The Windward Turn Theory

[Wizofoz]

Originally Posted by Vessbot

To make sure you haven't lost the plot -- what do you think my (attempted) point is?

I assume justifying your position that the way you are facing defines "negative" speed.

[Winemaker]

Okay, let's take off in the Cessna and fly at 50 knots. We manage to get aloft, our flight plan is to fly at 360° for one hour. The the wind picks up; all of a sudden it's blowing 60 knots from 90°. Fortunately we've managed to account for the sudden wind and know our starting point. The speed of our little plane is 50 knots and we chug along. We are flying north at 50 knots and we have no headwind; so our ground speed is 50 knots (air speed - wind speed). After one hour, where are we? Well, we've flown 50 nautical miles north, but we've also been blown 60 nautical miles west. Damn, where are we? From our starting point we're about 78 nautical miles away at a bearing of 320°. So (and please correct me if I'm wrong) we are about 78 nautical miles from our starting point, but west and north of where we want to be. So what's our ground speed? Air speed - wind speed = 50 knots/hr. But we're 78 nautical miles from our point of departure! Damn! Our ground speed is 78 knots/hour at a heading of 320°. Direction matters because we are dealing with velocity, not speed. There is no negative speed.

[George Glass]

Yikes! This the scariest thread on this forum. The fact that some professional(???) Pilots might entertain this drivel for a minute is frightening. My employer has recently abandoned Year 12 ( ie A level or equivalent)Physics and Maths as a prerequisite for interview for employment."Human Factors" and gender issues are apparently far more important. Lord save us.The "profession" of Pilot is in big trouble if this becomes the norm.Time for a major re-think and institution of formal training pathways and truly professional qualification standards.

[Wizofoz]

Originally Posted by George Glass

Yikes! This the scariest thread on this forum. The fact that some professional(???) Pilots might entertain this drivel for a minute is frightening. My employer has recently abandoned Year 12 ( ie A level or equivalent)Physics and Maths as a prerequisite for interview for employment."Human Factors" and gender issues are apparently far more important. Lord save us.The "profession" of Pilot is in big trouble if this becomes the norm.Time for a major re-think and institution of formal training pathways and truly professional qualification standards.

Just to be clear, whose drivel are you objecting to?

[Jet_Fan]

Originally Posted by Wizofoz

ET TU Wiki-

https://en.wikipedia.org/wiki/Speed

in everyday use and in kinematics, the speed of an object is the magnitude of its velocity (the rate of change of its position); it is thus a scalar quantity.

A position can't have a negative rate of change.

According to NASA: https://www.grc.nasa.gov/www/k-12/airplane/move2.html

If the plane took off to the West it would have a 20 mph tail wind (wind at your back). This gives a negative wind speed. At lift off, the airspeed is still 100 mph, the wind speed is -20 mph and the ground speed will now be 120 mph.

and:

Comparing this example with the ground reference, we see that the magnitudes of all the velocities are the same, but the sign of the wind speed has changed with the reference velocity direction. For a ground reference, we chose a positive wind velocity to be in the same direction as the aircraft (towards the nose). For an aircraft reference, we choose a positive wind velocity to be towards the tail.

Originally Posted by Winemaker

There is no negative speed.

​​​​​​​

[Wizofoz]

Originally Posted by Jet_Fan

According to NASA: https://www.grc.nasa.gov/www/k-12/airplane/move2.html



and:




​​​​​​​

but the sign of the wind speed has changed with the reference velocity direction.

They are talking velocity, not speed.

Try it this way- if you drive your car in reverse at -30KPH for an hour, how far are you from your origin?

That figure is a MAGNITITUDE (which is what scalar quantities like speed reference)- they do not have positive or negative signs. if you are 30K from where you were an hour ago, your average SPEED has been 30K/PH.

If you want to reference an origin and call a direction from it negative, you can, but this is velocity, not speed.

[Jet_Fan]

Originally Posted by Wizofoz

but the sign of the wind speed has changed with the reference velocity direction.

They are talking velocity, not speed.

Try it this way- if you drive your car in reverse at -30KPH for an hour, how far are you from your origin?

That figure is a MAGNITITUDE (which is what scalar quantities like speed reference)- they do not have positive or negative signs. if you are 30K from where you were an hour ago, your average SPEED has been 30K/PH.

If you want to reference an origin and call a direction from it negative, you can, but this is velocity, not speed.

NASA are very clear in their example 'the wind speed is -20 mph' in reference to the plane. A high enough positive sign wind can produce a negative sign GS in reference to a plane. There is no absolute value rule in the calculation for GS.

[Wizofoz]

Originally Posted by Jet_Fan

NASA are very clear in their example 'the wind speed is -20 mph' in reference to the plane. A high enough positive sign wind can produce a negative sign GS in reference to a plane. There is no absolute value rule in the calculation for GS.

I understand they used the term "speed", but they did so referencing a direction- that makes it a velocity.

Please answer my question regarding traveling at what you call a negative speed for a period of time- the displacement you have from your origin is a magnitude without sign or direction- that is what speed measures.

[Wizofoz]

Thing is, we agree on the actual physics, this is totally a matter of semantics- but it DOES lead to confusion when people don't understand the difference between a scalar and a vector quantity- it is part of our Down-Windian friends problem.

[Brercrow]

Originally Posted by Vessbot

Here's a typical flight example of the windward turn that should suffer an airspeed loss according to the windward turn theorists:

Vehicle making the turn: Cessna 172
Wind (uniform airmass over the ground): 10 knots, East to West
Initial heading: East
Initial airspeed: 100 knots
Initial groundspeed: 90 knots (airspeed minus headwind, 100-10)
Groundspeed after 180 degree turn: 110 knots (airspeed plus tailwind, 100+10)
Groundspeed change, aka "self created wind shear:" +20 knots (final groundspeed minus initial groundspeed, 110-90)

And my equivalent example:

Vehicle making the turn: Human body inside an airliner
Wind (uniform airmass inside the airliner): 500 knots, East to West
Initial heading: East
Initial airspeed: 1 knot
Initial groundspeed: negative 499 knots (airspeed minus headwind, 1-500)
Groundspeed after 180 degree turn: 501 knots (airspeed plus tailwind, 1+500)
Groundspeed change, aka "self created wind shear:" +1000 knots (final groundspeed minus initial groundspeed, 501 minus negative 499)

The windward turn theorists say that in the first example there is a tendancy to lose airspeed due to the headwind loss/tailwind gain, but in most situations it's minor enough not to notice since the turn is so slow comapared to the shear amount (20 knots over 1 minute) that the momentum is gradually changed to stay caught up with the airspeed.

If this logic is true, it implies that there could be an example, if we tweak the numbers enough, where the momentum doesn't have a chance to gradually change, and the result would be a noticable airspeed loss. So how about it, if 20 knots over a minute is not enough, how about 1000 knots over a second? Has anyone ever noticed any effects of this while walking up and down the isle of an airliner? Maybe it's still not enough for the effect to rise above the noise floor. Do we have to tweak the numbers further to make the airmass be the inside of a Concorde? Or an Apollo command module on translunar coast?

Of course not, this is bogus and Newtonian relativity holds true, i.e., if you close the window shades all physics occur as if it's sitting still. Or moving uniformly in any direction at any speed.

Vessbot your reasoning is flawed Look at this diagram
Clearly when the airspeed Va is greater than the windspeed W (a) when the aircraft makes a 180, the ground-velocity Vg reverses direction and the difference in groundspeed is twice the wind-speed (in your example 20 correct)
However, when the airspeed is less than the windspeed (b) after the 180 the groundspeed continues in the same direction and the difference in groundspeed is twice the air-speed (In your example 2 not 1000)

[Brercrow]

Wizofoz thinks that wind is the same as no wind because all inertial frames of reference (IFR) are equally valid and he can measure a velocity relative to any IFR

Discuss

[Wizofoz]

Originally Posted by Brercrow

Wizofoz thinks that wind is the same as no wind because all inertial frames of reference (IFR) are equally valid and he can measure a velocity relative to any IFR

Discuss

Wizofoz thinks this because Newton proved it.

Brercrow says this is not so, yet simultaneously says he understands Newton.

Explain to Brercrow his mistakes.

[Jet_Fan]

Originally Posted by Wizofoz

Wizofoz thinks this because Newton proved it.

Brercrow says this is not so, yet simultaneously says he understands Newton.

Explain to Brercrow his mistakes.

Brercrow's thinking is just hopelessly flawed. He's like a flat earth believer. He's a tragic figure.

[hans brinker]

Can we please stop talking about negative winds/speed/feelings and go back to making fun of brercrow?

[Peter H]

Brercrow: Wizofoz thinks that wind is the same as no wind because all inertial frames of reference (IFR) are equally valid and he can measure a velocity relative to any IFR
Discuss

[To be picky. To transform a velocity measure in one IFR to that which would be measured in another IFR you need to factor in the relative velocities of the two IFRs.]

If Wizofoz is wrong it looks like Einstein's theory of relativity must be as well.

https://en.wikipedia.org/wiki/Inertial_frame_of_reference
Measurements in one inertial frame can be converted to measurements in another by a simple transformation (the Galilean transformation in Newtonian physics and
the Lorentz transformation in special relativity).

Without exceptional evidence to the contrary I'll side with Wizofoz on this one (but see PS).

Regards, Peter

PS
I'd been wondering if one way of making the discussions more productive would be to try and devise a "critical experiment" which would provide real concrete evidence
rather than opinions and potentially flawed calculations.

I'm thinking of something that could be measured with a GPS receiver on a light plane. You'd probably also need a ground-based windsock and anemometer mounted
sufficiently high to be out of near-ground wind-shear and turbulence.

https://en.wikipedia.org/wiki/Experimentum_crucis
In the sciences, an experimentum crucis (English: crucial experiment or critical experiment) is an experiment capable of decisively determining whether or not a
particular hypothesis or theory is superior to all other hypotheses or theories whose acceptance is currently widespread in the scientific community.

[DaveReidUK]

Originally Posted by Brercrow

Clearly when the airspeed Va is greater than the windspeed W (a) when the aircraft makes a 180, the ground-velocity Vg reverses direction and the difference in groundspeed is twice the wind-speed
However, when the airspeed is less than the windspeed (b) after the 180 the groundspeed continues in the same direction and the difference in groundspeed is twice the air-speed

That's utter nonsense.

It would only work if you could mix velocities and speeds in the same calculation, i.e. ignore the direction component of some terms but not of others. You can't do that in any known universe.

[A Squared]

Originally Posted by Brercrow

Wizofoz thinks that wind is the same as no wind because all inertial frames of reference (IFR) are equally valid and he can measure a velocity relative to any IFR

Discuss

Wizofoz thinks this and so does anyone else with a functional grasp of physics. This is established physics. Any problem in newtonian physics will derive the same result in any un-accelerated (inertial) frame of reference. The arithmetic may be more complicated in some frames than others. As PeterH pointed out, you have to include the relative velocities between frames of reference, but in the end, if you do the arithmetic correctly, you get the same result. *THIS* is why people keep telling you over and over that you don't understand newtonian physics. Because you don't. It is abundantly clear to anyone with an understanding of physics that you don't grasp this fundamental concept. It's just the icing on the cake that you actually put it into words and mock Wizofoz, for "believing" something that is a fundamental tenet of physics.

[Brercrow]

Originally Posted by Peter H

Brercrow: Wizofoz thinks that wind is the same as no wind because all inertial frames of reference (IFR) are equally valid and he can measure a velocity relative to any IFR
Discuss

[To be picky. To transform a velocity measure in one IFR to that which would be measured in another IFR you need to factor in the relative velocities of the two IFRs.]

If Wizofoz is wrong it looks like Einstein's theory of relativity must be as well.

https://en.wikipedia.org/wiki/Inertial_frame_of_reference
Measurements in one inertial frame can be converted to measurements in another by a simple transformation (the Galilean transformation in Newtonian physics and
the Lorentz transformation in special relativity).

Without exceptional evidence to the contrary I'll side with Wizofoz on this one (but see PS).

Regards, Peter

PS
I'd been wondering if one way of making the discussions more productive would be to try and devise a "critical experiment" which would provide real concrete evidence
rather than opinions and potentially flawed calculations.

I'm thinking of something that could be measured with a GPS receiver on a light plane. You'd probably also need a ground-based windsock and anemometer mounted
sufficiently high to be out of near-ground wind-shear and turbulence.

https://en.wikipedia.org/wiki/Experimentum_crucis
In the sciences, an experimentum crucis (English: crucial experiment or critical experiment) is an experiment capable of decisively determining whether or not a
particular hypothesis or theory is superior to all other hypotheses or theories whose acceptance is currently widespread in the scientific community.

My dictionary defines the wind as 'motion of the air.' Personally, if I want to know the wind , I would use an anemometer set up on the ground.
What would you do? Read Principia Mathematica - in latin?

[Brercrow]

Originally Posted by A Squared

Wizofoz thinks this and so does anyone else with a functional grasp of physics. This is established physics. Any problem in newtonian physics will derive the same result in any un-accelerated (inertial) frame of reference. The arithmetic may be more complicated in some frames than others. As PeterH pointed out, you have to include the relative velocities between frames of reference, but in the end, if you do the arithmetic correctly, you get the same result. *THIS* is why people keep telling you over and over that you don't understand newtonian physics. Because you don't. It is abundantly clear to anyone with an understanding of physics that you don't grasp this fundamental concept. It's just the icing on the cake that you actually put it into words and mock Wizofoz, for "believing" something that is a fundamental tenet of physics.

It may be established physics.
It is not practical meteorology

[Brercrow]

Originally Posted by DaveReidUK

That's utter nonsense.

It would only work if you could mix velocities and speeds in the same calculation, i.e. ignore the direction component of some terms but not of others. You can't do that in any known universe.

Seriously? Whats wrong with the diagram?