RBS 88 Waverider
General Characteristics:
Type:Hypersonic Cruise Missile
Launch platform:Aircraft
Guidance:Stellar-inertial, GPS
Physical Characteristics:
Weight:1,000 kg cruiser, 2,300 kg with booster
Length:4.0 m cruiser, 6.3 m with booster
Diameter:0.6 m
Payload:
RBS 88A:4x Rb 71 loitering munitions
RBS 88B:2x PC 100S hart target submunitions
Performance Characteristics:
Propulsion:Dual mode scramjet (sustainer), solid fuel rocket (booster)
Speed:Mach 8.0
Cruise altitude:30,000 m
Range:2,500 km
Overview:
The RBS 88 Waverider cruise missile is a long range, air launched hypersonic cruise missile intended to penetrate heavily defended airspace and destroy hardened and time-critical high value targets deep inside protected enemy airpsace. The missile is a two-stage design consisting of a solid rocket booster stage and a scramjet-powered cruiser stage which carries one of two interchangeable payload modules: a pair of 100 kg class hart target submunitions for prosecuting hardened and deeply buried targets, or a quad pack of advanced autonomous powered loitering submunitions for engaging mobile IADS and TEL targets.
Airframe & Propulsion:
The Waverider is a two-stage missile consisting of a solid rocket booster (SRB) aft stage and a scramjet-powered cruiser forward stage. The solid rocket booster (SRB) stage provides the initial acceleration from captive carriage release conditions to the scramjet takeover conditions of approximately Mach 4.5 at 20,000 to 25,000 meters altitude. The booster is a single-stage solid propellant rocket motor with an interstage adapter that mates to the aft end of the cruiser stage. The booster weighs 1,300 kilograms and consists of a carbon fiber reinforced epoxy case containing approximately 1,000 kilograms of high energy solid propellant with a 90% solid loading consisting of 20% aluminum, 24% HMX, 46% AP, and 10% HTPB binder. The booster burns for 25 seconds with an average thrust of 95 kN. The booster is connected to the cruiser stage through a marman-clamp interstage adapter ring. Upon achieving scramjet takeover conditions (confirmed by the cruiser stage flight management computer via inertial measurement unit data), the interstage separation sequence is initiated. The marman clamp releases, and two pyrotechnic thruster assemblies mounted on the booster forward bulkhead push the booster cleanly aft and away from the cruiser.
Simultaneous with separation command, the cruiser stage scramjet engine fuel system initiates fuel flow to the engine, and the dual-mode scramjet transitions from ramjet pilot ignition to full ramjet operation within 1.5 seconds of fuel flow initiation. This overlap period is managed by the flight management computer to ensure continuous thrust during the booster-to-scramjet transition.
The cruiser stage employs a hypersonic lifting body derivative configuration. The forebody features a sharp-edged wedge-shaped compression surface that generates a planar shock wave, which is captured by the scramjet inlet located on the vehicle underside. The aftbody incorporates a single-expansion-ramp nozzle (SERN) that expands engine exhaust gases along the vehicle lower surface. The waverider-derived forebody is designed to operate efficiently across the Mach 4.5–8.0 speed range, encompassing the booster-to-cruiser transition regime through maximum cruise speed. The forebody compression ramp angle is set at 6.5 degrees, a design compromise between maximizing inlet pressure recovery at cruise Mach number and maintaining acceptable performance during ramjet-mode operation at lower Mach numbers. The leading edges of the forebody, inlet cowl, and control surfaces employ blunted geometries with radii selected to balance aeroheating loads against aerodynamic efficiency. The aerodynamic configuration provides a maximum trimmed lift-to-drag ratio (L/D) of approximately 3.5 at Mach 8.0 cruise conditions. The cruiser is constructed primarily from Ti-6242S (Ti-6Al-2Sn-4Zr-2Mo-0.1Si) near-alpha titanium alloy covered with an ablative silica phenolic based thermal protection system. The wedge shaped nose of the cruiser, which has to endure a leading edge temperature of over 1,600° C during Mach 8 cruise, is constructed from an Ultra-High Temperature Ceramic Matrix Composite (UHTCMC) composite consisting of hafnium diboride (HfB2) in a silicon carbide (SiC) fiber-reinforced matrix which is capable of sustained operation above 1700 °C. The four control fins of the cruiser are constructed from cast titanium-aluminide (TiAL) intermetallic alloy with UHTC coated carbon/carbon (C/C) leading edges.
The cruiser stage of the Waverider is powered by an SDI SRM 200 scramjet engine, a rectangular dual-mode scramjet (DMSJ) engine integrated into the underside the missile. . The vehicle forebody serves as the external inlet compression surface, generating an oblique shock system that pre-compresses freestream air before it enters the engine module. The engine module itself consists of an internal inlet section with additional compression, an isolator duct, a fuel injection and combustion section (combustor), and an internal nozzle/expansion section. The vehicle aftbody lower surface serves as the external single-expansion-ramp nozzle (SERN). The scramjet is fed using a fixed geometry two dimensional mixed compression nose inlet which consists of an aerodynamic compression ramp, sidewalls, a cowl lip, and an inlet duct which leads into the scramjet isolator. Downstream of the inlet, a constant-area isolator duct provides a buffer between the inlet and the combustor. The isolator during subsonic combustion (ramjet) mode at lower Mach numbers (Mach 3.5 to 5.0), the pre-combustion shock train generated by thermal choking in the combustor is contained within the isolator, preventing inlet unstart. The isolator length-to-height ratio (L/H) is 8.5, which provides adequate margin for shock train containment across the dual-mode operating range. The inlet ramp and isolator walls are fabricated from C/SiC CMC and are cooled by fuel routed through integrated catalytic heat exchanger/reactors (CHERs) where endothermic cracking of the hydrocarbon fuel is used to reduce the extremely high heat load experienced by the scramjet engine structure at hypersonic speeds. The combustor is a rectangular-section duct with a slight divergence to accommodate heat release and prevent thermal choking at the design cruise condition. Fuel injection is accomplished through a multi-stage system designed to optimize combustion efficiency across the full Mach range. Two recessed cavity flameholders are located on the (lower wall of the combustor. Fuel is injected upstream of each cavity through flush-wall sonic orifice injectors. The cavities provide a recirculating, near-stoichiometric, subsonic combustion zone that acts as a continuous ignition source for the main fuel injection. Downstream of the cavity flameholders, fuel is injected from the body-side and cowl-side walls through arrays of aerodynamic ramp injectors. Each aero-ramp injector consists of a pair of angled sonic orifices that generate counter-rotating streamwise vortex pairs in the supersonic crossflow, dramatically enhancing fuel penetration and mixing without the total pressure losses associated with physical strut or ramp injectors. The secondary injection provides the bulk of the fuel at the high-Mach cruise condition. A small set of pilot injectors with integral spark igniters are located at the forward end of the combustor, upstream of the primary cavities. These injectors supply a pre-cracked, highly reactive fuel fraction directly from the CHER system to ensure reliable ignition during the booster-to-scramjet transition and during any transient combustion events. The engine exhaust expands through an internal diverging duct section followed by the vehicle aftbody single-expansion-ramp nozzle (SERN). The internal nozzle provides initial expansion to a pressure ratio that prevents flow separation at the internal-to-external nozzle junction. The SERN lower surface is contoured to provide near-optimum expansion of the exhaust gases to ambient pressure at the design cruise altitude. Cowl-side closure of the SERN is provided by the freestream flow itself, creating an aerodynamic cowl. The nozzle forward section incorporates regenerative fuel cooling through passages machined into the carbon-carbon structure.
The dual mode scramjet engine that powers the Waverider is capable of operating as either a ramjet or scramjet, known as "dual-mode" operation. The dual-mode scramjet consists of four sections, an inlet, a constant volume isolator, a combustor, and a nozzle. The dual-mode scramjet is lit at Mach 4.5 and initially operates as a ramjet, decelerating the flow to subsonic speeds before combustion, with combustion taking place at constant pressure. As the Mach number is increased past 5 the the subsonic ramjet transitions into the dual-mode regime, where the combustor inlet Mach number is increased enough such that a thermal throat is created in the combustor and a pre-combustion shock train is generated. The isolator is designed to prevent this shock train from reaching the inlet to prevent inlet unstart which would choke the engine of airflow. In this regime the combustor operates in a mixed subsonic/supersonic, or dual-mode. As the Mach number is further increased past 6 the pre-combustion shock train moves out of the isolator and the combustor operates in the supersonic mode with combustion taking place at a constant volume, rather than at a constant pressure like in the subsonic combustion regime.
The scramjet engine is fueled with J9 high density synthetic endothermic hydrocarbon fuel which undergoes thermal cracking at high temperatures in the presence of a catalyst, undergoing catalytic dehydrogenation and yielding hydrogen gas and new hydrocarbon compounds while absorbing a significant amount of heat without forming any surface deposits. The Catalytic Heat Exchanger/Reactor (CHER) system consists ofmcompact, engine-integrated heat exchanger units in which the fuel flows through catalytic passages in intimate thermal contact with the hot engine structure walls. As the fuel absorbs heat, it reaches temperatures at which endothermic catalytic cracking reactions are initiated, breaking the long-chain hydrocarbon molecules into shorter-chain species (ethylene, propylene, methane, hydrogen) through dehydrogenation and carbon-carbon bond scission reactions. These endothermic cracking reactions are strongly heat-absorbing, providing a chemical heat sink that approximately doubles the effective cooling capacity of the fuel compared to sensible heating alone. The cracked fuel products (a mixture of lighter hydrocarbons and hydrogen) are then injected into the combustor, where they offer superior ignition and combustion characteristics compared to uncracked J9, due to their lower molecular weight, higher diffusivity, and the presence of highly reactive species such as hydrogen and ethylene. The catalytic heat exchanger/reactors (CHERs) constructed from beta 21S (15Mo2.7Nb3Al0.2Si) beta titanium alloy located inside the C/SiC walls of the engine. The B21S titanium alloy is insulated from the C/SiC walls with a small air gap, ensuring the beta 21S titanium stays within its 675° C operating temperature. The CHERs are constructed as brazed plate-fin heat exchanger assemblies fabricated from beta 21S with the fuel side passages being coated with a zeolite-supported platinum-rhenium (Pt-Re/ZSM-5) catalyst that promotes the desired endothermic cracking reactions at temperatures above 480°C . The hot-side passages interface directly with the engine structure walls (combustor walls, isolator walls, and inlet aft walls), receiving heat by conduction where the catalyst and the radiant heat from the C/SiC scramjet walls causes the J9 to decompose into hydrogen, cyclohexene, and various alkylcyclohexenes. The CHER system is distributed across three zones within the engine module, sized according to the local heat flux distribution. Two CHER panels are integrated into the isolator sidewalls and cowl-side wall and pre-heat the fuel to approximately 300–400°C with limited cracking (5–10% conversion). Fuel exiting the isolator CHERSs is split between the subsequent combustor CHERs and the the pilot injectors. Four CHER panels are integrated into the combustor body-side and cowl-side walls. Fuel enters at 300–400°C from Zone 1 and exits at 600 to 700°C with 40–60% endothermic cracking conversion. Finally a conventional regenerative cooling jacket (not catalytic) in the forward portion of the internal nozzle, where fuel absorbs additional heat before being routed to the secondary (aero-ramp) fuel injectors. The J9 fuel is stored in two conformal fuel tanks located within the cruiser stage body, forward and aft of the payload bay. Total fuel capacity is approximately 600 kg. Fuel is pressurized by a turbin -driven fuel pump, which is powered by a small turbine driven by hot, partially cracked fuel bled from the isolar CHER outlet. The fuel system operates at pressures of 60 to 80 bar throughout the cooling and injection circuits to suppress fuel coking and vapor formation at elevated temperatures. A fuel management controller (FMC) continuously monitors fuel temperatures, pressures, and flow rates at multiple points in the system, and modulates fuel flow splits between the CHER zones and fuel injection stages to maintain thermal equilibrium. The FMC operates under the authority of the vehicle flight management computer (FMC) and receives real-time engine health monitoring data from thermocouples and pressure transducers distributed throughout the engine flowpath.
Guidance:
The Waverider is guided in flight by a stellar-inertial guidance system which provides highly accurate midcourse guidance without reliance on GPS signals. The guidance system consists of a 6-axis SDI TNS 450 tactical-grade timing and inertial measurement Unit (TIMU) which combines three milli-Hemispherical Resonator Gyroscope (mHRG) and three quartz resonating beam accelerometers (RBA) in a low SWaP package (500 cc volume, <1.0 kg mass, <5 watts max power consumption) package which provides <0.0003°/√hr gyro angle random walk and < 0.0001 °/hr bias stability performance coupled to a CCD star-tracker camera which looks upward through a circular window located in the upper fuselage of the cruiser stage. The star tracker employs is uses to provide position fixes in flight accurate to within 90 meters in broad daylight using a pre-programmed 57 star catalog. The IMU and stellar sensor are further augmented by a 48 channel dual-frequency (L1/L2) SAASM (Selective Availability Anti-spoofing Module) based GPS receiver with M-Code compatibility and >90 dB J/S digital anti-jamming capability whuch employs twin controlled reception pattern antennas (CRPAs) on the aft fuselage of the cruiser with adaptive beam steering and directional nulling capability with ionosphere correction capability and simultaneous L1/L2 operation which provides the weapon with <1 meter position accuracy capability. in heavy GPS jamming environments.
Warhead:
RBS 88A: The RBS 88A is designed to attack time-critical relocatable targets including mobile surface-to-surface and surface-to-air missile batteries and dispenses a payload of four Rb 71 loitering autonomous submunitions onto the target area. Each Rb 71 submunition weighs 45 kilograms and consists a maneuvering airframe 90 centimeters long with a 1.2 meter wingspan powered by a small turbojet engine which contains a solid state LADAR sensor with automatic target recognition (ATR) capability coupled with a multimode explosively formed penetrator warhead. The Rb 71 is powered by a 130 N thrust SDI RM55 micro-turbojet engine which gives the munition a maximum speed of 430 kph (Mach 0.30) an an altitude of 250 meters AGL with a maximum range of 185 kilometers and a maximum flight endurance of 30 minutes. The munition's seeker consists of a solid state three-dimensional imaging LADAR sensor employing an uncooled, diode pumped Nd:YVO4 laser with a 1.06 μm wavelength. The LADAR seeker is capable of acquiring vehicle size targets at a range of 6 km in clear weather and produces high resolution 3D imagery which is processed by an automatic target recognition processor which compares the LADAR image to a database of threat vehicles. When the munition identifies a target it cuts its turbojet engine and glides towards the target to a point directly overhead where the munition's downward firing explosively formed penetrator (EFP) warhead is then fuzed. The warhead weighs 8.0 kilograms including 2.5 kg of polymer bonded explosive (92% HNIW, 4.8% BDNPA/F, 3.2% CAB) and can be miniated in one of three modes depending on target type and standoff range. Against armored targets the warhead is fired in a long rod penetrator mode which is designed for maximal armor penetration. Alternatively if fuzed from a greater altitude over the target the warhead is fired as an aerostable slug which maintains aerostability over greater standoff ranges while still having the capability to penetrate the thinner roof armor of most vehicles. Against softer targets such as TELs or radars the warhead is used in a directed fragmentation mode which causes the tantalum liner to break up into shrapnel which is projected towards the target area like a large shotgun blast.
RBS 88B: The RBS 88B is designed to penetrate and destroy hardened aircraft shelters, command bunkers, and other hard targets and contains a payload of twin PC 100S bombs which are released from the cruiser stage at high supersonic velocity prior to impact. Each PC 100S weighs 110 kilograms and employs a 100 kilogram hardened penetrator warhead consisting of a nickel-molybdenum-cobalt maraging steel (8Ni-14Mo-20Co-Fe) sub-caliber penetrating warhead filled with 20 kilograms of enhanced blast thermobaric explosive (50% HMX, 30% Al powder, 20% PCP/TMETN energetic binder/plasticizer). The warhead is fitted with a base mounted hard target smart fuze (HTSF) containing a precision MEMS accelerometer and micro-controller which features void sensing, layer counting, depth of penetration, and time time delay after impact fuzing modes. The detonator is entirely electronic with no moving parts and uses an exploding foil initiator (EFI) detonator to initiate the main explosive charge. The warhead is coupled to a guidance and control section consisting of a 6-axis SDI TNS 400 MEMS based inertial measurement unit along with a control section featuring three flip-out grid fins actuating using brushless DC electro-mechanical servomotors. With a terminal impact velocity of over 1,000 meters per second (mach 4) each PC 100 munition is capable of penetrating over 4 meters of 34 MPa (5,000 psi) reinforced concrete before exploding.
