Q400 or 737? Noise?

Question

Which one has lower outside noise emissions? Not interior cabin noise and comfort, I mean as in, which is more likely to be acceptable by airport noise limitations. Basically, which is quieter? The quiet turboprop of the jet?

Thanks

Answer 1

The Q400' s noise footprint can be found at

http://www.q400.com/q400/en/specificatio...

At Take-off it is only 78.3 dB.

You did not specify which model 737, but any 737 is much larger, designed to fly further and at twice the speed carrying at least twice the number of passengers. Boeing does not show a value for noise that I could find.

This is sort of like comparing a medium-sized truck to a station wagon.

Regards,

Dan

Answer 2

Noise produced is proportional to the square (if I recall correctly) of the diameter of the thrust tube (i.e. the prop wash or the jet flux) and of the 7th power of the speed of the air in that thrust tube.

Already, this means that a slower prop driven aircraft will be quieter than a jet, excepting for the supersonic waves at the tip of the unshrouded propeller, but in the case of a Q400 at takeoff, this is unlikely to occur.

Add to this the fact a 737 is about three time as heavy as a Q400, and thus has to have 3 times the installed power, and it is not even close. Q400 is far quieter.