SAAF JAS-39C Technical Data and Discussion

Thrust is getting reduced. Does @Metrallaroja know if they will also be adjusting the drag at the same time?

Yes I get that the thrust shouldn’t be as high as it is. But the temperature increase between the two being 10F but the RM12 on top of that having more flow and a bigger fan it shouldn’t be marginally higher. Going of mugs report it’s going to be worse than the 402 which doesn’t seem right.

Like the whole base of this report Community Bug Reporting System seems to be based around higher temperatures of the 402 meaning it should be better than the RM12 because the RM12 is a modified 400. The RM12 was modified to accommodate increased temperatures just like the 402 was along with increasing the size of the fan for further thrust increases. @GungniR posted a document showing just that.

I have to recheck the sources but I remember one of them stating that they increased the fan speed by something like 6% which in turn increased the thrust by 3%. The changing of the fan also had to do with their increased resilience against bird strikes or something like that.

All in all since the engine is temperature limited and the 402 increased the temperature limit over the RM12 by another 10°F and the difference in thrust from the fan being stated as being 3% I don’t think the RM12 will have more thrust in real life than the 402.

But since we don’t have actual information about that we can’t say for sure, this is just the best we can guess.

Which will only produce a 1-2% increase in thrust if that

@MiG_23M Your report seems to have yielded results


That’s a 3800lbf decrease at those high speeds and 1280lbf increase static?

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Thank god i got all the essential things in it

Yes, thrust will be higher than the -402 but not by much.

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Just hope it doesn’t wreck the top speed, it already feels oddly sluggish getting up to Mach 1.8 at 33,000ft, like one knot per second slow (min fuel no armament)… Removing nearly 4000lbf of thrust would pretty much make it impossible to reach the top speed, I’m assuming they’ll be fixing drag to keep the current top speed
I just realised, it’s stat card top speed is mach 1.8, shouldn’t it be mach 2? It recently got lowered from M2.2 to M2 IIRC?

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From what I understand what should be happening is drag should be reduced to compensate to match known acceleration times so technically this change should be a buff. Thats all if gaijin adjusts the drag which…idk.

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Well depends how you look at it, high speed maneuvering is likely taking a big hit regardless, 4000lbf is a lot

Well, the values they gave indicate 2% channel losses for a Y-intake which seems wrong to me as well.

F/A-18 has more with two straight intakes.

Well, this could indicate they left a overly high drag value.

And why am i not surprised?

This is what happens when you ask for nerfs before fixing the other ones.

yeah that’s my guess too. Maybe they’ll lower drag at just those higher speeds somehow, where static thrust wouldn’t matter anyways

Ive never seen F16C accelerating faster than me after takeoff…

I’ll compare it after the changes to the full afterburner short takeoff time videos and see how that looks. Gaijin used that as reference for the MiG-29 previously.

Are you aware of any videos like that? I can’t find any that are specifying afterburner modes and weight?

Airshow videos should be decent for that

We may not know the load, but we can assume a drop tank indicates full internal fuel + drop tank. There are also many videos to look at and develop an average from.

There’s also the well-documented and doctrinally important ability to use very short runways, >= 400 m.