High Taxi Thrust (not a bug)

I have no clue if this is a bug or working properly as I am no where near an SME, but is the current amount of thrust required to maintain a taxi correct? With full fuel and 2 drop tanks I expected a pretty high breakaway thrust requirement but needing a 10K RPM power setting seems high. Just curious if this is correct. Thanks for a great bird!

So, here is a track about that:

Brakes off / burner off

idle to 9500RPM, there is not enough thrust to move the plane

9500-9800, it starts to shake a bit, like something is about to happen

9800-10000, suddenly all the thrust is there! Note: look at the nozzle position and the EGT! There is no change there.

Just to be more clear I have also tested nominal and mil thrust in the track, so that actual nozzle movement is visible. There is certainly none between 9800 and 10000RPM.

I cannot think of any reason why an engine could behave like that with no indication on the instruments either. I mean RPM is almost the same and EGT is almost the same, then where does that sudden great thrust come from?

MiG-19P Throttle response.trk

I did a little reading in the manual last night and it does mention bringing the power up to 10500 RPM to start taxiing, and that seems about right for breakaway thrust. But you should not need that much thrust to maintain taxi speed as you have already have built some momentum.

https://www.cia.gov/library/readingroom/docs/CIA-RDP80T00246A061400380001-8.pdf

Well, the CIA manual says, on page 33:

"Caution1: It is permitted to increase thrust on both engines at the same time up to 10000 RPM"... otherwise one engine at a time during engine runup.

So that is a limit, rather than minimum taxi thrust.

on page 39:

brake check: 74. "The brakes must hold the aircraft at 10000 RPM"

So again it's a limit, according to this at 10500 they can not guarantee that the brakes can hold the plane. That is very different from minimum thrust to start rolling :)

I think that there might be a gross misinterpretation here somewhere...

Well, the thread just got a “not a bug” tag so we must be imagining things. :)

We have an F-5E in DCS that is considered a high quality and realistic product.

That plane features the GE J-85 single spool 9 stage axial compressor engine that has a certain behaviour that is more or less in line with all the other jet engines in DCS World

Now we have the RD-9 single spool 9 stage axial compressor engine in the Mig-19, that for some reason behaves totally different, than the J-85 and also all the other engines in DCS World, and other sims and IRL (okay, okay I only know the CFM-56 and that is quite a different construction:))

My question, again is how can the RD-9 suddenly jump from not producing almost any thrust at lets say 9500 RPM to producing huge amount of thrust at 9800 RPM while the nozzle doesn't even move? Even if it's not a bug I would like to understand this behaviour. This is study sim after all isn't it?

Take a look at this thread. The issue of high RPM for taxi and the sudden availability of thrust around 9500 RPM are mentioned a few times. This might all be tied to some needed FM corrections.

https://forums.eagle.ru/showthread.php?t=233533

Folks, the engine behaves as per the power curves it has.

So the real thing doesn't move at all at 9700rpm and gets thrust as much as making it unstoppable with the brakes at 9800rpm with the thr levers around 90% fwd at that point? I want to believe...

Probably also has to do with ED's sticky tarmac though

Edit: Not meant to offend. This just feels strange. If it's reasonable, I'm OK with it, and even if you got the power curve right there might be lots of other factors in such a complex simulation that make such peculiarities appear, like the "sticky" ground of DCS as every aircraft tends to need a lot more RPM compared to their real counterpart to start moving.

And while it's possible to stay on spot with full brakes even at full MIL on both engines, 12500rpm, it's impossible to come to a stop at just 9800rpm once going. As soon as I drop the throttle just a bit and RPM is 9700 or less, the plane suddenly brakes as if it just made a trap on the boat. This certainly is weird.

Folks, the engine behaves as per the power curves it has.

Is there any chance to let us have a look at some of that documentation you have, strictly limited to the absolutely relevant information?

Since we, the customers are always (and rightfully) required to present real world data in form of manuals and charts to back up our bug claims, I think the same should apply to the developers side to make things clear!

If that is not possible, I can understand, but in that case I would really like to know, what particular effect/feature is present in the simulated RD-9 that causes the engine thrust to suddenly increase that much in such a short RPM range. Again I am not saying it's wrong, just that it's very different from what we have seen so far, and therefore I am simply interested.

Thank you!

By the way, in the training videos, the behaviour was different.

Starts moving at ~8000rpm and smooth taxiing is possible even at just 7000.

Addition to the issue is the brake behavior. It is just set to full brakr/no brake, the moment you want to turn it applies full brake and the plane stops.

If you check other eastern modules like mig 15, when you press the brake button it applies it smoothly not suddenly to max which helps when turning.

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