Pyro; about 109...

[Pyro]

Thanks Niklas, I haven't really reviewed them yet, but I think I've seen them before.  I'm now getting into the detailed modeling and will take a good look at it when I get to the 109.  Anything further you want to send would be greatly appreciated.



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Doug "Pyro" Balmos
HiTech Creations

[wells]

chisel,

Critical altitude is defined by the ability to maintain manifold pressure.  The lower the required manifold pressure, the higher the critical altitude.  For the high boost pressures (1.98 ata), the altitude is lower.  From the engine data that I have, the boost would start falling at 5100m (1.98 ata) until 8000m where the maximum boost pressure would be 1.42.  Using MW50 at that height would have little effect as no higher boost pressure could be obtained, however according to Janes, MW50 could provide a 4% increase in  power for a constant boost pressure.  At 8000m, where the engine puts out 1200 hp or so, MW50 would only add about 50 hp, compared to some 300 or so at sea level.

[Westy]

Hmmm. More 109 discussion.
Ok. Here. Go read this.
 http://users.aol.com/dheitm8612/breed.htm

Talk amongst yourselves <hand stir>

[niklas]

ok wells, i think i understand it now:-)

mw50 doesn´t GIVE an engine more boost, it only  ALLOWS more boost- Because due to the cooling effect it reduces the thermical stress of the engine components, right?

niklas

[janneh]

Westy, interesting reading, but was DB601 really a direct injected engine, where fuel is injected directly to cylinder instead of intake manifold (near the intake valve), or is there an error ??

[Sorrow[S=A]]

I believe Direct is correct. A manifold would allow G forces to have too much effect on fuel. And historically we know the 109 never had any problems with this matter as opposed to RR Merlin engines.

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If your in range, so is the enemy.

[chisel]

Wells,
So basically what difference does the crit alt make to us?

 The max HP drops with the altitude change anyway ,even with the same MAP (I assume from energy lost to drive the blower/temp change with alt?). The only thing you can really compare engines with is the max brake HP at altitude.

Were all these ratings done with the 109 ram intake taken into account? Dont know there affect at altitude but they work at sea level if your going fast enough, 160mph+

Janneh
 im 99.9% sure they were direct injection with the injector mounted between the valves spraying into the combustion chamber.



[This message has been edited by chisel (edited 12-17-1999).]

[chisel]

Jeez! another question! Hope somebody answers  

If the Ram scoop does make a difference how much loss would there have been on plane fitted with a trop. filter?

Time for bed G'nite.

[Westy]

Janneh, I do not know. Chisel, I believe the report dealt with the plane as it related to combat.
 The 109 was not a feared aircraft from any story I've read. Unless the pilot had failed to check his 6 and allowed one to get back there or if it was coming down in a dive on him.  The 190 was a different story.

 Mustang pilots had no compunction from getting in the weeds with 109's or 190's
 People can whip out thier notebooks and rattle off specs left and right but it doesn't change how things WERE. Not what they hypothetically should have been.
 
 -Westy

[Fishu]

Westy: is this now from the point of living or fightning?  
Also could consider that was this generally considered thing... (note: I don't think every LW pilot were like Hartmann, whom must been more feared in 109 than 500 other pilots)

[funked]

Chisel you are correct - as you increase the altitude, the blower has to do more work to keep a constant M.P.

[janneh]

Sounds wery odd to me. If german engineers found out direct injection on gasoline engines on WWII, why the heck it wasn't an option, say, 1960 in cars ? I mean it is now, 1999 , but why so late ? After all turbos(HORRAY SCANDINAVIA  , direct ignition's and others...
I still don't believe it was direct injection, atleast, on those octanes.
Perhaps,Chisel, my friend, can help me with this   Yeah, I'm a suspicious, until, someone clears me.
If You inject gasoline in intake manifold enough in vaporized mode, it'll doesn't make any difference, if You're in negative or positive maneuver, that's for sure.Vapor is so much lighter than liquid gas, gravity doesn't effect so much...DOH am I totally lost here, or can someone show some proof here, just for interest ?

[juzz]

janneh, when was the last time you pushed any negative g's in your car?    

Direct fuel injection into the cylinders of the engine is provided by means of a twelve-unit high-pressure pump mounted between the cylinder blocks where it is fed by a Graitzin transfer pump.

quote from http://members.aol.com/bf109gust/webhtmls/engine.html

[Sorrow[S=A]]

Janneh think about it for a second, Direct injection is a very crude work around to get away from Negative G effects in 1939, Unlike your modern types it worked off a very (By todays standards) primitive fuel injection system. Those motors needed regular service to clean them and were always running very rich (I believe the richness had to be controlled by the pilot as well). no-one in their right mind would put one on an assembly line production car.

As for negative G's and fuel vapour, your comment makes no sense. G's affect the mixture of vapour. In your car you will never notice this but under any condition where you are pumping force onto a manifold you will have problems. I could not even try to go into all the affected things but Drag cars, aeroplanes and high performance boats all have systems to minimize the affect G has on them. As you introduce rapid changes the effects are: vapour becomes unevenly distributed, more fuel concentration to one side of the manifold less on the other causing lean burning. Vapour actually is forced back along the line of the force applied. Vapour is affected by the force of G, push on it and it moves. Thus in manifolds  the side closest to the force applied runs lean and is starved for fuel.

[juzz]

The Bf109 series only had manual controls for throttle and propellor pitch(not rpm as in British/American planes). Sorrow, why would a direct-injection engine always run rich? I would think such a situation would be unacceptable in a fighter aircraft engine.

Seems the DB600-series engines, were great engines unfortunately fitted to an average Bf109 airframe.  

[This message has been edited by juzz (edited 12-18-1999).]