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[Herra Tohtori]

When flaps applied in RL nose goes down

In RL what happens? You lower flaps, instantly nose tends to rise a bit by a tiny time, of course I didn't said doesn't happens, but nose rises because you're same airspeed and have more lift

Your cognitive dissonance is noted and my argument satisfied.


What you just described is exactly what I meant: If the aircraft starts to climb (which happens because of the higher lift produced by flaps while airspeed is still high), then the nose can also point up relative to horizon even if the angle of attack is reduced by the flaps, because the entire aircraft is traveling on an upward direction.

Not reading someone's post and still saying they're "wrong" is quite rude, you know? Maybe next time, you should read the posts you're replying to. Your pilot's license is not a magic authority badge that makes you correct in all things related to flight, nor does it prevent others from being correct either.

[Ala13_ManOWar]

Read further mate, that sentence finishes,

.. so your engine trying to keep your airspeed-AoA equilibrium instantly have excess power... your nose rises because that excess power, not lift.

I say again, an aircraft climbs because excess power, not lift . May be your head explodes now, but does a glider climbs alone with no help? So...

Your pilot's license is not a magic authority badge that makes you correct in all things related to flight, nor does it prevent others from being correct either.

Of course, never said it is and what I don't know I will say, I DON'T KNOW, but you started coming here saying, "WHAAAAAAA??? You're crazy", and so. All your long posts before said nothing, worth the while?

S!

[Herra Tohtori]

Read further mate, that sentence finishes,

.. so your engine trying to keep your airspeed-AoA equilibrium instantly have excess power... your nose rises because that excess power, not lift.

I say again, an aircraft climbs because excess power, not lift . May be your head explodes now, but does a glider climbs alone with no help? So...

I think excess airspeed would be more accurate in this case. How could the climb be caused by excess power when the engine power settings remain unchanged? This whole conversation is more about what the aircraft does with no control inputs when flaps are deployed, and seems like we are in complete agreement about what it does.

Instantly after flaps are deployed, the aircraft is still traveling at the same airspeed as before deploying the flaps, so the wing is now producing more lift than aircraft's weight, so of course without any input from the pilot or autopilot, the aircraft starts to go up. This causes the path, or velocity vector, to go slightly up (depending on how much excess airspeed the plane has). At the same time, the flaps affect the aircraft's stability so that the aircraft's nose goes down relative to airflow (angle of attack is reduced).

Whether the nose goes up or down relative to horizon depends on the combination of these two things, and which one has a greater effect.


In a sustained climb, you're right - the climb is sustained by engines working to maintain airspeed against the drag and gravity.

Your pilot's license is not a magic authority badge that makes you correct in all things related to flight, nor does it prevent others from being correct either.

Of course, never said it is and what I don't know I will say, I DON'T KNOW, but you started coming here saying, "WHAAAAAAA??? You're crazy", and so. All your long posts before said nothing, worth the while?

I wasn't saying you're crazy at all, that was your interpretation.

Now, enough about that. I'm more interested in hearing more about what you're saying regarding to simulation of flaps in IL-2.

I'm sure there are some specific planes in which the flaps are incorrectly simulated (too much lift increase, too little drag increase, etc. etc.) But what is it that makes you say they're "faked" in comparison to the rest of the game?

Which part in the flaps simulation is worse than rest of the simulator in IL-2?

[snachito]

Ala ManOwar and Herra,

Thank you for the flight and physics explanation, as that helped me understand more about flight and I was able to draw a mental picture of it which helps me immensely!! I actually talked with wifey last night and we both agreed that I will go get my Sport Pilot license (I can FLY kit planes and LSA planes) and not break the bank!!

[Ala13_ManOWar]

Thank you for the flight and physics explanation, as that helped me understand more about flight and I was able to draw a mental picture of it which helps me immensely!! I actually talked with wifey last night and we both agreed that I will go get my Sport Pilot license (I can FLY kit planes and LSA planes) and not break the bank!!

Glad to help, and glad to see you going to fly. Congratulations!!! 



OK Herra, fine... Still I think you came "too hard"...  ???

I think excess airspeed would be more accurate in this case

Negative Herra, I clearly said "power excess" not by chance,

http://en.wikipedia.org/wiki/Rate_of_climb

... This occurs at the speed for which the difference between engine power and the power required to overcome the aircraft's drag is the greatest (maximum excess power). Climb rate is proportional to excess power.

Think a glider always descent. Even inside a thermal glider is descending, just thermal is a vertical wind "faster" upwards than your rate of descent downwards. You can climb with the speed gave by your "power" (gravity) for a while, then you slow down and fall. The result always will be a lower altitude than start. So you can't never climb without an external power. Lift does "nothing" but keep you in the air.

How could the climb be caused by excess power when the engine power settings remain unchanged?

Easy, because power setting, airspeed and AoA-lift are in a thin related equilibrium. Flaps start deployment and drag still don't rises so much, aircraft have many inertia so airspeed is kept at first, you have a new equilibrium where power is in excess with your new AoA and airspeed by a moment, less AoA needed so you have a momentary excess power. There with that excess power nose try to rise a bit. Then drag and airspeed get to normal values, and aircraft takes normal attitude to that new equilibrium, less AoA needed so nose lowers. A different scenario would be having 10º flaps yet deployed and lower to 20º, as drag is yet present nose doesn't rise so much almost nothing, so you can see having more lift isn't a help to climb more clear.

But I go further, what if a bit lift at first makes you climb a bit, would it change physics? would it change Il-2 is wrong by concept? Would it change the way you have to fly (RL I mean) correctly? Really it doesn't matter... People many times want to think about lift instead of AoA because they think they understand better, lift is "something keeping you up there". But that's a big mistake, and in RL it's not even a question about who's right or wrong it's a question about understanding physics behind flight keeps you alive and wrong decisions made upon wrong principles of flight understanding are behind many GA accidents. Typical say "I'll lower flaps helping me climb"...  ??? You can see many videos in Youtube with accidents by wrong decisions taken because misunderstanding or directly lack of known and it's anything but fun...


So, Il-2 is wrong because it's made in an amateur point of view, sorta guesses, with a miserable misunderstanding in physics behind flight and aircraft behaviour. Yes, it's a game, you hit refly and that's all, but would you call that a "Simulator" if physics are faked because they didn't knew what they were modelling? I wouldn't... Wolfgang Langewiesche in his book circa around 1940 ( it wasn't yesterday...) explain it very clear: flight dynamics have a logic behind, but not a logic like we ground humans can think at first (the one you apply for example, and Oleg's one in Il-2), when you understand the real logic behind flight it's very clear and can be mastered by training, but if you apply what you think is "logic" (our ground logic) without that training you'll be dead sooner or later. Well, yes here we're in a game, but if we where talking in a flight school doing same as you guessing here and there would be very dangerous. It's a difference mate.

S!

[Herra Tohtori]

You're talking about "excess power", but the lift generated by the wing doesn't depend on engine power, it only depends on airspeed (and angle of attack and flaps configuration and air density and lift coefficient).

There's a break in the causal relationship there, because at any given airspeed, the wing can produce exactly the same amount of lift regardless of engine power. It doesn't matter for the wing if the engine is working at full power or flight idle. At that particular moment, the wing is flying through the air at a particular airspeed and the engine power doesn't affect the amount of lift available.

In our example, even if you completely shut down the engine at the same moment as you lower the flaps, the increased lift would still cause the aircraft to climb for a while, until airspeed is reduced.

Just like with a car, engine power doesn't directly control the speed you're going at, it controls the acceleration of the vehicle.


Clearly, maintaining airspeed (and therefore lift) is only possible if you have some device by which you can generate sufficient thrust to overcome drag, or if you are losing altitude in a glide, using your potential energy to maintain your airspeed; gliders in rising air obviously receive a continuous boost to their potential energy from the air current.



I think when you and I talk of a "climb" we are speaking of a different thing. When I say "climb" I mean that the aircraft is generally moving upwards. When you say "climb" you're talking about powered, sustained climb where vertical speed is constant and airspeed is constant.


An aircraft is like any other object, it obeys Newton's laws of motion (as long as it doesn't travel at near light speed which would be problematic for other reasons). It can be described pretty easily in a free-body diagram.

For example, if an aircraft is traveling straight and level, the sum of the forces acting upon it is exactly zero, and there are no accelerations (except gravitational acceleration, 1g load) either on up/down, forward/backward, or left/right axis.

In order to get it climbing in the first place you need to break the equilibrium of the forces: You need to create more upward force than downward force, which means you need to make the aircraft's wing produce more lift than the aircraft's weight. Usually this is done by deflecting the elevator to increase the angle of attack.

This causes an acceleration upwards, which gives the aircraft some vertical speed.

After you have reached the vertical speed you want, you need to equalize the forces again, so that the aircraft keeps moving on an upward slope at constant speed.

For that, you need to obviously re-adjust the lift so that upward and downward forces are equal, and adjust engine thrust so that airspeed stays constant. That's the sustained climb you're talking about.


But for transient maneuvers (where there is no requirement for airspeed to remain constant), engine power doesn't matter as much, you can even do aerobatic maneuvers in a glider. You can do loops and vertical turns in a glider. Both maneuvers include "going upwards" completely without an engine.

And I still maintain that when lift is greater than weight, a horizontally aligned aircraft gains vertical speed upwards. Since you like equations, here's one: F = dp/dt
That is the basis for everything in classical mechanics and even further.


For what it's worth, I study physics. I know how physics works. I don't need to "guess" anything, and I have a pretty good comprehension of how aircraft fly and how they control their direction of motion. From my perspective, the problem seems to be in your reading comprehension, if anything.


And IL-2 is, like any simulations, an approximation, but for the most part it doesn't seem to egregiously break any laws of physics. It may have incorrect parametres, resulting in weird or incorrect behaviour, but fundamentally it relies on a physics system that is most definitely based on real world physics, which honestly isn't really all that complicated.





Could you outline some particular points where the fundaments of the game world physics are incorrect?

Since the discussion was about flaps, could you explain why do you think the flaps in particular are "faked" in the game? From what I've seen they work as you would expect... at least, in most planes.

[Ala13_ManOWar]

Mate, really, have I to read that long and answer quoting everything? I explained, if you don't like look for Pilot Licence Theory and study it yourself, you have many sources over the net.


Il-2 flaps behaves wrong since they makes you CLIMB, assuming the more lift "the more you fly" as any amateur could guess without knowing the real thing. It's not the case in real life, to fly you need only one lift, your weight. Lift excess is useless and an aircraft with lots of lift without weight to keep would be unflyable like a bad shaped paper plane. Flaps makes you need less AoA so your nose goes DOWN, Il-2 behaves wrong on its entirety since behaves the opposite for every aircraft and that's unfixable since it's core engine who's wrong, I explained once, that's all.

S!

[Herra Tohtori]

to fly you need only one lift, your weight. Lift excess is useless and an aircraft with lots of lift without weight to keep would be unflyable like a bad shaped paper plane.

This is false, or at least gross oversimplification.

First, there is nothing forcing the lift produced by the wing to be equal to weight. The lift force can be smaller than the weight, it can be larger than the weight... it can even be negative.

The lift is equal to weight in a specific flight condition: Straight and level flight. For that, you do need an ability to balance lift with weight and this is done either by adjusting trim to make the aircraft fly level at a particular power setting, or by engaging autopilot with altitude hold mode.


In order to make the aircraft do anything else than fly straight and level, some adjustments of the lift must be done simply to make the aircraft change its direction. This is basic kinematics; to make an object change its motion, there must be an external non-zero net force acting upon it.

Most often this is achieved by adjusting the angle of attack with elevator control surface, but lift is also varied by high-lift devices (flaps and slats) and airbrakes (spoilers). If the pilot wants the aircraft to start a climb (or turn, for that matter) the lift must be increased; if the pilot wants to start a descent, the lift must be decreased in order to get the aircraft moving into the desired direction.


To facilitate this, an aircraft's wing can vary its lift within a wide range, usually announced by the g-limits of the aircraft. For example a Cessna 152 Aerobat has a cited load capability of +6g to -3g. That means the aircraft's wing can produce up to six times the aircraft's weight upward (in a particular load configuration of course) and three times aircraft's weight downward. And, usually there's at least 1.5x engineering margin in the structural limits to avoid damage in normal operation.


Also, saying that "excess lift" is useless simply boggles my mind. How can it possibly be useless when it is the cornerstone of any maneuvering capability? Why do you think wing loading is such an important factor for determining the maneuverability of an aircraft? The more "excess lift" an aircraft has in reserves, the more drastic maneuvers it is capable of doing; this is generally why low wing loading aircraft like the A6M Zero or early Spitfires generally turn better than aircraft with high wing loading - like a P-51 Mustang or Fw 190, for example.

High wing loading has other benefits that become evident at high speeds, but that does not in any way invalidate the benefits of having lots of "excess lift".

Il-2 flaps behaves wrong since they makes you CLIMB, assuming the more lift "the more you fly" as any amateur could guess without knowing the real thing.

According to my tests, this is incorrect. Deploying flaps in IL-2 without any other pilot input makes the aircraft climb a little, after which it turns to descend due to the increased drag.

Have you actually tested this?

Flaps makes you need less AoA so your nose goes DOWN, Il-2 behaves wrong on its entirety since behaves the opposite for every aircraft and that's unfixable since it's core engine who's wrong, I explained once, that's all.

"Need" implies controlled action to prevent the aircraft from climbing. If you enable the level stabilizer* or maintain level flight manually, indeed you shall find that deploying flaps requires the aircraft's nose to be pushed down, quite substantially in fact, in order to avoid a climb.

Without such control, there is nothing preventing the aircraft from climbing when its high airspeed combined with deployed flaps produces higher lift than aircraft's weight. The aircraft starts a slight climb, loses airspeed, and turns to a descent.

Again, have you actually tested this in IL-2 1946?


*The level stabilizer in some planes is actually broken and doesn't properly work in all circumstances.

[Ala13_ManOWar]

Yeah, I have no doubt it would be finally whatever you want. I have no time to net arguing. You're right, real world is wrong.

S!

[Herra Tohtori]

You made the argument that IL-2 (the game) handles flaps incorrectly because planes start climbing instead of descending.

I tested your claim in IL-2 and the results contradict your claim. The aircraft I tested with ended up descending.

What do you want me to do, to provide my test track so you can choose not to watch it because you "know" it's false anyway?


Whatever discussion we have been having about plane behaviour in real life is inconsequential - although, I maintain that nothing I have said in this thread is in contradiction with the laws of physical reality, while your explanations have inconsistencies, reversed causal relations, and possibly straight up misconceptions in them.

[Ala13_ManOWar]

YEAH, Principles of Flight have inconsistencies and many flaws... But still real aircraft (not a game) fly every day thankfully.

You made the argument that IL-2 (the game) handles flaps incorrectly because planes start climbing instead of descending.

Mate, really you like to argue. Your AoA can be negative while you climb or positive while you descent. I said AoA is lower, not aircraft descent... This is where it's all crystal clear about you don't understand principles of flight or real aircraft behaviour  . Even though you don't want to understand but say your terrestrial logic is right for flight. Fine mate, fine.

I know you tested and finally it descent as far as it lower your speed... but you can descent quicker with nose up than down and probes nothing about your claim. That's the logic of flight, not your terrestrial logic. Read Wolfgang Langewiesche "Stick&Rudder" and argue with him, I'll not any more.


For not arguing people, Il-2 raises your AoA with flaps deployment, RL lowers AoA. That's all.


the Man Of War OUT here.

[Herra Tohtori]

For not arguing people, Il-2 raises your AoA with flaps deployment

Again, incorrect. In my test, deploying the flaps reduced the angle of attack in all aircraft I've tested so far.

A typical case would be the B-25J where I obtained the following results:

Flying on Crimea, approx. 1000 metres altitude, Default loadout, 30% fuel.
Power set to 40% throttle (~25 inHg manifold pressure), prop pitch 66% (~2000 rpm)
Trimmed to fly straight and level with 15% elevator trim, rudder trim coordinated, wings kept level with aileron control.

In this configuration she flies at about 257 km/h (TAS) at altitude of 1024 metres ASL, with 4° AoA.



Flaps deployed, power settings unchanged, elevator and rudder trim unchanged. Aircraft's angle of attack is almost immediately reduced to 3°, but nose goes up because the aircraft starts to climb:



As flaps deploy fully, the angle of attack is further decreased to 2° and the aircraft is climbing quite fast. Airspeed is dropping quickly, however.



After the apex of the climb, the aircraft's nose starts to go down and it starts to descend.



The aircraft then settles into a a phugoid mode descent where rate of descent and airspeed vary somewhat but the general trend is descending. Angle of attack varies between 2°-3° depending on the stage of oscillation.


Conclusion: Deployment of flaps reduces the angle of attack, as expected. In this test, where there was no elevator or trim changes, the AoA dropped about 2°.


In a test with Level stabilizer enabled (to prevent the initial climb), the aircraft initially flew at 4° AoA, and with flaps deployed the nose dropped momentarily to -1° AoA, before returning to 0° as the aircraft slowed down due to drag. Power settings were not changed during the test.