NDRCC Sound Rules – 2020 Update

The goal of the North Dallas RC Club is to provide our members a safe, well maintained facility to enjoy model aviation while minimizing our impact on the surrounding community. To minimize the amount of noise that leaves our field and is audible in the surrounding community and to comply with local ordinances regarding noise and the operation of model aircraft, the following rules are established for all models operating at Eagle Field.
From the beginning of Daylight Savings Time in the Spring, until the end of Daylight Savings Time in the Fall, Daytime hours shall begin at 9:00am and end 60 minutes prior to sunset.
From the end of Daylight Savings Time in the Fall, until the beginning of Daylight Savings Time in the Spring, Daytime hours shall begin at 9:00am and end at sunset.
Evening hours will begin when Daytime hours end and will continue until 10:00pm.
All models are limited to 100dBa during Daytime Hours
All models are limited to 90dBa during Evening hours
No internal combustion powered models may be flown between 10:00pm and 9:00am.
Electric powered models may fly between 10:00pm and 9:00am, however, they must comply with the 90dBa limit during this time.
Turbine powered aircraft are exempt from sound limits, however, they may only be flown during Daytime hours.
The sound level of all aircraft flying at the NDRCC field shall be subject to a sound check measured with the Club’s dB meter, set to the “A” weighting, slow response and with the windscreen installed.

The meter may be held or placed on a stand approximately 24″ above the ground, crosswind and perpendicular to the side of the aircraft at a distance of 25 feet. The test area should be in the “south infield” area, clear of buildings and the runway. A minimum of a 5 second full throttle engine run is required.

All Club Members are empowered to conduct Sound Checks. However, the NDRCC Board may also appoint designated members (Sound Testing Members) to carry out Sounds Checks when an aircraft is suspected of being over the dB limit.

Often minor throttle programming adjustments can be made at the field which will reduce the noise level sufficiently to allow aircraft to continue to fly that day. However, if minor adjustments do not reduce the noise level sufficiently, the aircraft cannot fly at Eagle Field until appropriate modifications are made.

Common ways to reduce aircraft dB Levels;
Use the correct engine application for the model. Excessive engine sizes are hard on airframes and also hard to muffle properly.
“Pitts style” mufflers are better than side mounted exhaust diverters. When it comes to mufflers, larger is almost always quieter.
Three blade props are usually quieter. Second choice is smaller diameter, higher pitch 2 blade props (example 20 X 10 versus 22 x 8).
Canisters and muffled tuned pipes can really reduce exhaust noise if your aircraft has adequate room.
If an aircraft exceeds the sound limit, and there are no commercially available accessories to enable the aircraft to meet the sound limit, the owner may apply for a Waiver from the NDRCC Board by submitting a completed Waiver Application to the Board via the Sound Testing Member. The Board may either approve the Waiver or make recommendations to help reduce the sound level. The aircraft will be re-tested following any modifications. After reviewing the re-test results, the Board shall decide if a waiver is applicable. If at a future date commercially available accessories become available that will enable the waivered aircraft to meet the specified noise limits, the aircraft shall be modified immediately or not fly at Eagle Field. Sound waivered aircraft may only fly during Daytime hours.

Sound Checks may be waived for special events when recommended by the Event CD and approved by the NDRCC Board.