FW 190

[Dr_Molenbeek]

I would like to have opinion from people who fly with a stick extension.

 

If they feel a difference after the last update, the difference w/ and w/o the extension (wobbling and so),...

 

Thank you.

[9./JG27MAD-MM]

Pan it's not only comparing apple with banana, because a3 is 400 kg lighter then the D9 and still the same frame, should be the A3 more agile and the A version have the better roll rate then the D.

But it's overall useless when you get in a tail spin after change fast the direction, now you can say I am unable to fly possible....

[Dr_Molenbeek]

One more thing.

 

The plane now stalls at ~184 km/h while it stalled at ~173 km/h before the update (full fuel, no outboard cannons).

 

I think that explains the new behavior of the plane (less stable).

Edited April 1, 2016 by Ze_Hairy

[Crump]

 

 

Pan it's not only comparing apple with banana, because a3 is 400 kg lighter then the D9 and still the same frame, should be the A3 more agile and the A version have the better roll rate then the D. But it's overall useless when you get in a tail spin after change fast the direction, now you can say I am unable to fly possible....

 

It is the same wing design and is more like comparing the Spitfire Mk IX with the Spitfire Mk XIV. 

 

 

The plane now stalls at ~184 km/h while it stalled at ~173 km/h before the update.

 

What is the weight...do you know? 

[Dr_Molenbeek]

What is the weight...do you know? 

 

3855 kg

[Crump]

Thank You!

 

.  

[6./ZG26_5tuka]

Tested Critical Angle of Attack briefly to verify posible changes (note this was done in a very unprofessional way, I'm not claiming to be an expert or having all tools to make scientific messurements).

 

Conditions: Fw-190, full fuel, not outer cannons installes, neutral stabilizer trim, air spawn 1000m, Stalingrad autum, ISA conditions. Screenshots were taken a split second before wingdrop during stall.

 

First shot shows result with manual piloting. Stall speed was ~180 km/h.

 

Second one with auto level pilot. Stallspeed was 184 km/h.

 

Error Sources: - chord line not 100% alinged to the aircraft's real chord

                        - human error (for manual test)

                        - climbrate was not exactly 0 -> pitch angle (measured) ≠ AoA (unmeasureable)

                        - wings aren't 100% level

                        - inaccurate measurement of the AoA

 

Due to the listed error possebilities above pls take this wiht a great grain of salt. Even if we generoulsy round up to 13° the number seems too low to be realitsic. Unfortunately, unless having access to sufisicated test and plot programs, it's difficult gathering accurate data with inaccurate and primitive testing methods.

 

 

Edit: For comparison, Dev Diary 123 says Stall angle of attack in flight configuration: 15.5°

Edited April 1, 2016 by Stab/JG26_5tuka

[Crump]

Thank you Skua..

[LittleJP]

I own a stick extension, and I very much notice the new stall characteristics. What gets me is that this is pronounced at high speeds, stalling out of pullouts I would pull off without error previously.

[SR-F_Winger]

Well, i only got a few hours yesterday. Dunno if i just encountered easy prey but i was doing extremely well on Fighting legends. But i have a very good joystick (center Groundmounted) and I am used to be gentle on the FW stick. So maybe it needs some time more to say if its changed for the better or worse.

The better climbrate is definately nice.

 

Btw. WELCOME BACK HAIRY!!!!!!!

[LittleJP]

Flew a bit more. Feels like the stall isn't just coming earlier, but it's actually more aggressive, kicking in with less warning. Again, I'm not sure on the accuracy of this, but it'll take me a fair bit to adjust since I'm used to flying right on the envelope of the high AoA stall.

[Crump]

Power off stall speed in the FW-190A3.

 

It is pretty well documented the stalling speed of the aircraft.  

 

Faber's WNr 313 was one of the best documented examples and we will use as well as some other FW-190A3/A4 aircraft that are also equally well documented as well the leading expert on the FW-190, Focke Wulf, GmbH data.

 

Let's see how the British, American, and German data aligns within instrument margin of error with the fixed and defined relationship of Coefficient of lift and angle of attack to get a good ballpark of what performance is plausible and how far off that mark we can be for our FM to be a good representation of the aircraft.

 

The problem is that airspeed changes due to weight, instrument error, and density altitude.  It is NOT an absolute.

 

The only absolute relationship is a wing stalls at the same Angle of Attack.  This is one of the defining relationships in aircraft performance calculations.  Due to propeller effects, power on and power off stall angle of attack will not be the same with power on being the higher of the two, generally speaking.

 

Faber's WNr. 313 stalled at 110mph IAS clean configuration and 105 IAS mph in landing configuration, gear down and flaps 60 degrees.

 

Well our gauge in the cockpit is a poor indicator of the speed the wing is actually feeling as it moves thru the air.  An airplane is the only vehicle whose speedometer does not tell you how fast you are going and the altimeter does not tell you the altitude.

 

It only sort of tells us what the airplane feels.

 

In order to know what the airplane is feeling, we have to use Equivalent Airspeed which also called "perfect indicated airspeed" or "engineers speed".

 

To do that we have to convert Indicated Airspeed to Equivalent Airspeed.

 

Indicated airspeed + Position Error Correction = Calibrated Airspeed

 

Calibrated Airspeed + Compressibility Correction = Equivalent Airspeed

 

To get our calibrated airspeed we need a Position Error Curve.  This is nothing more than a curve that shows us the instrument error.  This is due to a number of factors mainly manufacturing differences and integrity of the pitot static system.

 

It generally measured by flying a course over the ground between know distances, accounting for wind speed, and using the rate formula to figure out the difference between the rate on the airspeed indicator and what the rate formula tells us it should be...

 

Position Error Correction is not universal but with a range of error, it is close enough.  The more data points one gathers, the better.

 

So lets see what we have for Position Error Curves on the same pitot static system design for the FW-190A3.  Remember, the pitot static system was changed in later variants and moved to the outboard wing tip.

 

Let's compare two PEC curves and get an idea of the Position Error Correction.

 

Here is the provisional investigation PEC curve done by the RAE on WNr 313.  

 

 

Here is an FW-190A4 EB-104 PEC curve:

 

 

The data points are plotted in each curve.  The RAE curve is derived from 5 data points while the USAAF curve was constructed from 9 measured points.  Atmospheric conditions such as gusty winds effect these datum points.  The fact that the USAAF curve has more points and the points are more consistent without the large spread that appears in the RAE PEC curve leads me to believe the USAAF datum was collected under more ideal conditions.

 

At 110mph the PEC curves both show the FW-190 airspeed indicator is showing the airplane is moving faster than it actually is going.  Neither curve goes to 110 mph IAS so we must ballpark it and our error shows the airspeed indicator anywhere from about 4 mph to 10 mph faster than the airplane is going.

 

So our calibrated airspeed is going to be a range from 106 mph CAS to 100 mph CAS.

 

Now to get our Equivalent Airspeed we need to account for compressibility effects.  In modern terms, below 10,000 feet there is no reason to apply a correction unless we are going over 200 knots CAS.  It is negligible.  In World War II, the expression is not universal and ranges from no compressibility at all to somewhat large compressibility corrections by today's standards.

 

I find it highly unlikely that any test pilot performed stall testing on a unknown enemy design below 10,000 feet.  Why?  Stalling runs the risk of spinning.  In, many World War II fighters the minimum safe altitude for spin recovery was 10,000 feet.  About .5 mph is a reasonable compressibility error correction.

 

So, Our Calibrated Airspeed brings our Equivalent airspeed range to 105.5mph to 99.5mph.

 

Our FW-190 should stall somewhere in that EAS mile per hour airspeed range.

 

Let's see if our absolute relationship of angle of attack and coefficient of lift, falls within that speed range as measured by the RAE and USAAF.

 

Focke Wulf used a CLmax of 1.58 for the FW-190A series as the airplanes design CL max.

 

That is found here, in "Widerstandsdaten von Flugzeugen".

 

 

The FW-190A  design maximum coefficient of lift is 1.58.

 

At 8580 lbs weight for WNr 313 at measured at a stall speed of 110mph IAS let's see what our Equivilent Airspeed has to be in order to achieve a Clmax of 1.58 and does that Equivalent Airspeed fall without our range of possible speeds.

 

 

Using the BGS system and a conversion factor for knots...

 

EAS means sigma (density ratio) = 1

 

Velocity in KEAS = SQRT{295 (8580lbs) / (1.58 * sigma * 197 ft^2)

 

Velocity equals = 90.2 Knots Equivilent Airspeed

 

90.2 KEAS * 1.15 = 104 mph EAS.

 

110 mph IAS - 104 mph EAS = Correction error of 6 mph.  

 

104 mph EAS + .5 mph CEC = 104.5 mph CAS = 104.5 mph CAS + 5.5 mph PEC = 110 mph IAS as recorded by the RAE on WNr 313.

 

The only absolute relationship of stall vs angle of attack easily returns a stall speed that is well within the margin of error found in airspeed measurement.

 

A Clmax of 1.58 represents the clean configuration (gear up, flaps up) design CLmax.  This can be used to find the correct stall speed for any weight or configuration of the aircraft.

 

 

[Crump]

Tested Critical Angle of Attack briefly to verify posible changes (note this was done in a very unprofessional way, I'm not claiming to be an expert or having all tools to make scientific messurements).

 

Conditions: Fw-190, full fuel, not outer cannons installes, neutral stabilizer trim, air spawn 1000m, Stalingrad autum, ISA conditions. Screenshots were taken a split second before wingdrop during stall.

 

First shot shows result with manual piloting. Stall speed was ~180 km/h.

 

Second one with auto level pilot. Stallspeed was 184 km/h.

 

Error Sources: - chord line not 100% alinged to the aircraft's real chord

                        - human error (for manual test)

                        - climbrate was not exactly 0 -> pitch angle (measured) ≠ AoA (unmeasureable)

                        - wings aren't 100% level

                        - inaccurate measurement of the AoA

 

Due to the listed error possebilities above pls take this wiht a great grain of salt. Even if we generoulsy round up to 13° the number seems too low to be realitsic. Unfortunately, unless having access to sufisicated test and plot programs, it's difficult gathering accurate data with inaccurate and primitive testing methods.

 

 

Edit: For comparison, Dev Diary 123 says Stall angle of attack in flight configuration: 15.5°

 

 

Not really sure if this is usable without more information.  In other games, there has been a fundamental error in the application of Induced angle of attack.  

 

90.2 KEAS = 152.2 fps

 

The Re (Reynolds number) for the vicinity of the stall using the design CLmax is:

 

Re = (152.2fps *  5.95ft) /.000158ft^2ps = 5,731,582

 

 

Our 2D data stall angle of attack is in the vicinity of ~18 degrees as long as we have a normal finish and not sand paper!!

 

Induced Angle of Attack = 18.24 (1.58/5.8) = 5 degrees

 

Body Angle in a high aspect ratio winged aircraft = Angle of Attack + Induced Angle of Attack + Angle Of incidence

 

Body angle = 18 degrees + 5 degrees - 2.5 degrees = 20.5 degrees

 

I think we can take it with a grain of salt.  

[JtD]

Actually, ca max given is for flaps down, landing configuration. As a side note, ca a is lift off configuration, flaps down 12°.

[Crump]

Actually, ca max given is for flaps down, landing configuration. As a side note, ca a is lift off configuration, flaps down 12°.

 

 

CaA = Approach (Vref) or LANDING speed 

 

That is how the Landing chart was constructed in the Flugzeug Handbuch...run the math.

 

CaR = Reiseflug or cruise flight

 

CaSt = Steigflug or climbing flight.

 

The Clmax is the CL max of the design.  

 

You would have to be a complete and total idiot to design a split flap system with a Clmax of only 1.58 on the NACA 23015 series airfoil.  

 

 

105 mpa IAS - 6 mph PEC = 99mph .869 = 86 KEAS 

 

Cl max at 86KEAS is Clmax 1.74.

 

That is in the ballpark for the NACA 23015 airfoil with a split flap design.

Given the PEC error at that speed, I would not be surprised if the wing design produced 1.9 or higher quite easily give the sections producing 2.3 and above....

[Crump]

All the usual suspects are showing up now...

[LukeFF]

All the usual suspects are showing up now...

 

Is that a problem for you?

[JtD]

Since Fw is German, the A is for "Abheben", not Approach. Also spelled out plainly in other Fw documentation.

 

Fw wind tunnel data Chalais-Meudon gives clmax clean as 1.3, clmax flaps down 1.55.

 

I'm just telling you. Feel free to 'know better', I don't care.

 

Cruising at a cl 1.1, lmao.

[Crump]

 

 

 

I would be happy to share the complete reports with IL2 Devs..

[Crump]

If you read the description, the 1G stall speed in clean configuration for the FW-190A series is the exact same as the touchdown speed in landing configuration........

[Turban]

It does look like an interesting read . Where does it come from? Any other type of aircraft available?

[Venturi]

source documents on all sorts of planes...

 

http://www.avialogs.com/index.php/aircraft/germany/focke-wulf/fw190.html

 

Here is a set of source document on the 190a-3 specifically

 

http://www.wwiiaircraftperformance.org/fw190/fw190a3.html

 

Overall, the internet has all sorts of documents out there. I'm sure the devs have most if not all of these already.

Edited April 1, 2016 by Venturi

[Crump]

Touchdown speed Vtd is NOT VS1 or stall speed in the landing configuration.  Most Taildraggers are designed to exceed the stall angle of attack on the landing gear.  This keeps the airplane from bouncing on touchdown which can be dangerous in a taildragger.

 

What Focke Wulf has done is the same thing many large transport category aircraft designers do for their pilots.  The unfactored ground runs or "WHAT IS THE SHORTEST runway I need to land if I have to use maximum braking performance" are based on that touchdown speed.  If you get the plane on the ground at the speed, it will not fall out of the air in a stall and you can be assured that you will NOT run out of runway to safely stop.

 

Some manufacturer use what we term as, "The Chuck Yeager Factor" for their unfactored ground runs.  That means the airplane is flown perfectly with maximum braking application the moment the wheels touch down.  

 

The problem is a few "experts" have convinced some FM makers that 1.58 represents the CLmax in Landing configuration only.  That is just not true nor is it correct.

You can add ~15% to 20% to the unfactored landing distance for the "Chuck Yeager" distance for most human beings.....

[Turban]

Interesting link.

Tendancy to stall when pulled fast is directly mentionned. (See H)

 

http://www.wwiiaircraftperformance.org/fw190/eb-104.html

Edited April 1, 2016 by Turban

[Crump]

 

 

Tendancy to stall when pulled fast is directly mentionned. (See H)

 

 

That is a clue you are pulling "too fast", lol.  

[Turban]

 

 

That is a clue you are pulling "too fast", lol.  

 

 

I don't know. it's written right there. Am I misinterpretating something?

[Crump]

No, if you pull any airplane too fast, it will stall.  Some airplanes have higher stick force gradients that make it harder than others.

[Turban]

No, if you pull any airplane too fast, it will stall.  Some airplanes have higher stick force gradients that make it harder than others.

 

Oh come on.

 

Are you saying the test pilot put something irrelevant in his report ???? That's disingenuous.

 

He wrote this with a deliberate intention to emphasize something about the plane that was being tested. 

 

Regardless of why it was happening,(stick force gradient...unlikely but that's not the point)  it was happening. And it was important enough for the pilot to have to pay attention to it. That's why it's in the report.

Edited April 1, 2016 by Turban

[Crump]

Turban....

 

Every airplane can stall at any speed or power setting...

 

 

[Turban]

Turban....

 

Every airplane can stall at any speed or power setting...

 

 

 

 

Again. The test pilot didn't write something irrelevant. He wanted to make a point about that particular plane. If you are going to argue bout that... well... 

 

[Crump]

Here you go:

 

Here is the Spitfire:

 

 

The P51 Mustang:

 

 

Here is the entire section on stalling for EB-104:

 

 

The pilot notes the stalling characteristics of the aircraft.  It is pretty normal for a high power piston engine fighter.

[Crump]

Again. The test pilot didn't write something irrelevant. He wanted to make a point about that particular plane. If you are going to argue bout that... well... 

 

 

No, he simple note the characteristics of the airplane.  That his job.  You are the one who thinks it is some abnormal behavior and it should be caricatured.

[Venturi]

Basically, the test pilot is checking low speed stall characteristics (aka, landing characteristics) in section G, and is checking accelerated (high-speed) stall characteristics in section H. Section H is the relevant section here to high speed accelerated stalls which is what players IN THE SIM are 99% discussing. 

 

However, you have just heard how both are the same, or both are different, depending on the point Crump is trying to prove or disprove. Of course he also doesn't have the game so actual usage is irrelevant to him.

[Crump]

 

 

Section H is the relevant section here to high speed accelerated stalls which is what players IN THE SIM are 99% discussing. 

 

What is different about Section H for the FW-190 as compared to the vast majority of World War II fighters?  

[Turban]

I don't see the relevance of the Spitfire bit. They describe stalls in it . So ?

 

In the FW passage you have two clearly different stalls. :

 

The typical "power-off" stall, when you reduced you power and speed to get to the stall speed.  (See G)

 

Then there is the accelerated maneuver stall encounter in aerobatics. (H)


And obviously the test pilot was writing about it because the plane showed a tendancy to enter that kind of stall worth mentionning, so probably stronger than other aircrafts.

[Crump]

It does not say it stalls without warning.  It says "if pulled fast"....

 

If you pull it fast enough to stall it, you pulled it too fast.  If you fly it correctly it will give plenty of warning.

 

You want to read a translated Luftwaffe memo on this same subject encouraging pilots to go out and turn tight circles to explore the envelope.  It also notes how important proper rigging of the aircraft is too its stall characteristics.  With ailerons improperly adjusted, it will stall early and often!

 

Properly rigged, it gives warning in the accelerated stall because the ailerons begin to vibrate.

 

 

 

 

[Turban]

Well it's settled then.

 

I guess BoS pilots will have to go out and turn tight circles to explore the envelope.

 

1/2 X jk

[Crump]

 

 

Basically, the test pilot is checking low speed stall characteristics (aka, landing characteristics) in section G, and is checking accelerated (high-speed) stall characteristics in section H. Section H is the relevant section here to high speed accelerated stalls which is what players IN THE SIM are 99% discussing.   

 

 

If it is caricature then it is no more correct that P-40's being outperformed by Bf-110's at combat power......

 

It is a direct result of the 1G stall speed being too high in the FM!!  

 

 

 

 

 

 

In the FW passage you have two clearly different stalls. :

 

 

All airplane have different acelerated stall characteristics from their level 1G power off stall.....

 

Not trying to trick you, guy. 

 

http://forum.il2sturmovik.com/user/1354-crump/

[Turban]

 

Are you seriously trying to impress someone right now???? 

 

 

 

I'm done here untill something interesting comes up.
 

Time to go enjoy the new patch.  (no pun intended to the FW pilots I swear, it's a nice patch what else can I say)

[Crump]

 

 

Are you seriously trying to impress someone right now???? 

 

No, just trying to get you to read what was written from multiple sources including my own very relevant education and experience!  Chill out and relax.