Pakistan has been developing and testing subsonic cruise missiles for more than a decade now. ISPR, Pakistan reported on 21 December 2021 that a successful test had been conducted of an enhanced range version of the indigenously developed Babur Cruise Missile 1B. More detailed information like range, image/video, launch platform, etc was not publicized that can corroborate vital information on the test. This is the second test of Babur missiles in the year 2021 post the successful training launch conducted of Babur Cruise Missile IA with a range of 450km. In 2018, Pakistan conducted a successful test of an enhanced range version of the indigenously developed Babur Cruise Missile 1B. It also highlighted that Babur Weapon System-1 (B) incorporates “advanced aerodynamics and avionics that can strike targets both at land and sea with high accuracy, at a range of 700 kilometres. It is a low flying, terrain hugging missile, which also carries certain stealth features and is capable of carrying various types of warheads. Equipped with state of the art navigational technologies of Terrain Contour Matching (TERCOM) and all-time Digital Scene Matching and Area Co-relation (DSMAC) which enables it to engage various types of targets with pinpoint accuracy even in the absence of GPS navigation, thus making it an important force multiplier for Pakistan’s strategic deterrence.” All the variants of Babur cruise missiles currently with Pakistan are claimed to be TERCOM compliant. A compendium of Babur cruise missile tests is presented below.
In 2018, ISPR had made clear statements on the performance and capabilities of the Babur-1B cruise missile. The December 2021 Babur-1B missile test press release insists on the range increment of the Babur-1B missile. Some media reports the Babur-1B that flew in December 2021 completed a 900km range. However, Pakistani media seems to be silent about such details of the test.
It is worthwhile to consider the video released by ISPR in 2018 on the Babur-1B missile test launch to draw vital information on the missile. Below listed are the observations from Pakistan’s official video:
- The missile was launched from a road-mobile TEL whose chassis contains 5 axles.
- The missile was contained in a single square cross sectioned canister with two missile tubes; one is seen open and the other in closed position.
- Missile launch angle is 90⁰.
- On visual inspection, the booster and sustainer diameters are same.
- No salvo firing of Babur-1B missile is observed.
Missile and subcomponent dimensions
Figure 1 Babur TEL at the test site before missile launch
Figure 2 Babur-1B missile launched from TEL in 2018 test
Figure 3 Babur-1B during cruise after booster separation
The dimensions of 2018 Babur-1B can be brought out from figures 1,2 and 3 obtained from the ISPR video. Pakistan produces 5-axle Babur TEL at the National Development Complex in Fatehjung and the same must have been used in this case. The dimensions of TEL and Babur-1B missile (table 2) are derived from images calibrated by the known dimensions of the medium utility truck found in figure 1.
For the missile dimensions measured, the length and mass breakup are presented in table 3. Guidance system mass constitutes the inertial guidance system, cameras, altimeters with processors, terminal guidance, GPS navigation capabilities, Terrain contour matching and digital scene matching and co-relation systems. The payload could be conventional or nuclear considering the nuclear warhead manufacturing capability acquired by Pakistan after Nasr TNW. The same 0.9 m long Babur engine is assumed for the current assessment. The main fuel tank is housed in the forebody of the missile. The mid-body houses wings, actuator and actuating systems, wing deployment systems, battery, and fuel tank. The total mass excluding solid rocket stage mass serves as the initial mass estimate for cruise while the final mass assumes 10% of fuel entrapped in the engine and pipelines.
Missile Performance
Considering the aerodynamic configuration of Babur-1B similar to that of Tomahawk missile, the same wing reference area and coefficient of drag relationship for range estimation. The approach of Nagappa et al for range estimation is followed in the current assessment. The initial and final masses considered for cruise conditions are 1520 kg and 1335.5 kg respectively. The range computation is carried out by increasing the coefficient of drag (Cd) value by 15% to account for the possible reduced aerodynamic efficiency compared to Tomahawk missiles. The full fuel capacity of Babur-1B is 205kg out of which 10% is assumed to have been entrapped in the engine and pipelines at the end of the cruise. The results of range estimation carried out for full fuel capacity are summarized below.
The range estimated in the above table is the maximum downrange coverable during a straight flight for the fuel available. It is to be noted that some of the downrange is reduced during a standard cruise missile mission consisting of climb and descent phases, additional maneuver and loiter requirements. Thus, the actual range of the missile is less than the maximum achievable straight flight range and can be approximated to 800-820 km.
Extended range demands extra fuel and weight changes accordingly. To cover a range of 900km in a cruise mission, the length of the forebody fuel tank and thereby the overall length must be increased by 0.5m with full fuel capacity. The cruise time also extends to 80mins to achieve the ∆range of 200km at the same speed. The increased length of the missile would subsequently increase the total weight to approximately 1800kg comprising of the fuel tank structure, airframe, and the fuel weight itself.
Conclusion
The absence of any video or images of the 2021 test suggests there could be no major changes in the missile dimensions and the subsequent configuration. With the dimensional constraints of the currently known Babur-1B missile, further range improvements up to 900 km may not be achievable. However, by increasing the overall length of the missile by 0.5m at full fuel capacity, a range of 900km is possible and can be expected from Pakistan in the coming years. The possibility of Pakistan incorporating a modified fuel with increased fuel energy density (MJ/L) and specific energy (MJ/kg) to achieve a longer range may not be ruled out.
Acknowledgement: The author is grateful to Prof. Rajaram Nagappa, Professor, ISSSP, NIAS, Bengaluru for the constant motivation, support, and guidance provided by him during the preparation of the article.