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Engine overheat when crosswinds are present


Tuuvas

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Just documenting an issue I found with the TF-51D where the engine overheats when wind is present.  Below example testcase is:

  1. Setup two identical missions apart from wind speed
    1. Cold/Dark TF-51D in Caucasus
    2. Default ambient temperature (20°C)
    3. Wind speed
      1. 0 knots
      2. 20 knots crosswind
  2. Startup TF-51D
  3. Warm-up engine using
    1. Parking brake ON
    2. 12,000 - 13,000 RPM
    3. Radiator flaps fully open
    4. RAM / HOT air levers fully forward
  4. Once at 40°C Oil Temperature, radiator flaps to Auto
  5. Speed up time and keep an eye on temperatures
  • Expected Results:
    • Whether or not wind is present, stable temperatures should be maintainable while on the ground at 12,000 - 13,000 RPM
    • Note: an inaccuracy of this startup is not going throttle IDLE after reaching 40°C Oil Temp, but as far as I can tell the engine still overheats like in actual results below:
  • Actual Results:
    • Without wind (0 knots), engine temperature is stable
    • With wind (20 knots), engine overheats.

Note: there is a new cooling system being implemented for WW2 aircraft so it's likely this won't be an issue after it is released.  The purpose of creating this bug report is to document the potential bug, put the replication steps in writing, and test again after the new system is in place.

unknown.png


Edited by Tuuvas
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If wind blows from behind it will reduce cooling efficiency, so with liquid cooled warbirds you always need to watch wind. Taxing with tail wind is always a problem.

20kts wind is way above P-51 capability for safe take off any way 😛

Even if this is perfect 90 degree crosswind is present it will push prop wash sideways so it will miss cooler scoop makes less efficient, so when wind is present always point nose of the plane head on the wind.  

20kts is quite strong wind.


Edited by grafspee
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1 hour ago, grafspee said:

If wind blows from behind it will reduce cooling efficiency, so with liquid cooled warbirds you always need to watch wind. Taxing with tail wind is always a problem.

20kts wind is way above P-51 capability for safe take off any way 😛

Even if this is perfect 90 degree crosswind is present it will push prop wash sideways so it will miss cooler scoop makes less efficient, so when wind is present always point nose of the plane head on the wind.  

20kts is quite strong wind.

 

So if that's the case, orienting parallel to the wind should result in better temps.  I'm running that test now to see what happens


Edited by Tuuvas
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Let us know the result, those details are modelled in DCS by the way.

 

15 hours ago, Tuuvas said:

4. Once at 40°C Oil Temperature, radiator flaps to Auto

I don't know if that's going to change when the new engine model is released, or how it could change, but in this step watch out. Even at "only" 20º if you warm up the engine too much (green lines, apparently good but already "warm") while on ground it might even blow up just about getting airborne, radiator flaps are automated but they move slowly so when you're already warm up and take off ~max power the system has no time to open radiators once airborne and engine can be destroyed. It only depends on weather conditions even when it's apparently not that hot, and how much wind and the direction it has might as well play a role there. You can only let them fully opened and wait until you're airborne to switch radiators to auto to prevent that.

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"I went into the British Army believing that if you want peace you must prepare for war. I believe now that if you prepare for war, you get war."

-- Major-General Frederick B. Maurice

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9 hours ago, Ala13_ManOWar said:

Let us know the result, those details are modelled in DCS by the way.

 

I don't know if that's going to change when the new engine model is released, or how it could change, but in this step watch out. Even at "only" 20º if you warm up the engine too much (green lines, apparently good but already "warm") while on ground it might even blow up just about getting airborne, radiator flaps are automated but they move slowly so when you're already warm up and take off ~max power the system has no time to open radiators once airborne and engine can be destroyed. It only depends on weather conditions even when it's apparently not that hot, and how much wind and the direction it has might as well play a role there. You can only let them fully opened and wait until you're airborne to switch radiators to auto to prevent that.

Oh sorry, forgot to update with my findings. Headwind results in less engine heating, however it's still higher temp than 0 wind which seems wrong. I'll need to keep testing to be sure about this observation though.

Thanks for the information!  I'll be sure to refine my startup and warmup procedure to prevent overheat as much as possible.  I'll be perfectly happy if this is just user error and intended behavior.


Edited by Tuuvas
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Head on wind will definitely help cooling, if it actually 0 wind provide better cooling, then this is definitely a bug.

System specs: I7 14700KF, Gigabyte Z690 Aorus Elite, 64GB DDR4 3600MHz, Gigabyte RTX 4090,Win 11, 48" OLED LG TV + 42" LG LED monitor

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Head on wind should help only if radiator is fully opened, if it's closed I guess it could actually slow and/or interfere with the airflow 🤔.

"I went into the British Army believing that if you want peace you must prepare for war. I believe now that if you prepare for war, you get war."

-- Major-General Frederick B. Maurice

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7 hours ago, Ala13_ManOWar said:

Head on wind should help only if radiator is fully opened, if it's closed I guess it could actually slow and/or interfere with the airflow 🤔.

It is never closed, it will help cooling regardless off radiator shutters position.

Wind is airflow.


Edited by grafspee

System specs: I7 14700KF, Gigabyte Z690 Aorus Elite, 64GB DDR4 3600MHz, Gigabyte RTX 4090,Win 11, 48" OLED LG TV + 42" LG LED monitor

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4 hours ago, grafspee said:

It is never closed, it will help cooling regardless off radiator shutters position.

Wind is airflow.

 

Yeah, I thought of that, but if entrance is bigger than exit the airflow would slow down, hence refrigeration can't be the same and wind velocity wouldn't matter. Something to test, I know it's been said by devs sometimes all those airflows are modelled but to what extent and detail I wouldn't know.

"I went into the British Army believing that if you want peace you must prepare for war. I believe now that if you prepare for war, you get war."

-- Major-General Frederick B. Maurice

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How do you know that inlet is bigger then outlet have you measured it.

Only means of airflow on the ground is prop wash and wind, in every case where wind blows against prop wash or blow from side which deflect prop wash will end up with crippled air flow through radiators simple as that. If wind blows in same direction as prop wash it will increase airflow through radiators.

System specs: I7 14700KF, Gigabyte Z690 Aorus Elite, 64GB DDR4 3600MHz, Gigabyte RTX 4090,Win 11, 48" OLED LG TV + 42" LG LED monitor

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5 hours ago, grafspee said:

How do you know that inlet is bigger then outlet have you measured it.

Yep, it can be seen even on model kits, but anyhow if the doors open and close obviously is going to be a difference y sizes while intake is a fix size 😉.

"I went into the British Army believing that if you want peace you must prepare for war. I believe now that if you prepare for war, you get war."

-- Major-General Frederick B. Maurice

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22 hours ago, Tuuvas said:

Oh sorry, forgot to update with my findings. Headwind results in less engine heating, however it's still higher temp than 0 wind which seems wrong. I'll need to keep testing to be sure about this observation though.

Thanks for the information!  I'll be sure to refine my startup and warmup procedure to prevent overheat as much as possible.  I'll be perfectly happy if this is just user error and intended behavior.

 

Can you tell me how do you test it ??  If you set your radiators to AUTO temp will not drop much because shutter will close more. If you want to test this effect you need to have them in manual mode fully closed or fully open to see wind effect.

Over heat in AUTO mode happens when shutters got wide open and still it is not enough

From my testing with shutters wide open i score a little lower temps.

20kts head wind

40A3Hto.jpeg

no wind

Rp7sf9U.jpeg

 


Edited by grafspee

System specs: I7 14700KF, Gigabyte Z690 Aorus Elite, 64GB DDR4 3600MHz, Gigabyte RTX 4090,Win 11, 48" OLED LG TV + 42" LG LED monitor

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