[FIXED INTERNALLY] Wind not accounted for in flight model and display.

[bkthunder]

I truly admire your tenacity guys, but there is no worse blind man than the one who doesn't want to see.

 

@The Falcon, just go out and READ about this stuff instead of asking us to prove the obvious. No one has to prove anything to you. Go and read about how airplanes fly, read about air masses, read about air navigation.

If you don't believe what even RL pilots are telling you what can we say?

[Dee-Jay]

You will stall

Absolutely not. (fortunately)

 

 

Edit: I've read the entire thread again. I understand where The Falcon misconception comes from. He does not have the same definition of "what the FM is" than the others.

Most of the time he is speaking about global motion relative to ground while the other are speaking airspeed. That is why you can't agree on what a "climb path" is (air path vs ground path) ... etc ...

 

 

But speaking about "in flight FM" (not speaking about on ground and transitioning between on ground and in flight) FM is tied to relative wind around wing and engine intakes = airspeed ... (IAS, TAS, EAS) ... ground speed and wind direction and force has nothing to play with flight model performances relative to air mass reference (Wich is moving independently relative to the ground).

 

 

Anything else (while potentially correct considering Enstein relativity theory) is nothing but intellectual masturbation and out of scope.

Edited January 31, 2020 by Dee-Jay

[Delareon]

not using the rudder in flight..... not using the rudder on landing....

jeeeeez, note to myself: never give the controls to a sim pilot :D

 

That might be true in an F-16, i never flew a jet, but not in a regular propeller plane so be aware to not simplify stuff there are differences between planes. You have to conquer Torque and even in Gliders whitout any torque you need slight rudder input even in straight flight. But thats another Topic in this Thread full of different Topics.

 

Guys, you are talking about different topics. Many of you try to explain the physical world, guys like The Falcon and me are more talking about a Game Engine and the experience as a whole.

Where things like headwind on start and drift are things to consider.

 

I would suggest we just wait until this FM Changes are available and discuss then if the behavior is now more like the behavior we think it should have.

[bbrz]

...not using the rudder on landing....

...even in Gliders whitout any torque you need slight rudder input even in straight flight.

Please don't tell me that you are correcting the heading with the rudder IRL during the approach.

Concerning gliders, either you are doing something wrong or the glider you are flying is bent.

[Delareon]

correcting the heading is in most cases a combination of rudder and stick.

crabbing just short before touchdown is only one of the possible solutions, you can also correct upfront.

 

Maybe the Glider is bent, its by far not the most modern one where rudders are perfectly optimized. Another Reason why its different between planes, ofc if there are good thermals that day (which you really want in a glider) there comes also thermal turbulences and caused by that and maybe landmarks different wind directions and speeds which also leading to corrections.

You almost never have such academic conditions in RL.

[bbrz]

With items like turbulence and thermals you are not making things easier to understand for The Falcon.

If you want discuss basic flying techniques with prop driven aircraft and gliders you should open a new thread.

[metzger]

correcting the heading is in most cases a combination of rudder and stick.

crabbing just short before touchdown is only one of the possible solutions, you can also correct upfront.

 

Maybe the Glider is bent, its by far not the most modern one where rudders are perfectly optimized. Another Reason why its different between planes, ofc if there are good thermals that day (which you really want in a glider) there comes also thermal turbulences and caused by that and maybe landmarks different wind directions and speeds which also leading to corrections.

You almost never have such academic conditions in RL.

 

 

In your examples, You are using the rudder to counter forces created by Aircraft motion in Longitudinal axis (bank and think do you need rudder in steady bank or only during motion ?) and torque created by Propeller. Not to correct for wind speed/direction, not really relevant to the topic. :) Anyway I went trough the thread to see how long it will take The_Falcon to realize how wrong he is :)

[David OC]

Anyway I went trough the thread to see how long it will take The_Falcon to realize how wrong he is

 

It's not about wrong or right.

 

Much of this has to do with how it's written here and the language barrier with The Falcon.

Many (Pilots like bbrz) want the correct information displayed correctly, or for the younger guys here learning to go read and understand this off aviation books and not be confused with the mismatch of info posted around.

 

The word wind and how it's used here has been very confusing.

 

Now tell me, why during the whole landing procedure the pilot uses the rudder to face the constant wind while at altitude he doesn't (according to what you say). I want an explanation of the physical phenomenon because nobody has given me.

 

The only time "wind" is a factor on an FM (Flight Model)

 

That's called "turbulence" inside the air mass you are flying in relative to you.

 

https://www.skybrary.aero/index.php/Turbulence

 

https://www.skybrary.aero/index.php/Air_Masses

 

The wind only affects how you fly in this air mass, relative to a "fix point" on the ground. You are just flying on an angle in this big air mass relative to how this air mass is floating over the fix set point.

 

An aerodynamic force is felt when YOU yaw the rudder in this air mass to align the aircraft with the runway.

 

de crab

 

 

Whats other things that can effect a flight model (FM)?

 

Air density and temperature

 

https://www.skybrary.aero/index.php/Density_Altitude

https://www.skybrary.aero/index.php/Hot_and_High_Operations

 

 

 

 

See last minute corrections

Edited January 31, 2020 by David OC

[The Falcon]

I want to make a clarification. The terrain is a fixed point in reality. However even in the air it is possible to stop a point, keep this in mind.

Anyway I went trough the thread to see how long it will take The_Falcon to realize how wrong he is

You seem to be sure so do you understand what I'm saying? read better

For FM i mean the whole system..the aerodynamic and the "physical" one.. or as cofcorpse called it material point..

..bkthunder said that state wind has 0 effect on the FM, and Delareon was also perplexed like me if you read his first post, and if you read my first post you will clearly see that I was trying to correct what bkthunder said..

So I mean that FM is not only composed of aerodynamic forces but also of the laws of mass/inertia gravity/energy.

airspeed is mainly part of the FM, however there are other forces, which is why i referred to ground speed.. as physical forces.

He doesn't use the rudder during the approach!

He simply applies the WCA (wind correction angle) and flies a corrected heading so his track in relationship to the ground leads him to the runway

The moment the pilot decides to oppose...

it is so difficult to make your understood when you use pilot preconceptions. You are right! but for me you also gave me reason now! Just to let everyone know what the WCA is

 

Why don't you have to use the rudder or a little roll? obviously because by precompensating the wind (through precise calculations that take into account the trajectory respect to a fixed point and this implies mass and energy) the plane does not have to maneuver against the wind because it is pointing the nose not much in the direction of the runway but in the direction of the wind. But what if it doesn't precompense the wind? what should he do? obviously rudder and ailerons-roll in general. that's why I said it affects the flight as a whole. Of course it doesn't change aerodynamics if the pilot do that maneuver with or without constant wind. If the pilot has to use the WCA he's dealing with the wind and this means that the constant wind influences the flight. I repeat, as long as you let yourself be carried by the wind, the aerodynamic part does not change but the physical part of the energy vector does, I will better explain this by responding to Dee-jay.

But on this I ask you another question. 2 different cases. No WCA.

 

First case, make a pass over the runway at maximum speed.

Second case, do the same passage at minimum speed.

How does it change in general or how does the FM change?

Think harder about my question, "What is wind?"

From the aircraft's perspective.. ..wind "gusts.. ..does not last long enough for inertia to be overcome...

I had understood your question before. You're right I also said the same thing, from the point of aerodynamic forces constant wind or 0 wind makes no difference while, as you also say, gusts affect precisely because they do not change inertia constantly.

But I had to answer that way because I wanted to explain another thing.

 

Like I said before Falcon.

When you write about this, (separate the two)

The plane will only feel the force of "wind" when the (wheels are on the ground)

When an aircraft is in the air, it's in that "bubble of air" It's all relative to "that aircraft" and proformance.

When you try and come out of this bubble (that's moving around) COMPARED to the (ground) only.

I can separate the aerodynamic part but not the physical part. The direction where the nose points is the speed vector, the faster you are the larger the vector, without using the WCA (or following a fixed point in space) that vector will get you out of the bubble.

Hi!

Rudder is not used during the whole landing but only at flare to de-crab.

There is another method which is call slideslip and require rudder action to keep the nose external to the trajectory (slip). But rudder action is no way intended to counteract the wind. Just to point the nose outboard of the velocity vector

Anything else (while potentially correct considering Enstein relativity theory) is nothing but intellectual masturbation and out of scope.

Thx for intervening. "Just to point the nose outboard of the velocity vector"

This is what I call "dealing with the wind". So I suppose the trajectory is an "intellectual masturbation" no because that too has nothing to do with aerodynamics, but wow if it has to do with the whole FM.

Imagine being stopped at 6 meters in horizontal flight, you are still above the ground because you have a headwind equal to the takeoff speed. Now roll 90 degrees, what happens? immediately fall to the ground, why? ..intellectual masturbation.. (and for sure that in real life will never happen to you, but if it does do not eject yourself because it would happen the same thing to your body and you would end up crawling in the ground:lol:)

If I can, I ask you the same questions that you asked in bbrz, if you want to answer otherwise patience.

2 different cases. No WCA.

 

First case, make a pass over the runway at maximum speed.

Second case, do the same passage at minimum speed.

How does it change in general or how does the FM change?

bbrz and bkthunder are fully correct

For me not especially bkthunder, even cofcorpse had to clarify

As I understand, you consider wind as navigational thing. In simulation we can roughly divide flight model to two parts - material point (which uses ground speed) and aerodynamic forces (which use airspeed). If one of the parts use incorrect speed, total result will be wrong.

I hope this brief explanation will clarify situtation a bit.

not using the rudder in flight..... not using the rudder on landing....

jeeeeez, note to myself: never give the controls to a sim pilot

Guys, you are talking about different topics. Many of you try to explain the physical world, guys like The Falcon and me are more talking about a Game Engine and the experience as a whole.

Where things like headwind on start and drift are things to consider.

Exactly, but also in reality, every time that the pilot wants to point with the nose a fixed point in the space, if there is constant wind he will have to consider it because that wind will constantly change the position of the a/c respect to that point. Not to mention the difference in climbing with the headwind or fuel consumption with the tailwind.

I truly admire your tenacity guys, but there is no worse blind man than the one who doesn't want to see.

@The Falcon, just go out and READ about this stuff instead of asking us to prove the obvious. No one has to prove anything to you. Go and read about how airplanes fly, read about air masses, read about air navigation.

If you don't believe what even RL pilots are telling you what can we say?

I don't respond to provocation. Your assertion "costant wind has 0 effect on the flight model except during take-off and landing ..." is incorrect or otherwise misleading imho. The moment the pilot has to follow a static point, he has to face the wind, especially without WCA. I still have this answer in my mind.

I think the wind affects once in the air, but it depends, and I don't talk about wind gusts. It depends on: wind speed/direction, exposed surface and weight of the aircraft. I believe that this is clearer to the reader.

So absolutely the wind must and can affects the FM

Sorry for the "massive" answer

Edited February 2, 2020 by The Falcon

[The Falcon]

But the climb rate of the two aircraft will be the same. They will not travel the same distance over the ground. But they will achieve the same altitude at the same time

Yes, if you start them already in the air they will achieve the same altitude at the same time, otherwise not. Climb rate as we have already said basically depends on lift = airspeed, but the whole climb performance changes between headwind and tailwind. For examples we take two a/c one headwind and the other tailwind. Both have a climb rate of 5ft/sec. Headwind takes off midway and tailwind at the end of the runway. It takes 10 seconds for the tailwind to takeoff and 5 seconds later than the headwind. Now they are both in flight but headwind is already at 50ft while tailwind is 25ft. The two will never meet at the same altitude. That's why I said that the whole climb performance changes

and if at the end of the runway with tailwind you are lower than the headwind, this means that for the same time you went up less!

Edited February 2, 2020 by The Falcon

[The Falcon]

You will stall

Absolutely not. (fortunately)

The context

 

Objection, your honor. The inertia comes into play. Lets say your aircraft has a stall speed of 70kts. Now you fly your aircraft at 100kts in a 50kts laminar headwind, guess what happens when you perform a 180° turn, if you perform that turn quickly, but without changing your pitch.

 

Fox

Now give me a chance to explain better why I replied Foxromeo that the plane stalled. Fox is talking about inertia and a "quick turn". Let's do this, take the quick turn off and say that magically you are hit by the tilwind in an instant, i know it is no longer constant wind but let's pretend it is, what happens? it happens that until the wind has overcome your inertia and has dragged you at its own speed, you will stall.

[Mar]

I apologize for implying that you were trolling The Falcon. You write English so well but with such subtle differences. It got me confused! Your last few posts helped me understand what you are saying better, thank you. It seems we agree after all!

[The Falcon]

Thx to you Mar. Right now reading again what i wrote i realize that i have said certain things in the most difficult possible way to understand:doh:, for example when i said "dealing with the constant wind" it would have been better if i had said dealing with your position to the ground considering the wind"

[Deano87]

Yes, if you start them already in the air they will achieve the same altitude at the same time, otherwise not. Climb rate as we have already said basically depends on lift = airspeed, but the whole climb performance changes between headwind and tailwind. For examples we take two a/c one headwind and the other tailwind. Both have a climb rate of 5ft/sec. Headwind takes off midway and tailwind at the end of the runway. It takes 10 seconds for the tailwind to takeoff and 5 seconds later than the headwind. Now they are both in flight but headwind is already at 50ft while tailwind is 25ft. The two will never meet at the same altitude. That's why I said that the whole climb performance changes

 

The climb starts when the wheels leave the ground, as that’s when the aircraft begins climbing. Anything that happens before that is the takeoff roll, and therefor not applicable to a conversation about climb performance. They climb at the same vs and they will reach the same altitude at the same time. There is no difference in climb performance with wind. What you’re talking about is a difference in takeoff performance. This is not the same thing. If you wish to avoid confusion when discussing a topic like this is it’s best to try and stick to definitions that are understood.

 

Edited February 2, 2020 by Deano87

[Dee-Jay]

When you are speaking about climb rate, ou are thinking climb path relative to the ground.

In flight climb rate and air path will be identical whatever the wind. Unless I was wrong during my 20y of flight experience and 5500 flight hours.

 

 

I am sorry The Falcon. Many things you are saying are correct. But it is OT relative to OP. Discussion is about a bug concerning how the code is taking the ground displacement in account for aero data calculation. In flight an engine will deliver the same thrust whatever the wing direction or speed. Same apply for lift and AOA. One have to keep the ground out of the equation. That is why I say than everything else is rather "intellectual masturbation".

 

We tried everything we could to make the point. Nothing more we can do.

 

Cheers!

Edited February 2, 2020 by Dee-Jay

[The Falcon]

Wind _does_ affect an airplane in-flight. The effect is most noticeable when you’re on or near the ground but it obviously affects the aircraft at any speed and altitude. A plane is like a boat... Just imagine what a captain of a boat would have to do in order to stay the course if he faced strong currents.

But a boat also has no clue if the water is moving or not, unless the boat has a GPS to measure "ground speed". Of course a boat and a plane need to correct their flight path to keep their course relative to the ground, but that does not mean a plane or boat is receiving side-forces all the time...they dont

For me these two comments are the essence of how we say the same thing but in two different ways, or how we see relative things as absolute.

One sees it only as aerodynamics, another as aerodynamics but related to maneuvers to counteract the wind that moves us relative to the ground, that's it. That's why i asked those two questions, but it seems that for some i am questioning the bug found by bkthunder, but i'm not doing it

[Svend_Dellepude]

I think you have to stop looking at aerodynamcis from a ground perspective.

You get things mixed up.

[The Falcon]

I think you have to stop looking at aerodynamcis from a ground perspective.

You get things mixed up.

I understand that i should have been more careful with certain terms.

Aerodynamics has nothing to do with the ground, the word "aero" says it.

The manuals separate things to explain in a certain way, but in reality things are not separate. So one thing is aerodynamics taken alone, another thing is the overall flight model. Although the aerodynamic effect is the same with or without constant wind, the perception of what is happening around us is given by a static reference point (which is real life since we cannot escape to the ground, except for very fast objects). That's why I asked those questions but no one has answered yet:

The questions were:

 

 

2 different cases. No WCA.

First case, make a pass over the runway at maximum speed.(pointing the nose steadily towards the center of the runway)

Second case, do the same passage at minimum speed.

How does it change in general or how does the FM change?

 

 

Imagine if you had to do this pass to bomb the runway, can you imagine dropping the bombs using the WCA? What happens to the bombs hitting the ground sideways?

 

 

Anyway I answer. It simply wouldn't be possible. Because the pilot should counteract the carries of the wind by pointing against it to keep the center of the runway. This maneuver involves resistance, same it's done with or without wind, but in one case it is because of the wind, in the other because of the shift relative to the ground.

 

 

However, what difference does the speed of the aircraft make? And i don't mean the airspeed but the speed in itself, therefore its energy. If you pass fast, you will be able to keep the center of the runway without too many problems for two reasons. First, because the overflight time decreases and the wind "has less time" to deviate you from the ground. Second because this energy is greater than the one impressed by the transport of the wind. This energy can be used by the pilot to his advantage. If instead you go slow it will be an impossible thing to do becouse your energy is slow and you will be more affected by that of the wind. This energy is what makes you understand that it cannot be said at 100％ that the constant wind does not change the FM because the FM must take this into account and this in relation to the energy impressed by the wind. I hope i was more clear.

Edited February 3, 2020 by The Falcon

[metzger]

The bug is marked at fixed, so let's see how it is after the next beta upgrade. It is a major flow tho hopefully it is really fixed.. good catch OP.

 

@The_Falcon it seems you are very confused of what is what in terms of aerodynamics and how airplane flies. I strongly suggest you to read carefully and uderstand "stick and rudder: an explanation of the art of flying" then come back at this thread and re-read your comments, only after you are sure you understand the book.

[bbrz]

...his energy is greater than the one impressed by the transport of the wind. This energy can be used by the pilot to his advantage. If instead you go slow it will be an impossible thing to do becouse your energy is slow and you will be more affected by that of the wind. This energy is what makes you understand that it cannot be said at 100％ that the constant wind does not change the FM because the FM must take this into account and this in relation to the energy impressed by the wind. I hope i was more clear.

You still haven't understood aerodynamics, the related physics and you are still throwing navigation into the equation which doesn't belong there.

 

IMO you weren't more clear. Rather the opposite. To me it was confusing and wrong as usual. I really don't understand why you keep discussing without knowing the basics about aerodynamics and aviation terminology.

[Deano87]

However, what difference does the speed of the aircraft make? And i don't mean the airspeed but the speed in itself, therefore its energy. If you pass fast, you will be able to keep the center of the runway without too many problems for two reasons. First, because the overflight time decreases and the wind "has less time" to deviate you from the ground. Second because this energy is greater than the one impressed by the transport of the wind. This energy can be used by the pilot to his advantage. If instead you go slow it will be an impossible thing to do becouse your energy is slow and you will be more affected by that of the wind. This energy is what makes you understand that it cannot be said at 100％ that the constant wind does not change the FM because the FM must take this into account and this in relation to the energy impressed by the wind. I hope i was more clear.

 

I'm guessing by energy you are talking about inertia or momentum, here is the thing, inertia is relative, and in the case of an aircraft its relative to the air its flying through NOT the ground. The air is what can allow the aircraft to maneuver, the inertia of the aircraft is acting on the air, via its wings. The ground has nothing to do with it. An aircraft flying at 200knots airspeed in a 200knot headwind will be at 0 knot groundspeed. But if it pulls to the vertical it will still have the same vertical energy as an aircraft flying downwind at 200 knots airspeed (400 knots groundspeed) this sounds counter intuitive, But it's how physics works.

[The Falcon]

The air is what can allow the aircraft to maneuver

of course

An aircraft flying at 200knots airspeed in a 200knot headwind will be at 0 knot groundspeed. But if it pulls to the vertical it will still have the same vertical energy as an aircraft flying downwind at 200 knots airspeed (400 knots groundspeed) this sounds counter intuitive, But it's how physics works.

Zero ground speed means 0 energy(material point=kinetic energy), regardless of the airspeed.

400 ground speed means energy much > 0, so in this case we have a vertical energy and we go up and we also have drag and lift. So in this case FM is totally different.

The only equal energy, inertia or momentum, of which you spoke above, is related to the aerodynamic maneuver, so the constant wind affects not the maneuver itself but the overall result.

For this reason in my first post i wrote that it depends...

..but it depends..

[The Falcon]

@The_Falcon it seems you are very confused of what is what in terms of aerodynamics and how airplane flies. I strongly suggest you to read carefully and uderstand "stick and rudder: an explanation of the art of flying" then come back at this thread and re-read your comments, only after you are sure you understand the book.

Cut the discussion by saying that "the manuals say" "you don't understand aerodynamics" doesn't disqualify me. I understand my comments don't match the terminology of the manuals but the reality is not made of manuals, things are not divided. The manuals give notions for pilots so that they know how to behave. cofcorpse said the FM is composed of two parts, material point and aerodynamic forces.

 

In reality we have such a thing. Aerodynamic forces and energy due to the mass/speed (not airspeed!)

The speech has degenerated also because instead of trying to understand you have focused everything on manualistic speech, ending up being experts giving me the troll and pathetic as if i were questioning the bug. So we dragged this far.

So in my defense, bkthunder made a good job by finding the bug, (among other things I agree with him when he says that such a mistake should not occur for a simulator like DCS), but the developers, who are not stupid, they know that for FM we have to consider the energies of the aircraft and those that the wind impresses them, as in the example of the vertical climb.

[billeinstein]

To evaluate the performance of an aircraft(speed, climb, turn rate, energy), we use True Airspeed, not Ground Speed. Ground speed is mainly for navigation.

 

If you "hover" in a 200 kts head wind, cut your thrust and you will get negative ground speed. If you use ground speed for kinetic energy caculation, you will find it's increasing. That's not correct. You must use True Airspeed, which is decreasing.

[bbrz]

Zero ground speed means 0 energy(material point=kinetic energy), regardless of the airspeed.

NO, and NO again.

 

According your flawed theory the energy is zero, hence and aircraft shouldn't be able to climb at 0kts groundspeed, which is obviously wrong.

 

An aircraft flying at 200kts indicated airspeed in a headwind of 200kts does NOT have zero energy despite a ground speed of 0kts!!!!!!!!!!!!!!!!!!!!!