Author Topic: Aircooled engines (Read 665 times)

Wilbus · « **on:** June 13, 2002, 01:07:22 PM »

Help me out here please, I've said it before and I say it again, I suck at engines, don't even know how the darn things work nor what all the "2.2liter and 42 liter" things means.

So to the real question, an Aircooled (radial, 190, F4u, P47 etc) engines use the airflow to cool them down, right? This is the reason the 190 had an extra "fan" to cool the engine. And it's also a reason these engines are much more sturdy and easy to maintain aswell as being able to have cylinders shot off and still fly.

So is there something in an aircooled engine that can be hit that will cause it to overheat like an aircooled engine that gets it radiator shot off?

Also, if I am not misstaking, there is no fluid to cool the radials so what is the smoke we see when we get radiator hits in our 190 and F4u and P47's?? (or can't we get radiator hits in them?).

whgates3 · « **Reply #1 on:** June 13, 2002, 01:40:13 PM »

anything that makes the oil leak would make the engine overheat. the F4U had oil coolers under the wing roots that were considered vulnerable, so i would have to assume that there is some conduit from oil coolers to the pistons that would be vulnerable. Also a hit in the blood resivoir could take down any plane

HFMudd · « **Reply #2 on:** June 13, 2002, 01:57:10 PM »

Yeah, a hit in the oil coolers would cause problems no doubt. Not the least of which is that the oil would leak out since I suspect that the oil is circulated directly through the radiators as the working fluid.

But I think the intent of the original post was that there is no coolant to leak out and make gray smoke. It seems reasonable that a radial engine plane should only have black (oil) and white (fuel) smoke while the inlines have these two plus gray (coolant).

Wilbus · « **Reply #3 on:** June 13, 2002, 02:09:43 PM »

Yes HFMudd, that's what I mean, the oil smoke should be on all planes, and should cause engine to overheat/stop (although P47 aswell as 190's were known to fly without oil and make it back home). But IMO, like HFMudd says, there shouldn't be any coolant fluid to leak out, right?

senna · « **Reply #4 on:** June 13, 2002, 03:25:59 PM »

Most high performace air cooled engines are also "oil cooled". Hitting a cylinder and knocking it off will cause an oil leak and gradual drop in oil pressure but this all depends on where and how much damage. Generally its harder to damage the oil system on an engine than the water system (not talking about hiting the oil coler which is a direct hit on the oil system) because the oil channels are much smaller than the water jackets of a water cooled engine. In a radial engine, the crancase is in the center surrounded by banks of cylinders and a prop reduction gearbox at the front.

HFMudd · « **Reply #5 on:** June 13, 2002, 03:32:09 PM »

Would the oil cooling system be isolated from the oil used for lubrication? I.e. is the oil passing through the cooler different than the oil in the crankcase?

Staga · « **Reply #6 on:** June 13, 2002, 03:59:35 PM »

Same oil both lubricates bearings and "valve ballets" and cools engine.

I've seen few engines and none of them aren't able to run without oil. Also if you run your engine too hot for too long oil will lose its capability to lubricate and it turns to something which looks like toffee or paste.

funkedup · « **Reply #7 on:** June 13, 2002, 03:59:41 PM »

It's the same oil HFMudd.
Water-cooled aircraft engines usually have an oil cooler too. But the oil cooler plays a bigger role on air-cooled engines.

dtango · « **Reply #8 on:** June 13, 2002, 04:10:42 PM »

Someone draw some pictures. I like pictures.

Really, I'm lost when it comes to engine details. Any diagrams illustrating the above would be greatly appreciated.

Tango, XO
412th FS Braunco Mustangs

Staga · « **Reply #9 on:** June 13, 2002, 05:18:14 PM »

Well you did ask this

WW2 fighters did use dry sump oil system; oil is storaged in a tank outside of the engine itself. Wet sump (like in cars usually) works just fine if there's no negative g-forces lifting oil from pan to the engine. It's also easier to build bigger oil tank between engine and cockpit than build a 15-20 gallon oil pan under the engine.

dtango · « **Reply #10 on:** June 13, 2002, 06:27:10 PM »

Staga:

Thanks for indulging us and providing a schematic

.

So the oil coolers for radial engine planes are located on various places on the aircraft as some have indicated?

Tango, XO
412th FS Braunco Mustangs

funkedup · « **Reply #11 on:** June 13, 2002, 06:39:56 PM »

Yes. Some are in the cowling, some are below the cowling, some are in the wings, some are under the wings, some are under the fuselage.

Wilbus · « **Reply #12 on:** June 13, 2002, 07:02:12 PM »

And an air cooled radial can't get a radiator leak right? Thus it shouldn't have grey smoke in AH, right?

Do we have grey smoke in AH for radials or was that in the past?

Staga · « **Reply #13 on:** June 13, 2002, 07:10:36 PM »

Fighters with water cooled inline engines had similar oil-systems like the planes with radial engines.
I'm not sure but afair P-51 Mustang had water cooled oil-cooler, i.e the water-glycol mixture for engine did also cool down oil in oil-cooler (Finnish term for system like that is "heat-exchanger")
Also straight from my (bad) memory: IIRC pilot of Me-109 could close one of the two underwing radiators if there was a leak and still fly the bird back home by using only one radiator (well not in "Full Ahead" mode...)

edit: P-51 had ordinary "oil to air" oil cooler; I'm not sure what plane had that water cooled system.
Edit II: Looks like P-51K had a heat-exchancer type oil-cooler.

GRUNHERZ · « **Reply #14 on:** June 13, 2002, 07:11:38 PM »

Sure you can get light gray smoke from an air cooled radial, ever see B17s and B24s smoking after damage?