Official P51 and 109G10 oil leak tests

[juzz]

The Yak-9 damage tree is identical to the Me 109. Could it be that they share the same basic damage model?

[Toad]

 

Originally posted by GRUNHERZ:
The P47 is irellavant to this discussion... Toad, both 109 and P51 use glycol type radiators to cool the engine, they do not use engine oil for cooling
[This message has been edited by GRUNHERZ (edited 12-03-2000).]

Grun,

It seems that we have a lot of variation even within similar engine types in the planeset. Therefore, discussions of air-cooled, oil lubricated radials is germane to this discussion, if you're using a "big picture" approach.

I'm looking at the engine oil/glycol cooling damage model overall, too, not for any one specific aircraft. It seems they should be similar.

Are they in the game? Are there RW design reasons that might explain it if they are not? Or are all the designs so similar in cooling ability that there should be essentially no difference? For example, does the Spit have any significant differences in cooling capacity/capability with respect to the -51? How do those then compare to the 109?

Or we could just ask Pyro how he did all the planes oil & cooling damage models I guess.  

[-lynx-]

I just wonder how does one inflict "zero oil" damage? Is there a tap somewhere I'm not aware of?

[Lephturn]

Just for reference.  I used to race stock cars with V8 chevies in them.  Both use oil for lubrication only.  However, we had two different types of oiling systems.  Dry sump and wet sump.  Wet sump is the normal type where the oil resevoir, pump, and all are built into the engine with the oil resevoir being the oil pan on the bottom of it.  A dry sump is a much smaller oil pan with an external pumping system with an external oil tank of much larger capacity.

I've had a wet sump system run for several minutes after being holed before losing oil pressure and even made a few laps before detonating.  I've also has one blow itself to bits literally seconds after being holed.  A dry sump system will depend on where you lose oil... the tank or the oil pan.  If the engine gets hit or you lose the pump, you lose oil pressure instantly and the thing can seize in seconds if it's under load.  If you get a tank hole with a dry sump motor you will still have pressure until all the oil runs out of the sump and you get a pressure loss in the engine.  Run time after a leak will depend on engine load as well.  You can idle an engine with no oil presure for quite a while, many minutes even.  Try to run one under heavy load at full throttle and it will seize seconds after loss of oil pressure most times.

I'm just pointing out that there are lots of variables here.  We need Pyro to tell us what variables he is modelling and how it feeds into the run time after a hit.

------------------
Lephturn - Chief Trainer
A member of The Flying Pigs  http://www.flyingpigs.com
 
"A pig is a jolly companion, Boar, sow, barrow, or gilt --
A pig is a pal, who'll boost your morale, Though mountains may topple and tilt.
When they've blackballed, bamboozled, and burned you, When they've turned on you, Tory and Whig,
Though you may be thrown over by Tabby and Rover, You'll never go wrong with a pig, a pig,
You'll never go wrong with a pig!" -- Thomas Pynchon, "Gravity's Rainbow"



[This message has been edited by Lephturn (edited 12-04-2000).]

[Jigster]

engine life during oil starvation would depend alot on power settings. Running MW50 on a 109 with the oil leaking out (which is usually the norm) would probably lead to a quick seize, but I've noticed it quits quickly no matter the RPM/MP.

Oh yeah, while on lubrication and pump types, we still don't have negative G effects on oil pressure. For an example, the F4U used a wet sump, which can lead to oil starvation (and engine damage) during prolonged negative G forces, taking into account that the plane has been running long enough to burn off some oil in the tank.

I would say that because of the relatively slow RPM of aircraft engines that they would be capable of surviving considerble lengths oil starvation, but not without damaging it to the point where it could not be used again. Case in point, the F4U, that in a spin condition over 20 seconds or so the engine would start losing power, and while still capable of running, the engine suffered a massive power loss and (sometimes) later seized.


The engine damage model is just too basic right now to expect much from historical characteristics.

[This message has been edited by Jigster (edited 12-04-2000).]

[Dowding]

Here's something that may have relevance (and I think it corroborates something you are already aware of).

It's an excert from a Soviet book written in 1943 (translated from Russia this year).

"...it must be remembered that the Me-109 can only hold the maximum airspeed indicated above for no longer than 1 or 2 minutes in horizontal flight, as their engine overheats and causes the coolant to boil. Therefore, if a Me-109 encounters our Yak 1 or La 5 that have the altitude advantage, he would not be able to disengage just by using superior airspeed.

Wouldn't therefore any loss of oil have an immediate effect (due to the increased heat load on the coolant)? Sounds to me like 30 seconds is too LONG, not short.

As for the P51 - perhaps it dows run for too long with an oil leak. But if you change that, then perhaps the Bf 109 needs lose its engine 10 seconds into an oil leak.

[Westy]

 Not saying anything about the lenght of time for anything on any plane,  but a major difference between the Merlin and a DB-60x is that the DB-60x engines are inverted. And I cannot recall if that was a boon or a bust for the 109 as far as coolingand/or oil  issues go.

 In the Merlin the crankshaft and major bearings are down by the oil. I believe paddles splash the oil around those parts out of the sump. The oil is needed to be pumped up to the heads which if there was no oil the valve train would degrade and eventualy seize if it didn't grind into small metal peices first. Whereas the DB-60x engines also have the oil in the bottom, which is good for the heads and such, but the crankshaft and the major bearings are at the top, furthest from the oil. No oil flow = a very quick siezure by the DB-60x engines for sure.

  -Westy

 DB605:
       

 Merlin:
       


[This message has been edited by Westy (edited 12-04-2000).]

[Toad]

Have I ever mentioned that almost nothing in aviation is real simple?  

Good posts in here, from top to bottom. Well, except for one typical one.  

[Jigster]

Btw the DB was suspect (as were all radials) to oil pooling beneath the pistons, (in the top of the cylinder, when the engine is turned up with the pistons pointing up, that is). Required a hand turn over for at least 1 revolution to ensure that the oil was not present, due to possibility of over-compression and cyclinder rupture.



[This message has been edited by Jigster (edited 12-04-2000).]

[Toad]

Just about anything with an inverted cylinder is a prospect for hydraulic lock.

You pull them through until all cylinders have had a chance to open and close the valves and drain the oil out of the head.

Or else be ready for a bent rod, minimum.  

[This message has been edited by Toad (edited 12-05-2000).]

[Jigster]

I hear that Wasp Major was almost impossible to turn over by hand, as was the Naiper-Saber even without being in a state hydraulic lock  

[Lephturn]

Interesting.

In that configuration I would expect the DB to be a dry sump motor.  I wonder if that's the pump on the bottom, or if it was external.  In any case, a loss of oil pressure in the DB should kill it quicker with the bearings up high like that.

Can anybody point me to more detailed drawings and/or info on the DB engine?

------------------
Lephturn - Chief Trainer
A member of The Flying Pigs  http://www.flyingpigs.com
 
"A pig is a jolly companion, Boar, sow, barrow, or gilt --
A pig is a pal, who'll boost your morale, Though mountains may topple and tilt.
When they've blackballed, bamboozled, and burned you, When they've turned on you, Tory and Whig,
Though you may be thrown over by Tabby and Rover, You'll never go wrong with a pig, a pig,
You'll never go wrong with a pig!" -- Thomas Pynchon, "Gravity's Rainbow"

[Westy]

 Lephturn, I used www.lycos.com  and searched first for "Merlin engine" and then another for "Daimler Benz DB605". In all the hits that came back I could find only a few cutaway drawings of the Db60x engine (smalledt and most usable above) and none for the Merlin. The problem with the Merlin is that it is still a used engine for racing( aircraft and boating). so you get alot of unwanted responses too. Hmmm. If the DB605 was SOOOOOO good (<GGG> ) why wasn't it used after the war in racing? Hmmmm?   (obligatory tease)
 
 Anyway. I also could not find any reference to why they inverted the engine. And it's been many, many years since I read the purpose behind it but there was some valid reasoning for doing so. Not validating the reason mind you. Oddly the DB motors were the only ones that were inverted while just about all other liquid cooled, inline engine equipped aircraft, made by other nations and companies, were done in the standard upright position - all that I can think of anway.

  -Westy

[Rooster]

The real secret here is the Allied miracle engine additive, Slick 50  

[Eagler]

 

Originally posted by Rooster:
The real secret here is the Allied miracle engine additive, Slick 50    

It would make a great info commercial  

Great thread guys, great info. Would like to see AH's ideas on the subject. Heck, you guys are doing the R&D for them. Me thinks the 109's are a little fragile in many respects or the LW would rule the sky's just as they did early in the war before the odds/resources went against them. Then again I love 109's  

 
my 20th wedding anniversary present from the wife  

Eagler