Is there a specific reason the Tejas went for the GSh-23 twin barrel?

Because they already own a huge stock. It’s simple and it’s enough to do the job.

it can be a quite correct point defence fighter, especially if equipped with modern avionics, a decent radar and carrying enough fuel to remain airborne for more than 15 minutes (joke inside, for those who take it too seriously 😀 ), and cheaper to operate than the big flanker.

Haven’t you evenr wondered why the US use F-16s while they could use the F-15 to do all what the F-16 does?

Considering the sfc of the MiG is upwards of 75% for a fighter that is roughly 66% the size of the flanker – and quite a bit lower in capability – your money is better spent on the Flanker. The MiG has roughly the same ground crew, manpower cost, and availability rate; so where are the savings?

It sounded like WS-15 is more than 10% bigger than WS-10 family, but even 10% is quite a margin. Its probably more like six inches wider, otherewise they virtually overlap in capability.

What makes you assume WS-15 will be based off an existing engine, in other words?

I don’t assume, its been published in both Chinese and Russian circles. Its one of those accepted facts that the Yak-141 engine (the R-79) was terminated by the Soviets only to be sold by the Russians during the cash crisis. The R-79 was developed in Russia for up to 14 tons of thrust. The design goal of the Chinese (using Chinese and Russian engineers) is 18 tons. (None of the sources seem to clarify which type of ton, but they imply the mertic ton.) And the data put out for the WS-15 seems to be sourced from them. They also point to four versions of the WS-15:

WS-15X for the J-20 prototype flight testing
WS-15-10 for the enlarged J-10B; export
WS-15-13 for the enlarged J-10B; domestic
WS-15-CJ for the F-35B equivalent

If the WS-15 is reworked technology gleaned from buying the Yak-141 program then it’s hardly ground breaking. It may not be the D-30, but it’s not a leap to F119 class by any stretch of the imagination. It’s more like FADEC controls added to an F101-size engine. Once again they bought a foreign design and pumped it up as if it was indigenous.

I wouldn’t think the IAF deal would include any new builds outside of the agreements. I thought the basis was it relieves European partners the burden of paying for surplus jets.

I see them better from my desktop. Was looking at them from the iPod. The tails looked pointy on the small screen and just didn’t look right. But on my desktop they do look like the R-60.