Saturday, March 31, 2018

Does ISRO Plan For SpaceX-type Reusable Rockets For Its Space Shuttle?

It sure appears so, going by the hints it has dropped.

Vertical Takeoff Vertical Landing - VTVL - Rocket - ISRO

Ever so often, some new nuggets of information appears in the public domain, that raises excitement level through the roof. One such nugget morsel  found its way out, in a conference brochure. Featured on the Liquid Propulsion Systems Centre's [LPSC] publication was a CGI rendering of new Rocket Engine design. Unlike anything ISRO has flown, so far, this shows the Rocket standing on, what looks like, 4 landing legs, a concept similar to the kind one has seen on SpaceX's Falcon 9 v1.1+ Space Launch Vehicles.

Appearance of this render conforms with the Indian Space Research Organisation ISRO - Scramjet Test - ATV-D02[ISRO] plans to develop a fully-reusable Two Stage To Orbit [TSTO] vehicle, for future missions. Technology for its Upper/Second stage was flight-tested, for the first time, when ISRO successfully launched the Reusable Launch Vehicle - Technology Demonstrator [RLV-TD], on May 23, 2016 [video above].  This was followed by the successful flight-test demonstration of its Scramjet technology, aboard a modified Sounding Rocket, ATV-D02, on August 28, 2016, where the scaled-down engine performed for 5 seconds. Earlier, on March 03, 2010, ISRO strapped them onto a Sounding Rocket, ATV-D01, flying it without lighting up, to attain conditions under which the future engine would have to perform.

ISRO - Reusable Launch Vehicle - TSTO - Flight Profile


ISRO has, so far, shared a couple of design considerations for it's First-stage engine. Back in 2009, plans of such a Vertical Take-off Vertical Landing [VTVL] concept emerged, along with its TSTO goals. The illustration, above, shows a cluster of 2 engines powering Stage I. The render, on the other hand, shows a single engine, unless it is depicted from a side where both engines are lined-up, one behind the other. Nevertheless, it would be safe to assume, that ISRO would first start with a Technology Demonstrator, validating underlying concepts & sub-systems, before incrementally testing the design, approaching final configuration.

ISRO - Reusable Launch Vehicle - TSTO - Flight Profile

The other design shows the 1st Stage functioning in a Vertical Takeoff, Horizontal Landing [VTHL] mode, where deployable parachutes help safely bring it back to Terra, on Airbags. Whatever, the design eventually chosen, it is imperative that cost of access to Space be brought down, to ensure that benefits of Space Technology reach greater number of people. In an old estimate [archive], ISRO figured it cost the Indian exchequer between $12,000 - $15,000 USD to put 1 kilogram of payload into Space. All it's operational Launch Vehicles still being expendable, the cost hasn't reduced significantly today, either. Therefore, in order to achieve the its stated goal of bringing cost down by more than 96%, to around $500 - $1,000 per kg, reusability is critical.

Although ISRO hasn't formally provided additional details of the design, per se, one can draw some inferences based on the Brochure's illustration. First spotted by an observant Redditor, actively participating in the ISRO Sub-Reddit, who has done a fine summarization of the observation,

Speculation time. Scale is hard to tell but this is clearly a suborbital vertical take-off vertical landing test article possibly for development of technologies related to re-usability with just a simple nosecone without much volume space. Propellant/Oxidizer cylindrical tank size is 1:1 and pressurant tanks are small so engine on this vehicle could be pump fed and likely uses hypergolic propellant. The fins indicate this vehicle could have some atmospheric flight time later in development and not just short hops from A to B but at the same time control surface doesn't look actuated.

All this and ISRO's way of working suggests this test vehicle might have some shared heritage and looking at inter-tank region I can't help but see in render its close resemblance to L40 strap-ons of GSLV Mk II (2.1 meter diameter), that is where those toroidal water tanks are. Toroidal water tanks (blue donuts) in GS2/PS2 and L110 are at the bottom of stage above Vikas engine(s) (sprayed water is used to control temperatures in gas generator). Apart from that there is some bits in inter tank area not sure if for roll control or something else. Vikas engine gimbal on L40 Strap-ons is limited to single plane so that would change for this vehicle among other things.

Legs look one time deployable. May be at some time in development they'd be in stowed configuration during launch. Talking about launch and development tests what facilities and high ceiling test areas are suitable for this? Mahendragiri doesn't fit the the bill for flight tests, Challakere in Chitradurga district doesn't have much at the moment so SDSC SHAR (Sriharikota) again could be an obvious choice.

Here is side by side comparison with L40 strapon.



Watch out for more.


Also Read: Did You Know About ISRO's Launch Of A British Military Satellite?