Maiden Test-Firing Of India’s Nirbhay Strategic Subsonic Cruise Missile A Moderate Success

With the maiden test-firing yesterday of the indigenously-developed, 1,200km-range subsonic Nirbhay (Fearless) nuclear-armed cruise missile (which will eventually be available in both air-launched and submarine-launched versions), India took the first significant baby-steps toward fielding what will eventually—by 2017--become a family of multi-role subsonic cruise missiles available to both the Indian Air Force (IAF) and the Indian  Navy (IN). The maiden test-firing was conducted at 11.50am and what followed was a flawless liftoff, with its first-stage solid-rocket booster separating from the missile-body after attaining a height of 500 metres at a distance of 1.5km away from the launch-point. Thereafter, the missile’s sustainer powerplant, a turbofan, successfully came on-line and took the missile out to an altitude of 4km while cruising at Mach 0.7. However, some 10 minutes after liftoff, after the missile had travelled a distance of 200km and cruising at an altitude of 4km along a southwesterly flight-path skirting India’s eastern seaboard coastline, a deviation from its pre-programmed flight trajectory was observed due to a suspected navigational waypoint pre-programming error, following which it was decided by mission controllers located at the Integrated Test Range (ITR) at Chandipur-on-Sea to abort the flight-test to ensure coastal safety by cutting off the missile’s engine power, which led to the missile safely gliding down and crashing at the coastline of Odisha’s Jagatsinghpur district. This should not be surprising at all, since this has been a global norm in the history of long-range cruise missile R & D. For instance, the maiden flight-test of Pakistan’s 800km-range Hatf–VII (Babur) could fly out to only a distance of 17km on August 12, 2005, while its second test-firing saw the Babur attain a range of only 22km on March 22, 2007.

Despite this temporary setback, a number of mission objectives were achieved from this maiden test-launch of Nirbhay. Firstly, the robustness of the missile’s airframe and that of its two-stage propulsion system was proven beyond doubt, as was the reliability of the inertial navigation system and flight-control system. Secondly, this was the first time in the history of the MoD-owned Defence Research & Development Organisation (DRDO) that a real-time, combined RF/optronic flight trajectory-cum missile health tracking system was successfully employed for the Nirbhay's maiden cruise flight. This was done by equipping an IAF Su-30MKI chase-aircraft (out from Kalaikunda AFS) with a centreline pod containing tele-command guidance avionics (designed and developed by the Defence Avionics Research Establishment) that was responsible for receiving health-monitoring inputs from the Nirbhay’s specially configured on-board flight management avionics (these being located in the forward-mounted bulkheads designed for housing the digital terrain profile matching sensor and the warhead), and also for relaying flight termination commands in case of mission abort. In addition, the Su-30MKI also carried a FLIR sensor-equipped Litening-2 LDP for real-time visual tracking and monitoring of the Nirbhay’s cruise flight.

There are still nine more planned flight-tests of the Nirbhay through to 2017. The first two are meant for validating the robustness of the missile’s airframe and that of its two-stage propulsion system (and hence are not equipped with digital terrain profile matching sensor and warheads. The next two, also to be conducted from ITR, will seek to validate the Nirbhay’s flight management system, inclusive of the digital terrain profile matching sensor (an X-band SAR). The following two will involve the fully integrated missile being test-fired (one over land & one over the sea) from a Su-30MKI, which will be followed by two SLCM versions being test-fired (one over land and one over the sea) from a submerged SSBN, the S-2/Arihant. The final two test-firings will involve fully integrated Nirbhays armed with live conventional warheads, with one being launched from a Su-30MKI and the other from the S-2/Arihant.

The Nirbhay’s nuclear warhead-armed ALCM version (minus the solid-rocket booster) will be qualified for use by 20 specially customised Su-30MKIs, while the nuclear warhead-armed SLCM variant (incorporating the solid-rocket booster) will go on board the S-2, S-3 and S-4 SSBNs. The air-launched and nuclear-armed Nirbhay will have a length of 6 metres, diameter of 0.55 metres, wingspan of 2.7 metres, launch mass of 1,200kg, cruise speed of Mach 0.7, and a 250kg warhead-section. Its cruising altitude over water will be 10 metres (33 feet), while its cruising altitude over land will be 30 metres (98 feet). The MoD-owned Hindustan Aeronautics Ltd’s (HAL) Bengaluru-based Engine Test Bed Research & Development Centre (ETBRDC) has developed a turbofan for powering all members of the Nirbhay cruise missile family. A hybrid inertial navigation system using a ring-laser gyro (RINS) coupled with a GPS receiver and a digital radar altimeter (all developed by the DRDO’s Research centre Imarat, or RCI, and integrated jointly by the Advanced Systems Laboratory, or ASL, and the Aeronautical Development Establishment, or ADE) will provide a CEP of 20 metres. All on-board avionics, inclusive of the ones mentioned above, plus the mission computer and missile interface unit, have been developed as spinoffs from the BrahMos-1 supersonic multi-role cruise missile’s R & D cycle, which lasted between 1998 and 2005.

While the ASQRs and NSQRs for the nuclear-armed Nirbhay were drafted by 2005, hands-on R & D work began in only 2007, with all R & D-related activity due for completion by late 2017. Following the entry into service of the nuclear-armed Nirbhay’s ALCM and SLCM versions, India’s Strategic Forces Command (SFC) will have at its disposal four distinct types of highly survivable nuclear warhead delivery systems that will be optimised for retaliatory nuclear strikes, these being the 4,500km-range SLBM now under development, the 600km-range air-launched supersonic LRCM that is also now under development (for delivering tactical nuclear warheads), plus the Nirbhay’s ALCM and SLCM versions, both of which will be able to deliver boosted-fission nuclear warheads.

A spinoff from this programme is the development of a smaller, conventional warhead-armed air-launched variant of Nirbhay with a range of 750km, which will be qualified for launch from combat aircraft like the Su-30MKI, DARIN 3-standard Jaguar IS as well as Rafale M-MRCA. Presently, there are no plans for developing submarine-launched or surface-launched versions of this missile, which will have a length of 6.2 metres, diameter of 0.6 metres, launch mass of 1,350kg, a 400kg HE blast-fragmentation warhead, cruising altitude of 20 metres over land, cruise speed of 240 metres/second, target aspect angle of +/-180 degrees, and a launch altitude varying between 500 metres and 11,000 metres. The hybrid inertial navigation system will ensure autonomous navigation via at least 15 waypoints, while for terminal guidance, use will be made of a noise-immune guidance system that will employ an X-band monopulse SAR radar similar to the one now being developed for both the BrahMos-1’s Blocks-2/3 and the Prahaar NLOS-BSM. The conventionally-armed ALCM variant of Nirbhay will thus be procured in large numbers (exceeding 700) by both the IAF and the IN.

Lastly, here is a revelation for those congenital retards hailing from India’s ‘desi’ print/electronic media who had claimed recently that 36MT turbofans or HAL-built PTAE-7 turbojets would power the Nirbhay cruise missile. Guess what! The two slides below from NPO Saturn clearly state that the 36MT turbofan was never meant to power long-range cruise missiles and neither does it power cruise missiles like Novator’s 3M14E or 3M54E.