"Montblack" wrote

On flybys at OSH, the HondaJet sounded like a handheld hairdryer, left
running across the room - on medium.

"The HF118 produces 1,700 lbf of thrust, and meets ICAO Stage IV noise
requirements. The sole application as of 2006 is for the HA-420 HondaJet."

It is also very important as to how the engine is installed, and the
attention given to intake and exhaust profiles.

The C-17, for example, is about the quietest transport I have ever heard.
When you look at the intake, there is something unusual to it. All over on
the inside of the intake, there a hundreds if not thousands of small (1/8th
inch ?) holes, drilled in specific patterns. They are said to have a large
effect on absorbing the shrill noise coming from the compressor, and leaving
out the front of the engine. I would bet that there are some tricks to the
Honda ducting and installation, also.

It also occurs to me that the engine being above the wing would block some
of the noise from reaching the ground. Anyone know about that?
--
Jim in NC