Aircraft Noise: Take Off vs. Landing

Complexity level:	5
Project cost ($):	50
Time required:	1 hour to prepare, 2 day for experiment
Material availability:	Easily found. You can obtain a decibel meter from Radioshack at around US$50
Safety concerns:	The area around the airport will have tight security checks and safety requirements. Please ensure that you obtain proper clearance from airport authorities if the selected location is too close to the airport. Please wear proper ear protection

Hypothesis

An aircraft will make more noise during take off than during landing.

Overview

Type of aircraft noise

Aircraft noise can be heard during the taxi stage (aircraft moving on runway), take off, when the aircraft is flying overhead and when it is landing. The noise from an aircraft is amounts to noise pollution than can be a great nuisance and cause health problems for residents living close to an airport. The types of noise generated by an aircraft are listed below:-

Noise due to aerodynamics is caused by the flow of air across the surface of the airplane. The air flow causes the extremely rapid compression and expansion of the surrounding air resulting in noise. This noise will increase as the aircraft speed increases. It will also be higher pitched at lower altitudes due to higher air pressure.

Noise from jet engines is the main source of noise during take off and landing. The noise from a jet engine is proportional to the speed at of the jet during take off and landing.

Aircraft system noises are noises that origin within the cabin and the cockpit of the aircraft. This noise is from the power unit which generates the power to start the aircraft engines and provide the electricity to operate the electronics inside the aircraft.

Scientific Terms

Aerodynamics, compression, expansion, airflow, decibel meter

Materials

The materials required for the experiment:

A decibel meter for measuring noise
Ear plugs
A safe location near an airport to view aircraft take off and landing
Approval from the relevant airport authority (if necessary) to conduct the experiment near the airport

Procedure

For this experiment, the independent variable is the type of aircraft and the stage at which the noise is measured (take off and landing). The dependent variable is the noise level. This is determined by measuring the noise level with a decibel meter. The constants (control variables) are the distance from the aircraft, the length of the runway, and the type of decibel meter used to measure the noise levels.
The flight schedules for different types of aircraft types which are landing and taking off from the selected airport is obtained. Depending on your location, you might be able to obtain this information online from the airport authority website or you might have to speak to the relevant customer relations team. Three readings are taken during take off and landing for the following types of aircraft ?Boeing 747, Airbus 300 and Cessna 206.
The area surrounding the airport is surveyed to find a safe location to set-up the measuring equipment and be able to visually observe the types of aircraft taking off and landing.
As the aircrafts take off and land according to the schedule printed out, the measurements are taken and recorded in the table given below.

Results

The results show that the aircraft will generate more noise during take off as compared to during landing. The noise levels are also different for different types of aircraft. The Cessna 206 was the loudest and the Airbus 300 was the quietest aircraft.

Use the below graph to plot the results in the above table.

Conclusion

The hypothesis that aircraft will generate more noise during take off rather than during landing is proven to be true. The noise during take off is about 10 to 12 dB louder than the noise generated during landing.

Residents who live near an airport are normally affected by the noise of an aircraft during taking off, noise of aircraft landing and noise of low flying aircrafts. The problems faced by these residents include sleep deprivation, hearing problem, psychological problems and even cardiac disorder. Students and office workers living in these areas may face problems concentrating.

New technologies are being developed by aircraft manufacturers to reduce noise pollution. New standards are also being developed to measure noise from various types of aircraft. Local governments are also creating new laws to limit the noise levels near airports.

Also consider

The experiment can be repeated by taking the measurement at night.

Try to repeat the experiment when it is raining and observe how this affects your results.

References

Aircraft noise - http://en.wikipedia.org/wiki/Aircraft_noise

Aircraft noise - http://www.flyfrompti.com/ptipart150/AircraftNoise.htm

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