Reusable Launch Vehicle (RLV)

The cost of launching single-use rockets is a major deterrent to space exploration. Most of the components used to make rocket parts are expensive to manufacture and build. The significance of the Reusable Launch Vehicle (RLV) by ISRO is that it’s a technology demonstrator for future, low-cost rockets for space exploration. Flown successfully in May 2016, the RLV-TD experiment demonstrated several flight capabilities such as hypersonic flight, thermal protection, flight management, autonomous navigation, guidance, and control. Let’s take a flight over the RLV-TD mission to understand the finer details. 

What Is the RLV-TD?

• The RLV-TD is a winged space vehicle launched like a rocket and flies back down like a glider. 

• It can fly at hypersonic speeds: speeds greater than 5 times the speed of sound (6174 km/hr). 

• 600 heat-resistant tiles cover the RLV-TD on its underside, protecting it from the high temperatures encountered while re-entering the Earth’s atmosphere at hypersonic speeds. 

• The RLV-TD is 6.5m long with a wingspan of 3.6m. It weighs 1.75 tons.

• It is controlled like an airplane using control surfaces called elevons and rudder. 

• The launch stack is made up of the RLV-TD vehicle and the rocket booster called HS9. The booster is meant to lift the vehicle into the upper atmosphere and accelerate it to hypersonic test speeds. 

Objectives of the RLV-TD Mission 

The significance of the Reusable Launch Vehicle (RLV) was put to the test in different aspects, such as:

• Characteristics of aero-thermodynamic flight of a winged body. 

• Evaluation of thermal protection system

• Evaluation of control systems such as autonomous navigation, guidance, and control (NGC). 

• Evaluation flight management 

Flight Profile of the RLV-TD 

To achieve all its mission objectives, the RLV-TD has a well-defined flight profile: 

1. Ascent phase: The solid rocket booster lifts the vehicle off the pad and burns for 91 seconds to propel it high into the atmosphere. 

2. Coasting phase: After the booster shuts down, the launch stack continues on an unpowered ascent trajectory to the apogee. 

3. Booster separation: At about 111s after launch, the booster separates from the vehicle as it ascends to apogee.

4. The peak of flight: The peak of flight or apogee occurs at 65 km, after which the RLV-TD starts a high-speed descent back into the denser parts of the atmosphere. 

5. Hypersonic testing: The flight control and thermal protection systems are systematically tested during the hypersonic phase. 

6. Landing maneuver simulation: After the hypersonic stage, the RLV-TD lands on a hypothetical runway to simulate an actual landing high above the ocean. 

7. Splashdown: After the landing maneuvers are successfully tested, the RLV-TD splashes down into the ocean to be recovered.  

List of India’s launchers

• Sounding Rockets

• SLV

• ASLV

• PSLV

• GSLV

• GSLV Mk III

• RLV-TD

• Scramjet Engine-TD

What About NASA’s Space Shuttle Programme?

The RLV-TD bears a striking resemblance to NASA’s Space Shuttle as it is an optimal design for a hypersonic orbital vehicle that can fly to orbit and back. NASA released the significance of the Reusable Launch Vehicle after the Apollo missions and came up with the Space Shuttle Program. 

For a period of 30 years, NASA operated a shuttle fleet with 135 launches to space. The Shuttles were capable of delivering and retrieving cargo from space and were instrumental in building the International Space Station. 

So what about NASA’s Space Shuttle programme now? The Space Shuttle Program ended on April 12, 2011 as NASA’s limited budget had to be allocated to new missions.

Future Missions of the RLV

The significance of the Reusable Launch Vehicle is tremendous. It is instrumental in developing and testing a range of technologies that will enable reusable flight in the future. With the success of the hypersonic flight experiment (HEX), ISRO has more missions planned for the future, such as: 

• Landing experiment (LEX)

• Return to flight experiment (REX)

• Scramjet propulsion experiment (SPEX)

Conclusion 

With a need for low-cost access to space, the significance of the Reusable Launch Vehicle cannot be understated. The RLV successfully achieved all its milestones, such as hypersonic flight, demonstration of flight control at hypersonic speeds, and thermal insulation needed for orbital re-entry missions. To understand what the future might look like for the RLV-TD, check out NASA’s Space Shuttle mission, and its long history of success.