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Sublime

With p47/51/38 youre better using unrealistic fuel mix

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If you use auto mix it leaves smome trails. Leaving it at lowww levels doesnt mess performance up and you dont smoke. Leaving a trail... This doesnt "feel" right

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But it is as it is supposed to be. Smoke trails is right. You lean out at high power, you‘ll burn your engine.

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19 minutes ago, Sublime said:

If you use auto mix it leaves smome trails. Leaving it at lowww levels doesnt mess performance up and you dont smoke. Leaving a trail... This doesnt "feel" right

I have found that low mixture does in fact decrease performance - at least in the in the P-47. I was accidentally running at too low of mixture for a sortie and noted that my engine was hotter than normal and a guy flying on my wing noted he was going much faster than me, despite same loadout, same fuel, and same power settings.

Even if it doesn't, low mixture at high power settings will make your engine overheat and force you to open your radiators farther to compensate.

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Same, in game to low or to high mix affects your airplanes performance, even in 38, 47 and 51s, and not just climb and top speed but temp of engine

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Why are people still perpetuating the myth about smoke free WW2 fighters?

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3 minutes ago, pfrances said:

Why are people still perpetuating the myth about smoke free WW2 fighters?

 

I have no idea. It honestly baffles me how many useless threads have been created in the past months. 

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9 minutes ago, pfrances said:

Why are people still perpetuating the myth about smoke free WW2 fighters?


Because restored warbirds burning modern, cleaner fuels don't smoke, and period footage from WW2 isn't high enough resolution to show the smoke back then

 

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12 minutes ago, 357th_Dog said:

Because restored warbirds burning modern, cleaner fuels don't smoke, and

... and run them at significantly reduced power ratings.

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2 minutes ago, ZachariasX said:

... and run them at significantly reduced power ratings.


Yup...modern non-racing P-51's run on 100 LL and usually don't run past about 45" of mercury and 2500 RPM

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58 minutes ago, 357th_Dog said:


Yup...modern non-racing P-51's run on 100 LL and usually don't run past about 45" of mercury and 2500 RPM

 

I believe those are the continuous cruise setting. The P-47 manual, as I recall had cruise settings of 2250 rpm, at 35" and auto-lean, even for the ones with the 2800hp rated engine. So if you're looking at films of them flying on that setting, you're probably not going to see much, the way you would if someone just turned on the water and ran the throttles to the firewall. 

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They use ratings today that are known to (somewhat) guarantee reasonable TBO for engines, say 500 hours. This is way more conservative than the original use case intended for them. Also, aircraft are now flown near their minimum weight. No ammo and maybe 50 gallons of fuel plus pilot. Especially later war fighters fly nicely at 2/3 of their max. power. PN ratings are not meant to preserve an aircraft for 80 years.

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2 hours ago, pfrances said:

Why are people still perpetuating the myth about smoke free WW2 fighters?

I dont exprct smoke free fighters - I more use the mixture as a method to make myself 'stealthy' at times. Lets say Im.approaching a target with a furball above it. I wanna drop and leave. Etc.

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Really, the smoke was as a result of over richening during max boosting, to suppress detonation. 

 

In actual fact, if you reduced mixture inappropriately at even moderate boost levels, you would suffer pretty catastrophic and quick engine failure.

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8 hours ago, -LUCKY-ThanksSkeletor said:

 

I have no idea. It honestly baffles me how many useless threads have been created in the past months. 

 

Look on the bright side: I take it as showing that there are lots of new people taking an interest in the game who are not up to date with all the forum discussions over the years.

 

The time you know a game is dying is when there are no new useless threads.....

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5 hours ago, Venturi said:

Really, the smoke was as a result of over richening during max boosting, to suppress detonation. 

 

In actual fact, if you reduced mixture inappropriately at even moderate boost levels, you would suffer pretty catastrophic and quick engine failure.

I really hope we get detonation modeled some day

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3 hours ago, RedKestrel said:

I really hope we get detonation modeled some day


I'm told the ticking noise in the up-rated WW1 German planes is detonation.

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Hmm Ill have to check more as others said they saw deceeased performance. No doubt if I thin it out enough youll audibly hear the engine weaken etc but the levels Im talking about (surprisingly.low - 28% etc) the engines seem to run fine as ever. At least as long as my qmb test fights would last (admittedly 5-15 min)

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11 minutes ago, Sublime said:

Hmm Ill have to check more as others said they saw deceeased performance. No doubt if I thin it out enough youll audibly hear the engine weaken etc but the levels Im talking about (surprisingly.low - 28% etc) the engines seem to run fine as ever. At least as long as my qmb test fights would last (admittedly 5-15 min)

I often used leaning out as way to hide. Even on the Spit IX, where the gradual movement of the mixture lever allows you to lean the „automatic“ mixture to the point of cut out. In fact, it should be either auto or closed, nothing in between. You do get performance degradation and higher engine temps, but it is very benign. On reality, you‘d just destroy your engine.

 

It is one of those things that really should be addressed in the sim. If you have an axis that selects discrete positions, the lever should snap between those positions instead of accepting intermediate positions. It makes it a pain for instance selecting proper mixture positions in the lightning. The Tempest has 100% - 50% - 0%. The Mustang has 100% - 70% - 0%. For the same. I mean, seriously...

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14 minutes ago, ZachariasX said:

The Tempest has 100% - 50% - 0%. The Mustang has 100% - 70% - 0%. For the same. I mean, seriously...

 

Yeah, I think a key-binding (either by "step gate up/ down" or as a discrete key binding for "cut-off", "auto lean" and "auto rich") would also work.

That way, you could set&forget at startup and never think of mixture again until shutdown.

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33 minutes ago, ZachariasX said:

I often used leaning out as way to hide. Even on the Spit IX, where the gradual movement of the mixture lever allows you to lean the „automatic“ mixture to the point of cut out. In fact, it should be either auto or closed, nothing in between. You do get performance degradation and higher engine temps, but it is very benign. On reality, you‘d just destroy your engine.

 

It is one of those things that really should be addressed in the sim. If you have an axis that selects discrete positions, the lever should snap between those positions instead of accepting intermediate positions. It makes it a pain for instance selecting proper mixture positions in the lightning. The Tempest has 100% - 50% - 0%. The Mustang has 100% - 70% - 0%. For the same. I mean, seriously...

Yes as far as settings. I HAVE noticed the %s in between the milestones you mentioned are where the cutoffs to make your engines smokeless are.

Ok so it affects the engine. Not as much as 30mm mk 108 does ;)

If I wanna get im and out or am flying towards distant comtacts Id rather not have the twin smoke trails always.

Thw mustangs engine smoke "twins" look *exactly* like the doras

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7 hours ago, ZachariasX said:

Even on the Spit IX, where the gradual movement of the mixture lever allows you to lean the „automatic“ mixture to the point of cut out. In fact, it should be either auto or closed, nothing in between. You do get performance degradation and higher engine temps, but it is very benign. On reality, you‘d just destroy your engine.

 

Things with the Spitfire IX have changed now, as it no longer has a mixture lever. :salute:

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On 10/12/2019 at 12:11 AM, J3Hetzer said:


I'm told the ticking noise in the up-rated WW1 German planes is detonation.


Yes but that Fokker does not have a supercharger - the engine is simply over compressed, by intrinsic design of the piston and cylinder head compression chamber, to compensate for thinning atmosphere as you climb. 
 

When you advance the throttle prematurely you are over compressing “thicker” air. So yes it is moving towards detonation, but it is slower onset and less severe than an aircraft with a true supercharger. Probably not a good way to model the onset in a much larger engine with a true supercharger.

 

In these WW2 engines onset of detonation is very rapid and with little warning. Much safer to be slightly over rich, than too lean. Also much safer to advance the mix, before you advance the throttle...


The exhaust smoke should be much more severe in German fighters than in Allied. The Germans did not have as effective anti detonation additives and they achieved the higher boost levels they did by over richening the mix, which was automatically done on most of their aircraft when the throttle was advanced (still, the boost levels were not even close to the levels western allied 150PN fuels allowed, unless Mw50 was used - artificially boosting PN even more).


PS the correct terminology for “octane” levels is actually Performance Number or PN. Since, “Octane” rating is simply the percentage of Octane or eight-carbon linear chains in the hydrocarbon mixture of the fuel. In other words, it is a reference standard as the burning characteristics of octane are known.
 

It is by definition it is nearly impossible to even get to 100% or 100 octane rating, as hydrocarbons are always a mixture of different kinds of hydrocarbons. When you get to numbers like “150 octane”, what you are really saying is it is 150 Performance Number - because there can be no such thing as 150% octane in a given solution of hydrocarbons. 
 

Semantics yes, but illustrative semantics. 

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On 10/12/2019 at 6:46 AM, ZachariasX said:

I often used leaning out as way to hide. Even on the Spit IX, where the gradual movement of the mixture lever allows you to lean the „automatic“ mixture to the point of cut out. In fact, it should be either auto or closed, nothing in between. You do get performance degradation and higher engine temps, but it is very benign. On reality, you‘d just destroy your engine.

 

It is one of those things that really should be addressed in the sim. If you have an axis that selects discrete positions, the lever should snap between those positions instead of accepting intermediate positions. It makes it a pain for instance selecting proper mixture positions in the lightning. The Tempest has 100% - 50% - 0%. The Mustang has 100% - 70% - 0%. For the same. I mean, seriously...

 

Haven't checked it on the Spitfire, but that *is* correct for the Stromberg Carburator on the P-47 and most allied fighters. It is semi-automatic, but apparently the knob is analogue and let's you adjust the mixture more than just Idle Cut off, AL, AR, Full.

 

The P-47N manual includes instructions to pull it back a bit when flying on humid days, to manually lean until the RPM drops for maximum economy cruise, and to directly manually plush it past the AR markings if the carb fails.

 

The Tempest, while it is listed as having only three settings has to use a catch gate to keep the knob in them, rather than it being a real toggle type switch.

 

I think the Stromberg did some compensation but was not actually a fully automatic mixture control system. 

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On 10/12/2019 at 7:46 AM, ZachariasX said:

It is one of those things that really should be addressed in the sim. If you have an axis that selects discrete positions, the lever should snap between those positions instead of accepting intermediate positions. It makes it a pain for instance selecting proper mixture positions in the lightning. The Tempest has 100% - 50% - 0%. The Mustang has 100% - 70% - 0%. For the same. I mean, seriously...

 

Speaking of this what mixture technochat % settings correspond with auto rich and auto lean in the P-38?  It's not obvious from inside the cockpit.

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1 hour ago, RobCarter3 said:

 

Speaking of this what mixture technochat % settings correspond with auto rich and auto lean in the P-38?  It's not obvious from inside the cockpit.

 

70% for auto rich it seems to me, 30% for auto lean.

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On 10/11/2019 at 11:16 PM, unreasonable said:

 

Look on the bright side: I take it as showing that there are lots of new people taking an interest in the game who are not up to date with all the forum discussions over the years.

 

The time you know a game is dying is when there are no new useless threads.....

Agree. When you enter a forum and see only 3 ol'guys in general discussion in english version of the forum, you know that game is dead.

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