Reed

Im just curious as to why oil does not collect in the cylinders of flat engines. Whataver the reason is, would it also be applicable to engines with angles over 180 degrees as in an engine where the crank would be placed above the cylinders? I am aware (due to being trained as an A&P) that in aviation it is not uncommon to see rotary engines (not like the 13b but like 9 cylinders aranged in a circle). how do these engines keep oil from collecting in the cylinders? (I really should know this but its been a few years and quite a few beers since i graduated from airplane school)

Basically, could one design a "V" engine where the crank is above the cylinders without oil/hydrolic lock problems?

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Black Lotus

Most flat engines I've seen have an oil sump below the crankshaft. On the pushrod designs, the camshaft is even below the crank.
On radial engines, oil does seep into the cylinder. But after sitting awhile, the lower spark plugs are removed and the engine is cranked over by hand using the prop. The oil is forced out of the plug hole or exhaust valve. (so said my dad)

Reed

So if you had an inverted V engine with a dry sump lube system you shouldnt have any problems.

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2turboimports

Even then wouldn't oil that's run through the rods collect in the bottom of the piston?

2.2 Straight six

yes.

a dry sump isn't dry. it just means that most of the oil collects in a tank and is pumped around so there isn't much oil in the sump.

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2turboimports

Yes, I know. But that doesnt mean anything to the inverted V-block where (I'm assuming this is what was meant) it would be upside down. Then, dry sump, or sloshy sump, oil will still fill up in the bottom of the pistons.

2.2 Straight six

well, it would collect in the bottom of the piston, but on the "down" stroke (up in the case of an inverted V) most of the oil would be thrown up out of the piston, but only to go back later.

having oil splash onto the bottom of the piston like that is actually beneficial when the engine is running, it provides excellent lubrication and the oil hitting the bottom of the piston aids cooling the piston. it acts like an oil-squirter, cooling the piston and adding extra lubrication to the cylinder.

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Reed

I am aware that a dry sump is not dry and the reason i brought it up was because the sump could be placed below the the cylinder and gravity would do its thing. Of course you would still need to find a way of getting the oil out of the cylinders to allow gravity to do its thing when the engine wasnt operating. One would probably burn a lot of oil too.

I'm just wondering these things for the sake of a lower CG.

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If it ain't fast it ain't shit.