For water-cooled propeller planes, in event of water leakage draining your radiator fluids - does an open radiator still provide some cooling, or should you close it?


I’ve recently had to glide across Kursk with a radiator leak. I managed to crashland thanks to having decent altitude, but I could not help but wonder:

Would my engine have lived longer if I kept my engine radiator flaps open after I saw that my “Water” display read empty, or did I choose right to close engine flaps to reduce drag?

I’d imagine, even without water cooling - open radiator ducting still passes some air over the overheating engine, does it not?

Also, more thermo questions: Does the oil and water cooling systems interact - e.g.: does opening oil radiator flaps more to compensate for lack of water coolant at all?


No. The fluid is what carries heat from the engine. When that is gone, the radiator provides nothing but drag. You should close the duct to at least minimize it.
Without main cooling, there is no point in cooling the oil either.

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Planes generally aren’t like cars (well, the old ones with combustion engines and radiators :) ) where the radiator is in front of the engine (most of the time). The radiators in planes are in a very different location to the engine, so radiator flaps will have nothing to do with airflow over an engine. You can check the radiator position using the x-ray view.

Note that air-cooled engines will have the “radiator” flaps around the engine, but while they serve a similar purpose, they aren’t radiator flaps – they’re cowling flaps. (And obviously you won’t have a water leak in an air-cooled engine).


So “emergency procedure” in event of radiator leak could be surmized as:

  1. While coolant exists, maintain current flap deployment and try to climb or at least maintain altitude while returning to airfield
  2. After “Water” reads empty, close both oil and water flaps.
  3. After engine dies, turn it off and feather the blades, begin shallow dive to maintain speed.

Or should I ditch radiator drag the moment I begin to RTB?

That is probably good.

You may already know this (but it’s not mentioned in the post), but one thing to be aware of is that if your intent is just to get back to base (and hopefully not get attacked along the way) then you can generally drop your throttle way back and still maintain a decent speed. People will often fly around constant 100% (or even WEP, but maybe not in Sim) when you can actually still do well at 60-80%. If you’re got some decent alt and are descending slowly then even 0 - 30% can suffice to keep speed up. This will reduce heat generation quite a bit and increase the time it takes for the engine to overheat, even if you’re out of water.

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Your procedure has 2 flaws:

  1. If your engine dies whilst you are rtb the enemy which “produced” this damage gets a “severe damage” (as killing all engines is a severe damage) - if you team mates clean up all enemies after your engine died, but before you repaired you get “written off”. Happened to me one or 2 times

  2. Depending on your experiences with certain planes you can “nurse” a lot of planes back to airfield whilst keeping your engine alive. So by switching to MEC with feathering the prop, closing all rads and put the engine off you can cool the engine during gliding phases - and then switch to AEC to reclimb until the temp gets too high and back to MEC with the feathered prop…works pretty good, although the time span of a “working” engine gets smaller and smaller…

This post has a Sim battle tag, and assuming this is a correct tag I don’t think this point is relevant?
(As it sounds like you’re talking about AirRB when the battle ends due to enemy team being all destroyed)

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So far, my 2 crash-landings with dead engine or completely black wing/missing rudder have allowed me to limp back and land (just barely, both times I skidded or wingstruck) I didn’t get written off and I could respawn fine.

One of them was player induced, one was an a.i bomber.

Both crashlandings:

The engine was black before propstrike:

The engine was also black before propstrike:

No fluids means no cooling, no cooling means more heat, so if you push your engine, you’re dead. Best case; you shut it for decreased drag and don’t overheat (depends on the plane and engine tho, I.e. A Bf-109 will overheat 9/10 times, because it’s a 12 cyl Benz engine) worst case, you blow it up or melt it down and can’t make it back.

You are correct, i don’t saw the sim tag - lmao…