fw 190a5 flight model

[Janosch]

Just one more thing, said Columbo. What about computer games besides Il-2? It seems that Fw-190 made first appearance in Secret Weapons of the Luftwaffe (1991) (I can do research too, ha ha ha), and it wasn't a great turnfighter there, and so it has been ever since in all games to follow. Do you guys think that the all of the game designers who put 190 in their games did their research wrong?

[K_Freddie]

It's like Stats.. you see what you want to see.
Before IL2 came out not many (in the west) knew that there was a war on the eastern front, never mind a tank busting machine like the IL2, I mean the P51 won the war.

I at the time believed all that 'research' too, but Oleg opened our eyes.
Now I'm a bit wiser about being too judgmental.

[Oryx]

Wow, I haven't posted about Il-2 for a very long time, but just cannot resist with a comment like the one below:

Originally Posted by K_Freddie

So, aerodynamic maths explain 100% of flight, a 100% of the time

Actually, it does. For the simple reason that flight is described "perfectly" by the laws of physics. There are no exceptions. At least, in many years of flight testing from inside the aircraft and from a telemetry station on the ground, I have yet to see a single case of an aircraft defying the laws of physics. Also, today the knowledge surrounding the various factors that contribute to the forces acting on the aircraft are very well understood and can be modelled very accurately - at least accurate enough that the prediction models get extremely close to the measured ones.

When it comes to flight simulation, however, the programmers must strike a balance between fidelity and practicality. The most difficult part is not to model the kinematics - the equations are quite simple - but to generate the data to populate the models. To generate this data is both time consuming and costly. I have worked with simulators where the fidelity was so high, that we would sometimes only use spot checks in actual flight to confirm the simulator predictions. However, to achieve that level of fidelity took wind tunnel tests, numerical predictions (such as CFD) and also in-flight systems identification. The costs are obviously staggering to create such a model. This is not feasible for a game, especially ones where more than one aircraft needs to be modelled, so developers have to make some decisions on how far to go in the modelling process. The result will always be a compromise. It doesn't mean there are some voodoo aerodynamic effects going on that engineers don't understand.

and the pilot's always wrong, according to the 'propellor head' on the ground.

I don't think it is one or the other: I often rely on test pilot comments during testing. However, what is very true and I think both you and Gaston seem to miss, is that the combat environment is probably the worst possible time to compare aircraft performance. There are just too many things going on to make any quantitative judgement, unless the differences between the aircraft are really large, such as a jet vs a piston-prop. For example, does the other guy really have a faster aircraft, or did he just start the fight slightly higher and was able to build up some energy into the merge? Or does he really turn better or is the fight just happening closer to his corner speed than yours? Half the time, you won't even remember your own configuration during the fight (speed, height, throttle settings, etc), let alone what the other guy was doing. Even if one aircraft type consistently outperformed another on a certain aspect during combat, the reason might very well still lie with better tactics rather than a true performance advantage.

I say the above with utmost respect to fighter pilots with whom I have also worked extensively. I have seen clearly inferior aircraft consistently beat superior aircraft in mock combat when the pilot in the inferior aircraft was experienced, especially when he was experienced in both types. An example that I have seen with my own eyes were fights between fighter trainers and front-line fighters, where instructors in the trainers could consistently give rookies in the front-line fighters a hard time. I bet some of those rookies were thinking to themselves that their mounts were not nearly as good as advertised, while in reality the instructors just understood better how to exploit the strengths and weaknesses of the two types.

Somewhere earlier in the thread I think Gaston referred to "canned tests". Yes, that is exactly what one has to do during flight tests to determine the true potential of the aircraft. The only way to really know is to isolate parameters one by one and then test them. Combat is not the time to measure what the aircraft can do - combat is the time to put that knowledge to use.

By the way, flight testing is about much more than performance - I have spent much more time on flying qualities and handling qualities testing than performance testing. Handling qualities are extremely important when the question comes up on whether you can consistently extract the maximum potential out of the aircraft. Yet, on gaming simulations the topic of handling qualities seldom come up as few people know how to measure and interpret them. Of course, these days even more time is spent on avionics and systems testing, but that is another topic.

A small final comment before I let you guys be. I honestly don't have the time or energy to comment on every point made by Gaston, but this one really stood out:

Originally Posted by Gaston

My note: horizontal combat was never considered outdated in all of WWII, except for the Allies in the Pacific: It covers about 95%+ of all Western air battle in 1944

This is simply not true. There were many dogfights in WWII and many did indeed end up in horizontal combat. In fact, I bet the natural reaction when bounced is to turn. However, attacking from superior height was the preferred method for just about everyone and it remains so today. Horizontal combat (in fact, dogfighting in general) is always a gamble - you may or may not win depending on the relative skill of your oponent. Attacking from superior height gives the attacker an "unfair" advantage, even if he has an inferior aircraft. Entering a fight with the plan to immediately enter horizontal combat is never a good idea. Only once the fight developes into a dogfight might a pilot with an aircraft with known good turning performance prefer to stay in the horizontal. The most consistent results always came from attacking using an energy advantage (height or speed) and then to get the victim on the first pass, ideally without him ever seeing you and without letting a "dogfight" develop - and this is exactly what accounted for the majority of aerial kills in WWII.

[IceFire]

Oryx: Agreed, that comment does stand out and it's in stark contrast to any volume of reading on WWII air combat on nearly all fronts of the war.

I love this quote from a Russian pilot in particular:

Q: Could you describe ordinary dogfight?
I can’t understand the question… There were no dogfights. You saw an airplane, approach it from behind, attack and leave. Bombers were not advised to attack from straight behind – the gunner would get you. Better attack it from behind-low, with an angle 20-30 degrees. Take lead and fire your weapons.
On the other hand over Kuban it was always cloudy, enemy would suddenly appear out of the clouds in front of you… And you just press the button… Single shot. I do not remember a single case when there would be a “dogfight”. Speed and maneuver is everything!

http://mig3.sovietwarplanes.com/pilo...in/zyvagin.htm

This would not be an isolated comment either. It's not to say that dogfights didn't happen but they are much romanticized I think.

[MaxGunz]

Holy Crow! A WWII pilot quote not being taken out of context or otherwise misused!

[Herra Tohtori]

Originally Posted by K_Freddie

So, aerodynamic maths explain 100% of flight, a 100% of the time and the pilot's always wrong, according to the 'propellor head' on the ground.

Aerodynamics as a science explains the flight characteristics of any aircraft with excellent precision.

Simulators are a different thing. Not only is the performance and handling characteristics always an approximation to some degree, the amount of things simulated may affect the actual combat performance of the aircraft.

For example, if you choose to fly with wonderwoman view, the visibility (cockpit design) ceases to be a factor, which gives a lot of advantage to planes such as F4U, Bf-109, and many others. When you restrict views to cockpit view only, planes with better visibility suddenly become a lot more effective in combat because the pilot can maintain their situational awareness better.

This is an example of a factor affecting combat performance in simulator, without having any difference in hard aerodynamic performance.

Similar example would be the thing I mentioned earlier: Handling qualities, control forces required to maneuver the aircraft, things that the simulation can only approximate to some degree based on some data. How hard can a pilot deflect ailerons in A6M Zero flying at 500 km/h? How hard is it to actually turn a Bf-109 diving at 650 km/h?

In other words, while simulators can usually be very accurate with the aerodynamic performance modeling, the combat performance of aircraft in virtual sky doesn't necessarily fully take into account the other things that were a definite factor in real life. Pilot skill, physical condition, fatigue level, tactical situation in majority of engagements, tactics that are used, fabrication differences between individual planes, visibility from the cockpit - none of this is usually even discussed when we're comparing aircraft performance.


The notion that any combat pilot with any practical experience (bar the very beginning of the war) would have voluntarily offered fight in horizontal plane if their plane was faster than the other is quite amusing. Even if your plane has better turn radius and turn rate, you would still want to retain all the energy you can in case the bandit's friends pop up when you're working on them.

Losing your energy puts you in more vulnerable position, no matter what your aircraft can do.

[KG26_Alpha]

Originally Posted by IceFire

Oryx: Agreed, that comment does stand out and it's in stark contrast to any volume of reading on WWII air combat on nearly all fronts of the war.


http://mig3.sovietwarplanes.com/pilo...in/zyvagin.htm

This would not be an isolated comment either. It's not to say that dogfights didn't happen but they are much romanticized I think.

Actually, in the interview over Kuban, not once does he mention he actually intentionally put his aircraft on the six of an enemy, rather they seemed to fly into his gun-sight.




.

[MaxGunz]

Originally Posted by Herra Tohtori

Similar example would be the thing I mentioned earlier: Handling qualities, control forces required to maneuver the aircraft, things that the simulation can only approximate to some degree based on some data. How hard can a pilot deflect ailerons in A6M Zero flying at 500 km/h? How hard is it to actually turn a Bf-109 diving at 650 km/h?

Oleg did model stick forces along with trim. IL2 pilots are restricted to 20 kg strength for game considerations, possibly because fatigue modeling was too much code. The IL-2 stick interface is strength based, how far you move your joystick modified by your stick settings says how much strength the virtual pilot applies to the virtual stick. And trim affects the virtual back forces (from control surfaces) that IL-2 does model. Oleg having been a test pilot did have ideas he wanted in his sim.

[Gaston]

Originally Posted by Herra Tohtori

Well, I'm just pretty sure no pilot flying ANY PLANE would have ever wanted to enter a prolonged turning fight with any fighter, if they had alternatives...).

How come then most of the time they did dogfight, and even more so if they were flying a P-47D or a FW-190A?

When they avoided dogfights was when they flew Spitfires... I've never seen any aircraft type that avoided dogfighting as consistently as the Spitfire...

In fact the avoidance of dogfighting by the late Spitfire marks is so consistent and so extreme I had a hard time believing it, thinking as I was that the weakness of guns forced turnfighting even on 1944 pilots: Because only 2% of shots are on target, the target has to be peppered for a sustained time to be brought down, which doesn't help diving and zooming...

It turns out the Spitfire's 20 mm are really long-range and powerful, and allows the Spitfire to avoid turnfighting where it is at a disadvantage compared to most types, except the Me-109G or P-51 which are roughly equal or slightly inferior to it...

Originally Posted by Herra Tohtori

To be sure, I personally think IL-2 does not sufficiently model the control forces required to maneuver at high speeds. An FW-190 would very likely out-turn a Bf-109 if the pilot in 109 could not use full control deflection due to excessive control forces. Same applies to P-51.

The Me-109G easily out-turns the FW-190 in unsustained high speed high G turns, despite much heavier elevator controls (which the trim does lighten, but not that much).

Same with the P-51 vs the P-47D, despite the P-47 having much lighter high speed elevator controls and the P-51 being described "as a real two-hander"...

So heavier controls are here inversely related to high-speed turn performance... Just because it is counter-intuitive doesn't mean our eyes have to be glued shut to what actually happens...

The FW-190A easily out-turns the Me-109G at low speeds sustained turns despite a much higher wingloading...

My theory explains perfectly well why those counter-intuitive things are the way they are.... And that includes how reducing the throttle reduces the wingloading...

Originally Posted by Herra Tohtori

The pilot makes an incredible difference in these birds. Especially in Bf-109 where not only pilot's skill but physical constitution and strength would definitely affect the aircraft's turn performance at high speeds. Just as A6M would roll better when pilot could exert higher force on the control column. .

Even at high speeds the pilot strength differences would actually be small compared to the enormous leverage forces acting on the aircraft, which actuall pre-determines what the pilot's strength actually is... In many cases the lightness of controls still results in poor high speed performance, which means the available leverage is sometimes way beyond what the airframe can do... It is leverages that matter, not pilot strength...

At high speed in a FW-190A, it might have better paid to have a light perceptive touch to avoid having the aircraft drop a wing or slip tail forward, if the aircraft's high speed turn/dive pull-out performance had not been so poor...

However the constant vibration in the FW-190A's control collumn killed the pilot's hand sensitivity to pressure anyway (like in the controls in the Black Hawk helicopter today), and this happened to a more or lesser extent on many types, and so the fine touch was just not available to a FW-190A pilot hoping to survive on this delicate touch at high speed: Better to fly at low speeds where the aircraft performance was far more capable of compensating the numb hands of the pilot...

Originally Posted by Herra Tohtori

The actual physics of the matter are not exactly up for debate, though. The comparative weighs, lift capabilities of the wings, thrust from the propeller... all these factors are well documented and can be modeled quite well, physical testing notwithstanding.

Well if they are so well documented, can you point me to the actual wing bending tests made during flight of WWII fighters aircrafts?

As far as I know nada... And if they had done any, the relationship between engine power and wingloading would be well established: The fact that it isn't shows it was never done in flight on big-engined nose-driven low-wing monoplane types...

Originally Posted by Herra Tohtori

Fact of the matter is that the 109 had lower wing loading, better thrust-to-weight ratio, and very similar wing chord profile as the FW-190. That means at similar airspeed and angle of attack, the Bf-109 wing would be able to produce better centripetal acceleration, reducing in better turn rate and (at same airspeed) smaller turn radius..

How come then the Me-109G is always out-turned by everything in sustained turns (except sometimes the P-51), unless it drops its throttle?

Originally Posted by Herra Tohtori

To me that tells that when flown to their capabilities the 109 would probably have no problems out-turning FW-190 in a prolonged horizontal plane turning fight, and moreover would have no problems controlling the engagement in vertical plane due to better turn rate. The FW-190 pilot would be insane to offer such fight when the plane is faster anyway (at low to medium altitudes).

How come Rechlin test conclusions are the opposite for the horizontal plane, and general pilot opinion, both friend and enemy, was usually the complete opposite?

And how come KG 200 unequivocally states "The P-47D (Razorback needle prop) out-turns our Bf-109G"?

And when they don't bother specifying the "turn", is intended to mean sustained low-speed, not short-lived high speed, where the term "radius" is used instead...

You just have to close your eyes on a lot to cling to more intuitively easy concepts.

More often than not, reality defeats intuitively easy ideas...

Gaston

[Oryx]

And this, ladies and gentleman, is why I and most other aeronautical engineers stopped posting on these forums.

Originally Posted by Gaston

And that includes how reducing the throttle reduces the wingloading...

Wing loading is measured in kg/m^2 - it is mass divided by area, not force divided by area. Unless you live in a different universe than us, throttle setting cannot change either the mass of the aircraft or the area of the wing.

There is no point trying to argue with you. You will believe what you want to believe, make up your own version of physics as required and suck random statistics out of your thumb - whatever. I have made my two posts for the decade.