You have trim settings AND Vmax switch which gives 4% extra thrust limited to 6min of continuous use(and when 1 hours of its use gets accumulated the engine need maintenance)
Trim on the 100 is done on the ground, on the 220 is done automatically.
No, I don’t. After the very first run of the jet engine the health would be at “99%” MCP and would degrade from there. No engine IRL after the first 5 mins is actually operating at “peak performance” for long.
Seems you are wrong. Its a measure to extend life, pilots going from AB to idle quickly and then back up to AB and back and forth, wear, temperature, stalls, etc. All stressing the engine and making performance drop. Enter in conflict, trim it for optimum thrust and voila. Just do more maintenance, the wartime extra thrust is the Vmax switch which you can only use at above M1.1.
Trimming also help to keep performance as engine degrades, and with the 220s the ground trimming feature was gone. Now 220s operate in the trim setting 100s don’t even do IN WARTIME!
Spoiler
During engine trim, the EEC was fed a false Tt2 signal of -7F, which set a N1 speed of 100.7% (104% corrected to -7F). Using the T.O. lookup table, the N2 speed was adjusted using a trim screw on the EEC to achieve the desired Engine Pressure Ratio (EPR) for the inlet temperature of the day. Increasing N2 would drive N1 up, which the EEC returned back to 100.7% N1 by trimming the nozzle closed, which increased EPR. Once this cold day N1 / N2 ratio was set, the FTIT limit was set using another EEC trim adjustment that set the number of “clicks” necessary for engine thrust performance. On a really healthy engine, the minimum was 5 clicks. As the engine deteriorated over time, the click setting could go up to 11, raising the FTIT temperature limit to maintain hot day performance.
When the engine was running on the FTIT limit, the EEC calculated a delta N2 that represented how far below the engine was running below the N2 schedule set during the false Tt2 trim. For every delta N2, there was a corresponding delta N1, where the EEC trimmed the nozzle to lower N1 speed below the 104% corrected cold day setting. This trimming was supposed to maintain EPR at the optimum level for performance and stall margin as the engine was running against the FTIT limit.
As the engine high pressure turbine deteriorated with time (primarily due to increasing tip clearances), the N2 would tend to slow down, with more energy passing to the low pressure turbine which tended to increase N1 speed. The EEC had a correction factor that looked at FTIT vs N2 to determine the level of deterioration and would automatically adjust its N1 speed targets to compensate.
When the F-15s were first stationed in Alaska, they began to experience AB initiation stalls on takeoff. It was determined that under really cold conditions, the UFC Mil power trim was higher than the EEC targets. On the first accel, the UFC Mil N2 was overshooting the EEC targets, with the EEC cranking the nozzle closed to keep N1 under control before it could unwind the UFC core fuel flows. During this N2 overshoot, the EPR would go too far above target just as the AB lit, resulting in the Fan stall. When this phenomenon became known, P&W developed “Arctic Trim”, which lowered the UFC Mil setting to prevent this overshoot.
Later, it was determined that the UFC Mil power trim setting would creep upward over time as the turbine deteriorated, and eventually the EPR overshoot could occur during non-Arctic conditions. “Arctic Trim” then became standard T.O. procedure for all F100-PW-100/200 engine trim actions. It had long been observed that AB takeoff stalls seemed to peak in the spring and fall with the temperature change, with only minor adjustments found during EEC trim and troubleshooting operation. No one had observed the regular UFC Mil power trim adjustment and made the connections to the EPR overshoot phenomena.
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You have no idea what I’m talking about. Has nothing to do with “trim” or “RPM”.
Turbines cannot continuously output 100% of the rated thrust until failure. Turbines degrade in power over time with use for a variety of reasons. They are only overhauled when something breaks, leaks, or output is below a certain percentage. USA has the benefit of a massive arms industry that allows us to swap engines or quickly overhaul them at smaller intervals - keeping the mission power at a higher percentage.
Mission capability power is a measure of the health of the engine as a percentage. 100% is the maximum expected output in static conditions. This is before temperature or altitude adjustments are made which must be adjusted by looking at a chart.
So, 100% thrust would be a fresh engine. Used engines (more than 5 minutes on mil power) will generally fall below 90-99%, if weather or altitude is adverse the percentage would be lower and the subsequent charts adjusting it for these conditions would give you the true “health”. An engine with several hundred hours on it may be as low as 70-80% and after adjustment come out to ~90%. I do not know at what percentage they deem it necessary to overhaul for a specific engine.
It is the digital electronic control units and associated sensors that allowed for maintenance to check the “health” (power output) of the motors more easily and regularly.
1.) this is completely irrelevant to ingame.
2.) you vastly underestimate how long engines can last at peak performance.
3.)
Lmao no. A single burner run is not going to degrade performance so drastically.
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Seems you are lost. The talk is about trim settings, which is what 102% 97.7%, 95% is about. Getting the context above helps.
Engine performance loss is a thing, trim helps with that.
You are overblowing it. 10% loss…
Well damn. If this was a thing then planes would be falling out of the sky within an hour into their flight. 10% loss is thrust for 5 minutes of use. I guess engines has 1% thrust after their 500 hours lmao. And if MIL power is 10% for 5 minutes I don’t want to imagine afterburner.
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Its not a long time. After an initial run they can drop substantially but they will settle for while and begin to wear out at a much slower phase. It’s not that big of a deal for new engines either way
You ignored the part where I said “before temp and altitude corrections”. I never said it would lose power after 5 mins on mil, only that the health test would not yield 100% (uncorrected) after the first run of the engine.
Cool, but turn charts at 102% aren’t being shared so what is the discussion?
If we are discussing “oh it’s not realistic to model it on 97.7 trim” well… I’ll be the first to tell you that most in service F-15’s are probably not outputting 100% thrust rating.
You also didn’t read or understand what was being said once again, please take your time or ask for further context / explanation instead of jumping to this pervasive hostile response.
Dunno. Same way 95% engine trim charts aren’t available, 102% aren’t.
No, it’s not that what is the discussion.
Downtrim engine to preserve the engine life, uptrim to get the best out of it during war time. How hard is this to get.
It’s a render distance thing, has always been ingame. Using radar increases the render distance
I know. It is the usual coupling problems with Gaijin basing so many things in the game on the visibility mechanic. However, ideally, this should not be happening, as whether your radar is on or not should not have any bearing on render distance.
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Frfr. Bol pods this update?
Also vapor cone
Hi guys. The F15C MSIP II engine intakes are not moving when looking at them from the cockpit view. They are moving when flying the F15A. For me, this ruins the experience when flying in the cockpit view a little bit. Could you maybe press the “I have the same issue” button on this 3 months old issue report?
https://community.gaijin.net/issues/p/warthunder/i/pOTq7oQzDjP2
Thank you in advance! :)
Thread on the stuff I was talking about here:
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Shit’s not good right?
Try to find a better source, chat gpt is not gonna be taken seriously. Try looking at the USAF national museum page on the C and maybe the E