Noise originating

[nels]

Where does the most most noise originate in an older Mooney and what is the best method of reducing it substantially.

[rob]

From the engine. If you turn it off, it's very quiet. Too quiet.

 

Sorry, I couldn't resist!

[DaV8or]

Not sure. Perhaps our friends in Europe could shed some light on this. I think in some European countries, they are required to install different mufflers for sound abatement. Maybe there is someone that has put one of these muffler mods on and can tell us how much difference it makes. If it makes a big difference, then the noise mostly exhaust. If doesn't make much difference, then perhaps it is mostly prop.

 

I personally think more sound than average is transmitted in the Mooney due to the steel cage. Just a personal opinion and I have no empirical proof.

[Alan Fox]

Where does the most most noise originate in an older Mooney and what is the best method of reducing it substantially.

Trade it in for a Bonanza.......

[TTaylor]

Trade it in for a Bonanza.......

Then the only sound louder will be the sucking sound on your wallet!

[triple8s]

I personally think the Bo's are more noisy although I like airplane sounds. When I was involved in my second annual inspection all of the old insulation was removed, ALL of it, and we replaced it with the foam type, I think it made a big difference in the interior noise. I wish I had've done a noise comparison back then but its too late now. I also put insulation down under the carpet and noticed a couple of things after doing that. When I fly in the winter or anytime the air is very cold, since the new insulation I noticed the trim is stiff to turn, also the hydraulic pump (for flaps) acts odd, you can really tell the oil is stiff. It is quiet in the cabin, you can easily carry on a conversation with headsets off while in cruise.

[duke]

I thought engine turned fan to keep pilot cool--noise though. when noise stops, fan stops and pilot sweats.

[Alan Fox]

My E has the soundproofing (foil backed foam) but it is still loud as hell....I couldnt fly it with out a set of ANR headsets..... I think most of the noise is from the prop.... As my Bo is a three blade , and my E is a two blade , and the Bo I could actually fly (comfortably) without the headsets ,

[nels]

I personally think more sound than average is transmitted in the Mooney due to the steel cage. Just a personal opinion and I have no empirical proof.

 

You might have something there. I would imagine the steel frame is a great telegraph from engine etc.

[1964-M20E]

Went flying with my cousin in his C180 on floats and it seamed much quiter than my Mooney but he also was turning lower RPMs.  I think most of the sound comes from the prop but I'm not ready to rule out a better muffler.

[KSMooniac]

Prop noise, exhaust noise, and aerodynamic noise are all contributors.  Another fact is that we sit much closer to the prop and engine compared to many other planes, so that is a major reason Mooneys are noisy.  Buy a good set of ANR or in-ear noise blocking headsets and protect your hearing!  I don't think regular passive headsets are good enough for Mooney use.

[Alan Fox]

Not sure. Perhaps our friends in Europe could shed some light on this. I think in some European countries, they are required to install different mufflers for sound abatement. Maybe there is someone that has put one of these muffler mods on and can tell us how much difference it makes. If it makes a big difference, then the noise mostly exhaust. If doesn't make much difference, then perhaps it is mostly prop.

 

I personally think more sound than average is transmitted in the Mooney due to the steel cage. Just a personal opinion and I have no empirical proof.

Close , but not quite... The sides of the fuselage are not stressed because of the cage.....therefore they are a lot more flexible and pick up harmonic vibrations much more easily than a typical monocouqe airframe..

[nels]

Close , but not quite... The sides of the fuselage are not stressed because of the cage.....therefore they are a lot more flexible and pick up harmonic vibrations much more easily than a typical monocouqe airframe..

 

You're right on the cab skin not carrying the load and I can see it moving relative to the steel frame. My thoughts have been to insulate all the skin areas with the appropriate foam sheets but double up if necessary or at least put enough between the skin and the steel tubes that would dampen and absorb any vibration in either the tube or the skin. I would think it would need to be a lead foam or something very dense that could actually absorb the energy. Does this sound plausible?

 

 

By the way guys, I have yet to fly in my Mooney. Hopefully it will be back in a month or so. In the mean time I am trying to get smart on the items I know I will want to improve.

[N601RX]

Their were some articles on the old modworks website and they offered a package to quieten things down.  I think they used the thicker stick on foam as well as thicker windows.  I have the thicker windows and a ANR headset and don't think it is excessively loud.

 

There is also a booklet available on soundproofing airplanes. If I remember correctly it is downloadable from spruce or the company of the soundproofing they sell.

 

Found it, here is the link.

 

http://soundproofing.org/infopages/soundprf.htm

[KSMooniac]

There are products in the car audio world that are very dense and stick to metal panels to dampen the vibrations...they are very effective, but very heavy.  Even if you did that treatment to a plane, you'd still need a headset so IMO it is a waste and just eats into your payload capacity.  Just get the best headsets you can.

[Hank]

Don't forget to put sound insulation under the panel and in the footwells. Engine noise will come right throught the firewall.

 

From outside, much of our noise comes from the prop. And Bo's are much, much louder when taking off! Something about 285 hp.

[Alan Fox]

Don't forget to put sound insulation under the panel and in the footwells. Engine noise will come right throught the firewall.

 

From outside, much of our noise comes from the prop. And Bo's are much, much louder when taking off! Something about 285 hp.

They are definitely louder from the ground,,,,, But much quieter in the cockpit.....