Does someone know why MiG29's engine thrust is so low at low speed but so high at high speed?

I did some testing with the MiG29 in test flight using localhost, and what I thought what was only my impression was about the thrust of the engines is actually true. In particular the engines (all figures are at sea level) produce about 6300Kgf of thrust when static and nearly 13000Kgf at ~1400kph, which is an huge increase compared to planes such as the MiG21bis (7200kgf to ~9000kgf) or the F14B (~10000kgf to ~13000kgf). I know about 6 months ago there was some discussion about the low speed thrust (as seen here Comparison of the dynamics of the R-24, R-27 and AIM-7 missiles - Aircraft Discussion - War Thunder - Official Forum ) but first of all this does not explain why there is such a massive increase at high speed, and second the reasons for the low static thrust compared to the 8300kgf Klimov aren’t really clear to me. First the main intakes being closed is not the problem since when flying at really low speed (like 250kph IAS) the main intakes are open and thrust is still low, while the “uneven mixing of flows from the upper and axial inlets” is also not entirely true since thrust is still a lot lower (7200kgf) than 8300kgf even at 500 kph IAS when the upper intakes are completely closed (besides, if the upper intakes really created that big of a problem I’m pretty sure the Russians would have created some system to close them and keep only the main ones open even at low speeds).

Can someone enlighten me?

Also before someone starts shouting, I am not asking for any performance increase on the MiG29, the thing is already a rocket ship and certainly does not need a buff. I was just curious about this since I couldn’t find anything online about it

Air volume entering the engine, and thus exiting the exhaust.
More air = more oxygen = more burn = more vroom.
[Does not happen with all jet engines, but ones that modulate fuel flow into the combustion chambers.]

Yes I know that, but the increase in this case is massive compared to any other aircraft (probably because the base thrust is very “low”).

F-16 goes from 9150kgf static, to 14900kgf at mach 1.

It’s still a far smaller increase… we are talking about a 62% increase versus almost a 100% increase… although using the 8300kgf base figure the increase is similar

I’ll get you exact numbers for a number of engines for you.
Different engines & airframes have different intake & speed performance.

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BTW, Mig-29’s intakes are closed partially on takeoff, which suffocates the engine leading to a lower thrust.
Goes from 7600kgf open intakes to 12000kgf for Mig-29.
I updated F-16’s engine.
Their the primary modulated engines, but F-16’s engine has an open air intake at all times, and obviously different engine characteristics leading to superior low-speed engine thrust over Mig-29’s engine relative to their top thrust.

yes, (as I said in the post) I know the intakes aren’t fully open in take off (engine temperature is also not at the max), that’s why I got the 6300kgf figure by flying really slow and low (about 200kph IAS) in air (where the main intakes and the upper intakes are both fully opened) and with the engines already at 922 degrees Celsius. I can’t get to 7600kgf even at 500kph IAS with main intakes fully open, how did you get 7600kgf static?

This graph for the MiG29 thrust shows ~7700kgf static (instead of 6300kgf) and ~11500kgf (instead of almost 13000kgf) at high speed.

It’s possible it’s a way for them to distinguish the MiG from the F16. Give the MiG advantages at high speed and the F16 advantages in low speed. Having the two true top tier planes with similar performances in all respects would lead to some pretty dull games.

This is why the Mig has two engines, their not as nimble as the F16 F100 is, the vent above opens for air, since the engines on 29 sit so low, the can pick up trash from the runway on takeoff so they close the main scoops. But the Mig 29 can takeoff from roadways where the F16 would end up being a scrap yard donkey for life if it tried that.

Short answer, the faster a plane goes, the more air goes into the turbine, creating a bigger combustion. More combustion = more power