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Reasons why i severely lowered my BoS flight time lately [from a BoS enthusiast]

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Whoever did it did not understand what they were looking at....

 

Not surprising at all.  Common theme around here.

Well the NACA did 'it'

 

Granted the P38L was not part of the orginal 868 chart..

 

But on the previous page you noted the P38L can NOT do 350 IAS at 10kft..

 

As if to imply the NACA test is invalid

 

Yet most of the planes on the 868 graph can NOT do 350 IAS at 10kft, let alone 390..

 

So, are you asking us to believe the NACA..

 

How did you say it?

 

Did not understand what they were looking at!

 

Is that what you would have us believe ?

If that is TAS...you need to shift the curve about 30-40% to the left....

Crump..

 

What part of me saying, i.e.

 

I have seen a P-38L roll rate chart, but it was in TRUE airspeed, not IAS, so, one would have to convert it to compare it to the values listed in the 868 report

Did you not understand?

 

Or is this just ONE MORE EXAMPLE of you not reading more than once and didn't realise I already said it, or is this just ONE MORE EXAMPLE of you feeling the need to repeat what others have already said and call it 'fixing'

 

PS I did not say the chart I saw was the same one imposed on the NACA 868, I simply noted that I have seen a P38L roll rate chart that was in TAS, I don't recall what the value were

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Whatever you have to convince yourself of.....

No convincing necessary..

 

There are several examples in this thread alone of where you have repeated what I said

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I merely corrected your erroneous assumption that the Tempest rolled in a similar manner to the Typhoon.

 

still can't see where i said that. Seems like you're having a good time weaving stories

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It's certainly how your message was received. What did you want to say when you referenced the Typhoon?

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still can't see where i said that. Seems like you're having a good time weaving stories

 

Oh for goodness sake. Your words:

 

 

where you got that from? i find that hard to believe, given the fact that the Tempest is the advancement of the Typhoon, and has an even bigger wing surface, which restricts the roll rate.

 

 

You then posted a graph showing the Typhoon's poor roll rate. For everyone else here, that indicated your belief that as the Typhoon has low rate of roll and the Tempest has a larger wing QED the latter had an even lower rate of roll. You are incorrect in the assertion that a larger wing automatically lowers rate of roll and you are wrong that the Tempest rolled slower than the Typhoon.

 

 

It's certainly how your message was received. What did you want to say when you referenced the Typhoon?

 

Thank you, JtD. More importantly, it is of marginal relevance to the discussion. Celestiale, you either made an erroneous assumption or failed to explain what you meant. It does  not really matter as the fact is that all models of Tempests, despite a larger wing, rolled faster than a Typhoon at all speeds owing to larger and better integrated ailerons. That is not a personal attack on you, it's just a fact, albeit one that does not help much when discussing the 190 vs Soviet fighters.

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Keep comments on topic and not personal. This thread has gone the way of most other similar ones, I see. Small wonder the Devs prefer to rely on only the most clearly presented, well-documented evidence when considering FM revisions.

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Okay, thanks for explaining, and I'm sincerely sorry if I seemed rude I didn't mean to be at all.

Still the questions stays. Having emotions about some plane's behavior is just not enough for a bug report. I personally don't like La-5, but I'm not saying it is wrong cause I got nothing to prove that with. That's what I mean by asking about player's expectations.

 

 

Ok thanks for the explaination, what you said makes sense to me now and is a fair point.

Also I didnt realize you are non English native and I thought it was your first language, but hence the lost in translation probably.

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Bug:   Density Altitude in the game are acting like Density Altitude effects on Indicated Altitude instead of how Density effects the airplane.

 

In this Post Han makes the following statement.

 

 

http://forum.il2stur...spond/?p=179346

 

While Density Altitude effects on Indicated Altitude will make Indicated altitude read lower than true altitude, the airplane only sees density.  Flight tested performance is gathered and evaluated at pressure altitude.

 

Our atmospheric pressure in the game is 760mmHg therefore Indicated Altitude = Pressure altitude and we can evaluate aircraft performance properly.

 

Pressure altitude is standard because 760mmHg = 29.92 inches of Mercury 

 

Therefore, Pressure ratio or delta = 29.92/29.92 = 1

 

Temperature is 30 degree lower than standard; Temperature = -15C = 5F

 

(5 deg F + 460) deg R/ (460 +59 deg F) deg R =  465 deg R / 519 deg R = Temperature ratio or theta .895954

 

sigma or density ratio = delta / theta =  1/.895954 = 1.1161

 

Now let's use the Density Altitude Formula to figure out our Density Altitude in the Game.

 

 

Density Altitude = [288.16*(1.1161)^1/4.2561-288.16]/-.0019812 = -3803.44 feet

 

So, when your airplane is setting on the runway at sea level it thinks and acts like it is 3803.44 feet  or 1159.288 meters below sea level.

 

FW190A3 Speed under the games atmosphere should be: 565kph = 305Knots SMOE = 1/SQRT Density Ratio = 1/SQRT 1.1161 = .946561 TAS = EAS at sea level = 305 KTAS = 305KEAS EAS * SMOE = TAS at altitude 305KEAS * .946561 SMOE at -3803.44 feet = 288.7KTAS = 534.57kph TAS

 

1.      Currently it appears that at low altitude, True Airspeed is faster than Indicated Airspeed.  On a cold day, a pilot is happy looking at IAS but sad when he sees the ground speed on a winds calm day.  Ground speed = TAS + Wind Velocity

 

2.      At high altitude, the airspeeds tested agree with standard curves at a lower pressure altitude than standard pointing to the atmosphere being less dense than a standard day.

 

3.      The engine just like the airplane only reacts and feels density altitude.  Critical Altitude in an engine is a density altitude not a pressure altitude.

 

a.      If the supercharger on a standard day changes gear at 2600m then your airplane must climb 1159.288 meters higher in the games atmosphere to reach the same conditions.  In other words, it should change supercharger gear at (2600 meters + 1159.288 meters) = 3759.29 meters True Altitude under the games atmospheric conditions when the density altitude equals the same conditions on a standard day.

 

Okay, I've got the reply from our engineers who read the post, and they asked to tell you, Crump, that you did very good job with these calculations, and they are really pleased that we have such a guy in the community.

To the subject. You've made only one mistake not taking into account the temperature gradient.

Firstly, the supercharger switches not depending atmosphere pressure but static pressure.

Secondly, temperature gradient implies that when the temperature goes down at the ground level the pressure does not change accordingly on all altitudes. With altitude increase the pressure grows faster than at standard temperature conditions (which are 15 celsius).

As a result, with conditions -15 celsius at the ground level and 760mm atmosphere pressure, the pressure at 2300 meters is going to be equal to the pressure at 2600 meters in standard (+15 celsius) conditions.

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 Just to save anyone worrying about what "static pressure" is and confuse it with "density altitude"  I extract from Wikipedia:

 

The static pressure system is open to the exterior of the aircraft to sense the pressure of the atmosphere at the altitude at which the aircraft is flying. This small opening is called the static port. In flight the air pressure is slightly different at different positions around the exterior of the aircraft. The aircraft designer must select the position of the static port carefully. There is no position on the exterior of an aircraft at which the air pressure, for all angles of attack, is identical to the atmospheric pressure at the altitude at which the aircraft is flying.[2] The difference in pressure causes a small error in the altitude indicated on the altimeter, and the airspeed indicated on the airspeed indicator. This error in indicated altitude and airspeed is called position error.[3][4]

When selecting the position for the static port, the aircraft designer’s objective is to ensure the pressure in the aircraft’s static pressure system is as close as possible to the atmospheric pressure at the altitude at which the aircraft is flying, across the operating range of weight and airspeed. Many authors describe the atmospheric pressure at the altitude at which the aircraft is flying as the freestream static pressure. At least one author takes a different approach in order to avoid a need for the expression freestream static pressure. Gracey has written "The static pressure is the atmospheric pressure at the flight level of the aircraft". [5][6] Gracey then refers to the air pressure at any point close to the aircraft as the local static pressure.

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I am really amused when reading english side of the forum and finding tons "FW190 underperforming - nerf russians" topics

Isn't it weird that there is not one topic of 109F underperforming? Why would that be?

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I am really amused when reading english side of the forum and finding tons "FW190 underperforming - nerf russians" topics

Isn't it weird that there is not one topic of 109F underperforming? Why would that be?

 

Last I heard, the 109 climb rate was a full minute faster than it was apparently capable of.  The lufties are outraged by this and one can only assume have taken it to the streets. 

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Very impressive indeed!

Being a student of mechatronics engineering i find it highly fascinating how many complex systems and forumals find their way into the physics simulation and those all together will create results that are even more complex and on a wide scale because of the numerous parameters that come into play. To see that there is such a team of professionals behind it is just great  :)

just had to get that down  :biggrin:

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That is nuffin' wait until we get the P-51 Mustang and the 'merican pilots try those .50 cals.

 

They will not be good enough nor hit hard enough.

 

And we all know the P-47 will be all wrong too.

 

Seen all this 10 years ago in the old IL-2 series games.

 

And it has virally infested the forums again.

 

Someone call the: 

 

 

Infection Prevention and Control Expert Working Group On Flight Models

 

 

Do it before it spreads like the ebola virus or  thousands of us will suffer.

Edited by WTornado
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You've made only one mistake not taking into account the temperature gradient.

 

I realized that, LOL.  Oops on my part....I figured he would catch it and redoing the math for a dry adiabatic lapse did not really change the outcome.  The FTH was still not correct.

 

 

 

Secondly, temperature gradient implies that when the temperature goes down at the ground level the pressure does not change accordingly on all altitudes. With altitude increase the pressure grows faster than at standard temperature conditions (which are 15 celsius).

 

I noticed that he did that and lowered the pressure IAW the real gas laws and I assume the standard dry adiabatic lapse rate.  Standard Aviation/Aircraft Performance calculations do not do this ....Pressure is a measured value converted to equivalent pressure altitude on a standard day and worked accordingly.

 

 

 

Firstly, the supercharger switches not depending atmosphere pressure but static pressure.

 

I do not know who convinced him of that but it does not work that way.  Only time static pressure can be used is if the pressure reading device is the same temperature as the charge air.  It is looking for air density changes which like the airplane is all it sees. 

 

All supercharged engines change IAW density altitude...even the manual ones.  It is the basic relationship that keeps the engine going!

Edited by Crump

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I was just going to say that.

 

Actually I wonder whether Zak's post and my post about defining static pressure do not both belong at the end of the epic Fw190 thread for historical completeness - they are a bit out of context here.

 

Edit: and Crump's last comment above - keep it all in one place?

Edited by unreasonable

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Okay, I've got the reply from our engineers who read the post, and they asked to tell you, Crump, that you did very good job with these calculations, and they are really pleased that we have such a guy in the community.

 

Tell them I said "Thank you!"

 

The recalculating pressure is unusual.  It might be a difference in technique but it seems to me doing it that way is going to throw your pressure ratio off.  You would be factoring pressure effects in twice.  Converting a measured sea level pressure to equivalent pressure altitude "already slips the scale".

 

Any temperature changes will be accounted for when you convert that pressure altitude to density altitude under non-standard conditions.

 

For the readers.....Pressure altitude already equals density altitude on a standard day.  Pressure altitude is a nonsense altitude used just as a conversion factor to find density altitude under non-standard conditions.  As a pilot, you live and die based on density altitude.

 

Pressure%20altitude%20%20density%20altit

 

If he does it once and does not refigure it will work.  He is just getting the pressure altitude for that specific condition.  

 

If he is re-figuring every altitude based on a lapse rate then it will throw your pressure altitude off. 

 

Can you ask him if he is recalculating pressure for each temperature change?  

 

We will have to agree to disagree on the gear changes based off static pressure.  I would be glad to discuss it with him!

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Secondly, temperature gradient implies that when the temperature goes down at the ground level the pressure does not change accordingly on all altitudes. With altitude increase the pressure grows faster than at standard temperature conditions (which are 15 celsius).

 

There is if pressure is recalculated at every altitude and combined with standard atmosphere calcs as used to determine aircraft performance...it will throw off your results.

 

All throughout flight testing, all data is gathered with the altimeter set to 1013Mb or 29.92.  The scale starts out slipped to account for such pressure changes.

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Jcomm,

 

What your saying is correct.  I do not want to "talk past each other".

 

What I am saying is correct too.  The difference is the mechanics of aircraft performance.  It is not meterology.

 

When aircraft performance data is collected, it is converted to a equivalent density altitude on a standard day.  

 

The mechanics are already factored in the basic math for aircraft performance.  It is not about finding the pressure at that altitude.  That is already factored in result of finding the new density altitude.

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Jcomm,

 

 

Here is the barocuffs mounted on an aircraft being tested.  That collected data is used to establish that baseline density altitude on a standard day performance.

 

Density%20altitude%20to%20density%20alti

 

Barocuff.jpg

 

barocuff2.jpg

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I am really amused when reading english side of the forum and finding tons "FW190 underperforming - nerf russians" topics

Isn't it weird that there is not one topic of 109F underperforming? Why would that be?

apparently you didn't even read the topic post

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To see that there is such a team of professionals behind it is just great 
 

 

+ (-i)² !!!!!!!!!!!!

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...[Crump is wrong]...

Just another case where the developers show they know what they are doing. Too bad Crump wasted some of their precious time.

 

Please check your PMs.

Edited by Bearcat
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If that is TAS...you need to shift the curve about 30-40% to the left....

A shift of 30% to 40%?

 

No, that is not correct..

 

Based on the scale of the graph and at an altitude of 10kft your looking at a 13% to 17% shift..

 

Depending on which method you use to convert TAS to IAS..

 

Therefore I recommend you add another check to your pre-post check list, i.e.

 

1) read posts more than once before replying, so you don't repeat what someone already said.

2) check your math before replying, so you don't make basic math errors.

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that happens at an height corresponding at a much lower height than it would happen under ISA conditions, given the much higher density.

 

It should be happening at a higher altitude in a high density atmosphere.  Problem is right now your supercharger is changing based off pressure....NOT density.

 

 

 

"hot day" of minus 1 º C :-)  we have a density altitude equivalent of - 970 feet at ground level.
 

 

If our density altitude is -970 feet then the airplane has to climb 970 before it reaches the equivalent density altitude on a standard day.

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Last I heard, the 109 climb rate was a full minute faster than it was apparently capable of.  The lufties are outraged by this and one can only assume have taken it to the streets. 

Maybe you should call them all dimwitted fascists again.

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Last I heard, the 109 climb rate was a full minute faster than it was apparently capable of.  The lufties are outraged by this and one can only assume have taken it to the streets. 

 

 

You say you heard?  So, this is anecdotal then?  Or have you paid your money and gone to the German aviation archive and purchased all the necessary reports and graphs, just like the Devs did?  

 

Err ... hang on a sec; if the devs already have the required info, how can the 109's climb rate be anything other than spot on?   ;)     

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Since when does an aneroid that is explicitely evacuated to exclude influences of temperature react to density?

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Maybe you should call them all dimwitted fascists again.

 

That is what they inferred.  Not what I said or meant.

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That is what they inferred.  Not what I said or meant.

 

My advice would be; don't go online if you're drunk or otherwise under the influence of drugs. 

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Since when does an aneroid that is explicitely evacuated to exclude influences of temperature react to density?

 

We have already had lots about this and other bizarre thoughts, see : thread "Does anyone have a clue (FW 190 performance again):)"

 

The answer to your question is "only in Crumpworld", which seems to be located somewhere between Discworld and Wonderland.

 

Please check your PMs.

 

 Spiralhole.jpg

Edited by Bearcat
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Wulf, nothing I have said was aimed at you.  Neither was it directed at Celestialle, Ambi or wellenbrecher etc.  I was referring to the Siggis and Thurbers of this world.

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Since when does an aneroid that is explicitely evacuated to exclude influences of temperature react to density?

 

That is part of the linkage and is used to maintain a constant throttle position to engine power relationship.  That sounds so simple...constant throttle position to engine power....

 

It is not.  Fixed linkage throttle in an airplanes throttle position to power relationship changes because the engine fuel to air requirements change with density altitude.

 

 

It is a big red herring and not what is determines the gear change.

 

I will give you guys all the documentation.

Edited by Crump

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I'm wondering is it prohibitively expensive to have someone working on fine tuning the FM's ? 

 

I can imagine that since FM's can never be perfect they would have to hire someone to work on them forever! If perfection was the goal.

 

This would be a bad business decision.  

 

IMHO modded CLOD is very good FM but it took years, patches and modding and multiple groups of people all bringing their different perspective and expertise to it to get it as good as it is now.

 

I can see the devs don't wanna see how far the rabbit hole goes when it comes to trying to get the FM perfect. They'll never get it "finished" and it will cost money to keep trying.

 

The ROF FM had some work done recently on the more obvious problems like the late model engines of the albatross running at higher compression than the early models even though the engine was the same in name. This was known for a long time but the time came when they could address it and they did.

 

Hopefully these threads and the tests done by us all will identify the main issues we would like to have addressed  in BOS and at some point in the future the devs may be in the position to try and fix them.

 

The unlocks is a very good omen. They are willing to listen...eventually.

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We have already had lots about this and other bizarre thoughts, see : thread "Does anyone have a clue (FW 190 performance again):)"

 

The answer to your question is "only in Crumpworld", which seems to be located somewhere between Discworld and Wonderland.

 

 

 Spiralhole.jpg

We got the definition of trolling right here. Do we?

This alright now in this forum?

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That is nuffin' wait until we get the P-51 Mustang and the 'merican pilots try those .50 cals.

They will not be good enough nor hit hard enough.

And we all know the P-47 will be all wrong too.

Seen all this 10 years ago in the old IL-2 series games.

And it has virally infested the forums again.

Someone call the:

Infection Prevention and Control Expert Working Group On Flight Models

Do it before it spreads like the ebola virus or  thousands of us will suffer.

 

Even in IL2 the level of drama over American aircraft never came close to the level of drama related to the 109s and 190s... not even. The term Luftwhiners was not coined in a vaccum. I have no idea why.. but that is how it has been.. for some reason the German aircraft seem to draw the most fanatically analytical folks .. Perhaps it is the engineering...

 

Keep comments on topic and not personal. This thread has gone the way of most other similar ones, I see. Small wonder the Devs prefer to rely on only the most clearly presented, well-documented evidence when considering FM revisions.

 

Do.....

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Crump, I see, although we have to take into consideration that the pressure gradient is also a lot more pronounced on such an air mass. Anyway, it now makes sense to me, and I really think you have a good point here !  Thanks for making it clear.

 

Finally ( it always takes some time with me :-) ) I understood the supercharger is based on density and not atmospheric pressure to change gears!

 

Regarding the other discussion about climb rates, that's the kind of stuff I pay the least attention to, but just in case you don't know, even in DCS, where I am 100% right now, we have a Bf109 K4 that climbs like a rocket! It's wrong, and will be fixed / tuned in upcoming patches.

 

No sim is perfect, they all have to evolve, even my emblematic sim - AEROWINX, now PSX - keeps receiving patches everyday!!! Sometimes more than one per day! So... provided the Dev Team doesn't take a discourse suggesting the revisions are closed, which I think it's really not a good idea, we just have to give them some time, and enjoy what we have right now - that's what I am doing with DCS, FSX and PSX :-) keeping an eye in BOS, which I will most certainly buy, again :-/

 

Glad you got it!  Good job...it is not an easy concept to understand.  Teaching Private Pilot, this is always a tough lesson.  It is not intuitive and the terminology is totally confusing...

 

High Density Altitude = Low density Atmosphere

 

Low Density Altitude = High Density Atmosphere

 

What the heck was the guy who came up with these terms thinking!!?!

 

Altimeter errors move opposite of the what the aircraft does.....really...could we make this concept even more confusing!!?!!

 

You are not the only one...trust me...every instructor gets this every time they introduce a new student to flying!

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