109 Exhaust Trail

[smink1701]

The 109 was famous for leaving a dirty exhaust trail due to inferior synthetic fuel.  I've read Allied pilot accounts saying they could tell when a 109s throttle was pushed wide open because you could see a big belch of black smoke.  I would like to see this modeled in the game.

[Sternjaeger]

The 109 was famous for leaving a dirty exhaust trail due to inferior synthetic fuel.  I've read Allied pilot accounts saying they could tell when a 109s throttle was pushed wide open because you could see a big belch of black smoke.  I would like to see this modeled in the game.

 

oh they still do, it's due to the cylinder configuration, it's basically oil that seeps through the rings and get burnt. 

 

The black trail is still quite visible here on this modern restoration, but I wonder whether it was actually any denser because of synthetic fuel..

 

[DB605]

oh they still do, it's due to the cylinder configuration, it's basically oil that seeps through the rings and get burnt. 

 

The black trail is still quite visible here on this modern restoration, but I wonder whether it was actually any denser because of synthetic fuel..

 

 It could also have been denser back then because max ata and rpm's were used in battles...

[Sternjaeger]

yep, surely a higher manifold pressure would have caused slightly more smoke, but it was a typical feature of all inverted V engines in general.

[Sternjaeger]

The main reason for the black smoke was a too rich mixture at high power settings. This was particularly obvious with MW50 installations, as there was neither reduced fuel nor extra air used with the MW50 active. The alcohol in the MW50 would make the mixture even more rich.

 

JtD can't probably see this, but his explanation is not fully correct. Surely a too rich mixture will cause black smoke at high power settings on all aeroplanes, but it wasn't the case of the 109, as the smoking from the DB power plants is almost always visible.

 

As for the MW50, it wasn't alcohol, it was actually water, methanol and Schutzöl 39 (which was an anticorrosive liquid), and its use actually increased the air intake.. 

 

Have a look here for a clear explanation http://en.wikipedia.org/wiki/MW_50

[StG2_Manfred]

JtD can't probably see this, but his explanation is not fully correct. Surely a too rich mixture will cause black smoke at high power settings on all aeroplanes, but it wasn't the case of the 109, as the smoking from the DB power plants is almost always visible.

 

As for the MW50, it wasn't alcohol, it was actually water, methanol and Schutzöl 39 (which was an anticorrosive liquid), and its use actually increased the air intake.. 

 

Have a look here for a clear explanation http://en.wikipedia.org/wiki/MW_50

 

You should read the German article, which differs from the English one: http://de.wikipedia.org/wiki/MW-50

 

It doesn't increased the air intake, instead of that the water cooled the air in the supercharger. And cooler air can absorb more oxygen. So the air intake was alway the same, with or without MW50...

 

Aaaaand methanol is actually alcohol...

http://en.wikipedia.org/wiki/Methanol (...Methanol is the simplest alcohol, and ...)

Maybe we meet one time and have a pint of ethanol

[Sternjaeger]

well methanol is a kind of alcohol, but it was anyway part of a specific mixture 

 

and yes, ethanol whenever you want, as long as it's not pure! 

[StG2_Manfred]

not pure of course... - Cheers

[Sternjaeger]

You should read the German article, which differs from the English one: http://de.wikipedia.org/wiki/MW-50

 

It doesn't increased the air intake, instead of that the water cooled the air in the supercharger. And cooler air can absorb more oxygen. So the air intake was alway the same, with or without MW50...

 

Aaaaand methanol is actually alcohol...

http://en.wikipedia.org/wiki/Methanol (...Methanol is the simplest alcohol, and ...)

Maybe we meet one time and have a pint of ethanol

 

mmmh no, air expands and becomes less dense when it's heated, so by cooling it down you in fact increase the intake of air, that's plain physics mate 

[Rama]

And cooler air can absorb more oxygen.

Don't understand. Air contains around 23% oxygen. In order to change this percentage, you have to add or remove some other gaz component of the air. cooling it will not change the composition (except if you cool it to the point of transforming the water vapour in liquid water)... but even then, it will change only the percentage, not the amount of oxygen who will stay the same.

 

[StG2_Manfred]

Don't understand. Air contains around 23% oxygen. In order to change this percentage, you have to add or remove some other gaz component of the air. cooling it will not change the composition (except if you cool it to the point of transforming the water vapour in liquid water)... but even then, it will change only the percentage, not the amount of oxygen who will stay the same.

No, the dense of air and thus the amount of oxygen (and other gases in the air) depends on their pressure. Try to breeze in 8000m, you won't get 20% oxygen into your lungs ;-) And cooler air contains more gases and therefore more oxygen because it's pressure is lower.

 

@Stern: That's what I said in fact. But the intake of the charger is the same. Imagine my example with the lungs on 8000. The amount of 'air intake' keeps the same as on sea level, but less oxy is consumed. Same for the charger.

 

PS: I understand physics ;-)

Edited December 29, 2013 by StG2_Manfred

[Rama]

No, the dense of air and thus the amount of oxygen (and other gases in the air) depends on their pressure. Try to breeze in 8000m, you won't get 20% oxygen into your lungs

Of course the air you will get in your lungs at 8000m will still contains 21% of oxygen, and you will have problem to breeze not because of this percentage, but because of the pressure of air at 8000m is 35% of the pressure of air at 0m, so the mass of it is also 35%, and the oxygen mass (and so the number of oxygen molecules) is 35% of what you have at 0... which means that at each breeze, you will only get this 35% of air and 35% of oxygen compared to what you get at 0m.... the only reason is the density because ot the pressure.

Now, you can heat or cool this air on the amount you want, it will still contains 21% of oxygen....

 

 

And cooler air contains more gases and therefore more oxygen

Yes, at same pressure, cooler air is more dense than hot air. That's what Sternjaeger told you. If you cool the air before injesting it in the same volume (the charger), you will be able to increase the mass of air in the charger, so later in the cylinders.... that's exactly what Sternjaeger told you: increasing air intake.

... and in all the process the % of oxygen will stay the same, it's only it's mass that will increase, because the mass ot air intake will increase.

 

in PV = nRT, if P and V are constant, then if you decrease T, n will increase (number of air molecules will increase), so density and mass of air will be higher.

[StG2_Manfred]

Well,ok to use the term percentage in my example was wrong, my fault.

[Crump]

 

MW 50 is something of a misnomer, as it is actually a mixture of three fluids: 50% methanol acting primarily to achieve optimum anti-detonant effect, secondarily as an anti-freeze; 49.5% water; and 0.5% Schutzöl 39, an oil-based anti-corrosion additive.

 

 

Exactly the same thing as the United States Water Injection system.  Water is extremely corrosive and alcohol increases the solutions affinity for water.  The oil added to the mixture helps to resist corrosion and gives some top end lubrication.