Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: Wilbus on June 13, 2002, 01:07:22 PM
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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?).
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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
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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).
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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?
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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.
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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?
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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.
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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.
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Someone draw some pictures. I like pictures. :D
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
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Well you did ask this :D
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.
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Staga:
Thanks for indulging us and providing a schematic :D.
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
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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.
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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?
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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.
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Sure you can get light gray smoke from an air cooled radial, ever see B17s and B24s smoking after damage?
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I guess that a white smoke pouring from a radial is actually fuel especially if the tanks are of self-sealing type. So the fuel lines of the engine has obvioiusly broken.
I remember an American pilot commenting about FW190 oilcooler that it was actually a rather weak constrution as it had an armored ring in front of it so any, even a small caliber, bullet fired from behind and ricoheting in engine compartment could cause the oil to spill on hot engine. He said that almost every FW he hit from behind started to pour a dense black smoke which was obviously caused by burning oil.
-Charge+
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Yes Charge I've read that too, do you have a source where he/any other pilot says those 12 kills were confirmed (did he see the pilot bail out or the plane blow up etc?).
The reason I ask is that, while no other pilot who shot down multiple 190's said that every 190 pored black smoke, or even that a big number of them pored black smoke it might be that every 190 this pilot encountered used teh MW50 boost when they were fired upon. (no not saying the pilot is lying just wanna see some confirmation, interesting reading).
The MW50 boost gave extra power BUT it was also used to "trick" the enemy, when engaged, the MW50 pored out dense grey/black smoke and often fooled many pilots that the plane was dead.
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Originally posted by Wilbus
The MW50 boost gave extra power BUT it was also used to "trick" the enemy, when engaged, the MW50 pored out dense grey/black smoke and often fooled many pilots that the plane was dead.
Is that true?...if it is you might be on something good here, wil ;)
AFAIK, what was vulnerable on the 190 was not the oil system (well the anular oil instalation was vulnerable to fire coming from the front), but the fuel injection system wich injected fuel directly into the cylinders. If one of those was blown out, the injection sistem kept on sending fuel to the broken cylinder, thus spraying the engine with high octane aviation fuel...something a bit tricky which causes high probabilities of a fire ;)
but other than that the 190 was renowned for being a very rugged machine, and in any case there are quite many stories around of 190s returning to base in one piece with badly damaged engines, despite the fire hazard already mentioned.
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Hi RRAM,
>If one of those was blown out, the injection sistem kept on sending fuel to the broken cylinder, thus spraying the engine with high octane aviation fuel...something a bit tricky which causes high probabilities of a fire
Ouch!
But what would happen to a carburetted engine? Wouldn't a damaged line between carburettor and engine mean losing the boost pressure as well as blowing a combustible fuel-air mixture into the damaged engine? I'm not quite sure if any engine could be safe with regard to that type of critical damage.
Regards,
Henning (HoHun)
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hmmm so many big enginers around and stuff like this :D are ever one of you ever seen the direct injection work ? mean the jet injector and how much fuel it ,, spray,, ?????????
if not then beter checkit out and surely you will be surprised about the volume of fuel :p
but a broken carburator exposed to air stream , that realy taking fuel around !
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hahaha
The fuel injector comments remind me of a show that was on the learning channel a number of years ago. I forget the name, or the name of the host. Was this wacky british guy that drew drew some wacky little animations. He would take things apart and show how they work.
Anyhow one episode was about how internal combustion engines worked.
when they got to the part about fuel injectors he had one setup on its side so it would shoot the fuel out horizontally. so he turns it on and fuel goes flying about 10-15 feet. then he takes a torch and ignites it. really neat. the flames went quite a ways..
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Yep, most modern day fuel injection systems run about 40 to 60 PSI.
On an engine such as a radial, if a carb or /rod/piston/clylinder was broken, the fuel would stop since that cylinder would stop "breathing" however on say a fuel injected radial like the bmw-801, the fuel would continue to be pumped via its (back then) mechanical system (lower pressures than today I bet). There could be alot of scenereos but good chance of fire.
In regards to the intake system, if an area was "holed" that would cause every cylinder to be affected in terms of manifold pressure or intake charge, the engine could possibly still run but with much reduced power output. Especially a superchared or urbocharged engine since these engines generally had a lower compression value than a normally aspirated engine.
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starbird:
That was: "The Secret Life of Machines"
Hooligan
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A desciption of the Merlin
http://www.unlimitedexcitement.com/Pride%20of%20Pay%20n%20Pak/Rolls-Royce%20Merlin%20V-1650%20Engine.htm
and the P&W2800
http://www.stjohnsprep.org/htdocs/sjp_tec/projects/internet/gwojtkun/pr-2800.htm
and here (be sure to look, very interesting)
http://www.nomeking.com/radials.htm
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Originally posted by RRAM
AFAIK, what was vulnerable on the 190 was not the oil system (well the anular oil instalation was vulnerable to fire coming from the front), but the fuel injection system wich injected fuel directly into the cylinders. If one of those was blown out, the injection sistem kept on sending fuel to the broken cylinder, thus spraying the engine with high octane aviation fuel...something a bit tricky which causes high probabilities of a fire ;)
Oil system and fuel system has some relations.
Spraying fuel into non-functional cylinder would cause fuel not to evaporate enough thus "flowing" from between the cylinder and the piston mixing it with the oil and reducing its lubricating capability. Aviation fuel was high octane fuel, but I doubt it would all evaporate due the engine heat in broken cylinder.
What comes to fuel injection in WWII, we must remember that they actually were not electronically driver systems, they were mechanical. The amount of fuel sprayed into cylinder was way too much just because the clearance between the piston and cylinder was much greater than in present engines. You have any idea of how much oil burn was common in WWII aviation engines? WWII engines had very poor operating efficiency compared to present engines and that is the reason I would rise questions of engines loosing their lubriction capabilities instead of "burning". Sure, if engine runs long enough with reduced lubrication, camshaft and crankshaft would "cut" and make engine to "burn", but not engine to burn directly because of the fuel.
Just my food for thoughts :)
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Lots of gun camera footage of 190s getting hit in the forward fuselage and having huge engine fires...
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I know this much, if you leave the fuel hose coming from the fuel pump to the carberauter/fuel injection system unhooked and turn the motor over on a early model chevy engine, fuel will squirt a long ways:) lots of it too:)
I put an electric fuel pump on an old camaro my brother and I was souping up in high school. That thing would squirt fuel for 8 feet in a steady stream from 10 foot of hose.
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Originally posted by funkedup
Lots of gun camera footage of 190s getting hit in the forward fuselage and having huge engine fires...
Caused by.. (fuel or oil)? We never know. Both burns.
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Originally posted by -ammo-
I know this much, if you leave the fuel hose coming from the fuel pump to the carberauter/fuel injection system unhooked and turn the motor over on a early model chevy engine, fuel will squirt a long ways:) lots of it too:)
Sure will, but we must remember that in aircooled fighter there is huge air velocity in engine compartment due the speed of the fighter and the air velocity of the propeller, that would cause fuel to fall behind (away from the exhaust manifolds) the engine :)
Besides, fuel as in liquid state, doesn't detonate as easily as fuel steam and air mixture.
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Sure carburators sometimes use fuel pumps as well but once the fuel goes into the carburator the pressure is much much lower (in the fuel lines) than in a fuel injected engine.
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vector gravity feed to the carb went out with WW1. A fuel pump was always used as liquid can not run 'uphill' from wing or fuselage seat area fuel tanks.
What happens to fuel when put into the main barrel of the carb? The fuel is vapourized. So if a fuel line is cut in the radial engine's area, that high speed of air will do the same thing, vapourize or mist the fuel which will then burst into flame on the hot exhaust manifold.
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"He said that almost every FW he hit from behind started to pour a dense black smoke which was obviously caused by burning oil. "
sorry man any hick knows oil burns white. gas and diesel burn black.
you get a hit in engine if oil hits the manifold or ignights its is a dense white smoke. been there
you run fuel rich its a black smoke usualy much less billowy.
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If I'm not mistaken oil ignites at a lower temperature than gas. So as long as there isn't an ignition source (i.e. spark) the oil would catch on fire from heat before any gas would.
Spritle
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yea your mistaken