According to DRDO, the test saw the scramjet-powered HSTDV sustain a speed of Mach 6 during the course of its 22second flight at an altitude of 30 km.
By DEBAJIT SARKAR
India’s Defence Research & Development Organization (DRDO) successfully test-fired the Hypersonic Technology Demonstration Vehicle (HSTDV) from the Abdul Kalam Island off the coast of Odisha earlier this week. While many more such tests will have to be carried out, this test has certainly laid the building blocks for a credible development of future scramjet-powered hypersonic delivery system. According to DRDO, the test saw the scramjet-powered HSTDV sustain a speed of Mach 6 during the course of its 22second flight at an altitude of 30 km. Basically this means in 22 seconds the HSTD covered at least 40 kms.
Need for Speed
A missile powered by a solid rocket motor missile is like a gun. If you fire the gun from the ground you will get a certain distance for range. But take the same gun up 20,000 m and fire it and the same round will launch the projectile to much higher speed because of less drag and the projectile will travel much further. The HSTDV will comprise of a solid rocket component to get it into the air and flying and subsequently it will utilize its scramjet engine to rise and accelerate to a high elevation where its jet engine functions most proficiently. Being flown up to a high altitude at a realistic speed implies that its preliminary rocket motor boost will take it higher and faster so the scramjet motor can be employed less, thereby cutting back on fuel consumption. The hypersonic vehicle could steadily increase speed as it loses fuel weight exhausting the fuel more efficiently and increasing the range a bit.
The best protection that hypersonic cruise missiles have against Electronic Warfare is very high speed. This is because the homing systems onboard each missile can acquire the target position from a distance where the jamming density is still low and the missile can proceed up to a precomputed impact point, and thereafter can execute random high-G manoeuvres, without any more correction being provided from the homing system. Both the Indian Navy and the Indian Air Force will find such a hypersonic missile to be very valuable. This is because of a hypersonic attack can take place with very little forewarning. This dynamic and the randomness of the targets of a hypersonic attack reduces the timeline for a counter strike by the party being attacked. Hypersonic missiles also amplify the probability of a disarming attack.
Advantages of a Scramjet
Scramjets can be used to power, not just cruise missiles but also aircraft. A scramjet contains a tube of a design that lets the fuel to burn at supersonic speeds. Ergo, complicated air intake is not needed and the only constraint on speed is the heat capacity of the aircraft and the engines. Maximum speed for a scramjet is orbital speed or greater. Because of its shape, an aircraft can be equipped with scramjets, the intakes can be closed during take-off and it will inject fuel and oxygen into the chambers to gather speed down the runway on rocket propulsion. When moving forward, the oxygen could be cut off and the intakes opened to use air for the oxygen and lift-off could be attained by means of scramjet propulsion all the way up to space where the intakes can be closed again and thereafter, rocket mode can be used.
Counter to Counter Stealth
A number of countries including India’s adversaries like China are working on ways to counter stealth. Eventually, HSTD could well pave the way for the development of a counter to counter stealth aircraft. Low Observable in radio frequency bands combinedwith intensespeed will help to deteriorate the reaction time of a radar-guided surface to air missile. The massive infra-red signature will noticeably preclude the aircraft from truly being stealthy but the combination of speed, low observable radio frequency and altitude can make a difference if done appropriately. Shape and speed are directly related if an aircraft intends to fly at very low speed, then a biplane layout is pretty good. High subsonic speed necessitates a swept wing. Hypersonic speed works well in an aircraft that has a small wing and a lifting body shape. The dividing line between what is now described as a precision-guided munition and an unmanned vehicle will gradually blur. Aircraft dispensing such weapons will progressively become multipurpose battlefield aircraft, capable of being used for numerous long-range power projection assignments.
India also has a robust intercontinental ballistic missile (ICBM) program. ICBMs have excellent range and speed but new Anti-Ballistic Missile systems like the S-500 are being designed to shoot them down. Consequently, new warheads for ICBMs that can manoeuvre are being developed. However, the technology to manoeuvre within the atmosphere at those speeds necessitates new heat resistant materials and propulsion systems. Presumably, DRDO will take those materials and systems and apply them to their hypersonic cruise missiles thereby make them more effective and able to penetrate existing air defences. Similarly, India will also have to prepare to intercept hostile hypersonic missiles. Hypersonic threats compel the threatened states to take such actions as decentralization of command and control of strategic forces, extensive scattering of such forces, a launch-on-warning stance, or a strategy of pre-emption during an exigency. And to that end developing Directed Energy Weapons (DEW) especially solid-state laser is important. But that’s another tale for another time.
(The author is a subject matter expert on competitive intelligence and market research in the defence and aerospace and industry. Views expressed are personal.)