A summary of the 22nd Workshop, 6 September 2018 at NLR, Amsterdam
by Wouter Looman
1. Future aircraft design
- Engines on top will reduce aircraft noise enormously (no reflection on wings).
- Nice figures about the possible decrease of dB’s in the coming twenty years, like 51 dB below stage 4 in 2035.
- Happily at the moment they are not able to build supersonic aircraft as chapter 3.
- The technicians at the conference don’t believe in electric aircraft: it was no subject.
- Noise reduction with Boundary Layer Ingestion: engines as part of the fuselage; models show possibilities, but don’t achieve the NASA midterm goals of a reduction with 32-42 dB.
- There are serious gains possible with redesigning landing gear and flaps (reference article).
- But all measures together don’t achieve the NASA goals of a reduction with 32-42 dB in 2030.
- Overall: today’s computer modelling shows what is possible and what not, instead of all trial and error.
2. Noise impact
- References to Aviation Noise Impact, Basner e.a. 2017 (non-acoustic factors, sleep disturbances, learning processes, health impact).
- Nuisances differ from complaints.
- Lden versus frequencies versus peeks.
- Watch out for low-boom of new generation supersonic aircraft.
- Real weather prognoses qua impact of wind for noise forecast in Sweden (CSA – SAFT).
- US: although the number of people that suffer are only 5% of the number in earlier years, the number of concerned people has grown.
- In early days little flights with much noise, now many flights with less noise; not by definition better.
- More precise navigation drives people under the flight paths mad.
- “Put a loudspeaker under the aircraft with music only +10dB”.