How much noise do we make?
 

I'm sure we all know we are converting money to fuel and fuel to noise but I was going to use a noise sensitive airport late at night and I was doing some research to see if I could comply with the recommendations/limits. My Skymaster cannot. I am providing a link to a noise study the FAA did so many years ago. It's interesting that even back them we were among some of the noisiest aircraft and most all of the big offenders (Lear 23, Sabreliner, Jet Commander) are not flying any more. Be a good neighbor and comply with the restrictions/recommendations.
http://www.tc.faa.gov/its/worldpac/techrpt/rd71-98.pdf

Interesting that the 337 and the Cherokee Six had almost identical sound levels, whereas the 182 was about 14 decibels quieter. The 337 was the only piston twin in the study. It would have been more informative to see it compared against its direct competition. You can't say "we have some of the noisiest aircraft" when there were no other light twins tested. And when a Piper single can match us in loudness...LOL! Of course the jets they tested were on a whole different chart because they were so much louder than the pistons!

Interesting study. From the FAA's Noise Levels for U.S. Certificated and Foreign Aircraft, U.S. Certificated Propeller Driven Small Airplanes (14 CFR Part 36, Appendix F).

The Cessna 337H with the TSIO-360-C (the only model tested) is 78.6 dBA.

Did the airport you mention have posted noise restrictions?

One airport that I'm familiar with is SMO, which has a 95dBA limit 2,200 feet beyond the departure end of the runway for fixed-wing propeller aircraft (https://www.smgov.net/uploadedFiles/...Guide_2013.pdf). Straight up, our airplanes are below that limit.

Anyone know of other airports with posted limits.

I know KLGB (Long Beach CA), has noise limits with multiple community noise sensors.

Here is a link to the website which show times, location of monitors, runways, approach and take off limits, and a drawing of the airport and monitor locations.

http://www.longbeach.gov/lgb/resources/noise-abatement/

Kevin

According to that study, a P337H is quieter than a P210R - Read 'em and weep.

The Skymaster is well inside the noise requirements; it can operate at any time of the day at LGB.

Okay, a bit bored so I dug up everything that I could find that is current. Read the rules, how noise is determined, etc. The noise is not what is generated at takeoff, but rather max continuous power. The last link is to a spreadsheet on my server, it is an "ods" (OpenOffice), but excel will open it. The file has the GA aircraft separated in three different groups and is the latest published. I found a file that updates the list further with some additional airplanes, Cirrus, for one (which is loud). I will update the file mentioned at the bottom later as it does not effect the C337.

Honestly, I doubt there is a place that you cannot fly the Skymaster unless it has a "Noise Curfew" which restricts all aircraft. It seems that the minimum noise level that airports can restrict to is 90 dBA which is basically "freeway" noise.

The reason that the 337 entries are doubled is because the difference between front and rear propellers. Aircraft noise is still the same, sum of the two engines and airframe, but it requires two line entries.

Current Advisory Circular, 36-1H, change 1, 5/25/12, Noise Levels for U.S. Certificated and Foreign Aircraft

The Rules

General Aviation Noise

The airport was Beverly MA KBVY. In the A/FD there is a VOLUNTARY noise restriction of 75db between 0400-1200Z. I was simply trying to comply with the request and fly as quiet as I can given the admittedly OLD DATA. No matter what time of day I fly.

Honestly I believe you could fly almost any GA piston out of there without causing a stink. I've operated out of airports that had microphones at the end of each runway, and automatic letters were generated to noise violators, but it was never the piston airplanes getting the letters. Ask me how I know...

I agree with mshac; the Skymaster is a good neighbor. In that the dBA value was recorded at Max Continuous vs. Max Power, it is essential to make the power reduction as soon as close-in obstacles are cleared, and single-engine flight ensured.

Like mshac, I spent 34 years flying some very noise-sensitive airports with auto reporting monitors, airplanes from the Lear 25B through the Boeing 737-800. The profile I outlined above covers just about any aircraft.

The BVY Abatement Procedure is very reasonable and fits well with how I fly my Skymaster:
"Retract the landing gear as soon as a landing straight ahead on the runway can longer be accomplished. If practical, maintain best angle-of-climb airspeed until reaching 50 feet or an altitude that provides clearance from terrain or obstacles. Then accelerate to best rate-of-climb airspeed. If consistent with safety, make the first power reduction at 500 feet."

I like your thoroughness, GAdams, looking at the AFD for starters. Not many seem to do that. When I see the "Noise sensitive" comment, I google the airport ID and "noise compliance procedures." Outside of the quiet hours, which I would not operate, here is how I would leave this morning.

Using this morning's weather, I would plan a takeoff weight not to exceed 4500 pounds ('77G), which would allow my single-engine performance to meet the TERPs DER climb performance of 200'/nm. Not required by Part 91, but I have flown too long, and with the airplane's excellent performance range, no need to smack the ground now.

I would make my standard takeoff, RWY 16, this morning. I let the airplane fly when it's ready and while in ground effect, accelerate to be at 80 knots at 50'. With an engine failure before this point, I would close the throttles and land while I manipulated the flaps to aid that landing (Accelerate-Stop Distance this morning is 3715'. Takeoff Distance to '50 is 1740' and landing 1670', a total of 3410'). At 80 knots, I'm flying, and I mark this point by bringing the flaps up. With that, the airspeed is near 90 knots, and the gear comes up. When it "clunks" closed, I would make the power reduction and maintain 90 knots at BVY's request up to 1100' MSL.

Next time you takeoff, try this...
 

Years ago I did the calculations, and the blade tip speeds are near supersonic.

Bring the RPM back a hair after takeoff and you will hear that 'gnrrrrr;' dropoff instantly.

Also, the rear prop 'chops' the rear exhaust. On my T337 that's a large exhaust pipe.

But never an issue.