Late model vs older model noise

[skidoo]

I did some touch and go's yesterday with the T182T and the wife went to observe and shoot some video. She was out right near the runway and the shots would have been good had she been able to hold the camera steady. Anyway after we got back to the hangar and put everything away, another 182 older model (pre-1986) was being prepped for flight. So, we stopped and watched it take off. We were about 1000 feet from the runway as we watched and the wife notices that he was much louder than mine.

My instructor has me reduce the rpm's very shortly after takeoff with the reasoning to reduce noise on the ground. But, I am wondering if that is even necessary and if he is basing this on experience in the older models. Anyone know what makes the difference in noise between the newer models and older ones?

 

[dmccormack]

I did some touch and go's yesterday with the T182T and the wife went to observe and shoot some video. She was out right near the runway and the shots would have been good had she been able to hold the camera steady. Anyway after we got back to the hangar and put everything away, another 182 older model (pre-1986) was being prepped for flight. So, we stopped and watched it take off. We were about 1000 feet from the runway as we watched and the wife notices that he was much louder than mine.

My instructor has me reduce the rpm's very shortly after takeoff with the reasoning to reduce noise on the ground. But, I am wondering if that is even necessary and if he is basing this on experience in the older models. Anyone know what makes the difference in noise between the newer models and older ones?

Mufflers? (Older models of a long-lived design such as the C182 have been modified in many ways -- one change over time has been reduced overall ambient noise).

 

[Trapper John]

My instructor has me reduce the rpm's very shortly after takeoff with the reasoning to reduce noise on the ground. But, I am wondering if that is even necessary and if he is basing this on experience in the older models.

Best way to find out is to ask him. It's nice to be a good neighbor noise-wise, but I like to climb fairly aggressively to get altitude to work with in case the engine goes south.

Anyone know what makes the difference in noise between the newer models and older ones?

Without looking at type certificate data, I would guess your Lycoming is turning fewer rpm at 100% power than the older Continentals, and that your 3-blade prop is probably smaller diameter than the older 2-blades. Since you're standing off to the side, you're probably hearing a lot more prop noise than exhaust noise, but I suppose there could be differences there, too.


Trapper John

 

[Ted]

Turbocharged engines are significantly quieter, and most of the changes in prop designs over the years have quieted them down. Also, 3-bladed props are frequently smaller diameter, which further reduces noise (slower tip speeds). The Lycomings do spin slower than the Continentals in the 182, which makes a difference there. I'd just view it as plane to plane.

As to whether or not you need to? If there's no noise abatement procedure in effect that states that you need to reduce RPM after takeoff, then I don't see why there's any need to other than you choose to. I tend to keep the RPMs up for climb.

 

[alaskaflyer]

The other 182 may well have had a prop modification aka a "seaplane prop" resulting in supersonic tip speeds on takeoff. Just a guess.

But three-blade props have always struck me as quieter anyways.

 

[Pilawt]

Stock 182's before the 1977 model year had 2600 max rpm; 1977 and later were 2400 max rpm.

 

[skidoo]

Thanks, your answers do make sense. And, I do have to say that the quiet performance sure is nice.

 

[gismo]

Stock 182's before the 1977 model year had 2600 max rpm; 1977 and later were 2400 max rpm.

And AFaIK that low RPM limit was designed in specifically to reduce the noise footprint on takeoff to levels acceptable in Europe.

 

[flyingcheesehead]

Stock 182's before the 1977 model year had 2600 max rpm; 1977 and later were 2400 max rpm.

Yup. According to the TCDS, the 182Q and later have the 2400 max RPM limit.

And AFaIK that low RPM limit was designed in specifically to reduce the noise footprint on takeoff to levels acceptable in Europe.

I didn't realize it had been there since the Q, I thought it was the newer Lycoming IO-540 powered models that had gone down to 2400 and that the lower limit was part of how they de-rated it to 230hp. However, it appears that the Q and R models used the O-470-U (older ones were the O-470-R) and had the lower limit. Hmmm.

Either way - The average older 182 like the one I fly spins an 80-82 inch prop at 2600 RPM, while your T182T spins a 77.5-79 inch prop at 2400 RPM.