Was trying not to respond, as per certain directives ... but since names are being used, I guess it's ok to be seen as "forced to respond".rohitvats wrote:But I did.ramana wrote:I guess you have not read the LCA aerodynamics discussion especially the contradiction between ITR and STR and the wing shapes coupled with underpowered engine?
Where the line of argument is that if the LCA does not meet STR and ITR parameters, it must be because IAF indulged in 'best of brochure' activity. And all this is basis assertion by one BRF member (@maitya) who has gone to the extent of claiming that IAF deliberately drafted performance expectations which can never be met and were meant to kill the LCA program!
Let me ask you a couple of very straight forward question:
(a) If the LCA design choice means that ITR and STR as specified in ASR cannot be met (and are actually contradictory as per wisdom of BRF), then how come LCA Mk2, which involves minimum design changes, will meet these ASR requirements?
(b) Is the engine on LCA Mk1 under-powered or is the aircraft overweight? The CAG Report on the LCA Program clearly shows that LCA is 1,366 Kg overweight with fuel load. And 1,370 kg overweight as basic empty.
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Basic understanding of science would have made the answers (to the questions asked above) quite self-explanatory as answers for these were there in those posts as well ... and that doesn't really need aerodynamic expertise really, as the answers were provided in layman words etc.
But then again when emotions run high, logic etc will always be in short supply.
Why will LCA Mk2 meet the ASRs? It won't ... not the ones set out in 1993 etc.
It will attempt to meet the impossible-ASR-specified-STR by getting more Thrust from a more powerful engine (which will also increase weight) - as STR is more about amount of Thrust available to overcome the drag of a certain wing geometry (alongwith fuselage and fuselage-wing interface design etc).
And that design itself is necessitated because of High ITR specification of the ASR itself ... but if the intended role was of "replacing MiG-21" itself, plus some additional ground-attack capability, then specifying a high ITR is quite expected.
But then the planform can't be designed to neglect this @primary requirement of high ITR - so in comes delta planform. And alongwith comes the attended higher drag (but other benefits as well) and thus the need of higher and higher thrust to overcome it, so that STR figures can be achieved.
That's the reason for going to a higher thrust engine ...
Never mind the F414 was originally a Navy requirement, a higher thrust level required to offset the inevitable weight creep due to heavier landing gear, higher acceleration required for carrier T/O etc ... too much of H&D issue for IAF to allow the Navy folks being able to specify "realistically" and maybe even saving the program.
But how will Mk2 meet the rest of the original unobtanium ASR of 5.5Kg empty weight. dimensions of a MiG-21 etc - it can't and it won't!!
Was Mk1 overweight? Or Mk1 post ASR revisions overweight?
Answer is yes and yes ... when you do an ab-initio program like this, with no experience whatsoever, some amount of weight creep is inevitable. LCA Mk1 pre-ASR revision was over-weight, with an attended goal of reducing that margin as it's productionised ... all contemporary A/C dev programs have had this issue anyway. And LCA of early 2000s was no exception.
But IAF kept changing the requirements - the serious-most was asking the outermost station to be R73 class (so say about 120Kg weight level) from being R60 class (so approx 50Kg class). The entire wingbox structure would require significant redesign and strengthening when such dramatic increase happens. The structural weight and thus the whole platform weight is bound to go up quite a bit and it did ...
Plus what about internal SPJ class self-protection system etc etc ... except for dginn tech etc, weight is bound to go up and it did (and killed the Kaveri program as well). Where is the reason to be surprised now?
(Note: I for one, would support such incremental changes for a program such as this - but to not acknowledge the consequence of such asks and worse, to turn around and blame the program precisely for it, is plain intellectual dishonesty, to put it mildly.)
Betw nice try building consensus via falsehoods such as highlighted above ... the mood of the forum can easily be judged via open-minded reading posts of other forum members, even if it doesn't match the make-believe puny world of yours.rohitvats wrote:And all this is basis assertion by one BRF member (@maitya) who has gone to the extent of claiming that IAF deliberately drafted performance expectations which can never be met and were meant to kill the LCA program ...
Rest of you post is not worth responding ...