OVERVIEW
The SM-72 is an Advanced Air Mobility Transport Aircraft Concept presently undergoing consideration to enter into full scale engineering design and development by Stavatti Military Aerospace as a company sponsored, commercial initiative to meet anticipated future NATO/Allied Tactical Airlift needs. Designed for global airlift, air-drop, in-flight refueling, infiltration/exfiltration of U.S. and allied SOF personnel and equipment to/from and in-hostile and denied airspace, the SM-72 will serve as an all-weather tactical transport capable of operating day and night in extremely adverse conditions over all terrain. The SM-72 will deliver and/or air-drop payload on unprepared, austere, marked and unmarked clearings, landing zones and drop zones.
A next generation, fixed wing, Short Take Off and Landing (STOL) Medium Transport Aircraft, the SM-72 is an extremely flexible multi-mission platform with significant cargo carrying capacity. The SM-72 will form the basis of a family of military air transport and air weapon systems including advanced global transport, advanced tanker, advanced reconnaissance, advanced electronic warfare, advanced re-supply, advanced psychological operations and advanced gunship platforms.
The SM-72 Tactical Transport will be produced in multiple variants including Tactical Airlift (SM-72A), Humanitarian Relief (SM-72HR), Combat Rescue Tanker (SM-72CRT), Airborne Battlefield Command and Control (SM-72EC), Gunship (SM-72AC) and Commercial Transport (SM-72C). Designed to succeed the C-130 and compete with the A400M, the SM-72 will be produced in a wide variety of configurations while providing significantly greater capability than the Lockheed Martin C-130J Hercules.
The SM-72 is the Tactical Transport member of Stavatti's SM-70 family of military transport, maritime patrol/anti-submarine warfare and regional commercial transport aircraft. A series of fixed wing, twin engine turboprop transport aircraft that benefit from a common wing, empennage and powerplant arrangement, the SM-70 series includes the SM-72 Medium Transport, the SM-73 Rigel™ Anti-Submarine Warfare/Maritime Multi-mission Aircraft (ASW/MMA) and the SM-74 Turboprop Regional Airliner (TRA). These three models will feature unique fuselage configurations to satisfy specific mission and market requirements.
The SM-72 would likely be manufactured at a single production facility and may enter Low Rate Initial Production (LRIP) between 2014 and 2016, or approximately six to eight years after the introduction of the SM-27 Machete. The SM-72 program is managed by Stavatti Military Aerospace. Stavatti anticipates production of between 60 and 115 SM-72s annually by 2017.
ACCOMMODATION
The SM-72 Tactical Transport is a cargo delivery aircraft featuring a rectangular cross section fuselage to maximize mission effectiveness while offering significant load flexibility. Conceived for a true 52,000 lb payload with full standard internal fuel, the SM-72 main cabin/cargo bay measures 58 ft long and 11 ft wide at the floor, providing approximately 638 sq ft of cargo bay floor, not including additional area provided by the cargo ramp which totals 168 sq ft. Overall main cabin/cargo bay dimensions include a maximum usable internal width of 15 ft 6 inches and a maximum usable internal height of 11 ft 6 inches. Useful main cabin/cargo bay volume, excluding the cargo ramp, is approximately 9,450 cu ft. Typical comparable SM-72 cargos include four HMMWVs (Humvees) or seven 88” x 108” 463L standard pallets, with up to one additional pallet carried on the cargo ramp. The SM-72 will carry a wide variety of military vehicles and will be able to airdrop an entire field artillery section in one pass. The SM-72 benefits from a Loadmaster Control System, consisting of an integrated workstation and control panel for electronic cargo control including ground loading an airborne cargo drops.
Hydraulically actuated, the main ramp drops 23.4º with a ramp angle of 7.3º. The aircraft fuselage features four additional doors, each measuring 7 ft high and 3 ft 6 in wide with two doors located on the port and starboard sides of the forward cabin and two paratroop doors located on the port and starboard sides of the aft cabin.
POWERPLANT
The SM-72 is powered by two 14,500 SHP D-27 turbopropfan free turbine propulsion engines with a shaft output of 950 RPM. The propulsion engines drive two 17 ft 6 in diameter, eight bladed propellers. The propulsion engines drive an integrated auxiliary axial flow compressor that interfaces on-demand with the propulsion engines through a clutch in the engine gearbox. When the CCW system is engaged, the compressors draw approximately 31% of the SHP from the propulsion engines for the purpose of producing compressed air to supply the aircraft CCW/BLC system.
The turbine propulsion engines are mounted, one per wing, in a tractor configuration whereby the tip of the propeller is located immediately aft of the wing channel‘s trailing edge, with the wing channel approximately the same radius as the propeller. This propeller location/engine arrangement is a principal element of the lift enhancing, channel wing configuration. The turbine propulsion engines are housed in individual nacelles featuring an extended nacelle boom/aft section. This provides additional volume to house the CCW compressors and electronic countermeasures and avionic systems. Individual nacelles are supported vertically by engine support pylons mounted ventrally to the nacelles and supported directly by landing gear support sponsons integrated into the wing channel.
The D-27 turbopropfan, designed by ZMDB Progress of Zaporozhye, Ukraine and produced by OAO Motor Sich Joint Stock Company (JSC), presently powers the Antonov AN-70. D-27 design began in 1985 with the AN-70 prototype rolling out in 1992 and the AN-70 first flight occurring in 1994. To enhance SM-70 series performance, it is likely that an Improved Performance Derivative D-27 (IPD D-27) will be produced specifically for the Stavatti application either entirely by Motor Sich, or through a Joint Venture company involving Motor Sich in partnership with a United States turbine engine manufacturer. A U.S. joint venture partner for IPD is not yet negotiated, however, potential candidates include a new company formed specifically by Stavatti Heavy Industries, Ltd., in joint venture with Motor Sich to produce IPD D-27 engines in the U.S. The IPD D-27 Turbopropfan will build upon the success of the proven D-27 powerplant, while increasing overall powerplant performance to create a propulsion system that develops a maximum of 15,000 to 18,000 SHP.
The baseline SM-72 Tactical Transport is unarmed. Stavatti Military Aerospace does envision the production of the SM-72AC Gunship variant of the SM-72. The SM-72AC will be equipped with four M61A2 20mm Vulcan cannons with 6,000 rounds, one L60 40mm Bofors cannon with 300 rounds, and one M102 105mm howitzer with 100 rounds for satisfaction of Close Air Support, Air Interdiction and Armed Reconnaissance. Contact Stavatti Military Aerospace for more information regarding the SM-72AC.
A C-130 successor, the SM-72 will be produced in numerous variants incorporating a diverse array of mission-specific avionics, sensors, electronic countermeasures, and, in the case of gunship and psy-ops variants, armament and broadcast systems. SM-72 avionics will be integrated about a MIL-STD-1553B Interface/Data Bus with Data Bus Wiring used throughout the system architecture to reduce wiring bundles. The SM-72 will employ a comprehensive navigation/communications suite with the SM-72 avionics system emphasizing mission completion, reliability, flexibility and ease of serviceability. Avionics may be of a variety of types including either COTS or MOTS. Wherever possible, avionics are of modular LRU type with BIT.
The avionics/sensor suite is designed and integrated by Stavatti based upon customer specifications, however, Stavatti Military Aerospace has developed a Standard Configuration for baseline SM-72 avionics for those customers who desire to procure an aircraft with a proven, integrated suite of baseline avionics. A detailed listing of principal avionics and sensors which will be considered to be Standard Configuration Avionics are provided on the SM-72 Performance & Specifications webpage.
The cockpit is equipped with a Cockpit Video Recording (CVR) system capable for recording at least 120 minutes of HUD symbology, the external HUD field of view, cockpit LCD MFD symbology and all aircraft communication system audio. The aircraft is also equipped with a crash survivable Flight Data Recorder (FDR) capable of storing the last 90 minutes of flight data for post-crash flight reconstruction. The aircraft is fitted with a Crash Position Indicator (CPI) and a survivable Underwater Locator Beacon (ULB). Halon 1301 will be employed for avionic system fire suppression within sealed avionic bays.
FLIGHT DECK
The SM-72 features a cockpit designed for two-person, human-centered, reduced workload operations. The flight deck design accommodates a wide spectrum of male and female crewmembers encompassing the 1st percentile female through the 99th percentile male (NATO) population range, corresponding to crewmembers ranging from 5 ft 4in/100 lbs through 6 ft 4 in/250 lbs.
Employing a traditional yoke, full deflection rudder pedals, and FADEC engine control system, the SM-70 panel features redundant, dual instrumentation and displays. The primary pilot flight reference instrument is a Honeywell-produced derivative of the Primus Epic Integrated Avionics system that includes a total of six 10 x 13 in multi-functional Liquid Crystal Flat Panel Displays with Integrated Primary Flight Display (IPFD) and Integrated Navigation (INAV) technology. To interface with the Primus Epic system, a side-mounted cursor control system and keyboard interface is provided for the pilot and co-pilot. The Honeywell Visual Guidance System Head-Up Display (VGS HUD) offering a 25 x 30 degree field of view is provided for both the pilot and co-pilot. For in-flight emergencies, all SM-70 series aircraft are equipped with stand-by analog instruments including attitude and airspeed indicators as well as an altimeter, HSI, and clock.
Cockpits are designed for day/night VFR/IFR operations and are Generation IV night-vision compliant. With avionics integrated about a MIL-STD-1553B interface/data bus, all SM-70 series models feature additional avionic and sensor systems appropriate to their mission profiles. For crew comfort, the cockpit is pressurized to 6,000 ft equivalent atmosphere at altitude with standby crew oxygen provided by a Carlton OBOGS.
The SM-72 features a comprehensive Electronic Counter Measures (ECM) suite including the AN/AAR-47 missile warning system, AN/ALE-47 chaff/flare dispensing system, the AN/ALR-56 Radar Warning Receiver (RWR), and the AN/ALR-69 enhanced radar warning system. A detailed listing of Electronic Counter Measures which will be considered to be Standard Configuration Avionics are provided on the SM-72 Performance & Specifications webpage.
STRUCTURE
The SM-72 is of fail-safe, semi-monocoque construction composed of an alloy internal substructure consisting of Titanium load bearing elements with Aircraft Aluminum and Graphite Reinforced Plastic (GRP) as load-bearing stressed external skins and Kevlar Reinforced Plastic (KRP) secondary structural skins. Approximately 46% of the aircraft structure is composite by weight, with the remaining 54% is advanced aerospace alloys Approximately 34% of the SM-72 primary structure is GRP, while 10% is KRP. Principal composite materials employed throughout the SM-70 structure include Hexcel IM-9 Graphite Fiber/Polyimide Resin as the GRP and Dupont Kevlar/Polymer Resin as the KRP. The primary Polyimide resins employed include high-temperature, autoclave cured RP46, BIM-AC non-mutagenic/non-carcinogenic polyimide, AMB-21polyimide or DMBZ-15 polyimide.
A significatn number of aircraft components are made from Titanium, which totals 22% of the aircraft structural weight. Chosen due to its high strength to weight ratio and resistance to galvanic corrosion when fastened to composite materials, titanium components are produced using laser forming, laser machining and traditional aerospace Titanium part production methodologies. Aluminum alloys constitute approximately 33% of the aircraft primary structure by weight, with principal aluminum alloys employed including Alcan/Alcoa produced aluminum alloys such as 7150-T7751 Aluminum, 7075-T651 Aluminum, 7055-T7751 Aluminum and other high performance aircraft aluminum.
The SM-72 benefits from advanced structural manufacturing techniques where primary alloy structural members including fuselage frames and ribs are unitized, single-piece construction produced by Stavatti qualified Industry Team Members. Individual alloy structural members, including primary spars, ribs, longerons and frames are mechanically fastened together using rivets or bolts or welded using inert/laser processes. Composite materials are mechanically fastened to the alloy substructure using rivets, bolts and proprietary fastening systems, or alternatively, co-cured to high temperature titanium elements during the component autoclave cure cycle. The SM-70 features no bonded components.
The SM-72 is designed for a maximum limit load factor of +4.5/-2.0 at MTOW. The composite and corrosion resistant alloy construction offers a minimum 40-year service life corresponding to approximately 60,000 flight hours.
The SM-72 features a rectangular cross section fuselage to maximize mission effectiveness while offering significant load flexibility. Of modular four-section construction, the SM-72 fuselage includes a reduced drag nose section and reduced base-drag aft fuselage with aft drop-down cargo ramp. The fuselage is of fail-safe sandwich construction is composed of a distinct inner skin and outer skin. Unique to Stavatti, the double-hull fuselage design is composed of load-bearing Aluminum inner and Aluminum and KRP outer skins separate on the order of six inches by an internal sandwich structure composed of a titanium keel, multiple titanium longerons and titanium frames. To augment the Aluminum frames, Titanium frames are also employed in the fuselage sandwich structure, constituting approximately one-third of all frames. Over 75% of the SM-72 fuselage is composed of Aluminum, 25% of the fuselage is Titanium, anda approximately 5% is KRP. SM-72 internal fuselage skins are designed for pressurization levels equivalent to 6,000 ft at altitudes of 36,000 ft.
The SM-72 is a high-wing model plane with traditional vertical and horizontal stabilizers. SM-72 wings are high-wing, dorsal fuselage mounted cantilever, M-planform and Channel-Wing configuration. Inspired by work performed by Georgia Tech Research Institute (GTRI) and NASA Langley Research Center regarding Pneumatic Channel Wing Powered-Lift Advanced Super STOL Aircraft, the SM-72 wing combines a semi-elliptical, compound swept planform with a powered-lift channel wing, double slotted Fowler Flaps with leading edge slats and significant boundary layer control.
The SM-72 will benefit from the Channel Wing. Originally developed by Willard Custer during the 1950s, the “Custer Channel Wing” realizes high local lift coefficients and corresponding effective downward deflection of propulsive thrust through the placement of an aircraft's engine-driven propeller at the trailing edge of a 180º circular arc wing channel. Placing the propeller at the trailing edge of the circular arc channel increases airspeed over the channel's upper wing surface and augments lift production.
AIAA 2002-3275: Pneumatic Channel Wing Powered-Lift Advanced Super-STOL Aircraft
Experimental Development and Evaluation of Pneumatic Powered-Lift Super-STOL Aircraft
As a structural element, the wing channel is a mounting point for aircraft landing gear sponsons that incorporate port and starboard main landing gear bogies, respectively. The sponsons provide additional volume for avionics systems, electronic warfare systems, storing ground handing systems and in the case of the port sponson, serve as the interface for the aircraft Single Point Refueling System (SPRS). The sponsons are also the primary ventral mounting fixture for the engine support pylons.
The SM-72 empennage is a fixed horizontal stabilizer mounted dorsally to the aft fuselage section and a single, dorsally mounted vertical stabilizer. The horizontal stabilizer is connected structurally to the aircraft fuselage at its root chord while the tip chord is mounted to the trailing portion of the aircraft engine nacelles, providing a rigid cantilever body for nacelle attachment. The vertical stabilizer is connected structurally to the aircraft aft fuselage at its root chord. The horizontal stabilizer is composed of four titanium spars augmented by titanium ribs with mechanically fastened GRP skins. The vertical stabilizer is composed of two titanium and one GRP spar with GRP external skins. Numerous GRP construction internal ribs and false spars are employed throughout the vertical tail structure. The rudder is composed of GRP external skins with titanium and GRP internal elements, including spars and ribs.
FUEL SYSTEM
The SM-72 is equipped with a standard Internal Fuel System (IFS) that provides approximately 52,000 lbs of jet fuel, corresponding to 7,704 USG of JP-8 or 8,000 USG of JP-4. The IFS consists of eight discrete, sealed-cell fuel tanks contained within the SM-72 wings. Fuel tanks include two tanks mounted in the inboard wing sections (one tank per inboard wing) and four tanks mounted in the channel wing sections (two tanks per channel wing section) and two feeder/reserve tanks located within each engine nacelle. The OBIGGS aircraft fuel system is pressurized using the Carlton NC1069. Provisions for in-flight refueling include a dorsal fuselage integrated Universal Aerial Refueling Receptacle Slipaway Installation (UARRSI) located immediately above and aft of the flight deck.
To be developed in conjunction with Sergent Fletcher, Inc., the SM-72 CRT ARS consists of four permanent wing fuel tanks, one 3,600 USG removable, roll-on/roll-off Auxiliary Fuel Tank System and three Aerial Refueling Hose Drum Units. Functioning as auxiliary aircraft fuel tanks, these provide an additional 5,524 USG of fuel, equivalent to 37,287 lbs of JP-8 and are equipped with a Carlton NC1069 OBIGGS.
The SM-72 CRT ARS fuel delivery/pumping system consists of three retractable refueling drogue units including two wing tip, permanently mounted, integral refueling pods and one aft fuselage mounted refueling drogue unit located immediately above and aft of the aircraft main cargo ramp. All three refueling drogue units benefit from the proven Sergent Fletcher, Inc. Model FR-300 Aerial Refueling Hose Drum Unit. The FR-300 provides a fuel transfer rate of 150 to 500 GPM with a fuel pressure at coupling of 30 to 60 psi. Offering an operating airspeed range of 95 to 325 kts, the FR-300 provides an 82 ft long extended hose length. The SM-72 ARS permits simultaneous aerial refueling of up to three MV-22 Ospreys.
The SM-72 will feature full-authority, four channel digital Fly-By-Wire (FBW) flight controls with artificial force-feedback and yaw dampening. The SM-70 is equipped with a 4,000 psi hydraulic system for landing gear extension/retraction, cargo door actuation (SM-72) and flap extension and retraction. The SM-70 electrical system is driven by two 40kVA alternators and supplies 115-volt, three-phase, 400-cycle AC power and 28Vdc per MIL-STD-704D. Power is generated by engine driven alternators, the APU or a Ram-Air Turbine for in-flight emergencies.
Aircraft Self-start capability and onboard electric power generation is provided by a Honeywell 331-250 or Hamilton Sunstrand APU mounted within the aircraft wing/fuselage junction box. The 331-250 APU provides 90kVA and 447kW.
SM-72 Landing gear is hydraulically retractable, tricycle type consisting of a tandem wheel forward retracting nose unit and two quad-wheel trucks to serve as main gear, each of which retract into wing mounted sponsons. SM-70 series nose-wheels use a Goodyear Type VII 39 x 13, 16 ply Flight Leader tire rated to 225 mph at a maximum inflation pressure of 115 psi. Main wheels use the Goodyear Type VII 40 x 14, 24 ply Flight Leader tire rated to 225 mph at 170 psi. The nose wheel is steerable while all landing gear struts incorporate hydraulically actuated kneeling to improve cargo handling. All wheels are equipped with Goodrich carbon disk brakes.
