Oil temp threshhold for engine breakage? (Mainly Merlin engines)

[Crumpp]

he higher you go, the cooler the engines should run, and less likely the chance of damage.

That is wrong.

The higher you go, the less effective the cooling due to pressure and density reduction despite the cooler temperatures.

So while the temperature does get cooler IAW the lapse rate, the density is reduced so we end up with less molecules to transfer heat away from our engine.

[*Buzzsaw*]

Originally Posted by Crumpp

That is wrong.

The higher you go, the less effective the cooling due to pressure and density reduction despite the cooler temperatures.

So while the temperature does get cooler IAW the lapse rate, the density is reduced so we end up with less molecules to transfer heat away from our engine.

I can't say I am an expert on this matter. I made the assumption there is enough flow with the higher speeds at altitude and the cooler temps to cool the aircraft faster. Ie. IAS at sea level and 6000 meters may read the same, but TAS is much higher at altitude, and therefore airflow is much higher.

Anyone else want to comment?

[Crumpp]

IAS at sea level and 6000 meters may read the same, but TAS is much higher at altitude, and therefore airflow is much higher.

Airflow is not much higher because of True Airspeed.

[bongodriver]

Indicated airspeed is what matters, if indicated is high enough then cooling will be sufficient.

[ACE-OF-ACES]

Originally Posted by bongodriver

Indicated airspeed is what matters, if indicated is high enough then cooling will be sufficient.

Bingo!

[ATAG_Dutch]

Originally Posted by Crumpp

That is wrong.

Originally Posted by ACE-OF-ACES

Bingo!

Nothing changes here, does it?

Oil temp. Whatever settings people tell you to fly at, fly at less, apart from airspeed. Whether it be RPM or boost. Most people in a game fly at max poss everything all the time. Total rubbish.

What is the oil temp at which your engine blows? Find out. Run your mouse over the oil temp gauge and wait for it. Try it at different rpms. Try it at different boost settings. Just fly. Offline until you find out. Then you'll know.

Everything is there for you to find this out for yourself. Go to it.

Edit: 97 degrees. If memory serves correctly........

[Crumpp]

Indicated airspeed is what matters, if indicated is high enough then cooling will be sufficient.

Why don't you take the time to explain the relationship of Indicated airspeed, True airspeed, and altitude?

Then take some to explain the general behavior of a altitude effects on thrust production at constant power setting and indicated airspeed.

After you have done that, you can sum it all up as:

Crumpp says:

The higher you go, the less effective the cooling due to pressure and density reduction despite the cooler temperatures.

[JtD]

Originally Posted by ATAG_Dutch

Nothing changes here, does it?

Annoying, isn't it? I don't think this is the best subject to make generalisations, because temperature over altitude characteristics depend on aircraft, engine, engine settings, flying regime. So I suggest to find a different excuse for being rude to each other.