Some kind of autopilot?

No it's doesn't work liked that. Once airborne the plane have no idea which way over the ground the air mass is traveling.

Ground has nothing to do with it. It is the wind interacting with your plane... If wind is blowing against your fuselage and the center of gravity isn't exactly in the pivot point defining the force wise center of your fuselage it will apply force asymmetricly and yaw the plane around the center of gravity. As most planes do not sport the exhausts in the middle of the fuselage/wings where the center of gravity is, the little shift puts the thrust to the offside of the center of gravity pushing the nose around, even more.

As long as you do not counteract by rudder or ailerons (or trim the rudder or ailerons, or adjust thrust on one side in a dual/multiengine plane) this will happen. Else, Einstein would have been an idiot and you have reinvented a new physical law.

In a glider (soaring plane) this is most obvious, as you can't just push the throttle. Even in a motorized glider under power it is prevalent.

It has nothing to do with flight licenses, knowledge or experience, it is basic physics and application of vectored forces... You push here, it moves there. :dunno:

No it's doesn't work liked that. Once airborne the plane has no idea which way over the ground the air mass is traveling.

By the way, you did read the little article from the National Aeronautics and Space Administration about the physics, that kylekatarn720 so kindly pointed out?

Because it shows the force vectors and explains what the effects of crosswinds on objects in the air does, pretty well.

https://spaceflightsystems.grc.nasa.gov/education/rocket/rktcock.html

Shagrat - it's largely semantics, but really he's right.

Once you're in the air and in the the wind the plane will align itself so that it's heading into the airflow relative to itself.

If you looked at the plane's movement relative to the ground, it would look like it was weather-vaning, but relative to the air - it's flying straight.

It only 'weathervanes' because it's trying to align itself with the airflow in the first place.

Once it isn't being stopped from doing so by the force applied by the tyres, ruder etc, it stops weather-vaning and simply flies straight into the apparent airflow.

I love my autopilot, especially whilst banking and it's great for makin a cuppa.

Just saying

:):thumbup::pilotfly:

Sub note: I also noticed in one campaign mission I was flying at night in a horrendous storm with high winds that my Auto Pilot wouldn't stay in an engaged state. It was only until the weather eased that I could engage the Auto Pilot and I'm wondering if that's the case in real life?

Shagrat - it's largely semantics, but really he's right.

Once you're in the air and in the the wind the plane will align itself so that it's heading into the airflow relative to itself.

If you looked at the plane's movement relative to the ground, it would look like it was weather-vaning, but relative to the air - it's flying straight.

 

It only 'weathervanes' because it's trying to align itself with the airflow in the first place.

Once it isn't being stopped from doing so by the force applied by the tyres, ruder etc, it stops weather-vaning and simply flies straight into the apparent airflow.

You are right, yet the airflow relative to the aircraft is a combined force of the thrust and wind vectors (tan b = V/w).

And that means it is tan b of the intended course and you need to compensate that... Even if tan b is just a fraction of a degree because you fly mach 3.5.

Or do you mean the NASA engineers are wrong?

If the wind force is strong enough (strong enough wind and large enough surface to attack) you will directly notice the effect.

If the wind is not strong enough you won't, but it is still there... as it is a combination of laws of physics.

So it will show if not countered on longer flights as it cumulates.

Draw the force diagram and try to make the wind energy vanish.

But I will stop arguing now. All facts and arguments have been presented.

As this is just a Sim and nobody gets hurt, no problem.

If you wonder, why on take off roll /shortly after take off a clean A-10C with its two big rudders and engines on the tail yaws a bit to the side in DCS, may or may not look at the wind. Most of the time you will simply compensate automatically anyway and quickly trim the aircraft, so it's mostly irrelevant after getting the feel for the plane.

Ok, think I get what you guys mean. IF you don't hold a course after take off, the plane stops turning into the wind when it is aligned with the relative wind.

Yet, as the original post was about "feeling" like there is an "autopilot" at work in the take off instant action mission, I assume he wants to keep his plane flying a correct departure and keep it aligned with the runway during and shortly after take off.

The effects you will be fighting is a combination of asymmetric loadout (weight and drag) and crosswind.

If you do not trim or compensate with controls shortly after take off the plane turns (weather cocks) into the relative wind and won't follow the intended course.

Ok, think I get what you guys mean. IF you don't hold a course after take off, the plane stops turning into the wind when it is aligned with the relative wind.

 

Yet, as the original post was about "feeling" like there is an "autopilot" at work in the take off instant action mission, I assume he wants to keep his plane flying a correct departure and keep it aligned with the runway during and shortly after take off.

 

The effects you will be fighting is a combination of asymmetric loadout (weight and drag) and crosswind.

If you do not trim or compensate with controls shortly after take off the plane turns (weather cocks) into the relative wind and won't follow the intended course.

The crosswind is irrelevant to the aerodynamics of the plane in flight, it only affects groundtrack/navigation. This is actually a very important principle, in fact it is arguably the most basic and fundamental principle of aerodynamics.

Of course gusts will have an affect, but only momentarily, and by their nature they will tend to cancel themselves out over time.

The crosswind is irrelevant to the aerodynamics of the plane in flight, it only affects groundtrack/navigation. This is actually a very important principle, in fact it is arguably the most basic and fundamental principle of aerodynamics.

If you just want to fly where the wind takes you, possibly. If you want to stay on the extended runway after take off, though, I guess tan b becomes pretty relevant to this task if there is a crosswind.

We were talking about a specific behaviour and what causes it.

Pointed at the crosswind turning you into the wind, what could feel, like someone else is controlling your plane, especially if you are used to the missions with zero wind...

If you just want to fly where the wind takes you, possibly. If you want to stay on the extended runway after take off, though, I guess tan b becomes pretty relevant to this task if there is a crosswind.

 

We were talking about a specific behaviour and what causes it.

 

Pointed at the crosswind turning you into the wind, what could feel, like someone else is controlling your plane, especially if you are used to the missions with zero wind...

These issues are all about the wind affecting NAVIGATION not aerodynamics. As you only fly simulators it doesn't really matter if you understand or not, but we might as well get things right for the benefit of others.

Anyway, a plane flying in a crosswind will not weathervane into the wind, however, uncontrolled it will wander around a bit but not in one particular direction due to the movement of the airmass within which it is flying in in relation to the ground.

To maintain the runway heading/groundtrack all you do is point the nose more into wind to cancel out the drift. You don't need to keep the rudder kicked in to do this. Simple stuff with simple explanations.

These issues are all about the wind affecting NAVIGATION not aerodynamics. As you only fly simulators it doesn't really matter if you understand or not, but we might as well get things right for the benefit of others.

 

Anyway, a plane flying in a crosswind will not weathervane into the wind, however, uncontrolled it will wander around a bit but not in one particular direction due to the movement of the airmass within which it is flying in in relation to the ground.

Laws of physics still apply, even without ground reference.

And most of the time the course to a point B from point A is, what you want to fly... if the relative wind comes from C to A and you don't compensate, you won't fly A-B.

I'm not only flying simulators, I also have a PPL/A and a glider pilot's license. And after takeoff, all planes are weathervaning, due to wind blowing against a large tail. When taking off due north with 45degrees western crosswind, the nose will turn left ánd the plane will drift to the right.

I'm not only flying simulators, I also have a PPL/A and a glider pilot's license. And after takeoff, all planes are weathervaning, due to wind blowing against a large tail. When taking off due north with 45degrees western crosswind, the nose will turn left ánd the plane will drift to the right.

They weathervane into the relative wind. Next you'll be claiming that a 20kt tailwind reduces airspeed by 20kts because that is where this kind of 'logic' leads. A crosswind does not continuously rotate an aircraft into the wind. When flying cross country with a crosswind, you just change your heading to maintain the correct groundtrack from point to point. Are you telling me you throw in yaw to keep your heading the same as the required groundtrack?

Laws of physics still apply, even without ground reference.

And most of the time the course to a point B from point A is, what you want to fly... if the relative wind comes from C to A and you don't compensate, you won't fly A-B.

This is a navigational issue and you compensate by pointing the nose more into the wind. The crosswind is not applying a continuous aerodynamic force to the plane. I don't think you understand what relative wind is versus just the wind (movement of an airmass in relation to the ground).

This is a navigational issue and you compensate by pointing the nose more into the wind. The crosswind is not applying a continuous aerodynamic force to the plane. I don't think you understand what relative wind is versus just the wind (movement of an airmass in relation to the ground).

No, I understand pretty well, and I know how to compensate the navigational issues by flying a wind corrected course.

I would still kindly ask you to read and understand the formula from the NASA article.

It is not about continuous force.

If you point the nose of a plane flying 200kts to 180° (S) and you have a wind of 20kts from 270° (W) and leave the controls alone, what would happen?

Your plane will magically turn into the wind and point the nose on a course of roughly 185.5° (course plus WCA).

My guess was, this looks like "something else" is controlling your plane to the original poster, as you make no other input than throttle.

Even more so, when he increases or decreases thrust the plane veers left and right (to adjust to the relative wind/WCA).

We basically talk about the same thing, just from different points of view.

After learning navigation and course plotting basics, this is natural and logic to us, but if you jump into a study sim for the first time and just expect the plane to point the nose according to your rudder inputs, it can be irritating.

Edit - more so, if most missions have no or very moderate winds and default mission editor setting is no wind at all.

Next you'll be claiming that a 20kt tailwind reduces airspeed by 20kts because that is where this kind of 'logic' leads.

A steady 20kt tailwind will not reduce airspeed but a 20kt tailwind gust will, the aircraft will not instantaneously match speed with the air mass and there is a change in relative airspeed.

A crosswind does not continuously rotate an aircraft into the wind.

On takeoff as the crosswind accelerates the aircraft/air-frame to match the moving air mass is there not a tenancy for the nose to point into the wind (weathervane).

As you say, once in a steady state, the 'crosswind' component of a moving air mass will not 'turn' an aircraft. However if the crosswind is gusting/changing, it will have a noticeable effect.

A steady 20kt tailwind will not reduce airspeed but a 20kt tailwind gust will, the aircraft will not instantaneously match speed with the air mass and there is a change in relative airspeed.

 

 

On takeoff as the crosswind accelerates the aircraft/air-frame to match the moving air mass is there not a tenancy for the nose to point into the wind (weathervane).

 

As you say, once in a steady state, the 'crosswind' component of a moving air mass will not 'turn' an aircraft. However if the crosswind is gusting/changing, it will have a noticeable effect.

I agree with all that. I've already covered the transient effects from gusts in an early post, my point being that for every gust there's a lull and the net affect is close to nil over time.

No, I understand pretty well, and I know how to compensate the navigational issues by flying a wind corrected course.

I would still kindly ask you to read and understand the formula from the NASA article.

It is not about continuous force.

 

If you point the nose of a plane flying 200kts to 180° (S) and you have a wind of 20kts from 270° (W) and leave the controls alone, what would happen?

 

Your plane will magically turn into the wind and point the nose on a course of roughly 185.5° (course plus WCA).

 

My guess was, this looks like "something else" is controlling your plane to the original poster, as you make no other input than throttle.

 

Even more so, when he increases or decreases thrust the plane veers left and right (to adjust to the relative wind/WCA).

 

We basically talk about the same thing, just from different points of view.

 

After learning navigation and course plotting basics, this is natural and logic to us, but if you jump into a study sim for the first time and just expect the plane to point the nose according to your rudder inputs, it can be irritating.

 

Edit - more so, if most missions have no or very moderate winds and default mission editor setting is no wind at all.

Right, we don't agree on the central point which is that you claim that a crosswind pushes harder against the tail of a plane in flight than it does the nose. Thus, according to you, causing the nose to point further and further into wind until it has weathervane completely into the headwind. I've got no better explanation than I've already given as to why this is completely wrong.

Right, we don't agree on the central point which is that you claim that a crosswind pushes harder against the tail of a plane in flight than it does the nose.

Because you usually don't have a barn door of a rudder on the planes nose??? :doh:

...and the center of gravity in a plane usually sits somewhere near and between the airfoils, which is some feet forward of the rudder and thus you have a lever against the center of gravity... unless you have a monofoil with no tailrudder, that is.

Next you'll be claiming that a 20kt tailwind reduces airspeed by 20kts because that is where this kind of 'logic' leads.

Just recorded video in dcs flying in to the wind and away from the wind. It seems like the tail wind effects the speed a lot. Uploading it right now it will be ready in half an hour or so.

Loadout i picked was this, all pylons where empty, 0 chaff, 0 flare, 0 gau8 ammunition, %50 fuel.

About the weathervaning issue, ive never flown an aircraft in my life or stayed in side the cockpit so i can observe. But we can try and see what happens in dcs, gonna record a video for that and upload that too.

Right, we don't agree on the central point which is that you claim that a crosswind pushes harder against the tail of a plane in flight than it does the nose. Thus, according to you, causing the nose to point further and further into wind until it has weathervane completely into the headwind. I've got no better explanation than I've already given as to why this is completely wrong.

It actually does "push harder" at the tail, since there is nothing to "grab onto" anywhere at the nose of an airplane for a crosswind component. In other terms, the profile shape of the tailfin generates lift pointing in a horizontal direction (left or right, one might call it), thus generating torque around the center of gravity of the plane, resulting in rotational acceleration around the planes vertical axis (also some roll, since the tailfin is usually above the CoG). Lift is generated, since the crosswind component lets the air hit the tailfin at an angle of attack >0, so that even a symmetrical profile as used on tailfins generates lift (beware this is angle of attack on the profile of the tailfin as a result of the sideslip angle beta, not the typical angle of attack alpha).

So yeah, theoretically, a plane would, without any inputs, weathervane into the wind (provided it is aerodynamically stable). But since an airplane usually gets controlled (and trimmed) by a pilot, it does not turn into the wind, but flys into another direction accordingly. Thereafter, only navigational corrections due to a potential crosswind component need to be applied.

I agree with all that. I've already covered the transient effects from gusts in an early post, my point being that for every gust there's a lull and the net affect is close to nil over time.

But the whole point wasn't the effects over time. It was about a take off and the effects from crosswind on take off rolls and directly after take off and when you fly a heading without corrections.

Over time even an off course of 45° and same time at -45° from the intended course will get you to the point, but you wouldn't say that the net effect was a "straight" flight?

here is the video of tail winds effect on speed.

Edit: gonna post the the one about weathervaning tonight.

here is the video of tail winds effect on speed.

 

 

Edit: gonna post the the one about weathervaning tonight.

Yep, the only thing affected by the wind is the groundspeed as can clearly be seen before and after your 180 turn.

Ok I will chime in a little. On the ground all Aircraft weather vane into wind during the Take-off roll and you use rudder to compensate as you roll down the Runway after you apply Thrust, due to the side force on the Rudder. As you rotate the Aircraft and the nosewheel comes off the ground it will naturally turn into wind if you dont compensate. If you are in a large Aircraft we hold the nose straight using rudder due to the time it takes for the Aircraft to lift off and will end up slightly cross controlled. Once Airborne we balance the Aircraft and fly away either flying a track or a heading. When Airborne the Aircraft flys straight unless you are out of balance. Unless you fly through a shear where the Aircraft sees a change in the wind, then the Aircraft basically doesnt care what wind it fly, there is no weathervaneing in as you call it. If you fly a track then the Aircraft nose will be heading into wind but there is no Aircraft movement into the wind that is just your Autopilot flying the Track. Now if you are dropping a dumb bomb off an Aircraft with no CCIP and the Wind is from Rt to Left over the Target then you need to fly your backside over the Target.

Your nose will be pointing into the wind slightly to maintain the Aircraft track over the Target. Again tho you are the one flying the track once off the ground the Aircraft doesnt know or care about any wind force as it is normally constant.

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It actually does "push harder" at the tail, since there is nothing to "grab onto" anywhere at the nose of an airplane for a crosswind component. In other terms, the profile shape of the tailfin generates lift pointing in a horizontal direction (left or right, one might call it), thus generating torque around the center of gravity of the plane, resulting in rotational acceleration around the planes vertical axis (also some roll, since the tailfin is usually above the CoG). Lift is generated, since the crosswind component lets the air hit the tailfin at an angle of attack >0, so that even a symmetrical profile as used on tailfins generates lift (beware this is angle of attack on the profile of the tailfin as a result of the sideslip angle beta, not the typical angle of attack alpha).

 

So yeah, theoretically, a plane would, without any inputs, weathervane into the wind (provided it is aerodynamically stable). But since an airplane usually gets controlled (and trimmed) by a pilot, it does not turn into the wind, but flys into another direction accordingly. Thereafter, only navigational corrections due to a potential crosswind component need to be applied.

No, completely wrong. The crosswind isn't pushing harder on the tail and trying to rotate the plane. Go and try it in the A-10 for yourself. Properly trimmed and flying hands off, you won't see a tendency for the plane to weathervane into the wind.