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#1
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Howling noise from nose vent
I have a Grob 102 and it's making a very loud noise when flying fast
with the nose vent closed down. The noise comes from the nose area and goes away when I open the vent. I would like to be able to close the vent sometimes, because it gets cold :-) Any ideas what might be happening ? It didn't always do this. Todd Smith 3S |
#2
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Howling noise from nose vent
On Feb 20, 7:17*am, toad wrote:
I have a Grob 102 and it's making a very loud noise when flying fast with the nose vent closed down. *The noise comes from the nose area and goes away when I open the vent. I would like to be able to close the vent sometimes, because it gets cold :-) Any ideas what might be happening ? * It didn't always do this. Todd Smith 3S I had a similar problem with my canopy not sealing up front. I added foam weather-stripping and the problem went away. Nice and quiet now. |
#3
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Howling noise from nose vent
Probably what's happening is that the weather sealing around the vent
flap has failed, leaving a small gap when the vent is closed. Have you checked the sealing of the vent when it's closed? -John On Feb 20, 8:17 am, toad wrote: I have a Grob 102 and it's making a very loud noise when flying fast with the nose vent closed down. The noise comes from the nose area and goes away when I open the vent. I would like to be able to close the vent sometimes, because it gets cold :-) Any ideas what might be happening ? It didn't always do this. Todd Smith 3S |
#4
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Howling noise from nose vent
On Feb 20, 8:35*am, jcarlyle wrote:
Probably what's happening is that the weather sealing around the vent flap has failed, leaving a small gap when the vent is closed. Have you checked the sealing of the vent when it's closed? -John I'll check that seal if I can. I'm going to try an re-create the issue on the ground with a shop vac or leaf blower. Of course I might not be able to hear the vent noise over the motor then :-) It's not the canopy seal. That used to whistle right by my ear until I replaced the seal and added foam. Thanks Todd |
#6
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Howling noise from nose vent
On Feb 20, 6:26*pm, Eric Greenwell wrote:
wrote: On Feb 20, 8:35 am, jcarlyle wrote: Probably what's happening is that the weather sealing around the vent flap has failed, leaving a small gap when the vent is closed. Have you checked the sealing of the vent when it's closed? -John I'll check that seal if I can. *I'm going to try an re-create the issue on the ground with a shop vac or leaf blower. *Of course I might not be able to hear the vent noise over the motor then :-) It's not the canopy seal. *That used to whistle right by my ear until I replaced the seal and added foam. Be really careful with blowers if the pitot is in the nose and will see the blower pressure. -- Eric Greenwell - Washington State, USA * Change "netto" to "net" to email me directly * Updated! "Transponders in Sailplanes"http://tinyurl.com/y739x4 * * * New Jan '08 - sections on Mode S, TPAS, ADS-B, Flarm, more * "A Guide to Self-launching Sailplane Operation" atwww.motorglider.org Thanks for the warning, I had not though of it, but I do think that the pitot in my Grob is from the tail probe. I'll make sure before I power up the blower. My goal would be about a 120 knot flight pressure anyway, but might not have the ability to fine tune the blower. Thanks Todd 3S |
#7
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Howling noise from nose vent
On Feb 20, 10:36*am, wrote:
On Feb 20, 8:35*am, jcarlyle wrote: Probably what's happening is that the weather sealing around the vent flap has failed, leaving a small gap when the vent is closed. Have you checked the sealing of the vent when it's closed? -John I'll check that seal if I can. *I'm going to try an re-create the issue on the ground with a shop vac or leaf blower. *Of course I might not be able to hear the vent noise over the motor then :-) It's not the canopy seal. *That used to whistle right by my ear until I replaced the seal and added foam. Thanks Todd Todd, When I had my problem, it was the same symptom as yours. When I opened my vent, the howling noise subsided. When closed, it came back...loud! Once I sealed the canopy up front, the noise went away and the vent no longer had any effect (other than the minimal noise from the incoming air). The only thing I could come up with to explain this is the vent was having some effect on the pressure differential between inside and outside of the cockpit. Although I could be wrong on that. All I know is sealing the canopy fixed the problem. Dave |
#8
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Howling noise from nose vent
On Feb 20, 5:17*am, toad wrote:
I have a Grob 102 and it's making a very loud noise when flying fast with the nose vent closed down. *The noise comes from the nose area and goes away when I open the vent. I would like to be able to close the vent sometimes, because it gets cold :-) Any ideas what might be happening ? * It didn't always do this. Todd Smith 3S Todd, Put a bunch of drinking straws 3" to 4" in length fill the hole in the vent from the rear. That solved the problem for me in a ventus b Richard www.craggyaero.com |
#9
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Howling noise from nose vent
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#10
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Howling noise from nose vent
The only thing I could come up with to explain this is the vent
was having some effect on the pressure differential between inside and outside of the cockpit. Although I could be wrong on that. All I know is sealing the canopy fixed the problem. Sounds like your letting more air in than your allowing to exit. Many ships have this problem and need a bigger air exit hole in the rear which should be 1.5 X the entry vent size. One way to check this situation is with your altimeter NOT hooked to the static system, the altimeter reading will change slightly as the vent is opened and closed. I have been able to find the bad area on a noisy canopy by pulling down on the frame in several locations while in flight. When back on the ground check all around the canopy with a feeler guage (strip of paper works) the feeler guage will move freely in the bad area. Hope this helps, JJ |
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