Undeterred by development headaches on some of its indigenous fighter programs, in the next two decades Indian military researchers are looking to explore a range of stealth technologies for future-generation manned and unmanned aircraft.
At the same time, the country is exploring ways to better detect stealth aircraft. Detecting low-observable aircraft is a key element of the Indian 2020 airborne early warning and control development effort, a program likely to start in late 2014. It will be based on a yet-to-be selected widebody. This initiative follows the currentEMB-145-based airborne early warning program featuring an Indian-developed, 240-deg. field-of-view radar. The first of the modified regional jets is due for delivery to India in August, with radar integration to start in October.
The new system will feature a rotodome radar and be integrated with unmanned aircraft and aerostats to allow bi-static radar operations to detect stealth aircraft, says Vijay Kumar Saraswat, scientific adviser to the director general of the Indian Defense Research and Development Organization (DRDO). The distributed transmitter and receiver approach should also aid in detecting small targets, such as unmanned aircraft, and provide extended-range detection, Saraswat recently told the Aerospace Forum Sweden 2012.
The advances on India's own stealth technology are largely centered on two efforts. The first is the Advanced Medium Combat Aircraft (AMCA), which would operate with a range of 400-600 km (249-373 mi.) between the Fifth-Generation Fighter Aircraft (being developed with Russia), and the Tejas Light Combat Aircraft (LCA). The second is the notional Indian unmanned combat air vehicle development, which could take another 10-15 years. The AMCA is a 25-metric-ton-class, twin-engine fighter with an empty weight of around 18 metric tons and 2 hr. of endurance, featuring supercruise; thrust vector control; an active, electronically scanned array radar; and integrated modular avionics.
Many of these technologies could also find their way into the Light Combat Aircraft Mk. 3 that is to be more stealthy than the current Mk. 2 version, which is due to fly in the next two years with theF414 engine and be ready for operational trials in 2016. The Mk. 3 is to have up to 70% composite content, almost double the current version's level, and could be powered by India's Kaveri turbofan, if that troubled program gets back on track.
Although much of DRDO's research focus is on reducing an aircraft's radar cross section, that is not the only area of activity. Reducing exhaust temperatures and smokeless engine exhaust to suppress an air vehicle's infrared signature also is on the agenda. “There are major areas where research and development is going on at the moment,” Saraswat notes.
A particular near-term focus is on fuselage-shaping, including curved jet pipes and serpentine engine ducts to support low radar cross section designs. In the latter case in particular, Indian researchers are grappling with flow separation in the serpentine duct and seeking to apply advanced flow-control technologies to mitigate the effects. This includes exploring pulse jets and other active devices to eliminate separation problems.
More long-term, Saraswat points to continuing work on the development of very low-observable stealth technology. That includes research on conformal antennas, active radar cross section control and even the use of plasma field generation to suppress an aircraft's radar signature.
To advance work on low-observable air shapes, DRDO also is investigating issues such as thrust vector control and yaw control with spoiler elevons to help control flying wing-shaped air vehicles. Adaptive structures are also on the long-term technology horizon. Saraswat notes that efforts to examine the aerodynamic challenges of using an internal weapons bay are also underway.
Although the Independent Unmanned Surveillance Air Vehicle or Iusav (a precursor to the unmanned combat air vehicle concept) may be the most ambitious unmanned program in DRDO's plan, a number of other efforts are ongoing. More near-term is development of the Rustom-2 UAV, flying at 35,000 ft. with 24-hr. endurance and a 350-kg payload. The system could be operational in 2016, Saraswat says. Initially it will be used for surveillance, but it could evolve into an armed platform.
Also on the agenda is a solar-powered high-altitude unmanned aircraft and a range of enabling technology for large and small unmanned aircraft, including nano-UAVs.
Saraswat stresses that these are not all solo initiatives for India and that DRDO is looking for international partners on many projects.
India's expansive research appetite also continues in the space domain, where Saraswat sees progress advancing on a two-stage-to-orbit reusable launch vehicle and hypersonic launcher, as well as a low-cost expendable reusable launch vehicle.
India is also considering marrying its Agni ballistic missile technology with its ballistic missile-defense kill vehicle to develop a potential anti-satellite (ASAT) weapon. Saraswat stresses, though, that India's policy is not to militarize space, and views the ASAT effort as merely a preventative technology project to deter adversaries.