(Diederik) wrote in message . com...
At our gliding club we have a ls-4 which has exactly the same problem,
although it only manifests itself at high speed. I think it is
resonance of the air inside the fuselage (almost the same as blowing
on a bottle or a organ pipe). We haven't looked for a solution jet.
Would like to know if anyone has...

I could imagine that a restriction in the fuselage would help so that
you change the wavelength and therefore the resonance frequency.

Diederik

(Jerz Rossignol) wrote in message . com...
Hi Guys,

My LS-6a makes some serious humming noises. Not wind noises, not
loose gap seal tape noise, not noises from the glider not being
aligned with the airflow, not noises from my gear doors. The noise is
like a loud revirberation or resinance or loud humming coming from the
rear of the fuselage. When both of my cockpit vents (canopy and nose
vent) are closed I hear the noise. When I go faster the noise just
gets much louder all the way to redline. As soon as I open either
canopy or nose vent the noise completely goes away. This has not
bothered me too much this summer but it's fall now and it's getting
cold. My choice to not be cold is to listen to that loud noise or
bundle up.

When the front nose vent is all the way closed there is still a fair
bit of air coming through the vent because of the animal hair as the
seal for the vent. I understand that this is done on purpose to keep
the canopy from getting fogged up and also to keep the
internal/external pressures the same. I am hoping someone has come up
with a solution to this problem I am having. If anyone can give me
some helpful advice to this problem I would really appreciate it.

I am curious if sealing the front nose vent with foam instead of
animal hair might help. I'm curious if sealing the rudder with
external seals would help.

Thanks for any help!!

Greg


Hi,
My LS6b has the same problem if I do not tape the horizontal/vertical fin gap.
Or if I do not seal the square opening on top the elevator.
S6