In 1973 there was an offer from Germany to jointly develop the HF 24 into the Hindustan Supersonic Strike Aircraft labelled the HSS 73 later to be known as the HF-73. This would retain the original mainframe, with radical changes to the fuselage, air intakes and the centre wing section. The cockpit was to be modified for better visibility, fuel capacity increased, and with a completely new avionics suite and powered by the Rolls Royce RB 199-34R engine would have a radius of action double that of the HF 24. “Eventually, this project had to be abandoned because, as some said, of non clearance of the RB 199 by the UK and Germany, the two partner governments involved in the engine development for the Tornado MRCA programme. Thus all efforts in developing an Indian combat aircraft had come to naught.”
Subsequently HAL took on a feasibility study for a small multi role passenger aircraft, the HAC 33. “A wind tunnel model was built but not tested as development funds, were once again, not approved.”
In the mid-70s, the IAF showed interest in development of an air superiority fighter. In 1974 HAL undertook designing and studying a configuration for the Air Superiority Fighter (ASF). The ASF 300 was considered with either an Indian GTX or a SNECMA engine. The configuration proposed by HAL, “even though it did not meet the ASR, could have provided a reasonable solution…..”
https://marutfans.wordpress.com/2010/05/09/the-other-side-of-the-coin/
