Indian Hypersonic Technology Demonstrator (HSTDV) Could Fly Next Year
Aviation Week & Space Technology
Michael A. Taverna Hyderabad, India
Douglas Barrie London
India is pushing ahead with the development of ground and flight test hardware as part of an ambitious plan for a hypersonic cruise missile.
The Defense Research and Development Laboratoryâ€™s Hypersonic Technology Demonstrator Vehicle (HSTDV) is intended to attain autonomous scramjet flight for 20 sec., using a solid rocket launch booster. The research will also inform Indiaâ€™s interest in reusable launch vehicles. The eventual target is to reach Mach 6.5 at an altitude of 32.5 km. (20 mi.).
Initial flight testing is aimed at validating the aerodynamics of the air vehicle, as well as its thermal properties and scramjet engine performance. A mock-up of the HSTDV was shown at the Aero India exhibition in Bangalore in February (see photo), and S. Panneerselvam, the DRDLâ€™s project director, says engineers aim to begin flight testing a full-scale air-breathing model powered by a 1,300-lb.-thrust scramjet engine as early as next year.
The HSTDVâ€™s shape, on which future cruise missile technology could be based, is evident in this mock-up shown at Aero India in February.
Panneerselvam says there is no connection between the HSTDV and a parallel civil scramjet project being conducted at Vikram Sarabhai Space Center. VSSC is adopting an incremental approach, starting with a 220-lb.-thrust-class engine and gradually work up to a 1-ton capability, using a new Mach 8 test facility to go into operation next year. This is expected to take 3-6 years. However, industry observers, noting the difficulties encountered in all hypersonic programs, say it could take at least a decade for India to have a full-scale working hypersonic design.
Israel has provided some assistance on the HSTDV program, including wind tunnel testing, as has Cranfield University of the U.K. An unnamed third country is helping as well. Indiaâ€™s main defense-industrial partner is Russia, which has carried out considerable research into hypersonic propulsion.
The 1-metric-ton, 5.6-meter (18-ft.)-long air vehicle under construction features a flattened octagonal cross section with mid-body stub-wings and raked tail fins and a 3.7-meter rectangular section air intake. The scramjet engine is located under the mid-body, with the aftbody serving as part of the exhaust nozzle. Development work on the engine is also in progress.
Two parallel fences in the forebody are meant to reduce spillage and increase thrust. Part span flaps are provided at the trailing edge of the wings for roll control. A deflectable nozzle cowl at the combustor end can deflect up to 25 deg. to ensure satisfactory performance during power-off and power-on phases.
Surfaces of the airframeâ€™s bottom, wings and tail are made of titanium alloy, while aluminum alloy comprises the top surface. The inner surface of the double-wall engine is niobium alloy and the outer surface is nimonic alloy.
A 1:16 scale model of the vehicle was tested at a hypersonic wind tunnel operated by Israel Aerospace Industries. The isolated intake has been tested at a trisonic wind tunnel at Indiaâ€™s National Aerospace Laboratory (NAL) in Bangalore.
Two types of combustorâ€”strut-based and ramp-cavity-basedâ€”are under evaluation, and 10 tests have been carried out to date. The nozzle features a cowl extension and fence to improve vehicle performance. Trim analysis shows a thrust margin of 30% will be available at normal operating conditions.
The solid booster, under construction, is a derivative of the S9 that powers Indiaâ€™s Agni ballistic missile and PSLV launch vehicle. The booster features a cone ogive-shape with a spherically blunt nose tip. The nose is made of carbon epoxy and carbon-phenolic materials; the latter is also used for the nose tip. Mass at liftoff is 12 metric tons. The booster has been wind-tunnel tested to Mach 4 at NAL and is now undergoing testing abroad to Mach 8.