with a rag dampened with acetone. Tessa tape (available from Wings and Wheels, among others) is the preferred tape for safety taping Mylar. It's thinner, but doesn't stretch. Fine for straight application, but getting Tesa tape to bend around a curve is an exercise in futility.The canopy seal is a fairly easy fix. We see this fairly often on racing sailplanes, particularly in cold weather. We use sticky-backed open cell foam weatherstrip (1/4" works great). You can test the canopy seal by sticking a strip of paper on the joint and close the canopy. Pull on the strip. If it comes out easy, i.e., with no resistance, your canopy seal is probably leaking. You can repeat this around the perimeter of the canopy and find exactly where it's leaking, or you can just put it on the underside of the canopy rail (out of sight) all around for a quicker fix. Wipe the existing seal with denatured alcohol to remove wax/grease that might be on the seal so the foam will stick better. Be sure that you use open cell foam or your canopy might not close properly. I also use 1/4" open cell foam weatherstrip on my gear doors and fuel drain access doors to seal them up. The gray urethane stuff seems to handle the UV better than the tan stuff. Hope it helps!Regards,John LawtonWhitwell, TN (TN89)Ximango #135 Quote Link to comment Share on other sites More sharing options...
horst31 Posted May 10, 2012 Report Share Posted May 10, 2012 Thanks John, but why is there no noise when I am decending and why does it stop above 5000" MSL? Quote Link to comment Share on other sites More sharing options...
horst31 Posted May 10, 2012 Report Share Posted May 10, 2012 Thanks John, but why is there no noise when I am decending and why does it stop above 5000" MSL? Quote Link to comment Share on other sites More sharing options...
Thermalseeker Posted May 11, 2012 Report Share Posted May 11, 2012 Might be gremlins~ The altitude part is probably a density thing. As far as angle of attack, that's what made me think it was probably coming from the alignment rivets. There's all sorts of places on airplanes that can act like a whistle under certain conditions. The most common place we've seen to produce a whistle on gliders is the wing root seal and the canopy seal, but there are drain holes in the wings and fuselage that can whistle, as well as the gear doors, the wing hinge fairings, etc. Could be something to do with the way your spoilers close, or air whistling through the ailerons, too. I get a brief rattle coming from the floor area sometimes at about 80-85 kts when exiting wing overs. It's intermittent and I can't always get it to do it. I did about 15 wing overs yesterday at the end of my flight and it didn't rattle once. Last week it rattled on every wing over, though. I think it's the cowl flap rattling, but I can't reproduce the noise on the ground. The cowl flap closes good and tight. Doesn't do it when I'm cruising straight and level at 80-85 kts, though.I also am told my Ximango "howls" when l fly by the local hang gliding ramp in ridge lift. They say the noise sets off the coyotes and gets them howling. I can't hear it, though. I think it's the tail wheel or maybe something to do with the rudder where the rudder cables exit. Keep looking and eventually you'll find it.Regards,John Lawton Whitwell, TN (TN89)Ximango #135 Quote Link to comment Share on other sites More sharing options...
Thermalseeker Posted May 11, 2012 Report Share Posted May 11, 2012 Might be gremlins~ The altitude part is probably a density thing. As far as angle of attack, that's what made me think it was probably coming from the alignment rivets. There's all sorts of places on airplanes that can act like a whistle under certain conditions. The most common place we've seen to produce a whistle on gliders is the wing root seal and the canopy seal, but there are drain holes in the wings and fuselage that can whistle, as well as the gear doors, the wing hinge fairings, etc. Could be something to do with the way your spoilers close, or air whistling through the ailerons, too. I get a brief rattle coming from the floor area sometimes at about 80-85 kts when exiting wing overs. It's intermittent and I can't always get it to do it. I did about 15 wing overs yesterday at the end of my flight and it didn't rattle once. Last week it rattled on every wing over, though. I think it's the cowl flap rattling, but I can't reproduce the noise on the ground. The cowl flap closes good and tight. Doesn't do it when I'm cruising straight and level at 80-85 kts, though.I also am told my Ximango "howls" when l fly by the local hang gliding ramp in ridge lift. They say the noise sets off the coyotes and gets them howling. I can't hear it, though. I think it's the tail wheel or maybe something to do with the rudder where the rudder cables exit. Keep looking and eventually you'll find it.Regards,John Lawton Whitwell, TN (TN89)Ximango #135 Quote Link to comment Share on other sites More sharing options...
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