This is the no 2 article in the three part series by Dr Anantha Krishnan M of Tarmak 007 .
He sheds light on the developmental challenges , the various technologies developed and what changes were incorporated in the cruise and launch vehicle after the first test.
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Some points to note.
1. The scientists associated with this project carried out extensive tests on the thermo structural dynamics of both the cruise and launch vehicles , static and dynamic tests of the upper panel separation mechanism, payload ejection for the better part a decade.
The flight envelope of the Agni 1 booster used for this test is distinctly different than when it is used as a ballistic missile. I reckon it has more to do with extended horizontal flight for a good period of time through the dense parts of the atmosphere which imposes additional thermal loads on the booster.
2. Extensive resonance testing were carried out for the cruise and launch vehicle combination to identify and validate the vehicle dynamics
Excessive Vibration levels can make or break a mission by imposing additional aerodynamic loads and stresses on the vehicles. Remember The Martian .
3. The people want the cruise vehicle aka HSTDV to cruise for a distance of 2000 kms. That's the intended target for range. To be covered in 16 minutes . This will be awesome if it can be achieved. I will even be happy for 1500-1600 km range .
4. The actual hardware realisation phase began in 2016 .
5. Extensive thermo aerodynamics studies were carried out on cruise vehicle flow path, intake design, single expansion ramp nozzle, engine flow path, combustors ,etc.
6. After the first test, the scientists and engineers changed a portion of airframe section based on its previous dynamic behaviour. They modified the ejection mechanism and panel seperation scheme too . The first test proved valuable insight on where and how to improve further . The changes were then proved through resonance testing of the integrated vehicles.
7. Thermal barrier coatings have been developed exclusively for use on HSTDV. Besides materials and alloys were properly chosen to cope with the enormous thermal tests and still maintain its structural integrity .
Establishing cost effective production processes with a high QA/QC standard for these various alloys and ceramics will be the next big challenge.
Materials is one side of the coin. The other side is manufacturing them in bulk in a cheap manner buy while maintaining the correct quality and dimensional accuracies. This part is even harder than most of us think.
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