Hypersonic Technology Demonstrator Vehicle

The HSTDV is an unmanned scramjet demonstration aircraft for hypersonic flight (Mach 6.5). The HSTDV program is run by the DRDO.

Introduction
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 Laboratory’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 India’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 DRDL’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 in near future.

Design and development
The design for airframe attachment with the engine was completed in the year 2004.

In May 2008 Dr. Saraswat said:

The HSTDV project, through which we want to demonstrate the performance of a scram-jet engine at an altitude of 15 km to 20 km, is on. Under this project, we are developing a hypersonic vehicle that will be powered by a scram-jet engine. This is dual-use technology, which when developed, will have multiple civilian applications. It can be used for launching satellites at low cost. It will also be available for long-range cruise missiles of the future.

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. India’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 airframe’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.

Due to technology denial of material for the scramjet engine, a new program was initiated and the materials were developed in-house. This led to self sufficiency in the area and the scramjet engine was ground tested successfully for 20s instead of the initial 3s.

Testing
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 India’s National Aerospace Laboratory (NAL) in Bangalore. During the lab testing the scramjet engine was tested twice for 20s. A total of five to six tests are required before the test flight. The test flight was expected to take place by the end of 2010.

In November 2010, DRDO officials told press that they were in the process of opening four state-of-the-art facilities inside as well as in the vicinity of Hyderabad at a cost of more than inr 10000000000 over the next five years. Reportedly, they will invest ₹3 to 4 billion (US$66 to 88 million) for setting up a much-needed hypersonic wind tunnel at Hyderabad’s Missile Complex.

The facility facilitate testing of various parameters of the Hypersonic Technology Development Vehicle (HSTDV), including engine performance.

"It is pivotal to test the [HSTDV] in the range of up to Mach 12. This will be a unique installation in India," Saraswat told AW&ST on 22 November 2010.

As of December 2011, the scientists had proved technologies for aerodynamics, aero-thermodynamics, engine and hot structures through design and ground testing. "Ahead of the launch, we will have to now focus on the mechanical and electrical integration, control and guidance system along with their packaging, checkout system, HILS (hardware in loop simulation) and launch readiness," sources said.