S- 40 Freedom is a twin-engine mid-sized business jet designed and being built by US-based Spectrum Aeronautical. It is derived from the S-33 Independence business jet. It will be the second aircraft in the series to be developed by Spectrum Aeronautical.

Delivery of the S-40 was initially planned in 2009, but it was delayed due to the financial crisis. The prototype was under development as of March 2012.

Orders for the S-40 from Jet Pool and Starfish Aviation

Jet Pool ordered a fleet of S-40 Freedom jets in February 2008. Another S-40 order was received from Starfish Aviation in September 2008.

Aerodynamic design and development of the twin-engine mid-sized business jet

The sleek and aerodynamic design of the S-40 Freedom will accomplish more fuel efficiency compared to conventional business jets. The tricycle-type undercarriage design allows the aircraft to take-off from and land on muddy airstrips and short runways.

The airframe will be built with fibeX carbon-fibre technology to improve robustness, avoid corrosion and optimise drag in-flight. The unique combination of carbon-fibre and epoxy will reduce the empty weight of the S-40 jet by 40%, compared to conventional aircraft built of aluminium.

The development plan for the S-40 was rolled-out in October 2006 at the National Business Aviation Association (NBAA) convention.

Spectrum Aeronautical awarded a contract to GE Honda Aero Engines in October 2006 to supply Honda HF-120 engines for integration in to the S-40 jet. The first fuselage of the S-40 was produced in June 2009.

Digital flight deck and spacious cabin of Spectrum Aeronautical’s aircraft

The digital flight deck will feature four high resolution screens, including two 15.6-inch primary flight displays and two 10.4-inch multifunctional displays to exhibit the navigational, flight instrumentation, fuel and engine-related data to the flight crew.

The S-40 will boast a pressurised cabin measuring 6.4m long, 1.8m wide and 1.8m high. The cabin can accommodate seven to nine passengers with ample leg space. It will provide in-flight access to the 80 cubic feet of available volume in the external baggage compartment.

The cabin will incorporate a refreshment centre, electronically shaded windows, private aft lavatory, plug-in stations for electronic equipment, an air conditioning system, an in-flight entertainment system and interior storage closets measuring 15 cubic feet.

Honeywell Aerospace’s Primus Apex avionics suite used on the S-40

Honeywell Aerospace was contracted by Spectrum Aeronautical in May 2008 to incorporate its Primus Apex avionics suite on the S-40 Freedom business jet.

The avionics suite will include AH-1000 attitude heading reference system, KXP-2290 mode S transponder, KGS-200 global positioning system receiver, KMA-29 audio panel, AZ-200 air data module, KTR-2280 multimode digital radio and KMC-2230 cursor control device.

Other avionics will encompass automatic flight control system, terrain collision and avoidance system, terrain awareness warning system, engine indication and crew alert system, aural warning computer, flight management system, wide area augmentation system, flight data recorder, cockpit voice recorder, emergency locator transmitter, automated dependent surveillance system, XM satellite weather radar and central aircraft maintenance system.

Turbofan engines supplied by GE Honda Aero Engines

The S-40 will be powered by two HF120 turbofan engines, producing 8.04kN of maximum thrust each. The engines were designed and developed by General Electric Honda Aero Engine at their plant in Burlington, North Carolina.

The HF-120 features dual controlled ultra compact FADEC system, a single-stage fan, a two-stage compressor and a two-stage turbine. It is equipped with an advanced reverse flow combustor and fuel nozzles to minimise fuel consumption, ground detected noise and harmful emissions, such as nitrogen oxide (NOx), carbon monoxide (CO) and hydrocarbons (HC).

The length and diameter of the engine are 1.1m and 0.53m respectively. The dry weight is 181kg. The time between overhaul of the engine is 5,000 hours.

Performance of Spectrum’s S- 40 Freedom light business jet

The S-40 can climb at the rate of 15.2m/s. Its maximum speed will be 815km/h. The maximum range and service ceiling of the aircraft will be 4,170km and 13.7km respectively. The take-off distance will be 914m, while the landing distance will be 822m.