NASA panel analyzes GO FAST

[Mendel]

Ok, so the NASA analysis is not the subject of this thread, and including the wind effect in the analyses refines nothing.
Have a nice discussion.

The NASA analysis is the subject of this thread. It does not consider wind.

Other threads on Metabunk do, e.g. the "balloon hypothesis" thread that I referenced above.
If you wish to present your own analysis, or comment on an analysis that considers wind, do it in the appropriate thread, please.
This is not difficult.

 

[Mick West]

The user previously known as "dimebag2" posts on Twitter as TheCholla. To avoid confusion, he suggested I rename his account here as TheCholla, which I've done.

 

[jplaza]

Just to be clear, Lehto was a USAF F-16 pilot.

I think it's not the plane what matters here, but the FLIR system onboard. I don't know what system the F-16 had, nor its reliability respect to the range.

 

[Mick West]

I think it's not the plane what matters here, but the FLIR system onboard. I don't know what system the F-16 had, nor its reliability respect to the range.

Lehto says he did not use the ATFLIR. I think he used the Sniper ATP.

 

[taurusclover21]

I think it's not the plane what matters here, but the FLIR system onboard. I don't know what system the F-16 had, nor its reliability respect to the range.

I neither claimed nor implied that the plane "matters." I simply corrected yoshy with specifics in regard to Lehto, not the F-16's systems.

 

[jplaza]

I neither claimed nor implied that the plane "matters." I simply corrected yoshy with specifics in regard to Lehto, not the F-16's systems.

Then I misunderstood you, sorry.

 

[Eburacum]

Thanks. That does explain it. But wouldn't a 'highly trained Top Gun pilot' take corrective action to maintain the desired heading?

Nah, normally a pilot would adjust the heading of the aircraft to maintain the desired course. Which I expect they did.

I'm confused. Is it possible to tell the difference between a plane which is being blown off-course by wind at 25000 feet (but correcting for it) and a plane which is not subject to significant wind, using only the data available in the clip?

 

[Mendel]

I'm confused. Is it possible to tell the difference between a plane which is being blown off-course by wind at 25000 feet (but correcting for it) and a plane which is not subject to significant wind, using only the data available in the clip?

If we had an estimate of the wave speed, maybe.

If the aircraft isn't "flying straight", you'd notice by looking out the window, because the apparent motion of the ground would be at an angle. The problem with the ocean background is that it's not static, it moves, too, though presumably slower than the wind. And the camera is rotated left and down with the aircraft banked, which complicates the picture.

But if someone was to track the ocean in that video, we'd know more.

 

[Ann K]

If we had an estimate of the wave speed, maybe.

If the aircraft isn't "flying straight", you'd notice by looking out the window, because the apparent motion of the ground would be at an angle. The problem with the ocean background is that it's not static, it moves, too, though presumably slower than the wind. And the camera is rotated left and down with the aircraft banked, which complicates the picture.

But if someone was to track the ocean in that video, we'd know more.

The reply I get when I ask that is:

Wind waves (deep-water waves) have a period of about 20 seconds. The speed of all ocean waves is controlled by gravity, wavelength, and water depth.

https://bikehike.org/how-fast-do-oc...olled by gravity, wavelength, and water depth.
That's a confirmation of what I suspected, that wave SPEED is not a function of wind speed. Amplitude, yes, but not speed.

 

[JMartJr]

The problem with the ocean background is that it's not static, it moves, too, though presumably slower than the wind.

That's a confirmation of what I suspected, that wave SPEED is not a function of wind speed. Amplitude, yes, but not speed.

That contradicts what I found, which shows wind speed as one factor in wave speed, if for no other reason than wind speed influences amplitude. (Duration below refers to how long the wind has been blowing, "fetch" is how long an open stretch of water the wind is blowing across -- you get bigger waves in oceans than in ponds!) The interaction of various factors seems complex:

Source: https://opentextbc.ca/geology/chapter/17-1-waves/


Meanwhile, over on https://scripps.ucsd.edu/news/voyager-how-fast-and-far-do-waves-travel

While they are in deep water, far offshore, the slowest wave components with the shortest period and the smallest distance between crests could be traveling at less than 5 miles per hour. The components with the longest periods could be moving at more than 35 miles per hour.

Wokipedia chimes in:

Wind waves (deep-water waves) have a period up to about 20 seconds.

Source: https://en.wikipedia.org/wiki/Wind_wave


My takeaway from all that is that the speed the waves are moving and other factors maybe difficult to determine in the video with precision, but a rough estimate of 10-20 seconds for the peak of one wave to move one wavelength may be close enough. I am not sure how to determine wave DIRECTION in the video, however.

 

[Eburacum]

If the aircraft isn't "flying straight", you'd notice by looking out the window, because the apparent motion of the ground would be at an angle. The problem with the ocean background is that it's not static, it moves, too, though presumably slower than the wind. And the camera is rotated left and down with the aircraft banked, which complicates the picture.

That is part of the difficulty with the FLIR-on-gimbals system. The cameras are mounted on gimbals which compensate for any tilt that the airplane might have, and point in a different direction to the heading (and the course) of the plane. This makes the whole system difficult to grasp intuitively, and must even cause problems for seasoned pilots. Using a gimballed camera makes it difficult to intuitively grasp the location of an object compared to the aircraft's actual movement. It is like trying to ride a bicycle with a coelostat on your head.

I am wondering if there was any artificial horizon display on the clip which I've missed; this might give a clue as to whether the plane is banked and is compensating for a side-wind.

 

[jarlrmai]

That is part of the difficulty with the FLIR-on-gimbals system. The cameras are mounted on gimbals which compensate for any tilt that the airplane might have, and point in a different direction to the heading (and the course) of the plane. This makes the whole system difficult to grasp intuitively, and must even cause problems for seasoned pilots. Using a gimballed camera makes it difficult to intuitively grasp the location of an object compared to the aircraft's actual movement. It is like trying to ride a bicycle with a coelostat on your head.

I am wondering if there was any artificial horizon display on the clip which I've missed; this might give a clue as to whether the plane is banked and is compensating for a side-wind.

>artificial horizon

They also sometimes bank to give the ATFLIR more room as it is mounted on the side.

 

[Eburacum]

Thanks!

 

[Mendel]

My takeaway from all that is that the speed the waves are moving and other factors maybe difficult to determine in the video with precision, but a rough estimate of 10-20 seconds for the peak of one wave to move one wavelength may be close enough.

Article:

Until, in deep water with water depth h larger than half the wavelength λ (so for h/λ > 0.5), the phase velocity cp​ is independent of the water depth:[2]​

with T the wave period (the reciprocal of the frequency f, T=1/f ). So in deep water the phase speed increases with the wavelength, and with the period.

Source: https://en.m.wikipedia.org/wiki/Dispersion_(water_waves)

9.8m/s² /2 /3.141 *20s = 31m/s = 60 knots
That's fast. (It'd be 30 knots for 10s waves.)

The direction ought to be perpendicular to the crests.

 

[JMartJr]

The direction ought to be perpendicular to the crests.

Yeah, but that is two directions: