ISRO :: Guiding the World into the next era of Space Technology

[knight11]

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By - Arya Bhatta

In a few months from now, ISRO is going to test its RLV-TD hypersonic flight experiment. This is also known as the HEX (hypersonic flight experiment). But why? And how?


REQUIREMENT:

The cost of putting 1 Kg of something in Lower Earth Orbit is 10,000$ on avg. and 20,000$ to Geostationary Transfer Orbit.

ISRO hopes to cut down the cost to half by completing soon its LMV3 / GSLV Mk3. Even then, costs remain high and a lot of time is taken between launches. Henceforth the idea of developing a reusable spaceplane dawned, which can bring down the costs by a fraction and a single neat unit which can carry out launches instead of an array of subsystems that needs to be remanufactured after a launch.


A SNEEK PEEK INTO HISTORY:

Everyone is aware of the Space Shuttle Program of NASA (USA) owing to the huge publicity it received during the Space Race Era. But the origin of space planes can be traced right back to the Nazi Germany, where the idea of developing a spaceplane with a military application as sub-orbital bomber dawned. Silbervogel was the name of the plane and had the mind-blowing concept of a lifting body, but unfortunately owing to wartime hurry, another legendary plane was made called Skoda-Kauba Sk P.14 ramjet fighter. This concept gave the birth to idea of a spaceplane.


A LOOK AT THE MISSION AND VISION:

The ultimate goal is to develop a hyperplane that can perform a take-off just like your regular Jet Airways plane, and then eventually reach orbit. The plane name has been given AVATAR (Aerobic Vehicle for Transatmospheric Hypersonic Aerospace Transportation). But for this it needs to have these features:

- Consist of a Liquid air cycle engine – one that can collect air, separate Oxygen to be used beyond atmosphere. This needs liquid Hydrogen fuel on board which make up for 60% of its mass. As this method uses lift in place of drag, extensive thermal heat protection is required. Nothing of this type has been made since funds for research of LACE dried up in US in 1960.

- Consist of a turbo-ramjet (technology already homemade), that can burn this hydrogen and stored oxygen.

- A scramjet engine (progress still on), that can push into action at the cruising altitude to accelerate to reach finally into orbit.


The assembly can be a difficult task but the 1st mountain to climb is to develop these subsystems along with flight controls and avionics. However, one wise decision is to make it unmanned, saving cost, weight, and risk of termination /suspension of program in case of accidents owing to political pressure. Now the RLV-TD is a mini version of this AVATAR spaceplane. RLV is being made to test the characteristics of the airframe, heat tiles during re-entry, etc. 4 stages are planned before the actual AVATAR makes its debut: these are:

1) HEX (Hypersonic Flight Experiment)
2) LEX (Landing Experiment)
3) REX (Return Flight Experiment)
4) SPEX (Scramjet Propulsion Experiment)
The RLV-TD will be attached to a booster and hence a TSTO (Two Stage to Orbit experiment). So, it will be partially reusable.


It is speculated the scramjet engine modules developed will remain passive in this flight and be made live in future tests.
Now, this is the mega-plan of the unmanned SSTO (Single Stage to Orbit) vision of ISRO. Thousands of technological challenges remain but there remain a team of dedicated men determined to emerge triumphant at the end.


HOW IS THIS IDEA DIFFERENT FROM SPACEPLANES OF THE WEST?

The American Space Shuttle Program was manned and partially reusable. It was a 2 stage mission with the Orbiter Vehicle, External Tank and solid booster collected separately to be reused, and they suffered damage. Similar is the Buran Program of USSR. The recent Dream Chaser and X-37 of Boeing are inherently designed not to be any SSTO and are only upgrades to the Space Shuttle design. So, the future seems much more promising in the design of ISRO.


DOES THERE EXIST ANYTHING SIMILAR?

Well, the world is a big place. Competition exists. UK has a program called Skylon which is nearly similar to AVATAR concept with differences in airframe. It has made admirable progress in SABRE – a LACE.

It remains to be seen how the 2 projects proceed and what we can achieve. If successful, it may rewrite space launches. Vertical rocket lift-off will slowly become a thing of the past, with hyperplanes that will narrow the differences between spaceports and airports. And India will lead this innovation from the front !