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Howling noise from nose vent



 
 
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  #1  
Old February 20th 09, 02:17 PM posted to rec.aviation.soaring
toad
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Posts: 229
Default 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  
Old February 20th 09, 02:29 PM posted to rec.aviation.soaring
[email protected]
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Posts: 154
Default 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  
Old February 20th 09, 02:35 PM posted to rec.aviation.soaring
jcarlyle
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Posts: 522
Default 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  
Old February 20th 09, 05:36 PM posted to rec.aviation.soaring
[email protected]
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Posts: 23
Default 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  
Old February 22nd 09, 08:36 PM posted to rec.aviation.soaring
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Posts: 23
Default 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  
Old February 23rd 09, 01:21 AM posted to rec.aviation.soaring
[email protected]
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Posts: 154
Default 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  
Old February 23rd 09, 04:38 AM posted to rec.aviation.soaring
[email protected]
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Posts: 17
Default 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
  #10  
Old February 23rd 09, 03:23 PM posted to rec.aviation.soaring
[email protected]
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Posts: 10
Default 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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