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reverse predicting the characteristics of a single part of a plane which is a chaotic system, from incomplete and often highly critiquable sources is possible yes.
But it is not gonna be 100% accurate, its gonna be an educated guesstimation at best and if the devs start this practice then the bias claims will be inevitably true.
Bad enough that the sources are thinly spread no need to make it even worse by filling the blank spots with predictions.

Of course the part you highlited is meant only as a humoristic analogy!
EDIT: It is possible to calculate that example if you know all the infinitely small factors that contribute to it, but you dont, especially not in history.

Edited by =ARTOA=Bombenleger

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The Yak-1's dive speed limits as per the manuals is 650 km/h.

 

And 800 / 650 = 1.23. This would be a quite standard safety factor for the plane's structure (planes generally have a fairly low safety factor to minimize weight). I.e. it falls apart at ca 120 - 125 % of its by instruction permitted maximum speed. That way there's some margin for pilot mistakes, and some margin for possible structure deficiencies and material fatigue.

 

Likewise for the 109 it has a structural failure speed of 900 / 750 = 1.2, i.e. it too has a safety factor of ca 1.2. Same as the Yak-1.

Edited by Inkoslav

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Cheap shots like these are why your more valid points will get ignored by anyone with any knowledge of the development of the sim over time.

 

When you say that the developers are trying to achieve balance - when they have repeatedly said that they are not - you are just calling them liars. 

 

As to the marketing stuff - yes I am sure that everyone has noticed that. Many of us will also have noticed that they are a Russian group (Jason apart) based in Moscow.  They are subject to Russian law - hence the complete ban on swastikas and the more general ban on the glorification of  anything nazi.  While I might think that a few promotional videos or pictures of Soviets being shot down by Germans would not be glorification, you can (or should be able to ) understand why they do not wish to take any chances. Not only might they get a visit from the man from the Lubyanka, but even worse they might get a mob of stalinist skinhead yobs arrive to smash their offices to bits. You really should show a little more consideration of their position.

 

 

Wow.  Did you just say the devs may be subject to intimidation and that consequently the in-game performance of the aircraft should be viewed in that context? 

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reverse predicting the characteristics of a single part of a plane which is a chaotic system, from incomplete and often highly critiquable sources is possible yes.

But it is not gonna be 100% accurate, its gonna be an educated guesstimation at best and if the devs start this practice then the bias claims will be inevitably true.

Bad enough that the sources are thinly spread no need to make it even worse by filling the blank spots with predictions.

 

Of course the part you highlited is meant only as a humoristic analogy!

 

The sources and information on Bf-109 performance is quite extensive I'd say, with plenty of detailed speed & climb rate charts available.

 

The hard part for the dev team is getting their FM to match all of these precisely as incorrect figures in even a small number of the aerodynamic coefficients dealt with will completely botch up the performance in one or more flight parameters. In other words accurate drag, lift & thrust figures are paramount.

Edited by Panthera

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The hard part for the dev team is getting their FM to match all of these precisely as incorrect figures in even a small number of the aerodynamic coefficients dealt with will completely botch up the performance in one or more flight parameters.

That is absolutely correct and currently they probably have historians getting the numbers and programmers/physicians (is that the right word? physicists?) getting the simulation right, the thing is calculating the characteristics is gonna introduce new small deviations from reality on top of those that are added by the sim. Which is, I think, the argument against this practice. Also it would probably cost money...

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This shows a lack of understanding how props are designed because the new prop was no "easy solution", it was a prop designed to maximise the better performance at altitude of the new engine with no penalty to low alt performance. This was important in the west as most of the fighting took place at bomber cruising altitudes. The US followed the same path in their adoption of wider paddle props for their fighters.

Your reasoning is flawed.

 

First: The paddle prop was the “easier” solution, compared to switching to a four bladed prop (as was done with the Spitfire) or increasing the span of the prop. Doesn’t mean no effort was put into it or that it wasn’t the smarter choice.

 

Second: The paddle prop was introduced at a time when high altitude daylight bombing was a non-issue for the Luftwaffe, a time where the Channel Front was a minor sideshow, North Africa was only starting to get underway and the far, far majority of the Luftwaffe was committed on the Eastern Front. At the same time the RAF was starting to build dedicated low-altitude versions of their Spitfires. Why on Earth would the Luftwaffe want a main daylight fighter that was optimized for high altitude operations in mid-1941?

 

Third: Regardless of all this, my point was, that there are many solutions to changing a prop to fit a more powerful engine, and they are not equal, nor did British, American, Soviet and German engineers all settle on the same solution. Therefore it makes no sense to assume, that you can just use British or American figures when calculating prop efficiency of a German fighter.

Edited by Finkeren
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Your reasoning is flawed.

 

First: The paddle prop was the “easier” solution, compared to switching to a four bladed prop (as was done with the Spitfire) or increasing the span of the prop. Doesn’t mean no effort was put into it or that it wasn’t the smarter choice.

 

Second: The paddle prop was introduced at a time when high altitude daylight bombing was a non-issue for the Luftwaffe, a time where the Channel Front was a minor sideshow, North Africa was only starting to get underway and the far, far majority of the Luftwaffe was committed on the Eastern Front. At the same time the RAF was starting to build dedicated low-altitude versions of their Spitfires. Why on Earth would the Luftwaffe want a main daylight fighter that was optimized for high altitude operations in mid-1941?

 

Third: Regardless of all this, my point was, that there are many solutions to changing a prop to fit a more powerful engine, and they are not equal, nor did British, American, Soviet and German engineers all settle on the same solution. Therefore it makes no sense to assume, that you can just use British or American figures when calculating prop efficiency of a German fighter.

 

 

Britain started bombing Germany already in 1940, and general fighting had taken place at higher altitudes than on the eastern front since the beginning. During this time it was soon found that those who could more effectively "hold the high ground" so to speak had a useful advantage. Hence a lot of work went into improving high altitude performance, the Germans introducing GM-1 very early on for example. 

 

As for propeller design you mistakenly assumed that more blades = more efficiency and that 4 blades would've benefitted the 109 more when reality is quite different. The German engineers thuroughly investigated & tested what type of prop was more efficient for the 109's (or any other aircraft's) particular engine power curve & gear ratio within the allowed diameter and designed a new one accordingly. If you think they instead simply got lazy and went with the "easy" solution then it's your logic which is severely flawed as it wouldn't get any easier nomatter the number of blades the new prop had, the same amount of RD & testing would be required regardless. You'd know this if you had ever studied blade element theory.

Edited by Panthera

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Britain started bombing Germany already in 1940, and general fighting had taken place at higher altitudes than on the eastern front since the beginning. During this time it was soon found that those who could more effectively "hold the high ground" so to speak had a useful advantage. Hence a lot of work went into improving high altitude performance, the Germans introducing GM-1 very early on for example.

 

As for propeller design you mistakenly assumed that more blades = more efficiency and that 4 blades would've benefitted the 109 more when reality is quite different. The German engineers thuroughly investigated & tested what type of prop was more efficient for the 109's (or any other aircraft's) particular engine power curve & gear ratio and designed a new one accordingly. If you think they instead simply got lazy and went with the "easy" solution then it's your logic which is severely flawed as it wouldn't get any easier nomatter the number of blades the new prop had, the same amount of RD & testing would be required regardless. You'd know this if you had ever studied blade element theory.

I never said they “got lazy” and yeah, a significant amount of development went into the 109’s prop blades. Still there is no question that it is waaaaay easier to introduce a new propeller blade into production than a completely redesigned propeller hub, spinner and a new synchronization gear for the cowling guns. That is just a fact.

 

And to say that a 4-bladed prop with higher aspect ratio on the blades isn’t potentially more efficient than 3 lower aspect ratio blades is simply not correct. There is a reason why 4 or more blades of high aspect ratio was the norm for high powered piston engines at the end of WW2 and afterwards.

 

Still, none of this matters, because this wasn’t tangential to my original point: That you can’t simply use British or American data to calculate efficiency of German props.

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I never said they “got lazy” and yeah, a significant amount of development went into the 109’s prop blades. Still there is no question that it is waaaaay easier to introduce a new propeller blade into production than a completely redesigned propeller hub, spinner and a new synchronization gear for the cowling guns. That is just a fact.

 

And to say that a 4-bladed prop with higher aspect ratio on the blades isn’t potentially more efficient than 3 lower aspect ratio blades is simply not correct. There is a reason why 4 or more blades of high aspect ratio was the norm for high powered piston engines at the end of WW2 and afterwards.

 

Still, none of this matters, because this wasn’t tangential to my original point: That you can’t simply use British or American data to calculate efficiency of German props.

 

No'one said it isn't potentially more efficient, what you're being told is that choice of blade design & number are based on engine power curves, gear ratios & diameter constraints and finally where you want the efficiency to be at its highest. The engineers at Messerschmitt chose a 3 bladed prop for the 109 because it performed the best in relation to the balance in performance they were looking for, all the above considered. The K-6 for example was to be fitted with a four bladed prop for increased high altitude performance and speed in particular, sacrificing efficiency at lower speeds and decreasing climb performance. It was the same deal with the initial prototypes for a high altitude turbocharged Fw190 © variant.

 

In summation no'one EVER said that you should use British, American or Russian data to calculate the efficiency of German props, that in itself wouldn't make any sense as they all used different engines. No the point that I was trying to get across was that the engineers of both sides were pretty darn good at chosing the right prop for the job, and in the end they all probably ended up achieving roughly the same overall efficiency. I believe Holtzauge will be of the same opinion.

Edited by Panthera

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Wow.  Did you just say the devs may be subject to intimidation and that consequently the in-game performance of the aircraft should be viewed in that context? 

 

Only an idiot could interpret what I said in that way. We were discussing the promotional pictures etc, "the marketing stuff".

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In summation no'one EVER said that you should use British, American or Russian data to calculate the efficiency of German props, that in itself wouldn't make any sense as they all used different engines. No the point that I was trying to get across was that the engineers of both sides were pretty darn good at chosing the right prop for the job, and in the end they all probably ended up achieving roughly the same overall efficiency. I believe Holtzauge will be of the same opinion.

That’s the leap of faith I’m opposed to. We have no basis for making that assumption other than the general notion, that engineers in all the major companies/design committees were “pretty good”. We simply don’t know.

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In summation no'one EVER said that you should use British, American or Russian data to calculate the efficiency of German props, that in itself wouldn't make any sense as they all used different engines. No the point that I was trying to get across was that the engineers of both sides were pretty darn good at chosing the right prop for the job, and in the end they all probably ended up achieving roughly the same overall efficiency. I believe Holtzauge will be of the same opinion.

Efficiency cant just be measured quntitatively though, yes the props the germans designed where probably pretty darn good just as all the other props.

But the efficiency has also a qualitative aspect, efficiency at low speed/high speed, low alt/high alt and those vary greatly from prop to prop so you cant just assume that Holtzauge magically gets all those aspects right. 

His results are an approximation and not a guideline for the development of il2.

 

As i said earlier basing an approximation on an approximation is gonna introduce a systematic error, which we would want to avoid.

 

Many people tried argumentation along the same lines with the FW flight model, yes it was incorrect but it only got fixed when proper soures where delivered, not by showing why it must be wrong.

Edited by =ARTOA=Bombenleger

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Btw: Just want to make clear, that I’m not disparaging Holtzauge’s work. His results are always an interesting read and contribute greatly to the debate.

Edited by Finkeren

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Well, it was either this thread or the other one about the Yak-1B that is going on right now.

 

Tuesday's not wrong, though. People flock to the LW side of this game because they believe that the German equipment will be superior to the Soviet to such a degree that they will enjoy the kind of success in the sim that the experten did IRL. When that inevitably does not happen (for many reasons, flight models being just one), they suffer great frustration and disappointment.

Both sides have their share of silly quirks. The key is to fly Red and Blue for superior perspective. Fly too much of one side and you can become overly invested in it. Both sides will preach garbage from their holier than thou scriptures. Avoid inundating yourself with the philosophy of either side.

 

Tell Teusday to take a chill pill and fly some Blue. Sounds like it would do him some good.

 

von Luck

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Guys,

 

Just a note, FM/DM discussions have to take place elsewhere, not here. Next post in that direction and I will lock this one (Do not have time right now to clean this topic)

 

Also, next Bias accusation will result in rules been applied. If you want to keep posting here, do not do such thing. The team take those accusations very seriously.

 

2. This forum is provided by 1C-777 Ltd. as a courtesy and its usage is a privilege and 1C-777 Ltd. reserves the right to ban any member temporarily or permanently for any reason at any time. Any penalties listed below for violations of the rules are guidelines only and forum administration may take additional action if they feel it is warranted. Use of the forum is not connected to usage of the game and access to this forum is not guaranteed to users as a consequence of purchasing the game.

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Both sides have their share of silly quirks. The key is to fly Red and Blue for superior perspective. Fly too much of one side and you can become overly invested in it. Both sides will preach garbage from their holier than thou scriptures. Avoid inundating yourself with the philosophy of either side.

 

Tell Teusday to take a chill pill and fly some Blue. Sounds like it would do him some good.

 

von Luck

 

LOL Tuesday ain't perfect, but he flies as much blue as the Hartmanns allow him (and the rest of 19//) to fly... which ain't much...

 

Back on topic, I think the whole situation can be summed up as follows:

 

In general, it's easier to stay alive in the LW aircraft, but easier to get a kill in the VVS aircraft.

 

Let me break that down:

  • LW aircraft can dictate the fight and unless you get surprised, you can almost always escape with your life
  • VVS aircraft can't dictate the fight, but if you give them a chance to kill you, they are much more able to take advantage of it and seal the deal

So on a dogfight server like WoL or Berloga, the Russian aircraft really have an advantage, because everyone is going for kills, but on a more realistic server like TAW or RE, the German fighters have some advantages since most are focusing on survival.

 

Note that all of my comments above are in regards to a pure fighter vs fighter scenario. When escort an interception are involved, the game is changed once again.

Edited by 19//curiousGamblerr
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The key is to fly Red and Blue for superior perspective.

 

This was one of the problems I had when I flew the Yak. I gained no new perspective from flying both sides, I just confirmed how easy it was to fly.

 

In general, it's easier to stay alive in the LW aircraft, but easier to get a kill in the VVS aircraft..

 

You can't separate them out like that, they are intrinsically linked. Sure you can fly LW really safe but you need to trade your ability to survive if you actually want to have an impact. VVS can also dictate the fight in the sense that they can make it incredibly dangerous for a LW pilot to get in a position where they even have a chance of killing them in the first place. My point was that VVS can survive better because LW don't benefit from sticking around down low and VVS can disengage on the deck under the cover of their own swarms.

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VC, what he means by the LW planes being able to dictate the fight is that they can decide when the fight starts and when it finishes. A 109, or a 190 for that matter, can sit up at an altitude where VVS planes cannot effectively engage. This means the only real option is to wait for the LW to start the fight. If/when the fight starts the 109 or 190 has every opportunity to disengage from that fight whenever they want. The top cruising speed, in level flight, is just outside the capabilities of VVS fighters, and if they have room to dive a 109 will blow the doors off of anything they will face. This means all the LW has to do to end a fight is fly in a strait line. Can they get caught out doing this? Yes, there is a small window where they might be if there is someone in the right place at the right time, this window closes fast. The VVS fighters, on the other hand can do neither of these things. I can't make a 109 fight me in a Yak. I can't outrun a 109 in a Yak so I can't disengage from that 109. The tempo can be easily set by a 109 with relative ease. You are right though, the VVS can make taking fights an unattractive prospect but the ball is still in the LW's court.

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This was one of the problems I had when I flew the Yak. I gained no new perspective from flying both sides, I just confirmed how easy it was to fly.

 

con·fir·ma·tion bi·as

noun

noun: confirmation bias

the tendency to interpret new evidence as confirmation of one's existing beliefs or theories.

 

 

Perhaps you need to re think your approach here. Flying a couple of sorties as VVS then claiming it's too easy is rather narrow minded. Claiming you only confirmed you're suspicion when you flew a few times smacks of confirmation bias.

 

von Luck

Edited by von-Luck
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You can't separate them out like that, they are intrinsically linked. Sure you can fly LW really safe but you need to trade your ability to survive if you actually want to have an impact. VVS can also dictate the fight in the sense that they can make it incredibly dangerous for a LW pilot to get in a position where they even have a chance of killing them in the first place. My point was that VVS can survive better because LW don't benefit from sticking around down low and VVS can disengage on the deck under the cover of their own swarms.

Not really. A damaged VVS plane will have a very hard time of surviving, because it is better visible and easier to engage.

 

LW aircraft can engage in combat at low altitudes, provided they work in teams and stick to engagement discipline. That is dictating the fight.

 

LW can do the Kuban ladder aswell as VVS.

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Efficiency cant just be measured quntitatively though, yes the props the germans designed where probably pretty darn good just as all the other props.

But the efficiency has also a qualitative aspect, efficiency at low speed/high speed, low alt/high alt and those vary greatly from prop to prop so you cant just assume that Holtzauge magically gets all those aspects right. 

His results are an approximation and not a guideline for the development of il2.

 

As i said earlier basing an approximation on an approximation is gonna introduce a systematic error, which we would want to avoid.

 

 

I guess I didn't make myself clear: We have the numbers we need to calculate prop efficiency which includes detailed real life altitude specific power curves, speed & climb rate measurements all the way up to service ceiling, and from a multitude of sources no less. With these we can calculate the prop efficiency rather precisely, and I am 99.9% positive Holtzauge did exactly that.

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I understand what you're saying and I'll stop going on about this. I don't disagree with you in theory but the engage/don't engage decision has a fairly wide grey area, as do the circumstances in which you can or can't disengage at will. From my observations most people can't make those decisions very well while you're talking about what a very good pilot can achieve in ideal conditions.

 

Having said that, after practicing with trim and trying for discipline I had a much more positive 109 experience last night. I still lost 5 planes for only 3 kills (I counted more but oh well) over about 2 hours and felt like I spent half my time running away from something, but it was quite intense and satisfying overall. Gonna keep practicing, and I'll fly more VVS as well but likely stick to La-5s because that plane feels like it has more character to it.

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That’s the leap of faith I’m opposed to. We have no basis for making that assumption other than the general notion, that engineers in all the major companies/design committees were “pretty good”. We simply don’t know.

 

No leap of faith is being taken though as like I explained to Bombenleger we have the real life numbers we need to calculate the prop efficiency pretty precisely, and Holtzauge must have done this himself or his simulation wouldn't match so precisely with the real life flight test results. 

 

Having not run the numbers myself I made an educated guess that what he ended up with was a prop efficiency percentage rather similar between all the aircraft he plotted, within only a few percentages. 

Edited by Panthera

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If Holtzauge had the numbers required and has done the math, then I have no objections, though obviously we shouldn’t take his simulation as gospel. Still it’s a valuable contribution that can be used as a data point when trying to triangulate whether or not the FMs are hitting the mark.

Edited by Finkeren

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If Holtzauge had the numbers required and has done the math, then I have no objections, though obviously we shouldn’t take his simulation as gospel. Still it’s a valuable contribution that can be used as a data point when trying to triangulate whether or not the FMs are hitting the mark.

 

Considering that his numbers match the real life test figures so precisely I'd go as far as saying we can trust his C++ simulation's estimation of performance more than anything we've seen in a sim so far.

 

Now I am in no way certain of what the main problem causing the 109's to underperform so badly ingame is atm, but I if I was to base my assumption on the data sheets published by the developers (the ones showing all the aircraft performance specs etc), then it has something to do with using an incorrect max lift coefficient. I say this as the listed stall speeds don't match the real life ones at all.

 

To use an example the landing speed of the 109 K-4 was 150 km/h at 3,000 kg weight (power idle, gear & flaps down), which means the actual stall speed has to be lower (by at least 10 km/h) as you obviously don't want to stall on landing ;)  Yet the considerably lighter Bf-109 G2 as pr. the published IL2 data sheets stalls out at 154 km/h gear & flaps down ingame.

 

That this is the culprit could also explain how performance figures such as speed & climb rate can remain accurate at the same time as you're nowhere near the Clmax in those flight conditions, but once you approach flight conditions where it becomes important then the FM starts to fall apart accuracy wise.

Edited by Panthera

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There are VVS test of German fighters which showed 19.5s for F4 and 20s for G2. In game data show about 1.5-2s worse for 109 expecially for G2 and F2 where Yaks for ex. got accurate time about 19 sec. So something is not right with 109s turn times

Edited by 303_Kwiatek

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There are VVS test of German fighters which showed 19.5s for F4 and 20s for G2. In game data show about 1.5-2s worse for 109 expecially for G2 and F2 where Yaks for ex. got accurate time about 19 sec

 

Yes, and this could be due to using an incorrect max lift coefficient for the 109, something the ingame data sheets strongly suggest.

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Backing to topic VC got right impression that there is much easier to got kill when flying on VVS side then German one. Flying 109 or 190 need a lot more skill and difficulty to shot down VVS fighter then opposite. There is several things which got influence on these: more effective VVS firepower, more strenghtened VVS airframes, better manouverability at high speed VVS planes. German historical tactic boom and zoom in BoS is seriously restricted cause of poor manoverbility of 109 at higher speeds when VVS planes are not affected of these ex. Lagg3 IRL need about 1400m to recover from 600 kmh dive speed when in game its enough half of these. German test showed that 109 need similar 1500m to recover but from 740 kph IAS dive.

Add to these simplificeted flaps working in VVS planes without risk of damage and very effective high combat maximum dive speeds.

Edited by 303_Kwiatek

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Since I'm a bit late to the party and there has been some interesting discussions about propeller efficiency in this thread that I would like to add some input on (but which rightly belongs in the FM section) I added a reply here instead. :)

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I find it to be rather the opposite, Kwiatek. I can jump in a 109, find the enemy and secure a kill rather easily. The Yaks and LaGGs do take a bit more killing than the 109's, true but the engine power available to 109's makes up for this. I find myself much more capable of putting the plane where it needs to be to get the shots on target much more readily in a 109. Some of this could be down to knowing the target's capabilities and playing it's strengths against it but that doesn't account for all of it. In a Yak I have had easy kills, sure, but only when the German didn't see me coming. If it is a strait up fight, I end up walking away with a kill after a protracted maneuvering fight or a 30-40 Km chaise and then a maneuvering fight.

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<snip> Considering that his numbers match the real life test figures so precisely I'd go as far as saying we can trust his C++ simulation's estimation of performance more than anything we've seen in a sim so far.

 

Thanks for the vote of confidence Panthera, nice to know that there is at least someone who appreciates my input! And I agree with your reasoning regarding what can be trusted or not: I think you have to judge simulations and flight sims in the same way: Look at the data they provide and match that to IRL numbers. I have been doing the C++ simulations for more than 10 years now and posted a lot of results online so anyone who wants to can always backtrack and form their own opinion on how well the C++ model matches IRL results.

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Considering that his numbers match the real life test figures so precisely I'd go as far as saying we can trust his C++ simulation's estimation of performance more than anything we've seen in a sim so far.

 

Now I am in no way certain of what the main problem causing the 109's to underperform so badly ingame is atm, but I if I was to base my assumption on the data sheets published by the developers (the ones showing all the aircraft performance specs etc), then it has something to do with using an incorrect max lift coefficient. I say this as the listed stall speeds don't match the real life ones at all.

 

To use an example the landing speed of the 109 K-4 was 150 km/h at 3,000 kg weight (power idle, gear & flaps down), which means the actual stall speed has to be lower (by at least 10 km/h) as you obviously don't want to stall on landing ;)  Yet the considerably lighter Bf-109 G2 as pr. the published IL2 data sheets stalls out at 154 km/h gear & flaps down ingame.

 

That this is the culprit could also explain how performance figures such as speed & climb rate can remain accurate at the same time as you're nowhere near the Clmax in those flight conditions, but once you approach flight conditions where it becomes important then the FM starts to fall apart accuracy wise.

 

The issue of the stall speeds has been extensively discussed in the FM section which is where this kind of speculation belongs.  The stall speeds given in manuals etc are usually IAS as measured by the normal RL cockpit instruments: since this is the value that a pilot needs to know.  Cockpit instruments almost always under measure true speeds at low speeds and higher AoAs since the pitot tubes are at an angle to the airflow. edit - BoX does not model this particular instrument error - it did originally IIRC but it was taken out since it caused confusion. 

 

Where we have cases where the stall speeds were measured by more sophisticated instruments, such as a trailing pilot behind the aircraft, the measurement difference is obvious and can be very large. See the British tests on a 109 at Kurfurst's site as an example.   Hence taking stall speeds from manuals as an indicator of the CLmax will give you values that can be even greater than the maximum CLmax of the airfoil as measured in wind tunnel tests.

 

There was a long discussion about this in a thread about the P-40 before it got it's FM changed: you might want to read it. 

 

The CL values for the 109s might be wrong - but you have to look at test data to tell, not stall speeds from manuals, pilot notes or recollections - edit all of which will contain this instrument error which BoX does not model.

Edited by unreasonable

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There are VVS test of German fighters which showed 19.5s for F4 and 20s for G2. In game data show about 1.5-2s worse for 109 expecially for G2 and F2 where Yaks for ex. got accurate time about 19 sec. So something is not right with 109s turn times

 

Han already acknowledged there was an issue with the 109 turn times.

 

https://forum.il2sturmovik.com/topic/25336-another-look-turn-times/?p=559796

 

that is why the Devs asked the community to try to find info on German propellers way back in november 2016.

 

 

Therefore, as a part of this task we have a counter-favor to ask our community to help us to find the original German (or any other) sources with the aerodynamic characteristics of DVL series propellers, or VDM propeller particularly. In our work we have been forced to use the DVL propeller data taken from Soviet sources as we did not find anything better. We fully admit that the recalculating of propeller characteristics using our current curves could give incorrect results. Therefore, we very much hope for your help in finding the original DVL (VDM) diagrams like this:

 

https://forum.il2sturmovik.com/topic/168-developer-diary/?p=405724

 

 

We know it will be fixed, no need to keep bringing it up.

 

If anyone really wants to hurry the process along, use you energies trying to find the requested info.

Edited by Sgt_Joch
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Thanks for the vote of confidence Panthera, nice to know that there is at least someone who appreciates my input! And I agree with your reasoning regarding what can be trusted or not: I think you have to judge simulations and flight sims in the same way: Look at the data they provide and match that to IRL numbers. I have been doing the C++ simulations for more than 10 years now and posted a lot of results online so anyone who wants to can always backtrack and form their own opinion on how well the C++ model matches IRL results.

No need to thank me Holtzauge, I'm just calling it the way I see it :)

The issue of the stall speeds has been extensively discussed in the FM section which is where this kind of speculation belongs. The stall speeds given in manuals etc are usually IAS as measured by the normal RL cockpit instruments: since this is the value that a pilot needs to know. Cockpit instruments almost always under measure true speeds at low speeds and higher AoAs since the pitot tubes are at an angle to the airflow. edit - BoX does not model this particular instrument error - it did originally IIRC but it was taken out since it caused confusion.

 

Where we have cases where the stall speeds were measured by more sophisticated instruments, such as a trailing pilot behind the aircraft, the measurement difference is obvious and can be very large. See the British tests on a 109 at Kurfurst's site as an example. Hence taking stall speeds from manuals as an indicator of the CLmax will give you values that can be even greater than the maximum CLmax of the airfoil as measured in wind tunnel tests.

 

There was a long discussion about this in a thread about the P-40 before it got it's FM changed: you might want to read it.

 

The CL values for the 109s might be wrong - but you have to look at test data to tell, not stall speeds from manuals, pilot notes or recollections - edit all of which will contain this instrument error which BoX does not model.

I am well aware of indication errors which is why I am looking at reports that plot these out :) (some manuals even list the difference) In general the error lies in the range of 10 km/h, this being the case for the 109 and P-51 for example. Edited by Panthera

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Just for reference: I use a Clmax of circa 1.41 at M=0.3 in the C++ simulations which is slightly better than the Spitfire 1.36 but then the Me-109 had slats meaning the outer portions of the wing did not loose Cl due to wash-out like on the Spitfire etc.

 

Frankly, while I see the benefits of getting VDM data for redoing the Me-109 FM I don't think that should stop the developers from getting within a percent or two of the IRL data. Right now the turn times are off by 20% in some cases and that can be corrected without detailed VDM charts as outlined in this post.

 

BTW Panthera: You need to streamline your cow a bit: Looks like there is severe flow separation behind the front legs and tummy. In addition the brow rises too sharply just like the Spitfire front glass. ;)

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No need to thank me Holtzauge, I'm just calling it the way I see it :)

I am well aware of indication errors which is why I am looking at reports that plot these out :) (some manuals even list the difference) In general the error lies in the range of 10 km/h, this being the case for the 109 and P-51 for example.

 

I am not talking about the regular position error correction, which is mainly a speed issue which the pilot needs to know for navigation time/distance calculations.   I have not yet seen a single manual that gives a correction at or even close to the stall speed.  Different phenomenon.

 

The difference in IAS and estimated TAS for the Bf109E tested by the RAE was 20mph at stall speed. This makes a huge difference to any calculated CLmax.

 

Please read this report. http://kurfurst.org/Tactical_trials/109E_UKtrials/Morgan.html

Edited by unreasonable

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I am not talking about the regular position error correction, which is mainly a speed issue which the pilot needs to know for navigation time/distance calculations.   I have not yet seen a single manual that gives a correction at or even close to the stall speed.  Different phenomenon.

 

The difference in IAS and estimated TAS for the Bf109E tested by the RAE was 20mph at stall speed. This makes a huge difference to any calculated CLmax.

 

Please read this report. http://kurfurst.org/Tactical_trials/109E_UKtrials/Morgan.html

 

TAS is actually listed in the German 109F manuals for landing & take off speed, and the error lies in the 10 km/h range. IIRC a similar difference has been noted between IAS and GPS by modern pilots.

 

As for the British test it should be noted that the German manuals don't list speeds as low as those indicated on the captured 109E (60 mph = 100 km/h flaps & gear down), suggesting that there might have been some issues with the pitot tube or somewhere else on that particular aircraft. Hence why taking results from such tests, esp. when it involves foreign equipment, should always be done with a large amount of salt. Remember the British also ran into troubles with the slats, experiencing snatches and large disturbances to the aircraft's stability upon deployment, and as such they evidently never really understood (or got to explore) their true purpose, which also becomes quite evident when you read the AFDU trials where the 109 was said to be "embarrased" by the opening of its slats when'ever it tried to turn and the Fw190 being regarded as much better in the turn :)

Edited by Panthera

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I find it to be rather the opposite, Kwiatek. I can jump in a 109, find the enemy and secure a kill rather easily. ... I find myself much more capable of putting the plane where it needs to be to get the shots on target much more readily in a 109. Some of this could be down to knowing the target's capabilities and playing it's strengths against it but that doesn't account for all of it. ...

 

Care to share trade secrets ;)

 

I've thought of another way to phrase the feeling I have. No fighter really wants to be at an energy disadvantage, and the 109 is better at avoiding it overall, but the Yak is MUCH more capable of staging an effective defense from the position of being at an energy disadvantage. In fact it can leverage the 109s energy advantage against it very easily. It's all well and good saying don't get in that situation in the first place, but often you do and in a 109, with a co-E or E advantage Yak on your 6, you have this feeling of complete helplesness. You know you did something wrong but that was 2 minutes ago and now it's too late and you can't undo it, that's what's incredibly frustrating. In a Yak you don't get that, you have cards to play and while you're still at a disadvantage, you can keep playing them and feel like you're in the fight and what you do matters.

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Just for reference: I use a Clmax of circa 1.41 at M=0.3 in the C++ simulations which is slightly better than the Spitfire 1.36 but then the Me-109 had slats meaning the outer portions of the wing did not loose Cl due to wash-out like on the Spitfire etc.

 

Frankly, while I see the benefits of getting VDM data for redoing the Me-109 FM I don't think that should stop the developers from getting within a percent or two of the IRL data. Right now the turn times are off by 20% in some cases and that can be corrected without detailed VDM charts as outlined in this post.

 

BTW Panthera: You need to streamline your cow a bit: Looks like there is severe flow separation behind the front legs and tummy. In addition the brow rises too sharply just like the Spitfire front glass. ;)

 

Yes a CLmax of 1.40 to 1.45 between 0.2 to 0.4 M is what I've used for the 109 on previous occasions as well. Fits rather well taking the slats, higher AR and overall higher thickness ratio of airfoil root to tip into consideration as well.

 

I've used a similar CLmax for the 190 before in lack of better data, however I recently found new data on the NACA 230XX, 00XX & 66 series from a report posted on another forum which I posted in the FM section here :)

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Yep, its nasty to have someone on your six in a 109, but mostly due to its lower strength. Try to force an overshoot and manouver vertically afterwards if you have enough energy. If you are not in a firing solution you can get out of the fight if you are careful and extend in the right moment.

But yes, doing this you usually can't disengage in a Yak-1. Last friday I dodged a pair of 109s for 10 minutes, had they not been so reluctant to go into a knife fight with me, they would have had me after 1 minute. But I was at their mercy all the time, only losing them because they lost sight of me.

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