Major design features of the conceptual aircraft

The aircraft (SAX-40)

The aircraft is an ‘all-lifting’ design, producing lift on the centre-body as well as the wings. The airframe makes use of a novel centre-body shape with leading edge carving. This balances the aerodynamic forces without the need for a tail, and enables an optimal wing design with an elliptical lift distribution and low cruise drag.

Range: 5,000 nm
Number of passengers: 215 (3 class)

Cruise ML/D:
SAX-40: 20.1
Boeing PW BWB ML/D : 17-18
Boeing 777 ML/D : 17.0

ML/D = (Mach number) X (Lift) ÷ (Drag)

  1. Centrebody with leading edge carving 
  2. Winglet rudder
  3. Elevons
  4. Centrebody boundary layer ingested
  5. Thrust vectoring, variable area nozzle
  6. Deployable drooped leading edge
  7. Faired undercarriage
A labelled diagram of the underside of the SAX-40


Mach number: 0.8
Altitude: 40,000 – 45,000 ft
Lift/Drag: 25.1 – 23.5
Static margin: 5.9% – 9.5%
Centre of Gravity travel: 0.4 m

Span: 221.6 ft (incl. winglet)
Gross Area: 8,998 ft2

MTOW (Maximum Take-Off Weight): 332,560 lbs
OEW (Operational empty weight): 207,660 lbs
Structure: 104,870 lbs
Payload: 51,600 lbs
Fuel: 73,310 lbs

The engines (GRANTA – 3401)

The aircraft has three novel engines - the engine type is called GRANTA – 3401. Each engine has a single core, driving three high capacity low speed fans. This distributed propulsion system is designed to ingest the boundary layer on the aircraft centrebody which reduces the fuel burn. The multiple small fan design is easier to embed in the airframe, and leads to reduced weight and nacelle drag. It also enhances boundary layer ingestion, thereby improving fuel efficiency, and the low fan tip speeds lead to low noise. The engine has an ultra-high bypass ratio 18.3 at take-off for low jet noise, 12.3 at top of climb for good efficiency.

  1. axial-radial compressor
  2. extensive acoustics liners
  3. variable area nozzle
  4. low noise 5 stage
    Low Pressure Turbine
  5. transmission system to transit power from Low Pressure Turbine to Fans
  6. 3 high capacity,
    low speed Fans
A labelled diagram of the GRANTA – 3401 engine design

Fan Diameter: 1.20 m
Engine Length: 2.46 m
Cruise Fuel Flow: 0.86 kg/s

Bare weight: 6,566 lbs / engine
Installed weight: 12,058 lbs / engine

 Top of climbTake-off
Fan pressure ratio1.501.19
Bypass ratio12.318.3
Overall pressure ratio48.824.2


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