The SM-39 is a next generation air superiority fighter and fighter-bomber. Designed to perform the missions of the F-22, F-15, F/A-18E/F and the now retired F-14 Tomcat and A-6 Intruder, the SM-39 is a twin engine, piloted or unpiloted autonomous, low observable aircraft. With two internal weapon bays, a variable dihedral empennage, double slotted flaps with boundary layer blowing, thrust vectoring nozzles and titanium foam metal sandwich construction, the SM-39 is a sixth to seventh generation fighter and a direct bridge between atmospheric aircraft and future reusable space fighters.
Of radical planform, the SM-39 is a triple fuselage design featuring a streamlined center, high fineness ratio primary fuselage accompanied laterally by right and left mounted secondary fuselages. The secondary fuselages begin as highly swept wing strakes into which the aircraft wing, empennage, an a single ventral air intake and engine nacelle is blended. This planform configuration results in a significant reduction in supersonic wave-drag, allowing the aircraft to have a volume distribution that is very near the Sears-Haack ideal. Designed for supercruise, this configuration places the wing leading edge within the shock cone of the secondary fuselage wing strakes at Mach numbers as high as 2.5.
In addition to reducing wave drag, the SM-39's triple fuselage design allows for a an efficient distribution of primary aircraft systems. The center fuselage houses principal avionics, including the radome and AESA radar, as well as the cockpit, nose landing gear and two internal weapons bays. The secondary fuselages are home to a high pressure recovery, serpentine variable geometry internal compression air intake, a single variable cycle afterburning powerplant and the main landing gear. Both the center and secondary fuselages house internal fuel tanks, sensors and electronic countermeasures. Distributing aircraft systems laterally as well as longitudinally, the three fuselages result in greater internal volume with lower overall wave drag than any supersonic fighter in service today.
Designed for airspeeds in excess of Mach 3, the SM-39 will be powered by two 50,000 lb class afterburning powerplants. These engines may be enhanced performance derivatives of the P&W F119 or GE YF120, or next generation variable cycle powerplants. The current baseline design features a new design variable cycle turbofan/turbojet that benefits from a titanium diboride cermet compressor, combustor and turbine stage that allows TITs as high as 4,400º F, resulting in a maximum static thrust of 52,400 lbs with an SFC of 1.35. Cruise SFC of this new engine is predicted at values as low as 0.53.
For continuous high speed operations and a corrosion resistant 75 year operational life, the SM-39 will have titanium foam metal sandwich skins with a titanium diboride foam metal core. This nearly monocoque structure will be supporded by an internal framework of laser welded titanium frames, bulkheads and longerons.
Pioneering new approaches in aerodynamics, airframe structures, efficient variable cycle turbine propulsion, plasma low-observability and boundary layer control and integrated avionics, the SM-39 is a Mach 3.3+ fighter with a stall speed as low as 103 KTAS in the landing configuration.
