When the first prototype of India's LCA Navy (NP1) roared off the ski-jump at the Shore-based Test Facility (SBTF) for the first time on December 20 last year, no one from the team observing the jet from the flightline and from telemetry stations knew that something unseen had happened. Something that would only become known later in the day when performance data was analysed. And it was good, solid news, much needed for a team that has seen little more than questions, derision and barely veiled bemusement. Importantly, it was the first time the team felt it had an answer to the 'what use is this platform, really?' question.
The NP1, which had flown for the first time in 2012, had remained mostly on ground for the next two years, undergoing an extensive undercarriage re-design. In 2013, it climbed cautiously back into the air before going supersonic last year, and finally getting set for a shot off the simulated shore-based carrier deck in December 2014.
According to sources on Team LCA-N, "For a ski jump launch, the final design intent is to have a zero rate of climb after ramp exit to get the best performance of the aircraft. This places a great premium on the ability to fly at the maximum possible angles of attack with adequate control and also to have a complete understanding of the thrust available."
And that's where it gets interesting.
Top sources on the team say the NP1 was flown a few times conventially before the ski-jump test to soak up the thick sea-level air in Goa. As expected, engine performance was markedly better. Spirits were high, but as has become the norm on milestone tests in the Tejas programme, there was pervasive nervousness. Surprises can be nasty. And the ski-jump test would leave no recovery time if something went wrong. As the Team says, "The first attempt at any new activity is fraught with uncertainties and potential surprises. Given the 'leap off the edge' nature of the first launch, all the major possibilities of failure were identified and options to handle them were built into the plan."
The test flight team decided to lock 5.7 degrees as the minimum climb angle for the NP1 once it made the leap off the ski-jump. When the aircraft actually did roar into the sky, the actual minimum climb angle was observed to be in excess of 10 degrees. Also, the NP1 achieved an angle of attack after ramp exit of 21.6 degrees, giving the team healthy new margins to work with in terms of performance. Simply put, the aircraft performed better than the team ever thought it could.
Now you can argue that safety margins always allow for bumps in performance, but the number crunch that evening demonstrated that the NP1 had exceeded expectations healthily.
The test team's verdict: "This is certainly a welcome bonus for an aircraft that has been so often derided for lack of thrust, and this excess will be accounted for in future launches. Also the angle of attack after ramp exit reached 21.6 degrees which augers well for utilisation of even greater angles of attack for launch. It should certainly allay fears over the use of such high angles of attack and remove much of the pessimism that has surrounded the utility of the programme."
The NP2 single seat naval fighter prototype that took to the air yesterday will join sea-level flight test next month and quickly demonstrate its own carrier compatibility before long. The LCA-N team, in the meanwhile, has its spirits up. The Indian Navy, which has ordered six of LCA Navy Mk.1 has indicated, albeit unofficially, that the Mk.1 platform is likely never to see actual carrier service. While the performance surprises of December aren't likely to change that, the numbers have changed. And that's something.
Tomorrow: The Four 'Fixes' After LCA Navy's Ski-Jump Flight