Aircraft noise.

Tom-D

Tom-D

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Tom-D
When a non jet aircraft flys over, are you hearing the prop or the engine?
 
I’d say it’s a combination of both to some degree, but mostly the prop.
 
Mostly the prop - especially from the inconsiderate dumbasses that *have* to go high RPM on downwind. Way to make the airport neighbors love ya, jackwagon.
 
I just heard a plane fly over my house and it was definitely the prop.

Must have been one of the have to go to high rpm 4 miles from the airport flyers, as I heard him as he was 3 miles away.
 
Engine, prop and wind noise.
 
Wind whistling through the struts or flying wires from watching someone turning base to final always gets me excited. Especially followed by a big forward slip if it's a Cub, or full flaps from anything else. Not sure why, but I've always loved watching airplanes land with full flaps. Then again, I've seen a lot of airplanes land while standing right next to the runway, and that angle is so cool.

Oh yeah, airplane overhead noise = prop and engine for me.
 
Just listen to the noise that an electric airplane makes.

I do not remember where the post is, here on POA, of the electric airplane that was taking off.
 
I hear noise all the time from the jets flying over in the flight levels. I never thought the noise could be from their props....
 
Depends on whats going over at the time. YO-3 coming over is airframe noise only. B-29 is prop, engine and airframe noise. T-6 at takeoff is nothing but prop.
 
Sitting around Lake Hood? Prop. As planes fly over my cabin in lazy cruise? Engine. I can hear the difference between a Beaver, 206, 180/185, and Cub pretty easily without looking up. It isn’t prop noise that I recognize. The occasional Champ or Rotax Rans are easy, too.
 
Most of my acoustic training was in underwater searching for subs but sound is sound. All acoustic energy (sound) travels forever but looses energy to the medium around it as it propagates. It eventually gets so low it can't be heard. An airplane makes noise in the engine, the prop, and everywhere it disturbs the air. All of those sounds travel (with losses) to the receptor (your ear) and are added in a 3db formula that gets rather complicated but is easily found online. Of course, there are lots of other sounds reaching the same receptor and only the ones with the most energy in the frequency the receptor can process are "heard."

I doubt it but I hope that helped.
 
Listen closely to a turboprop flying overhead. The jet and prop sounds are very distinct with the jet sound sometimes hard to hear because the prop is so loud.
 
jkaduk said:
Listen closely to a turboprop flying overhead. The jet and prop sounds are very distinct with the jet sound sometimes hard to hear because the prop is so loud.
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Most of the turbine noise of a turbo-prop are above your hearing range.
 
Ryanb said:
I’d say it’s a combination of both to some degree, but mostly the prop.
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This. Prop is usually loader if the two, but you definitely get noise from the engine, especially if it is a radial.
 
EdFred said:
Mostly the prop - especially from the inconsiderate dumbasses that *have* to go high RPM on downwind. Way to make the airport neighbors love ya, jackwagon.
Click to expand...

This drives me nuts when I fly with someone for the first time and they jam the prop up way to soon just because it’s on the checklist. They have know idea as to why you move the prop to high rpm for landing.

(Hint: it actually for the landing)


It’s for a potential go around, folks!
 
Flat prop at low power settings makes for very effective braking. At low power the rpm won't be high enough to produce much noise.
 
Dave Theisen said:
This drives me nuts when I fly with someone for the first time and they jam the prop up way to soon just because it’s on the checklist. They have know idea as to why you move the prop to high rpm for landing.

(Hint: it actually for the landing)


It’s for a potential go around, folks!
Click to expand...

When my RPM finally starts to drop when reducing throttle, only then do I push the prop forward.
 
EdFred said:
When my RPM finally starts to drop when reducing throttle, only then do I push the prop forward.
Click to expand...

That’s the way I do it too. I agree the the prop can be used for braking, but in normal ops, I Just don’t feel like it’s necessary if you plan ahead.
 
Stewartb said:
Flat prop at low power settings makes for very effective braking. At low power the rpm won't be high enough to produce much noise.
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Exactly. The reason to increase the prop before landing is both for the drag and potential go around.

But, if you hold off until you are already at the low pitch stops, there is no surge or noise associated with moving the lever forward.
 
EdFred said:
Mostly the prop - especially from the inconsiderate dumbasses that *have* to go high RPM on downwind. Way to make the airport neighbors love ya, jackwagon.
Click to expand...

Fearless Tower said:
Exactly. The reason to increase the prop before landing is both for the drag and potential go around.
But, if you hold off until you are already at the low pitch stops, there is no surge or noise associated with moving the lever forward.
Click to expand...

I hold off, but it's because it's easier on the equipment.

I don't give two ****s about what the airport neighbors -- who moved in around the airport 40 years after the airport was there -- think about anything related to aircraft operations.

Looking over the actual reported noise complaints, it's only two sociopaths who really complain in any quantity, anyway. Why they're even given a forum for their grievances about their poor choice of purchase location for their homes, is beyond me.

For a while here, pilots were filing Defective Property Notices against any house that complained... which was nice, since the owner would both take a hit on sales price, as well as be required by law to show that notice to the next buyer.

Judge in county court got tired of it (he didn't feel like having extra case load and doing his job), and demanded the phone line that was installed with a recording device be disconnected for noise complaints, so the pro bono pilot/lawyers who were doing it, couldn't get names of complainers via FOIA.

Haven't found any lawyer/pilots to take up the mantle again by writing down names at the public meetings about noise, yet. Haven't really looked, either... but it'd be nice if a bored lawyer would do it again. Show up and complain, here have a Defective Property Notice. You're on public record stating your property has a nuisance you can't stand... enjoy the just fruits of your complaining nature.
 
Most of the aircraft going over the mouse house (that's Disneyland for you who haven't seen the TFR) this week have been turbine powered helicopters. I suspect most of the noise has been rotors, but I could be wrong.
 
cgrab said:
Most of my acoustic training was in underwater searching for subs but sound is sound. All acoustic energy (sound) travels forever but looses energy to the medium around it as it propagates. It eventually gets so low it can't be heard. An airplane makes noise in the engine, the prop, and everywhere it disturbs the air. All of those sounds travel (with losses) to the receptor (your ear) and are added in a 3db formula that gets rather complicated but is easily found online. Of course, there are lots of other sounds reaching the same receptor and only the ones with the most energy in the frequency the receptor can process are "heard."

I doubt it but I hope that helped.
Click to expand...

So what you’re saying is if the engine failed and there wasn’t any engine or prop noise we would be able to hear the pilot’s bunghole pucker if we listened hard enough?
 
Sound energy is sound energy, it's a combination of level and frequency. When my engine stopped in flight my bunghole pucker was not as loud as the wing noise in my slip to the runway I was overflying. That said, I'm sure my bunghole pucker sound is still propagating through the cosmos.
 
cgrab said:
All acoustic energy (sound) travels forever but looses energy to the medium around it as it propagates.
Click to expand...

There may be some other limits that will ultimately limit detectability. Turbulent mixing of the medium and ultimately, at low enough levels, the continuous approximation will break down, and then one is talking about potential quantum effects on single molecules.

(Rather far afield from the OP)
 
denverpilot said:
I hold off, but it's because it's easier on the equipment.

I don't give two ****s about what the airport neighbors -- who moved in around the airport 40 years after the airport was there -- think about anything related to aircraft operations.

Looking over the actual reported noise complaints, it's only two sociopaths who really complain in any quantity, anyway. Why they're even given a forum for their grievances about their poor choice of purchase location for their homes, is beyond me.

For a while here, pilots were filing Defective Property Notices against any house that complained... which was nice, since the owner would both take a hit on sales price, as well as be required by law to show that notice to the next buyer.

Judge in county court got tired of it (he didn't feel like having extra case load and doing his job), and demanded the phone line that was installed with a recording device be disconnected for noise complaints, so the pro bono pilot/lawyers who were doing it, couldn't get names of complainers via FOIA.

Haven't found any lawyer/pilots to take up the mantle again by writing down names at the public meetings about noise, yet. Haven't really looked, either... but it'd be nice if a bored lawyer would do it again. Show up and complain, here have a Defective Property Notice. You're on public record stating your property has a nuisance you can't stand... enjoy the just fruits of your complaining nature.
Click to expand...

Have a local pilot outside of town with a private grass strip that has been there for years and uses his plane to commute to work (757’s and alike). A few years ago thehouse down the street sold and the people complained constantly, even when we flew RC planes.
Well, that didn’t sit well with this ex-military guy. Every time he took off for over a month he would hang a left and rip the snot out of that prop. When the neighbors put up the white flag he quit.
 
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