Bf109-K4 control loads at higher speeds...

Im trying understand these German test 109 vs Fw 190

For me it looks that 109 need high stick forces ( 20 to 30 kg) push the stick to keep dive with increasing speed.

Fw 190 initialy need more elevator angle with low stick forces but with incresing speed there is reversal trim for nose heavy when there is need to pull stick with increasing stick load.

Dunno how much stick forces would need to out of dive for 109 but looks that 109 got tendency to nose up in dive at high speed where Fw 190 got tendency to nose down. So its mean that with no change in trim settings 109 could pull up more easly from high speed dive then Fw 190.

I dont know how it is with K-4 in DCS casue i dont have it yet but i tried Fw 190 D-9 and it looks that it has not too much stick forces during pull up from high speed dive with constans trim settings ( + 2 deg). D-9 is flying with slighty nose down with speed increasing but stick forces are very low. Fw 190 in German test need high stick force ( pull up) to keep plane flying straight so for pull up from dive with no change in trim would need even much more stick force to recover.

It looks that Il2 BOS made it better then DCS in these are but in BOS A-3 got too fast nose down tendency in dive ( at too low speed).

Also roll rate in video with 109 K-4 looks really high at these speeds but these need to be checked by numbers ( how much degree per second).

For me it looks that 109 need high stick forces ( 20 to 30 kg) push the stick to keep dive with increasing speed.

At the specified trim setting...yes. A push force is good and means the aircraft is trying to return to trim speed.

In this test, the pilot did not adjust the trim so the force development can be measured.

Think of the trim as moving the line up and down the Y-axis (stick force axis). When the line meets the X-axis....the aircraft is trimmed.

If you trimmed the Bf-109G at 610Kph Va to stay at Mach .7 in the dive, you would have to exert ~32Kg of pull force to recover.

That whole line would shift to intersect the zero stick forces point at Mach .7.

Yo-Yo is right.

Crumpp,

 

thx for your additional notes.

 

I am glad I'm wrong about this non-problem with the Bf109 K4 stick forces in DCS :-)

You are most welcome!!

The reality is the Bf-109 had a very good stick force gradient when measured by modern standards. To a 1940's pilot introduced to flying on a JN-4....it might have seemed excessive in their opinion.

I believe that the plane can overcome those issues if you put a automatic machine behind the stick and it will start pulling with unhuman strenght.

But the matter of fact is, that this is now the stick forces we are talking about. Something that influences the pilot. Humans are what they are, humans. And many both German and Allied pilots said that 109 was "stiff"

By stiff they, and I mean that the plane is getting unresponsive. It is not compresibility level of "I can't influence anything". It is the fact that you cannot use only one hand to move the stick to a given position. Physically it is impossible unless you are very fit.

Here is the part that I like the most. We take an average man. Fit but average man and use his force maesurment to model how the stick reacts to our inputs in the game. That is how you make a simulation of flight. Human factor is just as important as the plane itself.

That is why I feel that it needs changing, as it feels unnatural. Even in FW190 you can feel the elevator beeing less "powerful" at high speed.

Also, the suposedly correct behaviour was during 2 first days of beta present as David Red and DB605 have reported. So something is missing!

PS.. I am certain that Bf109 in any version is no match for Fw190 or P-51 at high speed roll rate.

I checked G-2 in BOS and with constant trim +1 deg with icreasing speed there is need high stick force to keep plane in dive. 109 in BOS got strong tendency to pull up byself.

It is like in German test posted above.

Fw 190 A-3 in BOS with increasing speed at trim +2 deg got increasing nose down tendency like in DCS but opposite to D-9 at high speed there is need high stick force to pull up from dive - A-3 recovery very slow. D-9 in DCS response imidietly and has no problem with pull up from dive even at 800 kph IAS at the same +2 deg trim settings.

32 Kg is well within average stick pull forces a pilot can deliver, Solty. In fact, it is high enough to help the pilot avoid overloading the airframe without being excessive enough to hinder recovery. At least that is what the modern standards are designed to do!

Here is some measured data on practical stick forces a pilot can exert. It is one of the things the NACA had to defined as part of developing a stability and control standard.

D-9 in DCS response imidietly and has no problem with pull up from dive even at 800 kph IAS at the same +2 deg trim settings.

The stability and control characteristics of the Dora vs Antons is not the same. The Dora moves the NP of the aircraft increasing the stability margin. If you know what your looking at...you can see the Antons exhibit some longitudinal instability.

The design change that moved the NP also gives a longer arm to the elevator control. In other-words, they are two different animals and there is every reason to believe Yo-Yo got the Dora right.

When it comes time to model the Anton or F series....specifically F8....:noexpression:...not hinting I would like an FW-190F8 or anything like that....:music_whistling:

Anyway...I am sure all will be as Kurt Tank designed! :thumbup:

Looking at USA raport about D-9 is not clearly that D-9 got so much better controlability at high speed then Anton:

http://www.wwiiaircraftperformance.org/fw190/wright-field-fw190d-9.pdf

They found that up to 375 mph IAS ( 600 kph) forces are moderate and controlablilty was good but from these speed elevator control became heavy and lateral forces are excessive.

Looking at USA raport about D-9 is not clearly that D-9 got so much better controlability at high speed then Anton:

 

http://www.wwiiaircraftperformance.org/fw190/wright-field-fw190d-9.pdf

 

They found that up to 375 mph IAS ( 600 kph) forces are moderate and controlablilty was good but from these speed elevator control became heavy and lateral forces are excessive.

Isn't this the D-12 that was misidentified as a D-9 which they rebuilt after the war?

Also, they did a pretty poor job at putting it back together. Just look at the second to last page. Nothing was working as it should have been.

Isn't this the D-12 that was misidentified as a D-9 which they rebuilt after the war?

It could be.

It could also be FW-190D-13 "Yellow 10".

http://www.cebudanderson.com/yellow10.htm

It is not an FW-190D9..Dora 9's had the Jumo 213A1 not the Jumo213E series engine.

Looking at USA raport about D-9 is not clearly that D-9 got so much better controlability at high speed then Anton:

That report is kind of subjective and there is nothing to quantify. It is way too general to make any definitive statements. Another pilot could have flown it and thought it was great or the worse aircraft ever built. Nothing is measured...just opinion. It does give us a CG location but without knowing what kind of aircraft he flew, we cannot glean any useful information based on CG location.

In the FW-190D9, the tail design is the same but the arm is longer. There is some definite improvement in the stability department. :smilewink:

That being said, the Anton's had longitudinal instability issues. You can see that in the trim plots. Be careful though, because some of that the flight test team attributes to their measuring instruments. The FW-190A did exhibit at a rearward CG force reversal at high altitude and speeds in a turn and dive. That is a form of longitudinal instability. Because the CG represents gravitational forces relative to the earth and the NP aerodynamic forces relative to the aircraft, changing body angle changes the stability margin.

The other issue is the airfoil on the horizontal stab could be entering compressibility. The airfoil did not change and the Antons definitely encountered compressibility effects in a dive.

The report does not give us an altitude with the 375IAS noted so there is no way to tell.

http://www.wwiiaircraftperformance.org/fw190/Fw_190_Dive.pdf

Anyway, there is no way to tell from that report!

Isn't this the D-12 that was misidentified as a D-9 which they rebuilt after the war?

Nope; FE-121 was Wnr. 401392 Black 5 of 6./JG 26 which surrendered at Neubiberg. Although the engine was called a Jumo 213E in the report, this was clearly an error and shouldn't be taken to mean FE-121 was flown with a 213-E.

No D-12s were captured by the Allies post-war. The D-13/R11 was Wnr. 836017, Yellow 10 - + - flown by Oblt Franz Götz, Geschwader Kommodore of JG 26, that was initially restored using the D-9 wing from Wnr. 601088 ex <1+~ . Both Ds still exist and the wings were swapped in 2004.

According to Dietmar Hermann...5 FW-190D12/D13's were returned to the US for testing post war at Wright Patt.

It is how Yellow 10 got in this country.

Nope; FE-121 was Wnr. 401392 Black 5 of 6./JG 26 which surrendered at Neubiberg.

I found it. I think you are right. Too bad the report is not more detailed.

 

The diagram of constant IAS trim for different Mach numbers shows (I am afraid that it was misinterpreted here) that 190 trim begins to suffer from compressibility earlier than 109 requiring pulling the stick.

Yo-Yo, thanks for the additional info.

Just one more question: Will the easy wingtip breaking be addressed in any upcoming patch?

But the matter of fact is, that this is now the stick forces we are talking about. Something that influences the pilot. Humans are what they are, humans. And many both German and Allied pilots said that 109 was "stiff"

 

By stiff they, and I mean that the plane is getting unresponsive. It is not compresibility level of "I can't influence anything". It is the fact that you cannot use only one hand to move the stick to a given position. Physically it is impossible unless you are very fit.

 

Here is the part that I like the most. We take an average man. Fit but average man and use his force maesurment to model how the stick reacts to our inputs in the game. That is how you make a simulation of flight. Human factor is just as important as the plane itself.

 

That is why I feel that it needs changing, as it feels unnatural. Even in FW190 you can feel the elevator beeing less "powerful" at high speed.

I think I agree with you here. The problem is the fact that we cannot expect realistic control forces in this desktop simulation. Simply because no one has the right hardware to generate them (FF Stick or no).

So what to do:

1. Either you can simulate only the aircraft itself, meaning joystick position is simulated stick position. This leaves control forces out of the equation and we feel the same spring tension for a given stick deflection at any flight condition.
   
2. or you can attempt to simulate the pilot experience within the limits given by inadequate hardware: Simulated aircraft inputs are now control forces, and the joystick input is filtered to provide a mapping from joystick position to simulated pilot control force. Now you can equate max joystick deflection to max pilot control force and provide some nonlinear function for lower forces to give the "right" feel. (The input curve setup allows some user customization, but it is flight condition independent)
   

So what if any of these is implemented in the simulation now, and how could it be changed/improved?

 

So what if any of these is implemented in the simulation now, and how could it be changed/improved?

+1, and that's exactly the point of my OP, and of this post here too.

This filtered input is actually used in MSFS / CFS, and when I tried both il2-BoS and il2-CloD I noticed it as well. Same applies for instance to Aerofly FS, and in X-Plane it can be modeled although by default hinge and control forces are not taken into consideration...

I actually think it is also reflected in the DCS P51d, or maybe that's just an effect of higher MoIs ( ? )

I checked G-2 in BOS and with constant trim +1 deg with icreasing speed there is need high stick force to keep plane in dive. 109 in BOS got strong tendency to pull up byself.

 

It is like in German test posted above.

 

Fw 190 A-3 in BOS with increasing speed at trim +2 deg got increasing nose down tendency like in DCS but opposite to D-9 at high speed there is need high stick force to pull up from dive - A-3 recovery very slow. D-9 in DCS response imidietly and has no problem with pull up from dive even at 800 kph IAS at the same +2 deg trim settings.

The Fw 190 a-3 stalls in BOS at over 400 km/h with combat flaps.Compare that wit the dcs 190.

And the BOS fw190 becomes a brick at over 600 km/h . It's behaves like nothing that i read.

The BOS FM is way off imho.

Even if the ED 109 k become mere stiff in control. It's stiil by far better simulated than in other "simulations".

I don't know if the stiffness level we have now is best, i'm no expert. But i have read about pilots pulling to many G's and loosing their wings.Same goes for spitfires.

+ There are only a few of us that have a joystick as long as a real 109 one . Like this superb replica:

If you take a look at the G-2 reports from the USSR NII VVS you will see, that the stick position for the CG position 24-26% of MAC was quite constant and did not exceed 1 deg of elevator deflection beyond 400-450 kph.

Even with 22-24% FULL RANGE of trim input range is not more than 6 degree for an elevator for 210-500+ kph.

All these numbers is for idle mode - at full power there is no significant changes or even slightly reverse (instability) of elevator angle.

 

So, the massive stick pushing for G2 in BoS does not seem authentic for G2. Even with empty tank and forward CoG.

 

The diagram of constant IAS trim for different Mach numbers shows (I am afraid that it was misinterpreted here) that 190 trim begins to suffer from compressibility earlier than 109 requiring pulling the stick.

Yo-Yo from German chart it looks that to keep 109 in dive there is need near const 2 deg elevator down but at higher speeds load force on stick are incresing to about 25-30 kg?

I got book " Oblatywacze ( Test Pilots)" by Wolgang Spate. There is info about dive test in 109 F-G made by pilot Lukas Szmid. After series of dives he found that:

- at trim +1 deg 45' he need initialy push stick then trim was reversal change at ab. 800 TAS/ 7km and he need to pull stick to keep dive angle, moreover he need to keep push stick during out of dive

- at trim +1 deg 15' - he need constantly push stick with increasing load, push load was decresing to moment ( ab. 900 TAS / 4.5 km) where he was initializing pull up from dive

The Fw 190 a-3 stalls in BOS at over 400 km/h with combat flaps.Compare that wit the dcs 190.

And the BOS fw190 becomes a brick at over 600 km/h . It's behaves like nothing that i read.

The BOS FM is way off imho.

 

 

I think BOS A-3 got some problem with trim settings. Firstly "0" position on trim guage mean 0 degree angle on horizontal stab. "0" on guage IRL mean +2 deg on horizontal stab ( like it is done in DCS D-9). Also what i read RL FW 190 dont need to much trim change in wide speed range. In BOS there is need consant trim change in A-3 depend of speed. At slow to medium speed it is need about +3 deg to prevent stall in turns, at high speed (from 600 kph IAS) to pull up from dive and for effective elevator in turns it is need about 0 deg trim, but when speed is decresing is again need +3 deg to prevent stall.

Well German test proved that Fw 190 got reversal trim change in dive with constant trim settings - +2.5 deg so it was modeled in BOS.

Question is if these revelsal change is start at correct speed. In BOS it is about 600-650 kph IAS.

Maby Yo-Yo could say something more at which speed Fw 190 should start to reversal?

At 0.7 Mach or 0.62 Mach ?

Is these TAS on these chart or IAS?

For me it looks like in BOS A-3 got reversal trim at ab. 0.62 Mach at 4 km.