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E69_geramos109

MW50 weird behavior

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Lets see if someone knows if that is correct or not. For me dynamic supercharger effect seems overmodelled. 

 

 

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Just another time where my first thought was 'what is wrong with text?' only to be followed a split second later by 'darn, I'm old'.

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Just now, L3Pl4K said:

Are climb rate and levelspeed ok?

I would like to test if but game is not providing complete charts about performances of the planes depending the power setting. I asked for that adition for a long time but sems that devs are not very interested on putting that charts and grafics to make test and to help pilots to know the plane. 

I will keep asking for that. Lets see if some time.

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I hope it is just graphical anomly and doesn't affect actual performance of G14! 

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1 hour ago, III/JG52_Otto_-I- said:

In accordance with this chart of DB-605AS , the 1.7 ATA manifold pressure was constant until 6,8 km of altitude.

me109-gj-fx.jpg
 

 

This is an AS model. 

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5 hours ago, E69_geramos109 said:

Lets see if someone knows if that is correct or not. For me dynamic supercharger effect seems overmodelled. 

 

 

 

Even worse, from the data sheet, the 605 AM should reach critical altitude with ram at 5 km, not 4 km.

 

http://kurfurst.org/Performance_tests/109G14_PBLeistungen/Leistungen_g14u4_am-asm.html

 

It seems to be underperforming in boost pressure and apparently exaggerating the effect of ram air pressure at the same time. I don't know how else to explain the MAP drop starting around 2 km during climbs, considering it shouldn't start dropping from 1.7 ATA at climb speed until an altitude of 4 km was reached.

 

Furthermore, the performance figures are displayed for a normal day, which means an ambient temperature of 15 °C on the ground and an ambient air pressure of 760 torr (1013.25 mbar). As such, one could probably expect to reach critical altitude in a 605 AM engined 109 G-14 at several hundred meters above 5 km on winter maps.

 

E: Source for atmosphere figures: https://books.google.de/books?id=yDPKBgAAQBAJ&pg=PA12&lpg=PA12&dq=normaltag+umgebungsdruck&source=bl&ots=-wzkxIh_C1&sig=2_klP72Q96qAN4I04Pj4oKzk_mI&hl=en&sa=X&ved=0ahUKEwit85jqv7jcAhUH_aQKHcKoD-AQ6AEIKTAA#v=onepage&q=normaltag umgebungsdruck&f=false

 

Page 10

 

E2: Just to meme this while it's fresh, the 109G-14 basically underperforms while it underperforms. Achievement unlocked! :P

Edited by PainGod85
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DB605AM's critical altitude without ram should be 4.1km at 1.7ata. As you can see, at top speed, ram effect increases critical altitude to ~4.9km in level flight
1.7ata critical altitude in a 270kmh IAS climb should be somewhere inbetween these values

G14_erflogen_May44_viaGGHopp.jpg

 

But since it starts loosing ata at ~2km there is definately something wrong with the G-14's engine modelling.

Edited by RoflSeal
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18 minutes ago, RoflSeal said:

DB605AM's critical altitude without ram should be 4.1km at 1.7ata. As you can see, at top speed, ram effect increases critical altitude to ~4.9km in level flight
1.7ata critical altitude in a 270kmh IAS climb should be somewhere inbetween these values

G14_erflogen_May44_viaGGHopp.jpg

 

But since it starts loosing ata at ~2km there is definately something wrong with the G-14's engine modelling.

 

That test is not to be taken without a grain of salt. We don't know the atmospheric conditions it was conducted in, and considering the plane is using MW-30 (which had a higher percentage of water than MW-50), thermodynamics dictates its engine produce slightly more power than it would when using MW-50 as:

 

1. More heat from the compressed air in the intake manifold can be sunk into the increased mass of water in the summer mix anti-detonant,

2. thus more adiabatic contraction of the air in the intake manifold takes place,

3. Which ultimately puts more oxygen into the cylinders, burning more fuel.

 

Considering these, the lower figures flown in May '44 can be explained to be caused by the test having been conducted on an exceedingly hot day, or the airframe's quality not having been up to spec, or both.

In light of the fact speeds achieved were very close to what factory documents say they should be, I gravitate towards high ambient temperature, personally.

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Critical altitude of the MW50 powered is 5.0km in horizontal fast flight. All in all, I consider any differences small, much smaller then the current ingame condition where the crit alt ingame in a climb is around 2km.

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5 minutes ago, RoflSeal said:

Critical altitude of the MW50 powered is 5.0km in horizontal fast flight. All in all, I consider any differences small, much smaller then the current ingame condition where the crit alt ingame in a climb is around 2km.

 

That's because you see only the 100 m difference in critical altitude, not the corresponding increase in engine power a 605 AM enjoys when fed with MW-30 instead of MW-50. One exacerbates the other - though I will admit the difference is almost certainly substantially below 100 PS for a given altitude and airspeed.

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But if power is modelled on the game with the ata and the ata is wrong is also on the discussion. 

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2 minutes ago, RoflSeal said:

This topic isn't about power, it is about critical altitude where max ata is maintained.

 

But that is exactly what I'm saying. With MW-30 the engine will produce more power for a given manifold air pressure than with MW-50, which means it'll be slightly faster, which means it can attain a higher altitude before MAP starts to drop off due to higher ram air pressure.

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8 minutes ago, PainGod85 said:

 

But that is exactly what I'm saying. With MW-30 the engine will produce more power for a given manifold air pressure than with MW-50, which means it'll be slightly faster, which means it can attain a higher altitude before MAP starts to drop off due to higher ram air pressure.

it's going to be slightly higher as in a couple, maybe a few hundred metres, not 2km higher.

Here is data sheet 605AM from Kurfurst with MW50
http://kurfurst.org/Engine/DB60x/DB605_datasheets_AM.html
4km critical altitude at 1.7 ata

And from G-14 flight tests, ram increases critical altitude in horizontal flight by 1km

Edited by RoflSeal

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1 minute ago, RoflSeal said:

it's going to be slightly higher as in a couple, maybe a few hundred metres, not 2km higher.

 

Where did I say it should be?

 

17 minutes ago, PainGod85 said:

<snip> - though I will admit the difference is almost certainly substantially below 100 PS for a given altitude and airspeed.

 

Not here.

 

3 minutes ago, PainGod85 said:

<snip> which means it'll be slightly faster, which means it can attain a higher altitude before MAP starts to drop off due to higher ram air pressure.

 

And not here, either.

 

What I was trying to say is how the increased engine power from MW-30's superior thermodynamic properties couldn't offset the reduced altitude performance during a day where surface ambient temperature was no more than 15 K above normal conditions of 15 °C.

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Please provide a source that MW30 injection produced more power than MW50 injection on the DB605AM in any relevant way, and lead to a measurable impact on critical altitude.

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1 hour ago, JtD said:

Please provide a source that MW30 injection produced more power than MW50 injection on the DB605AM in any relevant way, and lead to a measurable impact on critical altitude.

 

How about the massively higher heat capacity of water compared to methanol?

 

You do know about the principle of evaporative cooling, yes? Also, are you aware gaseous substances reduce in volume if you cool them?

 

Yes? Good. That means my work here is done.

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I'm asking for a source to quantify your statement, not an attitude over trivial physics.

 

MW50 added ~100hp. Effect on FTH - already barely noticeable. So please provide a source.

 

11 hours ago, PainGod85 said:

it can attain a higher altitude before MAP starts to drop off due to higher ram air pressure

 

Edited by JtD

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32 minutes ago, PainGod85 said:

 

How about the massively higher heat capacity of water compared to methanol?

 

You do know about the principle of evaporative cooling, yes? Also, are you aware gaseous substances reduce in volume if you cool them?

 

Yes? Good. That means my work here is done.

That statement about the heat capacities is incorrect.

 

Besides, it’s largely irrelevant; evaporative cooling primarily depends on the much larger enthalpy of vaporization, not the heat capacity.

Edited by Mitthrawnuruodo
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8 hours ago, JtD said:

I'm asking for a source to quantify your statement, not an attitude over trivial physics.

 

MW50 added ~100hp. Effect on FTH - already barely noticeable. So please provide a source.

 

 

 

8 hours ago, Mitthrawnuruodo said:

That statement about the heat capacities is incorrect.

 

Water: 4.1814 J / (g * K)  at 25 °C

 

Methanol: 2.53 J / (g * K) at 25 °C

 

And there's more mass of water replacing the 20% of methanol.

 

8 hours ago, Mitthrawnuruodo said:

Besides, it’s largely irrelevant; evaporative cooling primarily depends on the much larger enthalpy of vaporization, not the heat capacity.

 

Yeah, and there water becomes more than twice as good at sinking heat than methanol.

 

2257 J / g for water

1104 J / g for methanol

 

Now we add the fact more water in the cylinders means more gas in the cylinders because water is both denser than methanol and has a lower molecular weight as well.

Which means more moles of antidetonant fluid expanding in the cylinder, which means more cylinder pressure, which means more power.

 

The P-47D experienced a 250 hp increase in power at 65" just from adding water injection.

 

Assuming that a net increase of 20-25% in heat sinking capacity of the antidetonant fluid has so little effect it's completely negligible is folly at best.

 

P-47D_42-26167_Power.jpg

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38 minutes ago, PainGod85 said:

The P-47D experienced a 250 hp increase in power at 65" just from adding water injection.

This is due to the leaner mixture and higher efficiency of the burn. And again, this is due to the cooling effect of evaporation, not a heat transfer „to the cold water“.

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If we were to assume that the 10% higher charge cooling capability of the MW30 compared to MW50 did lead to a 10% higher power increase, we're talking about 10hp. That's good for maybe 1 km/h in top speed. And from that extra ram effect we get a meaningful increase of full throttle altitude?

 

Like I said, please provide a source. First to quantify the if, second to illustrate that it's of any practical value.

 

Please note the if is there for a reason, water injection testing shows that, in particular at rich fuel mixtures such as used at high power settings, more water may actually mean less power. As always, there's a best point of operation, and going beyond it will not do any good.

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5 hours ago, PainGod85 said:

Yeah, and there water becomes more than twice as good at sinking heat than methanol.

If it was just that, then you could only cool the manifold mixture to the temperature of the injected water. Great for a plane that is in a hot climate trying to take off.

 

You are aware of the fact that evaporation enthalpy gives you as much heat transfer as your rather impractical thermal capacity? Just imagine your injected water is 30* centigrades but you need to cool your manifold to 25* centigrades... hmm... But on the other hand you can use evaporation enthalpy to cool your mixture *below* the temperature of the components? Like effervecent powder in your drink? Or do you think this as optional?

 

I can tell you, that this is the whole great idea behind using this technique as well as the reason that nobody, and certainly not Wkikipedia, would even mention thermal capacity of water for this application.

 

 

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3 minutes ago, ZachariasX said:

If it was just that, then you could only cool the manifold mixture to the temperature of the injected water. Great for a plane that is in a hot climate trying to take off.

 

You are aware of the fact that evaporation enthalpy gives you as much heat transfer as your rather impractical thermal capacity? Just imagine your injected water is 30* centigrades but you need to cool your manifold to 25* centigrades... hmm... But on the other hand you can use evaporation enthalpy to cool your mixture *below* the temperature of the components? Like effervecent powder in your drink? Or do you think this as optional?

 

I can tell you, that this is the whole great idea behind using this technique as well as the reason that nobody, and certainly not Wkikipedia, would even mention thermal capacity of water for this application.

 

 

 

Read my last post again, carefully this time.

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10 hours ago, PainGod85 said:

 

Read my last post again, carefully this time.

Doesn‘t make it better. It makes just statements like this

 

16 hours ago, PainGod85 said:

Now we add the fact more water in the cylinders means more gas in the cylinders because water is both denser than methanol and has a lower molecular weight as well.

Which means more moles of antidetonant fluid expanding in the cylinder, which means more cylinder pressure, which means more power

stand out more. Everything you pour into the manifold is a gas when it *enters* the cylinder, this means expansion by combustion heat is about similar as other gases in the cylinder. Just for carburated engines, as your graph shows one. In case of injector engines, you still need to vaporize your injected juice *before* ignite it.

 

You can inject water into gas turbines, but the point there is that it is liquid when it enters the compressor. Like on the Mig25.

 

The chart you posted doesn‘t support your argument at all. You can ovelay it with a chart showing burn efficiency vs mixture. Would be revealing as well. Actually, I should use it to prove my point and the point of everyone out there knowing about engines. You really are alone with you „heat sinking theory“. There is a heat sink occasionally. But you call that intercooler.

 

Edit: With that injected water/methanol, you want to cool the mixture *before* it is compressed in the cylinder. It is much less about cooling the explosion temperature when iginiting.

 

Edited by ZachariasX

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I’d like to point out that cooling the air below the ambient temperature is not the purpose of water injection. In fact, that wouldn’t even be feasible in humid climates. 

 

Instead, water injection removes the heat of compression in the turbocharger or supercharger.

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Personally I don't see how this works, but engine testing with water injection into the impeller of the supercharger occasionally showed that some of the water only evaporated in the cylinders. Might be spray still getting there, can't say how it goes all the way in liquid condition. It primarily was a question of how much water you inject, but also depended on other variables. One should remember that the supercharger air does not heat up to insanely high temperatures and that the water doesn't have ages to evaporate. The DB605A in standard atmosphere only compressed air to about 110°C @2800rpm, on most altitudes a little less.

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2 hours ago, Mitthrawnuruodo said:

I’d like to point out that cooling the air below the ambient temperature is not the purpose of water injection.

Of course it is not. I'm just saying that in principle, by using evaporation enthalpy, you can do that.

 

His argument

19 hours ago, PainGod85 said:

carefully this time

seems to be that water cooling combustion would also increase more gas volume and making it more efficient, which in this application has nothing to do with real world physics. If that was the case, we'd all be pumping fuel that would be diluted with water (or had a water tank in the car for that purpose).

 

In fact, lowering combustion temperature makes your combustion engine less efficient. This is demonstrated by the Diesel engine that runs hotter than gasoline engine. This higher burn temperature (besides Diesel containing more carbon to burn per Gallon) makes it thermodynamically more efficient.

 

Also, PainGod85 seems to be unaware of the problem of controlling combustion. This is what water/methanol injection basically does. The time between spark and burn of gasoline/air is temperature dependent, as with any other fuel and oxidant combination. This timing is crucial for a gasoline engine and a large determinant for the produced power. This is why you must control manifold temperature and this is what you have a manifold temp gauge for in some planes.

 

The burn temperature itself is determined in principle by the choice of oxidant/reductive and the engine is bulit to substain the temperature produced.

 

Besides cooling an internal combustion engine that otherwise would suffer damage from overheating due to an insufficient cooling arrangement and in situations of ocasional extereme power output, there is however an example where PainGod85's water dilution of the fuel was applied, namely in Wernher VonBrauns A4 rocket. It used 70-30 mixture of alcohol and water as fuel, and liqud oxygen as oxidizer. WvB had to add water as the burn temperature would melt away the rocket engine before fuel is spent. It is a suboptimal solution, but it was still controllable enough to ignite it in real weather conditions and temperatures on the launch pad (for rocketry standards) without being certain of blowing up. (Proper ignition is much more of a problem that one might think!!!). Not much thought was given on fuel alternatives, like for instance using The performance is less than with kerosene used as fuel (that was later used (RP-1) by the same designer for a much more powerful rocket, the Saturn V) with liquid oxygen, but it was good enough until burn chamber temperature problems were solved. Also in the case of the A4, adding water to cool the burn REDUCED power.

 

The example of the P-47 is really wrong in that context, because the performance of internal combustion engines is air limited. You cannot just add steam to it and and you get more power. The engine is nothing but an air pump, throwing in juices you can do at , but how to get the air there is key. You CANNOT put more fuel than the air requires and expect more power, unless you do it for other purposes than burn. When you toggle the ADI, the airflow remains constant. What does change is the ratio of fuel/air mix that can be lowered again from rich-rich (to cool the manifold) to rich, where the burn is significantly more efficient and you get this power differential back. Water evaporation in the manifold and cylinder helps cooling instead of doing that with a great lot of excessive fuel. The water very muc so keeps temperatures lower throughout the whole process, from manifold to exhaust, but in principle, if you could do without by supplying cool air fuel mixture and get rid of the cylinder temps, you‘d be even more efficient without it.

 

The fact that you in practise have to cool the burn chamber by slowing the burn and making it less efficient, is simply due to the fact that building  an engine is a compromise. At most times, you don't use it at 100% performance all the time and hence you do not design its structural strenght and cooling for such. It would be too heavy if weight is an issue. If you added an inline water cooling that can deal with a 2000 hp output, you could run the engine at leaner mixture and higher efficiency if the cooling could keep chamber temperatures down. In other words, the more you are pushing the engine toward its limits of cooling (above 200° centigreades the metals start to lose strenght), the LESS efficient you let the engine run by imparing the burn. Also a problem is that when your engine heats up too much, the temperature of fuel and air will increase too much which in turn also affect the ignition timing. This is basically what happens if a running engine gets hot and starts to run "sour", losing power.

 

Enriching mixture reduces your mileage. Adding water to your fuel reduces your mileage.

 

1 hour ago, JtD said:

One should remember that the supercharger air does not heat up to insanely high temperatures and that the water doesn't have ages to evaporate. 

 

When compressing air to 200 bar (Hampson-Linde cycle) you get a temperature increse from 20°C to 65°C, so it is indeed not much in absolute values. But it does show how sensible the reaction initiation of oxidants and reductives are to temperature are (even with starter spark), especially when you are measuring that time in miliseconds.

 

1 hour ago, JtD said:

but engine testing with water injection into the impeller of the supercharger occasionally showed that some of the water only evaporated in the cylinders.

There's definitely limits of how much water you can inject for doing the right purpose. And most likely you have your answer there why MW50 was used and not MW30.

 

 

Edited by ZachariasX
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6 minutes ago, ZachariasX said:

Of course it is not. I'm just saying that in principle, by using evaporation enthalpy, you can do that.

 

His argument

seems to be that water cooling combustion would also increase more gas volume and making it more efficient, which in this application has nothing to do with real world physics. If that was the case, we'd all be pumping fuel that would be diluted with water (or had a water tank in the car for that purpose).

 

In fact, lowering combustion temperature makes your combustion engine less efficient. This is demonstrated by the Diesel engine that runs hotter than gasoline engine. This higher burn temperature (besides Diesel containing more carbon to burn per Gallon) makes it thermodynamically more efficient.

 

Also, PainGod85 seems to be unaware of the problem of controlling combustion. This is what water/methanol injection basically does. The time between spark and burn of gasoline/air is temperature dependent, as with any other fuel and oxidant combination. This timing is crucial for a gasoline engine and a large determinant for the produced power. This is why you must control manifold temperature and this is what you have a manifold temp gauge for in some planes.

 

The burn temperature itself is determined in principle by the choice of oxidant/reductive and the engine is bulit to substain the temperature produced.

 

There is however an example where PainGod85's water dilution of the fuel was applied, namely in Wernher VonBrauns A4 rocket. It used 70-30 mixture of alcohol and water as fuel, and liqud oxygen as oxidizer. WvB had to add water as the burn temperature would melt away the rocket engine before fuel is spent. It is a suboptimal solution, but it was still controllable enough to ignite it in real weather conditions and temperatures on the launch pad (for rocketry standards) without being certain of blowing up. (Proper ignition is much more of a problem that one might think!!!). Not much thought was given on fuel alternatives, like for instance using The performance is less than with kerosene used as fuel (that was later used (RP-1) by the same designer for a much more powerful rocket, the Saturn V) with liquid oxygen, but it was good enough until burn chamber temperature problems were solved. Also in the case of the A4, adding water to cool the burn REDUCED power.

 

The example of the P-47 is really wrong in that context, because the performance of internal combustion engines is air limited. You cannot just add steam to it and and you get more power. The engine is nothing but an air pump, throwing in juices you can do at , but how to get the air there is key. You CANNOT put more fuel than the air requires and expect more power, unless you do it for other purposes than burn. When you toggle the ADI, the airflow remains constant. What does change is the ratio of fuel/air mix that can be lowered again from rich-rich (to cool the manifold) to rich, where the burn is significantly more efficient and you get this power differential back. Water evaporation in the manifold and cylinder helps cooling instead of doing that with a great lot of excessive fuel.

 

The fact that you in practise have to cool the burn chamber by slowing the burn and making it less efficient, is simply due to the fact that building  an engine is a compromise. At most times, you don't use it at 100% performance all the time and hence you do not design its structural strenght and cooling for such. It would be too heavy if weight is an issue. If you added an inline water cooling that can deal with a 2000 hp output, you could run the engine at leaner mixture and higher efficiency if the cooling could keep chamber temperatures down. In other words, the more you are pushing the engine toward its limits of cooling (above 200° centigreades the metals start to lose strenght), the LESS efficient you let the engine run by imparing the burn. Also a problem is that when your engine heats up too much, the temperature of fuel and air will increase too much which in turn also affect the ignition timing. This is basically what happens if a running engine gets hot and starts to run "sour", losing power.

 

Enriching mixture reduces your mileage. Adding water to your fuel reduces your mileage.

 

 

When compressing air to 200 bar (Hampson-Linde cycle) you get a temperature increse from 20°C to 65°C, so it is indeed not much in absolute values. But it does show how sensible the reaction initiation of oxidants and reductives are to temperature are (even with starter spark), especially when you are measuring that time in miliseconds.

 

There's definitely limits of how much water you can inject for doing the right purpose. And most likely you have your answer there why MW50 was used and not MW30.

 

 

 

Is there a meaningful difference between the German MW-50 injection and American ADI?

No.

 

Is there a meaningful difference in the principle of operation of the DB 605 and the R-2800?

No.

 

Was the R-2800 tested to increase gross hp upon engaging water injection with boost staying constant?

Yes.

 

Would it then be reasonable for the DB 605 to expect a higher power rating with MW-50 injection engaged while keeping MAP constant?

Yes.

 

 

 

And now for something completely different:

 

https://forums.eagle.ru/showpost.php?p=1878294&amp;postcount=26

 

"Even if you just inject poor water into the supercharger it increases the power, because at constant boost pressure it increases the density of the air entering the cylinders. A similar effect is achieved due to inter / aftercooler. Lowering of the temperature increases the manifold pressure detonation begins at providing an additional opportunity to further manifold pressure safe increasing."

 

Which means a fluid with a higher heat capacity and higher energy requirements for evaporation would necessarily cause a higher mass of air to enter each cylinder per cycle.

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For several reasons, some of them mentioned above, it's not that simple. If you were to finally post a source showing how much more power MW30 injection generated than MW50 injection, it would be more helpful than continued blanket statements - which, even if not outright wrong, mean nothing.

 

For what it's worth, some differences between the P-47 ADI and the Bf109 MW50 injection: turbocharger vs. supercharger, distance & time to engine after water injection, fuel injection vs. carburettor, boost level, mixture, amount of water. Not to mention mechanical differences between the engines, that have an impact on fuel/air distribution to the individual cylinders. All in all, where the R-2800 gains 250hp or ~10%, the DB605 gains 100hp or ~6%. And to you, that's all the same. It illustrates why I keep missing the necessary accuracy in your statements.

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The thread has been derailed from a discussion about the critical altitude of 1.7ata/2800rpm to a discussion about a minuscule tiny power difference between MW30 and MW50

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On 7/24/2018 at 8:42 PM, Fumes said:

This is an AS model. 

The three conjugated system who regulated the inlet manifold pressure of the DB-601 and DB-605 engines series were the same for all.
The manifold pressure still the same from sea level to the compressor ceiling altitude. 
The ram air pressure, do not affect to manifold pressure until the compressor ceiling (rated altitude), because ram air was taken prior to the compressor. 
The compressor speed is regulated in accordance with manifold pressure. If the ram air pressure increase the manifold pressure, the boost control, and the compressor speed control, will reduce the compressor speed for compensating the final manifold pressure.
A.T.A means "Absolute Atmospheres", it is not in reference to exterior pressure of the system.

The exaggerated ram air influence in manifold pressure of the G-14 in game, is clearly a big bug.

Db-601&DB-605 engines_power_control.jpg

Edited by III/JG52_Otto_-I-
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I guess the way to corroborate if it affects actual engine performance is comparing climb rate, DerSheriff tested it and got this result:

G-14_in_game_climb.png

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That's pretty hard to say from that chart, not knowing accuracy of testing. Things are further complicated by lack of reference data. Easily available is only the climb test at Kurfürsts site. It is, however, a climb test of the U-4 subversion (MG151 gondolas) with a weight of 3500kg. Taking the gondolas off would increase figures by 1.3 m/s due to weight alone, somewhat more accounting for the reduced drag. So 23 m/s seems reasonable at low altitude - which the game seems to match.

 

What's odd in Sheriffs testing are the 'bends' at 2, 4 and 5 km, this would not exist in real life, but then this might be down to testing procedure and presentation of results. Or it could be the result of odd boost behaviour.

 

PBG14_ROC_SNplusMW50.jpg

Edited by JtD

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3 hours ago, -=PHX=-SuperEtendard said:

I guess the way to corroborate if it affects actual engine performance is comparing climb rate, DerSheriff tested it and got this result:

G-14_in_game_climb.png

 

That here says to me they simply took the G-4's 1.42 ATA setting, then shifted and compressed the power curve to 1800 PS and a lower critical altitude.

 

The DB605AM engine's critical altitude before the hydraulic SC gearing takes hold is 500 m while it's just shy of 2 km for the bog standard 605A. Furthermore, critical altitude at 1.42 ATA for the 605AM during climb is in the vicinity of 5.7 km.

 

MT-215_climb.jpg

Edited by PainGod85
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14 hours ago, III/JG52_Otto_-I- said:

The three conjugated system who regulated the inlet manifold pressure of the DB-601 and DB-605 engines series were the same for all.
The manifold pressure still the same from sea level to the compressor ceiling altitude. 
The ram air pressure, do not affect to manifold pressure until the compressor ceiling, because ram air was taken prior to the compressor. 
The compressor speed is regulated in accordance with manifold pressure. If the ram air pressure increase the manifold pressure, de boost control, and the compressor speed control, will reduce the compressor speed for compensating the final manifold pressure.
A.T.A means "Absolute Atmospheres", it is not in reference to exterior pressure of the system.

The exaggerated ram air influence in manifold pressure of the G-14 in game, is clearly a big bug.

Db-601&DB-605 engines_power_control.jpg

Great images about the engine. Thanks Otto

 

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OK, since I have trust issues when it comes to testing I climbed the G-14 myself. On the Lapino autumn map, from sea level to 5.5km. I had the rads on manuals 50%. In the test I linked above, they were at "Steigflugstellung" (climb position), whatever that is in game terms. I didn't want to have to deal with automatic adjustments and the related effects, so I put them on manual.

 

Boost first:

Boost drops off in accordance with the "Gebläsedruck" given in the DB605A manual. This is the raw supercharger pressure, before it goes through the throttles and into the manifold. So basically as far as the boost gauge is concerned, we only have a DB605A where the throttles have been re-tuned to allow 1.7ata. In real life, the hydraulic clutch of the supercharger was also re-tuned so that it engaged at a lower altitude, therefore ran at a higher speed and could provide 1.7ata where in game we're seeing 1.5ish. That's clearly a bug.

 

Climb second:

About the impact on performance I am somewhat undecided. At 500m I climbed with about 23m/s, at 4000m at about 18m/s and at 5500m at about 14m/s. At low altitude this is close to what I'd expect, higher up slightly worse than the above data with gondolas, so it is clearly less than I'd expect. However, it's not 100% clear to me how much of the error comes from where. So I venture into educated guesses:

 

Educated guess (treat with care):

I got 1.51ata at 4000m. At this altitude the engine (without MW50) developed 1400hp at 1.42ata, 1650hp at 1.70ata. So 1.51ata should get near 1450-1500hp. MW50 added 100hp at 1.7ata, so let me go with ~1550hp total for 1.51ata, MW50 at 4000m, about 200 less than at 1.70ata. Getting that extra power into the climb would result in about another 3m/s, somewhere around 21-22 m/s - which would imho be a proper match with the historical data and would mean the discrepancies could be explained with a single reason. Therefore, in my opinion the Bf109G-14 is wrong in terms of climb performance owing to improper programming of the supercharger.

Edited by JtD
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Cheap superchargers from china..maybe. Hope we will see genuine parts in the next update.

Edited by L3Pl4K
  • Haha 6

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