Howling sound when flying

[Armand Charbonneau]

My Ventus 2c makes a howling sound when flying at 0 flap setting. It is significantly less noticeable immediately after changing the flap setting either positive or negative. Pilots tell me they can hear it when flying overhead or landing. I can hear it seemingly behind me, inside the cockpit. Gear up or down does not seem to make a difference.

The glider was refinished with poly in 2012, so I suspect the wing seals are seven years old. Otherwise the ship in very good condition and soars nicely.

Does anyone know what could be causing this sound? I can replace all the seals this winter, but they appear to be in good condition, except maybe on the tail plane.

[krasw]

On Saturday, 12 October 2019 18:42:44 UTC+3, Armand Charbonneau wrote:
> My Ventus 2c makes a howling sound when flying at 0 flap setting. It is significantly less noticeable immediately after changing the flap setting either positive or negative. Pilots tell me they can hear it when flying overhead or landing. I can hear it seemingly behind me, inside the cockpit. Gear up or down does not seem to make a difference.
>
> The glider was refinished with poly in 2012, so I suspect the wing seals are seven years old. Otherwise the ship in very good condition and soars nicely.
>
> Does anyone know what could be causing this sound? I can replace all the seals this winter, but they appear to be in good condition, except maybe on the tail plane.

Ventus-2c (and D2b) has an extremely loud cockpit. You cannot do much for it.

[[email protected]]

Might also try rudder left and right, elevator, etc.

[Armand Charbonneau]

On Saturday, October 12, 2019 at 9:57:58 AM UTC-6, krasw wrote:
> On Saturday, 12 October 2019 18:42:44 UTC+3, Armand Charbonneau wrote:
> > My Ventus 2c makes a howling sound when flying at 0 flap setting. It is significantly less noticeable immediately after changing the flap setting either positive or negative. Pilots tell me they can hear it when flying overhead or landing. I can hear it seemingly behind me, inside the cockpit.. Gear up or down does not seem to make a difference.
> >
> > The glider was refinished with poly in 2012, so I suspect the wing seals are seven years old. Otherwise the ship in very good condition and soars nicely.
> >
> > Does anyone know what could be causing this sound? I can replace all the seals this winter, but they appear to be in good condition, except maybe on the tail plane.
>
> Ventus-2c (and D2b) has an extremely loud cockpit. You cannot do much for it.

It is not just in the cockpit. I am told it is loud on the ground when flown overhead.

[Jonathan St. Cloud]

On Saturday, October 12, 2019 at 9:45:01 AM UTC-7, Armand Charbonneau wrote:
> On Saturday, October 12, 2019 at 9:57:58 AM UTC-6, krasw wrote:
> > On Saturday, 12 October 2019 18:42:44 UTC+3, Armand Charbonneau wrote:
> > > My Ventus 2c makes a howling sound when flying at 0 flap setting. It is significantly less noticeable immediately after changing the flap setting either positive or negative. Pilots tell me they can hear it when flying overhead or landing. I can hear it seemingly behind me, inside the cockpit. Gear up or down does not seem to make a difference.
> > >
> > > The glider was refinished with poly in 2012, so I suspect the wing seals are seven years old. Otherwise the ship in very good condition and soars nicely.
> > >
> > > Does anyone know what could be causing this sound? I can replace all the seals this winter, but they appear to be in good condition, except maybe on the tail plane.
> >
> > Ventus-2c (and D2b) has an extremely loud cockpit. You cannot do much for it.
>
> It is not just in the cockpit. I am told it is loud on the ground when flown overhead.

Well that sucks, literally. Start sealing. I have owned two SH gliders (N4, V2C) and they both benefited from gear well sealing, canopy, rudder, and control surfaces needed S-tape under mylar.

[john firth]

On Saturday, October 12, 2019 at 11:42:44 AM UTC-4, Armand Charbonneau wrote:
> My Ventus 2c makes a howling sound when flying at 0 flap setting. It is significantly less noticeable immediately after changing the flap setting either positive or negative. Pilots tell me they can hear it when flying overhead or landing. I can hear it seemingly behind me, inside the cockpit. Gear up or down does not seem to make a difference.
>
> The glider was refinished with poly in 2012, so I suspect the wing seals are seven years old. Otherwise the ship in very good condition and soars nicely.
>
> Does anyone know what could be causing this sound? I can replace all the seals this winter, but they appear to be in good condition, except maybe on the tail plane.

It is surprising that this has not been aired before.
When I first flew my PIK 20 E there was a similar loud howl
at zero and neg flap settings. I speculated that this was resonant
vortex shedding from the top surface; the flap had an internal fabric seal
but this will not stop oscillatory flow.
The Aerodynamics prof at my alma mater replied that I was probably right;
resonant vortex shedding on the BAE 146 stol transport was close to
ending sales due to passenger complaints; when CU dept eng. found a solution.

[Eric Greenwell[_4_]]

Armand Charbonneau wrote on 10/12/2019 8:42 AM:
> My Ventus 2c makes a howling sound when flying at 0 flap setting. It is significantly less noticeable immediately after changing the flap setting either positive or negative. Pilots tell me they can hear it when flying overhead or landing. I can hear it seemingly behind me, inside the cockpit. Gear up or down does not seem to make a difference.
>
> The glider was refinished with poly in 2012, so I suspect the wing seals are seven years old. Otherwise the ship in very good condition and soars nicely.
>
> Does anyone know what could be causing this sound? I can replace all the seals this winter, but they appear to be in good condition, except maybe on the tail plane.

Did the howl start recently? Are the zig zag tapes in the correct position? Does
the back edge of the Mylar fairing strip (top and bottom) press against the
flap/ailerons in the Flap 0 position?


--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorgliders/publications/download-the-guide-1

[Armand Charbonneau]

On Saturday, October 12, 2019 at 4:57:48 PM UTC-6, Eric Greenwell wrote:
> Armand Charbonneau wrote on 10/12/2019 8:42 AM:
> > My Ventus 2c makes a howling sound when flying at 0 flap setting. It is significantly less noticeable immediately after changing the flap setting either positive or negative. Pilots tell me they can hear it when flying overhead or landing. I can hear it seemingly behind me, inside the cockpit.. Gear up or down does not seem to make a difference.
> >
> > The glider was refinished with poly in 2012, so I suspect the wing seals are seven years old. Otherwise the ship in very good condition and soars nicely.
> >
> > Does anyone know what could be causing this sound? I can replace all the seals this winter, but they appear to be in good condition, except maybe on the tail plane.
>
> Did the howl start recently? Are the zig zag tapes in the correct position? Does
> the back edge of the Mylar fairing strip (top and bottom) press against the
> flap/ailerons in the Flap 0 position?
>
>
> --
> Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
> - "A Guide to Self-Launching Sailplane Operation"
> https://sites.google.com/site/motorgliders/publications/download-the-guide-1

Howling has been there since I started flying about 105 hours ago. zig zag tapes look okay.

I will check the mylar strips (top and bottom) carefully with the wings assembled looking at flap 0.

[Eric Greenwell[_4_]]

Armand Charbonneau wrote on 10/12/2019 5:52 PM:
> Howling has been there since I started flying about 105 hours ago. zig zag tapes look okay.
>
> I will check the mylar strips (top and bottom) carefully with the wings assembled looking at flap 0.

Did the howling exist before the refinish? Perhaps the zig-zag was not placed in
the correct location, or it's the wrong zig-zag (too thin, perhaps).

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorgliders/publications/download-the-guide-1

[GliderCZ]

On Saturday, October 12, 2019 at 8:42:44 AM UTC-7, Armand Charbonneau wrote:
> My Ventus 2c makes a howling sound when flying at 0 flap setting. It is significantly less noticeable immediately after changing the flap setting either positive or negative. Pilots tell me they can hear it when flying overhead or landing. I can hear it seemingly behind me, inside the cockpit. Gear up or down does not seem to make a difference.
>
> The glider was refinished with poly in 2012, so I suspect the wing seals are seven years old. Otherwise the ship in very good condition and soars nicely.
>
> Does anyone know what could be causing this sound? I can replace all the seals this winter, but they appear to be in good condition, except maybe on the tail plane.

I own and fly V2C s/n 51 and have never experienced that problem. I also find the cockpit reasonably quiet if everything is well sealed; even more so since having a Hank Nixon turtleback vent installed.

But what initially struck me about your question though, is your use of the 0 flap setting. My SH flight manual doesn't even acknowledge 0-flaps as a cruise setting. By virtue of that (and advice from other V2C pilots) I never routinely use it. It's just a transit point between positive and negative settings. Sorry, if I steer the conversation off-topic.

[[email protected]]

Interesting - what is that Hank Nixon turtleback vent you mentioned?

[[email protected][_2_]]

Ventus-2c (and D2b) has an extremely loud cockpit. You cannot do much for it.” krsw

Your brain must have extremely loud tinnitus. I’ve own 4 SH, all quiet. No issues.
Moving on, with a positive contribution....we all agree any glass ship emitting noise will be due to airflow. Loud noise is from something acting like a ‘reed’ or horn instrument. 99% it is a reed and tape or gap seal is the noise producer. Couple this with the wing or fuselage being ‘bellows’, noise will amplify quite nicely.
I found a nuisance noise being created by gap tape at the right aileron pushrod connection. But only in neutral or left turns. Right turns had the connection
applying pressure on the tape keeping it from vibrating. The wing amplified the noise to sound like a gear warning horn. I doubled up on the tape and the noise stopped.
Something around the flaps becomes an instrument at zero to make a perfect E flat. A little experimentation with tape may prove telling.
Cheers.

R

[[email protected]]

I was amazed how quiet it got after I filled the cockpit vent air tube with drinking straws. They straighten out the flow just before it enters the cockpit.
JJ

[[email protected]]

sunnuntai 13. lokakuuta 2019 16.40.31 UTC+3 kirjoitti:
> Ventus-2c (and D2b) has an extremely loud cockpit. You cannot do much for it.” krsw
>
> Your brain must have extremely loud tinnitus. I’ve own 4 SH, all quiet. No issues.

Sorry I did not catch the specific models you have owned, as that is pretty important detail missing here.

I've flown regularly over dozen SHs ranging from Std.Cirrus to Arcus, and while there are some that are dead quiet (Nimbus-4DM, surprisingly), V2C and D2B are not by design. You wouldn't believe the effort we have spend sealing the canopy, rear fuselage etc. You can get the noise to reasonable level, but quiet, no.

[GliderCZ]

On Sunday, October 13, 2019 at 2:49:10 AM UTC-7, wrote:
> Interesting - what is that Hank Nixon turtleback vent you mentioned?

I guess it's more properly referred to as a "cockpit air extractor." Basically a pathway for pressurized air in the cockpit to exit the aircraft through an aerodynamically neutral vent atop the fuselage just behind the canopy.. In Hank Nixon's version, it includes an interior attachment that funnels the air directly into that opening. I find it creates a much more comfortably ventilated cockpit and significantly reduces noise. Without it, the increased pressure from vent air in the aircraft tries to force its way through the canopy seal or rattles its way aft through the fuselage.

Sorry, I'm not able to attach photographs, but if you do a topic search for cockpit vent or "fart scoop," you may be able to find links (and more than a few opinions). Hank Nixon is a frequent visitor to this group, and he may be able to provide more info, also.

Mine was expertly installed by Yankee Composites at Sky Sailing, Warner Springs, CA. I'm very happy with the result.

[Michael Opitz]

At 05:18 14 October 2019, wrote:
>sunnuntai 13. lokakuuta 2019 16.40.31 UTC+3
kirjoitti:
>> Ventus-2c (and D2b) has an extremely loud cockpit. You cannot
do much
>for=
> it.=E2=80=9D krsw=20
>>=20
>> Your brain must have extremely loud tinnitus. I=E2=80=99ve
own 4 SH, all
>=
>quiet. No issues.
>
>Sorry I did not catch the specific models you have owned, as that
is
>pretty=
> important detail missing here.
>
>I've flown regularly over dozen SHs ranging from Std.Cirrus to
Arcus, and
>w=
>hile there are some that are dead quiet (Nimbus-4DM,
surprisingly), V2C
>and=
> D2B are not by design. You wouldn't believe the effort we have
spend
>seali=
>ng the canopy, rear fuselage etc. You can get the noise to
reasonable
>level=
>, but quiet, no.
>

I have had my D-2B for 20 years now since new, and I have never
had any issues with a noisy cockpit. Maybe I am going deaf in my
old age, but I may have had an advantage when the glider was built
for me because the S-H final assembly inspector who signed off on
all of the parts was my old drinking buddy from when I worked at
S-H for the summer after college. I have been part of their "family"
ever since, and I know that they have taken a little "extra care"
when it came to making a glider for me. I also had them install
their extra factory seals before it left the factory. The glider still
has
no spar waves after all of these years either....

RO

[[email protected][_2_]]

How much for the package?

R

[Tom BravoMike]

On Sunday, October 13, 2019 at 9:59:59 AM UTC-5, wrote:
> I was amazed how quiet it got after I filled the cockpit vent air tube with drinking straws. They straighten out the flow just before it enters the cockpit.
> JJ

Interesting. I have to try it. So you just filled the entire cross-section of the vent tube with the straws? How long do they need to be to work?

[JS[_5_]]

On Monday, October 14, 2019 at 11:50:42 AM UTC-7, Tom BravoMike wrote:
> On Sunday, October 13, 2019 at 9:59:59 AM UTC-5, wrote:
> > I was amazed how quiet it got after I filled the cockpit vent air tube with drinking straws. They straighten out the flow just before it enters the cockpit.
> > JJ
>
> Interesting. I have to try it. So you just filled the entire cross-section of the vent tube with the straws? How long do they need to be to work?

Same technique as an automotive muffler/silencer/auspuff whatsit.
Jim

[[email protected]]

On Monday, October 14, 2019 at 7:56:29 PM UTC+1, JS wrote:
> On Monday, October 14, 2019 at 11:50:42 AM UTC-7, Tom BravoMike wrote:
> > On Sunday, October 13, 2019 at 9:59:59 AM UTC-5, wrote:
> > > I was amazed how quiet it got after I filled the cockpit vent air tube with drinking straws. They straighten out the flow just before it enters the cockpit.
> > > JJ
> >
> > Interesting. I have to try it. So you just filled the entire cross-section of the vent tube with the straws? How long do they need to be to work?
>
> Same technique as an automotive muffler/silencer/auspuff whatsit.
> Jim

Easier than straws is to get a single kitchen pot scrubber (not as fine as wire wool) tease it out and put it in the vent opening.

[[email protected]]

I removed the side eyelid vent and then cut large drinking straws, in half and stacked them inside the channel, up stream. A tad of glue will keep them in place, I used Shoe-Goo. This method doesn’t cutdown on total air flow, just straighten’s it out.
JJ

[Michael Opitz]

At 17:49 14 October 2019, wrote:
>How much for the package?
>
>R
>
If you are asking about the S-H factory extra sealing package, my
receipt shows DM 435. Who knows what it is in Euros now.

RO

[Tom BravoMike]

On Monday, October 14, 2019 at 2:51:26 PM UTC-5, wrote:
> I removed the side eyelid vent and then cut large drinking straws, in half and stacked them inside the channel, up stream. A tad of glue will keep them in place, I used Shoe-Goo. This method doesn’t cutdown on total air flow, just straighten’s it out.
> JJ

Thanks, guys, for sharing your methods. Somehow never thought or heard about them. The vent opening (with a closing flap) in my old Ventus B is in front of the canopy, and makes a lot of noise when opened. I hope your solutions will help, but it looks like I'll have to wait till spring with trying it out, now that the season seems to be over.

[[email protected]]

On my ventus b I used a flap of cloth on the bottom hinge covering the hinge and back into the channel. Iirc, it was a fairly fuzzy on the up side and smooth on the glued down side. cut the noise in half.

CH

[glidergeek]

Don't fly with dogs.

[Armand Charbonneau]

On Saturday, October 12, 2019 at 9:42:44 AM UTC-6, Armand Charbonneau wrote:
> My Ventus 2c makes a howling sound when flying at 0 flap setting. It is significantly less noticeable immediately after changing the flap setting either positive or negative. Pilots tell me they can hear it when flying overhead or landing. I can hear it seemingly behind me, inside the cockpit. Gear up or down does not seem to make a difference.
>
> The glider was refinished with poly in 2012, so I suspect the wing seals are seven years old. Otherwise the ship in very good condition and soars nicely.
>
> Does anyone know what could be causing this sound? I can replace all the seals this winter, but they appear to be in good condition, except maybe on the tail plane.



Update: I put foam in the top of the tail to block wind from going out the horizontal stabilizer/elevator. The interior air flow is now channeled out the bottom of the tail where there are openings for the rudder cables. While the noise is not gone, it is significantly diminished especially at 0 flap settings. I plan to change all the seals this winter, ensure the canopy is not drafty, and try the straws in front vent method mentioned in this tread.

[[email protected]]

Hi Armand,

there usually is a rubber seal at the opening of the elevator pushrod. This should be available from the factory in case it is missing on your ship. We installed V-Tape to cover the canopy front and aft canopy gaps of our Ventus 2cM. This reduced cockpit noise significantly. You will have to heat it up a bit in order to make it fit to the curvature of the canopy frame.

I once had straws in the front vent of my LS8. It was quiet, but they significantly reduced the airflow through the vent. A piece of fur did the same job without hindering the airflow.

Best
Christoph

[Armand Charbonneau]

On Sunday, October 20, 2019 at 2:22:57 PM UTC-6, wrote:
> Hi Armand,
>
> there usually is a rubber seal at the opening of the elevator pushrod. This should be available from the factory in case it is missing on your ship. We installed V-Tape to cover the canopy front and aft canopy gaps of our Ventus 2cM. This reduced cockpit noise significantly. You will have to heat it up a bit in order to make it fit to the curvature of the canopy frame.
>
> I once had straws in the front vent of my LS8. It was quiet, but they significantly reduced the airflow through the vent. A piece of fur did the same job without hindering the airflow.
>
> Best
> Christoph

The rubber seal is in place and seemingly good condition. I will try the V-tape and fur suggestions. Thanks.