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Are some light aircraft known as being significantly quieter in the cockpit than others ? How quiet might the quietest light aircraft be from the inside ?

At least ten years ago I was reading an aviation magazine and there was an article about someone who had gone all out to make their aircraft cockpit as quiet as possible. I can't remember the details but they'd made a whole lot of modifications with sound reduction in mind.

Ever since then I've wondered: are some light aircraft really noticeably quieter than others (and do they get sold on the basis of them being quieter) and is modding your aircraft to make it quieter a common thing ?

(I am of course referring to closed cockpit aircraft, I appreciate a Gypsy Moth would inevitably be quite noisy !).

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    $\begingroup$ there are typically 2 sources of noise: engine noise, and wind noise. You can dampen wind noise quite a bit (and engineers do as a side effect of minimizing drag), but not much can be done about the engine. $\endgroup$ – ratchet freak Nov 4 '14 at 21:00
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    $\begingroup$ @ratchetfreak Put the engine(s) as far from cockpit as possible. $\endgroup$ – Farhan Nov 4 '14 at 21:10
  • $\begingroup$ @Farhan except the noise/vibration transmits through the structure, unless you make all oscillation outside the hearing range and ensure no harmonics occur inside it you will always hear the engine $\endgroup$ – ratchet freak Nov 4 '14 at 21:13
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    $\begingroup$ Gliders are extremely quiet! $\endgroup$ – pericynthion Nov 5 '14 at 3:57
  • $\begingroup$ Its important to note that the dB scale is not linear, its logarithmic. This means that every 10 dB is 10x louder. So an airplane with a cockpit sound level of 90dB is 100X louder than one with at 70 dB. Let that sink in. Even just a difference of 10 dB (like 90dB vs 80dB) means it is 10X louder, (NOTE, not 10% louder, but 10 times more noise) as in, 1000% more noise. See noisehelp.com/decibel-scale.html $\endgroup$ – Devil07 Jun 28 at 6:23
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I assume that you're asking about piston engine light aircraft, so we can ignore gliders and electric engines for now.

The basic point is that they're all loud. One study compared a Cessna 172 (single engine) and a Piper Seminole (twin engine) and found that the average cabin noise was around 86 decibels, with no huge difference between the two aircraft. There's more analysis of a Seminole here. The FAA says that a light aircraft cabin is in the range of 70-90dB and this Cirrus owner measured 92-98dB in different Cirrus models. OSHA in the US requires ear protection and other measures for workers if the noise in their environment is 85dB or more.

Since decibels are on a logarithmic scale, the difference between 86dB and 98dB is large. But I searched a few aviation forums and there's very little discussion of cabin noise in light singles apart from a few subjective remarks. I couldn't find any good sources that said one aircraft type is well known as being noisier or quieter than average. The only consistent comment is that helicopters are louder than fixed-wing aircraft, which is also shown in the FAA document linked above.

Having said that, there are quite a few articles online about soundproofing aircraft in different ways. This one quotes the example of a jet:

Aero Sound Shield is currently soundproofing a particularly large corporate jet - a converted McDonnell-Douglas MD-87 - for a Las Vegas hotel owner who is almost totally blind and who has compensated by developing extremely sensitive hearing. "He wants a 60-dB airplane, which is quieter than a Lexus," Nelson points out.

But the same article makes the point that modifying any aircraft to add soundproofing increases the weight to a point that makes the aircraft much less useful:

Unfortunately, your airplane and mine can't accept the mass and weight of MD-87 measures. "I rode one time in a Piper Arrow that was very quiet," Nelson recalls, "but it was completely lead-lined. It could carry two people and half a load of fuel. That was fine for that guy, because that's all he ever wanted to carry, but it wasn't very practical."

Furthermore, it's worth remembering that modern noise-cancelling headsets are very good so the problem of noise (as opposed to vibration, which is also a factor for fatigue and health) has been more or less solved for most people. Even if you spend $1000 or more on a high-end ANR headset, that's a minor cost compared to altering the aircraft structure or materials and you still have full performance and useful load. I guess that for most GA pilots that's the decisive factor.

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  • $\begingroup$ Great answer. Thanks for the effort you put into it. I would love to try the "Lexus Jet" out ! $\endgroup$ – glaucon Nov 5 '14 at 20:27
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I have owned a 76 Piper Warrior (160 HP), 76 Piper Archer (180 HP) and a Piper Dakota (235 HP) .... I have also flown in Cessna 172, 182, 210, Mooney Executive, Bonanza A36.

The Warrior and the Archer Pipers had the "super soundproofing" option that Piper offered in the 70s... the Warrior and the Archer were both so quiet you never needed headphones and could carry on a conversation the same as if you were in a car traveling at 75 MPH on the interstate.

The Dakota did not have the super soundproofing and it was louder and I needed headphones. I installed a 1/4' thick windshield on the Archer and the first set of side widows and that reduced the then even quiet noise levels a lot... well worth the cost.

All of the other aircraft I listed that I have flown were much much much louder then the Warrior and the Archer, to the point I never would consider buying any of them.

If you want a quiet airplane try the Archer or a Warrior but they no longer make the Warrior (dated 2017).

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    $\begingroup$ One thing that's alway puzzled me is why airplane engines never seem to have effective mufflers. Is it just the Harley-Davidson effect - noise = power? $\endgroup$ – jamesqf May 14 '17 at 18:50
  • $\begingroup$ I recall the Pipers being MUCH quieter than Cessnas, especially the C15x which are deadening. I don't think the ones I was in had the super soundproofing. Anyone here compare with a Commander 112/114? They are generally commented on as being roomy and quiet. $\endgroup$ – Maury Markowitz Jul 17 '18 at 19:55
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From what I can remember of what I've flown, the Cessna 182 was far more quiet/smooth than the 172/other lighter trainers. No clue what the quietist aircraft is, or how nice you can get it. I'm not aware of any aircraft being marketed on it's quiet features.

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    $\begingroup$ Interesting, thank you. $\endgroup$ – glaucon Nov 5 '14 at 20:26
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    $\begingroup$ I can imagine why the 182 would be more quiet than the 172 when used at the same speed and altitude. It's a slightly larger aircraft (distance between cabin and engine a bit larger, plus maybe less vibrations), and the engine would run at a lower power setting, thus probably also more quiet. Run both at max power and I think the difference goes out the window. $\endgroup$ – jwenting Jan 25 '17 at 11:59
  • $\begingroup$ 182 is larger and has higher gross weight, which could allow for more insulation reducing cabin noise. I don't know if it actually has more, just a thought. $\endgroup$ – Greg Taylor May 8 '17 at 11:10

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