EW Engagement Modelling for Light Armoured Vehicles

Transcription

1 EW Engagement Modelling for Light Armoured Vehicles Vivienne Wheaton Electronic Warfare and Radar Division, DSTO Light Armoured Vehicles (LAVs) have many advantages in military operations but are significantly vulnerable to the increasingly lethal weaponry fielded in the land environment. EW technologies in the areas of threat warning, signature management and countermeasures potentially improve LAV survivability against such threats, if the technology is supported by effective tactics. We show some work with an infrared (IR) battlespace engagement simulation program, exploring LAV survivability in one-on-one engagements with guided and unguided missiles. The results shown in this presentation are generated from generic models of missiles and EW countermeasures, rather than validated models. As such they are not to be expected to provide results about actual tactical effectiveness of the countermeasures discussed here. This talk is about using an engagement modelling approach to generate advice on requirements for effective deployment of EW threat warning and countermeasure technologies on land platforms. This talk will show, through a series of examples, how this type of modelling can provide advice on system requirements for effectiveness of EW technologies, and on developing supporting tactics. Results from the series of simulated engagements demonstrate how timely threat warning can be combined with vehicle manoeuvres and IR decoys to improve survivability. The effect of thermal signature on vulnerability to IR tracked missiles is also investigated, and can be used to determine what levels of signature management are effective. These simulation results can provide groundwork for the development of tactics and operating concepts to maximise LAV survivability when the vehicle is enhanced by EW threat warning technology, countermeasures and signature management. 1

2 Problem: How do we protect LAVs? Layered Survivability: Light Armoured Vehicles (LAVs) number amongst their advantages high mobility and relatively low cost. We want to enhance their survivability against highly lethal weapons found on the battlefield today, but we want to retain these advantages. The traditional land vehicle solution is to add heavier and heavier armour, (the avoiding penetration layer in the figure here) but this approach seriously compromises a light vehicle s mobility well before the level of armouring necessary to protect it is reached. Therefore, we look to maximising the effectiveness of using technologies that work in the outer layers of the layered survivability approach: Hit Avoidance and Detection Avoidance. EW hit avoidance technologies include threat warning systems coupled with jamming systems and decoy or seduction systems. Detection avoidance technologies include camouflage materials, radar or heat absorbing materials and signature minimising design. This work will focus in the Avoid being Hit domain. That is, the engagements modelled are ones where the vehicle has been detected, acquired as a target and fired on. Detection avoidance systems can also potentially have a role in this sort of engagement, where improved signature management may make it difficult to track the vehicle under fire. 2

3 Missile Threats & Survivability Measures Unguided Missiles Manoeuvre SACLOS Missiles Manoeuvre Obscurant smoke Signature management Engagement Modelling: Simulated Scenarios Seeker Missiles Manoeuvre Obscurant smoke Signature management Modelling Software: CounterSim Land v (Chemring, UK)* *Walmsley, R. & Butters, B. Infrared Smoke Modelling in CounterSim, Proc. of SPIE (Technologies for Optical Countermeasures IV), 2007, vol 6738 We show some work with an infrared (IR) battlespace engagement simulation program, CounterSim, exploring LAV survivability in one-on-one engagements with guided and unguided missiles. Three types of missiles are modelled generically in this work an unguided missile, similar to an RPG, (pictured) a SACLOS missile using a thermal tracking sight (similar to the Metis system pictured), and a fireand-forget IR seeker missile (such as the Javelin missile illustrated). The results shown in this presentation are generated from missile models built from simple expectations of missile behaviour and some physical missile data from Janes Defence products, not validated missile models. As mentioned earlier, the examples shown here are therefore not to be expected to provide results about actual tactical effectiveness of the countermeasures (which are also modelled generically and with no validation) against these threats. Three types of vehicle survivability response are modelled: Vehicle manoeuvre, assuming threat warning, launch of IR pyrotechnic smoke grenades (again assuming threat warning) and improved signature management. A few example scenarios are shown in this work - vehicle manoeuvre against unguided missiles, vehicle manoeuvre and signature management against SACLOS missiles and vehicle manoeuvre and smoke grenade firing against seeker missiles responses italicised are those that are also possible given current LAV operating concepts, but that are not covered in the examples given here. EW threat warning technology is not physically simulated here; rather, a simple detection range is specified, and the vehicle is programmed to respond either immediately or after a specified delay. The question investigated with this construct is how soon after detection by a threat warning system does the vehicle need to initiate a response to survive the engagement? The answer to this question, when accurate models are used, would give vehicle system designers information about automating responses in what scenarios is automation necessary, and what time constraints exist on the process. A simple manoeuvre is executed by the vehicle in all these scenarios: the vehicle, moving at a constant speed, when prompted by the threat warning model, makes a manoeuvre response by turning through a specified angle and continuing at the same speed. By repeating the simulation through a range of turn angles, we can identify manoeuvres most likely to be effective. All these scenarios are modelled in a simple flat plain environment. Launch of IR pyrotechnic smoke grenades is modelled similarly using a delay after threat detection. The CounterSim smoke model, initially developed by Chemring for modelling their own smoke products for internal research and development, is a high-fidelity model of the physical dynamics of smoke production and dispersion. See Infrared Smoke Modelling in CounterSim by Walmsley&Butters for details. 3

4 Scenario 1: Vehicle Manoeuvre vs. Unguided Missile These are a set of representative results of the first scenario modelled, of a vehicle against a unguided missile. When targeted by an unguided missile, there are limited options for applying EW technologies. Some EW threat warning systems can detect RPG launch, but this is only useful if the vehicle can respond in some way to the information about the incoming threat. Running a series of simulations varying vehicle manoeuvre, and delay between missile firing and initiating manoeuvre, we see here how we can get results that can indicate the manoeuvre direction most likely to evade an incoming missile, and an estimate of the maximum delay time between missile firing and vehicle response. Miss distance is plotted here for each angle of vehicle manoeuvre four threat ranges, 100 to 400 metres, and for two delay times. These two figures show how the optimum angle of turn - i.e. the one that maximises miss distance - for a vehicle in this engagement depends on the threat range. This is a result of the fact that the closer the missile is fired from, the less time a vehicle has to respond turning through a large angle takes time, so the miss distance is maximised by a smaller angle of turn than for longer threat ranges. Comparing the two figures, you can see how you can generate results indicating the time constraint on any vehicle response in this example, where no delay between firing and vehicle response was assumed, the vehicle could survive all but the closest range engagement, but where even a very short (0.5 second) delay was introduced, the vehicle could only survive the farthest range engagement. 4

5 Scenario 1: Vehicle Manoeuvre vs. Unguided Missile These two figures show more information from the same scenario, this time looking at the effect of varying vehicle speed. Both figures here show miss distances plotted against angle of manoeuvre again, this time both assuming a 0.5 second delay between missile firing and vehicle response. Here we can see how results of these engagement simulations can provide further operational advice to deploying threat warning technology on LAVs the vehicle speed is important in determining whether it survives the engagement. In these scenarios, the addition of threat warning technology, combined with very fast response, aids survival in more instances when the vehicle can travel at high speeds. 5

6 Missile Threat & Survivability Measures SACLOS Missiles Manoeuvre Obscurant smoke Signature management Engagement Modelling: Simulated Scenario # 2 For a vehicle engagement with a SACLOS missile, the second type of threat scenario, the response options simulated are manoeuvre (assuming threat warning) and enhanced signature management. Launching smoke obscurants is another way of countering SACLOS missiles, which is not shown in this work. In this engagement, an IR-tracked SACLOS missile is fired at the vehicle from 2000 metres downrange. The vehicle executes a simple manoeuvre (a turn through a range of angles) after a delay, and miss distance is recorded for each engagement. The engagements are run with two levels of signature management a normal level, using the vehicle model with it s default radiated temperature settings, and a hypothetical stealthy level, with the vehicle model s radiated temperatures drastically reduced. 6

7 Scenario 2: Signature Management vs. SACLOS Missile Scene plain 60 Sum of ASLAV Miss Distance m Signature level Speed normal - 15 normal - 19 stealthy - 15 stealthy TurnAngle This figure plots miss distance vs. manoeuvre angle with varying vehicle speeds (15 m/s and 19m/s) for the two signature levels. The manoeuvre angles used here are a set of angles which maximised miss distances in the previous unguided missile engagement. We see here that in this scenario the massive Thermal IR signature reduction of the stealthy model (results indicated by the blue lines) has enabled the vehicle to survive the engagement, effectively causing the missile operator to be unable to track the manoeuvring vehicle. The normal vehicle (red lines) however did not survive any of these engagements. Results from this modelling this type of engagement can inform development of signature management systems, by indicating the levels of signature management needed to be effective, and can inform deployment concepts by indicating what range of scenarios and missile capabilities that level of signature management is effective for. This information can also inform development of requirements for EW threat warning, by determining what level of identification of threat missiles is necessary to enable the vehicle commander (or an automated system) to choose an effective response. For example, if the signature management system on a vehicle makes manoeuvre effective against one family of SACLOS missiles, but not another, then an EW threat detection system that is capable of identifying the difference between these two is more useful when a vehicle can fully exploit the threat information. We again see here in this scenario that higher vehicle speed maximises miss distance, information that, for example, could be use to inform development of operating concepts for deployment to theatres where this type of SACLOS missile is used. 7

8 Missile Threat & Survivability Measures Engagement Modelling: Simulated Scenario # 3 Seeker Missiles Manoeuvre Obscurant smoke Signature management For a vehicle engagement with a seeker missile, the third type of threat scenario, the response options simulated are manoeuvre (again assuming threat warning) and launching IR smoke obscurants. Improved signature management could potentially address this this threat, or enhance the results of using smoke, but this is not simulated here. In this engagement, a heat-seeking fire-and-forget type of missile is fired at the vehicle from 4000 metres downrange. The vehicle is again modelled assuming a capability to detect missile launch, and initiates two responses: a simple manoeuvre (a turn through a series of angles), and a launch of smoke grenades. 8

9 Vehicle vs. Seeker Missile Scenario Wind direction Missile System θ= 170 Manoeuvre angle θ θ=170 N In this scenario a moderate cross wind is simulated, blowing from the west, across the paths of the initially north-bound vehicle and south-bound missile. The vehicle s 3 simulated manoeuvre angles are all aimed to hide the vehicle behind the smoke cloud created. Different delay times between detection and launch of grenades and initiation of manoeuvre are again simulated. Miss distance is recorded for each engagement. 9

10 Scenario 4: IR Smoke vs. Seeker Missile This figure again plots miss distance against manoeuvre angle. The three manoeuvre angles are 170 degrees, which is a turn to travel slightly with the westerly wind, 180 degrees, a turn directly south, and -170 degrees, a turn to travel slightly against the wind. This figure shows three different delays (0.5, 1 and 1.5 seconds) before launching smoke grenades, and two delays (0.5 and 1 second) before initiating manoeuvre, for three manoeuvre angles. The blue lines show the miss distances resulting from the various manoeuvre angles for a 0.5 second delay launching smoke, the red lines a 1 second delay before launching smoke and the green lines the 1.5 second delay. We see that for most of these engagements, the combination of IR smoke and manoeuvre was effective in enabling the vehicle to survive the engagement. The turn slightly with wind produced a larger miss distance, but the range of this engagement is such that the missile arrives at the target in less than 10 seconds, in which time the smoke cloud has not drifted very far. Where the vehicle initiates manoeuvre before launching smoke, we see this mostly has an adverse effect on survivability, (seen comparing the red line manoeuvre before launch- to the orange line, launch before manoeuvre), as the missile is able to better track the manoeuvring vehicle before the smoke obscures it. We also see the effect of a too-long delay between detection and launching smoke grenades the green lines showing the 1.5 second delay between detection and launch show that only one of the three manoeuvre angles allowed effective screening of the vehicle. From this type of engagement simulation we can get information about how quickly vehicles need to be able to launch a smoke response, which can inform the development of constraints on an automated response system. We can also develop manoeuvre tactics based on the response time and any effect of wind on the smoke cloud. The dependency of the best manoeuvre tactic on wind can show how much information a vehicle system needs have about its environment, and indicate in what scenarios situational awareness tools need to be able give vehicle commanders and systems information about wind speed and direction. 10

11 Summary: Using Engagement Modelling for Deployment of EW threat warning technology Is automated response to threat warning necessary? What response should the vehicle initiate? What threat information is required? Deployment of IR Smoke Countermeasures Must smoke launch be automated? How do you need to manoeuvre to effectively deploy smoke countermeasures? Deployment of Signature Management Systems How good does your signature reduction have to be to be effective? In summary, this has been a brief overview of using engagement level modelling to draw information to inform the development of systems and tactics to support the effective deployment of those systems in the following areas: In Deployment of EW threat warning technology we can use engagement modelling to answer the questions: Is automated response to threat warning necessary? Analysis varying delay between detection and response can show that for surviving some engagements, response must be very fast, which indicates that automatic response may be necessary. What response should the vehicle initiate? Analysis comparing miss distances for various vehicle survivability strategies here vehicle manoeuvre, launch of smoke grenades, and improved signature management can indicate which scenarios each response is appropriate for. What threat information is required? We saw in the first example how the range of the threat indicated different optimum manoeuvres. For that scenario, information about the threat range would be of obvious interest. In the second example, different missile families may have different tracking capabilities, for which different vehicle responses may be indicated. Deployment of IR Smoke Countermeasures Must smoke launch be automated? We saw how only relatively short delays between detection and launch enabled the vehicle to survive the example engagements. If this is the case when validated models then automation of systems may be necessary. How do you need to manoeuvre to effectively deploy smoke countermeasures? We saw manoeuvring with or against the wind affected survivability in some of the example engagements, and how delaying manoeuvre until after smoke grenades were launched generally produced better results. This type of information can inform development of operating concepts and indicate what environmental information may be necessary for effective situational awareness. Deployment of Signature Management Systems How good does your signature reduction have to be to be effective? And following that, in what scenarios or against what threat capabilities are the limits of the effectiveness of signature management reached? 11