Some kind of autopilot?

[WindyTX]

Shagrat in a fighter you let the nose turn in to wind at lift off and fly runway track with tbe drift. Your technique is what you do in an Airliner cos the the rotation takes so long. Nothing wrong with it but Fighters do the other way.

 

In an airliner once wheels are safely off the ground you uncross the controls and fly balanced.

 

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Edited June 29, 2017 by WindyTX

[WindyTX]

Also

 

Fpv shows where tthe Aircraft is going relative to the earth as was pointed out.

 

If I fly low level and want to fly into a valley I put the fpv on it and I will track to it. The difference between it and the nose direction is your drift or wind drift angle in balanced flight.

 

 

It is not your sideslip angle which should be negligible in a normal Aircraft.

 

The Fpv does not show your Aoa . You can deduce that from the difference between the fpv and the pitch attitude.

I can fly level with 15 degrees pitch up and the fpv will show level.

 

David in zero wind flying crossed controls you will produce a Hud Picture similar to the one you showed and in that case you can deduce your sideslip angle from the fpv to nose.

 

Nothing to do with the wind and everything to do with your control inputs.

 

Finally if you fly in an east wind and are tracking north and south or you have the Autopilot in and you track North and South your heading will be slightly east both ways as in 005 Northbound and 175 southbound with 5 degrees of wind drift.

 

Nothing to do with sideslip or weathervaning just 3rd grade physics as someone pointed out.

 

 

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Edited June 29, 2017 by WindyTX
Spelling

[BigDuke6ixx]

While the inertia "anchors" the CoG you would turn the nose back on the extended centerline, as the rudder input induces a little drag you counter the drag with a bit of aileron to keep wings level... or at least that is what I do after liftoff in a crosswind.

You could also just sideslip to counter the upcoming drift until inertia is overcome, but I guess this is personal preference.

 

And what happens with the controls once you up in the cruise and establish on the required heading? You were claiming a few pages back that the crosswind would still push the tail harder than the nose even with full directional stability. You even produced a graphic to 'prove' this point.

 

Are you still insisting that a plane in the cruise will weathervane into the crosswind?

Edited June 29, 2017 by BigDuke6ixx

[shagrat]

And what happens with the controls once you up in the cruise and establish on the required heading? You were claiming a few pages back that the crosswind would still push the tail harder than the nose even with full directional stability. You even produced a graphic to 'prove' this point.

...that was the problem I was so focused on the airborne part after take off, that I misunderstood what you focused on.

 

The crucial point for pushing "around" the nose is that CoG works against the wind. After the inertia is overcome the plane settles and you would just travel with the crosswind part thus no pressure on the fuselage and tailrudder, until you change course.

 

Now IRL you would only notice the effect, on take off roll (when the carriage is acting as an anchor/pivot point) and in the phase after lift off, when the inertia still resists the wind.

 

Usually you would now apply control inputs anyway, to correct the course with WCA.

 

If you don't do control inputs it will stop turning after a few moments (depends on plane mass etc.) and when inertia is overcome only drifts with the wind (what you are pointing out).

 

Now, whenever you change the course again, the inertia will kick in again, though for the pilot it is irrelevant as he needs to control the inputs anyway and the added force from the wind will be masked by any input.

[BigDuke6ixx]

...that was the problem I was so focused on the airborne part after take off, that I misunderstood what you focused on.

 

The crucial point for pushing "around" the nose is that CoG works against the wind. After the inertia is overcome the plane settles and you would just travel with the crosswind part thus no pressure on the fuselage and tailrudder, until you change course.

 

Now IRL you would only notice the effect, on take off roll (when the carriage is acting as an anchor/pivot point) and in the phase after lift off, when the inertia still resists the wind.

 

Usually you would now apply control inputs anyway, to correct the course with WCA.

 

If you don't do control inputs it will stop turning after a few moments (depends on plane mass etc.) and when inertia is overcome only drifts with the wind (what you are pointing out).

 

Now, whenever you change the course again, the inertia will kick in again, though for the pilot it is irrelevant as he needs to control the inputs anyway and the added force from the wind will be masked by any input.

 

There's no extra aerodynamic influence from the wind when turning either, I can tell you that much for nothing as well. Apart from the momentary effects from gusts, the wind's influence is purely a navegatinal one.

[shagrat]

There's no extra aerodynamic influence from the wind when turning either, I can tell you that much for nothing as well. Apart from the momentary effects from gusts, the wind's influence is purely a navegatinal one.

 

You are right about aerodynamic influences, what we talk about here is Newtons axioms, specifically the 3rd law of motion, but as it is really irrelevant to the process of flying a plane in an atmosphere after take off, I'll leave it at that. I now what you mean now and for the pilot it is just stepping a millimeter more or less on the rudder compared to turning the opposite side. :smilewink:

 

He won't notice.

[Yurgon]

Can we agree on this?

 

During a crosswind take-off, an aircraft's tendency to achieve directional stability is hindered by the grip of the landing gear. At the moment of lift-off, this causes a weathervaning tendency until directional stability has been achieved.

 

Once directional stability has been achieved in flight, steady wind has no influence on directional stability whatsoever, regardless of wind direction, aircraft heading, and aircraft maneuvering.

 

Steady wind influences the aircraft's movement across the ground. It does not affect the aircraft's movement within the air.

[BigDuke6ixx]

You are right about aerodynamic influences, what we talk about here is Newtons axioms, specifically the 3rd law of motion, but as it is really irrelevant to the process of flying a plane in an atmosphere after take off, I'll leave it at that. I now what you mean now and for the pilot it is just stepping a millimeter more or less on the rudder compared to turning the opposite side. :smilewink:

 

He won't notice.

 

Obviously the 3rd law is completely relevant because powered aircraft are an excellent example of the application of the third law of motion, it's just that your interpretations were completely and utterly wrong. But your small fin rocket data was completely irrelevant, do you agree?

Edited June 29, 2017 by BigDuke6ixx

[shagrat]

Obviously the 3rd law is completely relevant because powered aircraft are an excellent example of the application of the third law of motion, it's just that your interpretations were completely and utterly wrong. But your small fin rocket data was completely irrelevant, do you agree?

Hmm, yet the Newton axioms apply to any(!) object, so the result is of different proportions, if we talk about different sized objects/forces, but the effect is the same.

 

And if you look at the math it simply must do something to the object until it accelerated it enough to reach equilibrium. Even if the "object" is a mass of air molecules at 20kts.

 

Only submolecular level and relativistic speeds, will be different, but that is another story.

 

Let's agree the take off roll and immediate phase after lift off in crosswind requires the pilot to compensate the forces acting on the plane.

It is possible the nose turns a little bit into the wind, that is not "some kind of autopilot" but a combination of wind, drag and asymmetric load where applicable.

 

The forces may vary as mass of plane, crosswind angle etc. changes.

 

After getting in a controlled flight attitude the effect of the crosswind on the body cease, as long as you keep the flight path.

Even if it applies it is of no consequence and unnoticeable, as you control the movement deliberately.

[BigDuke6ixx]

Hmm, yet the Newton axioms apply to any(!) object, so the result is of different proportions, if we talk about different sized objects/forces, but the effect is the same.

 

And if you look at the math it simply must do something to the object until it accelerated it enough to reach equilibrium. Even if the "object" is a mass of air molecules at 20kts.

 

Only submolecular level and relativistic speeds, will be different, but that is another story.

 

Let's agree the take off roll and immediate phase after lift off in crosswind requires the pilot to compensate the forces acting on the plane.

It is possible the nose turns a little bit into the wind, that is not "some kind of autopilot" but a combination of wind, drag and asymmetric load where applicable.

 

The forces may vary as mass of plane, crosswind angle etc. changes.

 

After getting in a controlled flight attitude the effect of the crosswind on the body cease, as long as you keep the flight path.

Even if it applies it is of no consequence and unnoticeable, as you control the movement deliberately.

 

This is just completely silly now. You're not fooling anyone, not even yourself, with this rubbish.

[shagrat]

This is just completely silly now. You're not fooling anyone, not even yourself, with this rubbish.

"For every action, there is an equal and opposite reaction."

 

Change the vector and Newton's 3rd law applies. Cange the speed and Newton's 3rd law applies, change the mass (fire weapons) Newton's 3rd law applies...

 

Just because you won't notice doesn't mean it doesn't happen.

[BigDuke6ixx]

"For every action, there is an equal and opposite reaction."

 

Change the vector and Newton's 3rd law applies. Cange the speed and Newton's 3rd law applies, change the mass (fire weapons) Newton's 3rd law applies...

 

Just because you won't notice doesn't mean it doesn't happen.

 

The pilot would notice these things. Again, you're just blowing smoke.

[shagrat]

The pilot would notice these things. Again, you're just blowing smoke.

You mean you would notice, that you need to push the left rudder pedal in a left turn about 1.5mm more than the right rudder pedal in a right turn with similar parameters??? Wow!!!

[shagrat]

Sorry, I had to...

 

[BigDuke6ixx]

You mean you would notice, that you need to push the left rudder pedal in a left turn about 1.5mm more than the right rudder pedal in a right turn with similar parameters??? Wow!!!

 

This is just ridiculous waffle. But, anyway, explain exactly why there needs to be 1.5mm more?

Edited June 29, 2017 by BigDuke6ixx

[shagrat]

Now you're trolling, aren't you?

[Yurgon]

You mean you would notice, that you need to push the left rudder pedal in a left turn about 1.5mm more than the right rudder pedal in a right turn with similar parameters??? Wow!!!

 

Okay, so now we're down to "this effect is so pronounced I had to argue for 3 consecutive days, but it's so minute you won't ever notice it"?

 

Yeah, makes complete sense. :noexpression:

[BigDuke6ixx]

Now you're trolling, aren't you?

 

I'd like you to explain this 1.5mm thing please? For sure if I'm doing a ground referenced turn and there's some wind, then there will be a difference in control input. That has never been disputed. But if it's just an air mass referenced turn, then it will be the same input with wind as with calm air.

Edited June 29, 2017 by BigDuke6ixx

[Frederf]

The relative wind is always opposite to the direction of flight. A crosswind does not change the relationship between the direction of flight and the relative wind. The wind correction angle is added to take account of drift in relation to the ground caused by the crosswind. A crosswind does not push harder against the tail and no cross control inputs are required to counter this. This is an issue that only exists in some people's minds.

 

This is incorrect. The relative wind is not always opposite to the direction of flight. A crosswind does change the relationship between the direction of flight and the relative wind.

 

Take the following values

Motion: 360° 100 knots

Wind: From 270° 10 knots

Heading: 354.3°

 

The relative wind is from 354.3° at 100.5 knots. The airplane's motion (or its opposite) is in a different direction than the relative wind.

 

The air flow does apply more force to the tail than the nose which explains positive directional stability. However when crabbed into the wind such that beta angle is zero there is no net yaw torque on the airplane.

 

It is correct that in the condition of being crabbed into a crosswind no special control input is required which is any different than flight without a crosswind.

 

This is called AOS Angle of side slip

 

This is an incorrect use of the term side slip. Side slip is an aerodynamic measurement. It is perfectly normal for an airplane to have a heading different than ground track and to have an angle of side slip of zero.

 

The difference in azimuth between where the airplane is pointing and moving is typically known as drift or drift angle. In normal flight with a crosswind there will be lateral drift but no sideslip.

 

I'm also not agreeing with your use of the word yaw. Yaw is not heading. Yaw is rotational motion, not rotational position. And the "yaw vector" is straight out of the top of the airplane just like the roll vector is forward and pitch vector toward the right wingtip.

[BigDuke6ixx]

This is incorrect. The relative wind is not always opposite to the direction of flight. A crosswind does change the relationship between the direction of flight and the relative wind.

 

 

 

Sorry, but the relative wind is the direction of movement of the atmosphere relative to an aircraft or an airfoil. It is opposite to the direction of movement of the aircraft or airfoil relative to the atmosphere. If the atmosphere just happens to be moving in relation to the ground (wind) that's neither here nor there when it comes to the relative wind.

Edited June 29, 2017 by BigDuke6ixx

[shagrat]

Okay, so now we're down to "this effect is so pronounced I had to argue for 3 consecutive days, but it's so minute you won't ever notice it"?

 

Yeah, makes complete sense. :noexpression:

It is on take off! Only in Air when all forces are balanced (Equilibrium) the effect is temporarily gone.

As soon as you change the balance of force inertia from the mass of the plane will act according to Newton's 3rd law and create an asymmetrical force, until the forces are in equilibrium, again.

 

While you are already using ailerons and rudder, to turn the plane and most of the force acts on the wings now, you would likely not notice the remaining fraction of the forces acting on the rudder.

 

Especially, as this is a dynamic process, with multiple controls, usually.

 

Not that I have been trying to explain this for about 20 pages including sketches to show how the asymmetrical reaction force works.

 

In the track example (with the mid-air spawn) you can see what happens if the inertia is "back" immediately, with no build up through control inputs and how it hits the plane.

 

I've done all I can to explain why Newton's axioms do not cease to affect a plane in flight. As soon as you have a mass that acts as an anchor and an imbalance in forces the object must turn, how much, how fast is determined by the parameters.

 

I don't see any benefit in going through yet another iteration of what I posted, already.

 

Leave it be! I have wasted enough time on this.

 

Let's agree we disagree....

[BigDuke6ixx]

It is on take off! Only in Air when all forces are balanced (Equilibrium) the effect is temporarily gone.

As soon as you change the balance of force inertia from the mass of the plane will act according to Newton's 3rd law and create an asymmetrical force, until the forces are in equilibrium, again.

 

While you are already using ailerons and rudder, to turn the plane and most of the force acts on the wings now, you would likely not notice the remaining fraction of the forces acting on the rudder.

 

Especially, as this is a dynamic process, with multiple controls, usually.

 

Not that I have been trying to explain this for about 20 pages including sketches to show how the asymmetrical reaction force works.

 

In the track example (with the mid-air spawn) you can see what happens if the inertia is "back" immediately, with no build up through control inputs and how it hits the plane.

 

I've done all I can to explain why Newton's axioms do not cease to affect a plane in flight. As soon as you have a mass that acts as an anchor and an imbalance in forces the object must turn, how much, how fast is determined by the parameters.

 

I don't see any benefit in going through yet another iteration of what I posted, already.

 

Leave it be! I have wasted enough time on this.

 

Let's agree we disagree....

 

There's no room for opinion here, just like there's no room for opinion when it comes to adding up two numbers. You're just spouting pseudo scientific waffle again.

[Frederf]

Sorry, but the relative wind is the direction of movement of the atmosphere relative to an aircraft or an airfoil. It is opposite to the direction of movement of the aircraft or airfoil relative to the atmosphere. If the atmosphere just happens to be moving in relation to the ground (wind) that's neither here nor there when it comes to the relative wind.

Then you have to state that explicitly the first time. No one is going to read "motion" and mentally substitute "motion relative to the airflow." It's a tautological and meaningless statement. The incoming airflow is opposite the motion relative to the airflow... duh?

[BigDuke6ixx]

Then you have to state that explicitly the first time. No one is going to read "motion" and mentally substitute "motion relative to the airflow." It's a tautological and meaningless statement. The incoming airflow is opposite the motion relative to the airflow... duh?

 

Relative wind is an aeronautical term. I defined it with a link right at the beginning of this argument and I put a simplified definition in brackets when I replied to you. Anyone well versed in the subject matter would know what it means. Anyone not well versed in the subject matter probably shouldn't be going around and corrected people who are.

Edited June 29, 2017 by BigDuke6ixx

[WindyTX]

Anyone not well versed in the subject matter probably should be going around

 

I like this statement Big tho evetually they will have to actually land