What is the 'Silent' Aircraft predicted to sound like?

CLICK HERE TO DOWNLOAD DOCUMENT

Conventional Engine compared with the Concept Engine (Granta-3401)

Simulated sound files constructed from the predicted sound

for FLY-OVER condition, 40degrees behind (3-sec each) (you will need RealPlayer to listen to this sound file)

  1. Modern conventional engine
  2. GRANTA 3401 bare engine
  3. GRANTA 3401 (with shielding)
  4. GRANTA 3401 (with liners)
  5. GRANTA 3401 (with shielding and liners)
An image of the SAX-40 with the angle of measurement labelled
for FLY-OVER condition, 40degrees ahead (3-sec each) (you will need RealPlayer to listen to this sound file)
  1. Modern conventional engine
  2. GRANTA 3401 bare engine
  3. GRANTA 3401 (with shielding )
  4. GRANTA 3401 (with liners)
  5. GRANTA 3401 (with shielding and liners)
An image of the SAX-40 with the angle of measurement labelled

The noise from SAX taking off / landing at a hypothetical runway, typical of a large international commercial airport, has been predicted. The airport we consider has: a perimeter 1km from the start of the runway, a 3.0 km long runway, with the airport perimeter a further 1.0 km from the end of the runway. The airport width is 0.45 km either side of the runway. For comparison the corresponding figures for London Heathrow are 0.7 km, 3.9 km long runway, 1.0 km, and 0.45 km to either side.

Distances for takeoff noise analysis

A diagram showing the distances used for the takoff noise estimate

Temperature: ISA+12?C

Sideline noise estimate

Challenge at Outset:

  • Sideline noise dominated by jet and fan buzz-saw

Solution:

  • High thrust and low jet velocity using variable area nozzle
  • Extensive liners
  • Airframe shielding
  • Airframe design for enhanced low speed performance

Charts showing the estimated noise at the sideline

Cut-back noise estimate

Challenge at Outset:

  • Jet noise reduction with steep, low speed climb-out.

Solution:

  • Takeoff power management and variable area nozzle
  • Extensive liners
  • Airframe shielding
  • Airframe design for enhanced low speed performance

SAX-40 noise overview

Temperature: ISA+12?C

Approach noise estimate

Challenge at outset:

  • Airframe, fan, and turbine noise.

Solution:

  • No flaps or slats.
  • Displaced threshold.
  • Undercarriage fairing.
  • Airframe design for enhanced low speed performance.
  • Deployable drooped leading edge.
  • Low noise LPT design.
  • Trailing edge brushes.
  • Low engine idle thrust.

SAX-40 FAQ:

What does the 'Silent' Aircraft concept design look like? | Why does the concept design look like this? | What are the major design features of the concept design? | What is the 'Silent' Aircraft predicted to sound like? | What is the predicted fuel burn of the 'Silent' Aircraft?

Last updated:06/11/06