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  1. Mick West

    Mick West Administrator Staff Member


    Source: https://www.youtube.com/watch?v=dMnBxI4fTac


    Source: https://www.washingtonpost.com/outl...bf9d112159c_story.html?utm_term=.7ef229f30df7
    TTSA:
    https://coi.tothestarsacademy.com/2015-go-fast-footage/
    [NOTE: 259 knots is incorrect. The number indicated is CAS (Calibrated Air Speed), which is the air speed read by the instruments calibrated for sea level. Adjusting for 25,000 feet altitude the actual True Air Speed is 369 knots. See: https://www.metabunk.org/posts/220136/]

    My first thought here is that it's a bird. When it first locks on we have:
    Metabunk 2018-03-09 14-21-43.

    -26°, 4.4 RNG, 25,000 feet barometer altitude.

    Then later,
    Metabunk 2018-03-09 14-23-13.

    -35°, 3.4 RNG, 25,010 alt (essentially the same alt)

    I'm assuming RNG is a straight line, not horizontal distance, then that gives us:
    4.4*sin(26 degrees) = 1.92 nautical miles below the plane
    3.4*sin(35 degrees) = 1.95 nautical miles

    So assuming those numbers are more or less accurate then it's an object that's around 13,000 feet ((25000 feet) - (1.95 nautical miles)) in altitude, viewed from a jet at 25,000 feet. Basically it's half way between the jet and the ocean surface.

    Hence the perceived motion of the object against the ocean surface, even if it were moving very slowly, would be the same as the speed of the jet itself. This is hugely magnified by the high zoom (NAR, or around 1.5° FOV). Here's an example of a static object that looks like it's moving through some trees:

    Source: https://www.youtube.com/watch?v=IRd1RY2PuvA



    The strangeness of the footage is largely a function of the ability of the ATFLIR camera to lock on to a white spot and track it. This accents the visual illusion that the object is moving because the parallax effect.

    The bird (or other slow moving object, but I suspect a large soaring sea bird) hypothesis tallies with the angle. The object starts out at 43° to the left, and continues left to 58°

    The white dot, whatever it is, would be invisible to the naked eye. It's in NAR mode, which has a FOV of 1.5°. Hence they were ONLY looking at it on the ATFLIR.

    Similar to the GIMBAL footage, but without the glare. See:
    https://www.metabunk.org/nyt-gimbal-video-of-u-s-navy-jet-encounter-with-unknown-object.t9333/

    [Update 3/15/2018]
    Analysis shows the object does vary altitude much, and the jet is also flying horizontally, so much of the analysis can be done in an overhead view.

    This animation shows the effect of varying the turn rate on the calculated speed. The blue line is the simple two point analysis of the target object path with jet (red line) traveling in a straight line. The orange line is the projected target object path with a variety of turn rates from the jet.
    [​IMG]
    With this model, the speed of the object could be anything from 28 knots to over 100 knots. This speed is relative to the atmosphere at the level of the jet, and so is consistent with a balloon + wind differential from 13,000 to 25,000 feet. Or a self powered bird.
     
    Last edited: Jul 5, 2018
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  2. Brian Vincent

    Brian Vincent New Member

    The first idea that I would want to explore is whether or not the "go fast" object is actually relatively stationary. During the first few seconds of the video, when the camera appears fixed, the angles are changing. This means that it's not actually fixed, but rather, the camera is panning in order to track a single spot on the ocean.

    A stationary object, high up, would be expected to appear moving, relative to the ocean.

    If it is relatively stationary, like a balloon, that would explain why it appears to have no wings or exhaust plume and isn't very hot.
     
    Last edited: Mar 9, 2018
  3. Mick West

    Mick West Administrator Staff Member

    Yes, that's essentially the gist of my post, above. A slow moving bird, and parallax.
     
  4. Brian Vincent

    Brian Vincent New Member

    I thought that a balloon would be more likely than a bird because 12,000 ft seemed rather high for birds to be flying. I was rather surprised to learn that 12,000 ft isn't very high and well within the range of many migratory birds and birds of prey.

    https://en.wikipedia.org/wiki/List_of_birds_by_flight_heights
     
  5. Mick West

    Mick West Administrator Staff Member

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  6. Mick West

    Mick West Administrator Staff Member

    Here's the motion of the ocean and of the UFO from 1seconds 22 frames to 3seconds 2 frames.
    Metabunk 2018-03-09 17-18-15.

    The camera here is not fixed, it is panning to the left, going from 36L to 37L over the course of this segment. This complicates matters. It's also tilting down from 22° to 23°

    i suspect the initial camera motion might be some kind of default ground tracking. After it locks onto the UFO/Bird this changes.

    But I think the fact that the motions are parallel indicates they are both derived from the motion of the plane.

    In fact with a FOV of 1.5° the camera MUST be attempting to track the ground in normal use. If the camera were not continually compensating for the motion of the plane then you would constantly be seeing the background just whizz past.
     
    Last edited: Mar 9, 2018
  7. Peter B

    Peter B New Member

    One problem common to all these TTAS videos is that they're just clips. No context. We don't know what happened before or after. If this one's a bird or a balloon (and why not, so far) how do we know one of the crewmen we hear didn't open the exchange by saying "Hey, is that a [gull/albatross/migrating dove down there? Betcha can't catch that on your FLIR!" —and so the guy does, with much whoo-hoo-ha from his mates. With all that kit to play with, and no war on, does anyone really expect these guys not to play games with it? (Infantrymen do the same with rifles after all. O, the stories one should not tell!)
     
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  8. Mick West

    Mick West Administrator Staff Member

    Size estimates. The video frame is 950 pixels across in the Washington Post version. When the object is closest (3.3 nautical miles), the object appears around 12 pixels across. Hard to say exactly. But from these numbers we can calculate the angle subtended by the object as as 12/950*1.5 degrees)

    tan(12/950*1.5 degrees)*3.3 nautical miles in feet =6.6 feet

    Metabunk 2018-03-09 22-07-30.

    Arguably you could say it's larger, but I think if anything it's smaller, as it's very blurry.

    So what birds have a 6 foot wingspan, and can fly at 13,000 feet?

    (or what other object, like weather balloons).
     
    Last edited: Mar 9, 2018
  9. Mick West

    Mick West Administrator Staff Member

    One possibly significant point is that the object appears colder than the water. BLK means black=hot, but it's white.
    Metabunk 2018-03-09 22-34-16.
    It is (probably) at 13,000 feet. Where the air would probably be colder than the water. Would a well insulated bird still show up as cold (on average). Or does this lean towards a balloon?
     
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  10. Mick West

    Mick West Administrator Staff Member

    It would be great o find some video of birds taken from planes. Here's one of a hawk taken from a helicopter. It's probably still moving at a similar speed to the chopper though - still looks weird.

    Source: https://youtu.be/h_f7ElR3oVs?t=28s
     
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  11. Mick West

    Mick West Administrator Staff Member

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  12. JFDee

    JFDee Senior Member

    The black/white thing is not helping much, unfortunately.

    A bird against the open sky will most certainly show up 'warm'.

    https://www.sciencedirect.com/science/article/pii/S1574954115001478
    [​IMG]


    However, a water surface reflects sky conditions (with a grade that also depends on the viewing angle of the observer). So it can vary.

    https://ubcsailbot.org/2014/12/28/using-ir-imaging-to-detect-floating-obstacles/

    Bird feathers are good insulators. When adding the cooling effect of the air flowing around a bird in flight, it's not clear if it will appear 'warm' against a background with possibly variable heat reflection.

    http://www.dailymail.co.uk/news/art...pictures-reveal-animals-hot-cold-secrets.html
    [​IMG]
     
    Last edited: Mar 10, 2018
  13. igoddard

    igoddard Active Member

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  14. JFDee

    JFDee Senior Member

    A very short FLIR video of a flying bird against sky and ground, from a freely available dataset provided by Oklahoma State University.

    The appearance of the bird is ambiguous at least. Even against the sky it's not a significantly warm object.

    The video is included with dataset 9 listed on this page:
    http://vcipl-okstate.org/pbvs/bench/
     

    Attached Files:

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  15. igoddard

    igoddard Active Member

    Here are the opening two segments where the camera appears to move very slowly and the waves look pretty sharp. Each segment is run at half speed 3x then the other 3x, ...



    It looks to me unremarkably like the cool feathers of a bird flying close over the sea. I also think we can make out a wing-flapping pattern (it sort of 'leaps' forward in steps, a differential rhythmic propulsion indicative of wing-flap-induced propulsion) that reminds me of the flying-insect UFOs called "rods."
     
    Last edited: Mar 10, 2018
  16. Whitebeard

    Whitebeard Senior Member

    There are quite a few, but to be more accurate we are going to need to know where the incident happened, obviously its over water, so it rules out certain species such as vultures and buzzards, which are mainly found over land. But birds such as boobies and pelicans tend to be found in more temperate climes, where as others such as certain swans and geese tend to be more northern.
     
  17. Kaen

    Kaen Member

    The ATFLIR also displays the closure speed (Vc), probably in knots.

    If the object was stationary, the closure speed at the start of the lock would be approximately 253 x cos(44) x cos(26) = 163 knots, 253 being the speed of the jet and the object being at a horizontal angle of 44 degrees and a vertical angle of 26 degrees.

    The measured closure speed is a bit higher, approx. 200 knots, which means that the object is travelling towards the jet. If we assume that the object is travelling in the same general direction but at different altitude, the additional 40 knots in closure speed (200 instead of 160) would mean that the object itself has a speed of 40/(cos(44) x cos(26)) = 60 knots (60 nm/hr). This corresponds to 70 mph which is the speed achieved by an albatross. An albatross has a length of about 5 feet and a wingspan of about 7 feet.
     
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  18. igoddard

    igoddard Active Member

    It seems to me the pilots are more engaged in the fun and excitement of target-acquisition training or challenge than freaking out about a UFO. While a couple times I seem to hear, "What is that thing?" in the mix of voices, there's no overall impression that these guys see the object itself as a serious issue. The issue seems to be 'can you get a lock on that target?' Wah hoo, you did it! If there is a "What is that thing?" stated in there, it's an aside at best. Seconds after the clip cuts a pilot might have answered that question, "It's a bird."

    And once again we get a 30-second snippet. What else can they do to look like they're trying to trick us?! Ah yes, also fail once again to release chain-of-custody documentation after promising to do so.
     
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  19. Mick West

    Mick West Administrator Staff Member

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  20. JFDee

    JFDee Senior Member

    Again, the TTSA release has made the main-stream news. Here is an opinion by Christopher Mellon, published in the Washington Post, ignoring all research that has been done since December:

    https://www.washingtonpost.com/outl...2c125c-22ee-11e8-94da-ebf9d112159c_story.html

    Excerpt:
     
  21. Mick West

    Mick West Administrator Staff Member

    Christopher Mellon, as he notes, is part of TTSA. This isn't really news, it's just an opinion piece by a UFO enthusiast.
     
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  22. Agent K

    Agent K Active Member

    Not just some UFO enthusiast, but one with a stake in TTSA. So instead of having experts debunk this and the previous TTSA videos, WaPo publishes an opinion by one of TTSA's people.
     
  23. jamesrav

    jamesrav New Member

    "The strangeness of the footage". To me it doesn't even qualify as strange. How is this any different than early-era video games whereby the object stayed motionless and the background moved, creating the illusion of motion? Yes, the object looks like it's zipping across the ocean at super speed, but don't we all - by the age of 5 - have an experience whereby we think we're moving but actually something else is moving? "Everything is relative", didn't somebody famous say that?
     
  24. Tom Mellett

    Tom Mellett New Member

    It does seem very odd that for the long-awaited release of the “Third Video” by TTSA, there was only this OpEd by Mellon in WaPo. Most TSA fans were expecting another mainstream media article like the original NY Times story of last December 16, which was co-authored by Leslie Kean.

    But it turns out that Leslie Kean and Christopher Mellon are 2 of the 5 Board Members for the UFODATA Project, which seeks “to break through the UFO taboo and do some real science on the problem.”
    http://www.ufodata.net/team.html

    With Tom DeLonge acting like the “Donald Trump of Disclosure,” I suppose it is comforting to know that there are responsible intelligent adults like Kean and Mellon in the “Disclosure Room” behind the garish storefront of TTSA. (On the other hand, “pay no attention to the man behind the curtain” who is Bob Bigelow, but I digress.)
     
  25. Tom Mellett

    Tom Mellett New Member

    Hello Mick,

    I was reading a Facebook page discussing the video and debunking Metabunk when someone quoted this passage from the AATIP FB page which I could not access, but I’m sure it’s accurate.

    Gary Nolan is a professor of genetics at Stanford and he is part of the “Dream Team” at TTSA. He reports:

     
    Last edited: Mar 11, 2018
  26. Mick West

    Mick West Administrator Staff Member

    Can you post links if you are posting quotes.

    I suspect that this "background information" is just a back-of-a-envelope calculation. But either way I'd be happy to take a look at it.
     
  27. Robert Sheaffer

    Robert Sheaffer New Member

    Bruce Maccabee posted his preliminary analysis on the Facebook group UFO Pragmatism. His conclusion is that the object is about 10-15 feet in diameter, and moving at 100 knots:

     
    Last edited by a moderator: Mar 11, 2018
  28. Tom Mellett

    Tom Mellett New Member

    Hi Mick,

    The problem is that I was on a UFO FB group which needs subscribing to and someone was quoting Gary Nolan from a FB group called AATIP which I cannot find. I’m sure the links will show up somewhere soon. Also not sure if Gary was making a “back of the envelope” calculation or else has access to actual radar tracking data that wasn’t released.
     
  29. Tom Mellett

    Tom Mellett New Member

    Meanwhile I posted Gary Nolan’s quote on Paracast and got this reply from someone who questions how Gary would have access to radar data.

    https://www.theparacast.com/forum/t...udy-media-monitoring.19069/page-2#post-270340

     
  30. Agent K

    Agent K Active Member

    It's moving about 1 degree per second, which at a range of 4 nmi is about 290 mph relative to the sensor, which happens to be moving at about that speed.
     
  31. Justin Shaw

    Justin Shaw New Member

    Nice analysis @Mick West. I've followed your lead and extracted the az/el/rng data from the video which allows you to compute the relative position of the object based on 30 frames per second.
    Code:
    ### seconds, deg
    az_data = array([
    	[12 + 10./30, -43],
    	[13 + 10./30, -44],
    	[13 + 20./30, -45],
    	[14 + 19./30, -46],
    	[15 + 13./30, -47],
    	[16 + 13./30, -48],
    	[18 +  0./30, -49],
    	[21 +  6./30, -50],
    	[23 +  6./30, -51],
    	[24 + 18./30, -52],
    	[26 +  6./30, -53],
    	[27 + 18./30, -54],
    	[29 +  6./30, -55],
    	[30 + 13./30, -56],
    	[31 + 19./30, -57],
    	[32 + 25./30, -58],
    	[33 +  0./30, -58]
    	])
    
    ## seconds, DEG
    el_data = array([
    	[12 + 10./30, -26],
    	[13 + 19./30, -27],
    	[16 +  6./30, -28],
    	[18 + 25./30, -29],
    	[21 +  7./30, -30],
    	[23 + 13./30, -31],
    	[25 + 25./30, -32],
    	[28 +  1./30, -33],
    	[30 +  1./30, -34],
    	[32 +  7./30, -35],
    	[33 +  0./30, -35]
    	])
    
    ## seconds, NMI
    rng_data = array([
    	[12 + 10./30, 4.4],
    	[13 + 10./30, 4.3],
    	[15 +  3./30, 4.2],
    	[17 +  4./30, 4.1],
    	[19 +  1./30, 4.0],
    	[20 + 29./30, 3.9],
    	[22 + 28./30, 3.8],
    	[24 + 28./30, 3.7],
    	[27 +  1./30, 3.6],
    	[29 + 13./30, 3.5],
    	[31 + 22./30, 3.4],
    	[33 +  0./30, 3.4],
    	])
    
    This data indicates that the object is traveling toward the camera with a closing speed of about 180 KTS.
    Here is a link to the raw data: https://photos.app.goo.gl/h172DtyuNcAiGbuS2

    Subtracting out the camera's forward velocity I get this 3D plot of the position. Red dot indicates initial position.
    https://photos.app.goo.gl/WgmGltNaYHFe3oBX2
    Figure_2.
    I'm open to suggestions, but this object does not appear to be moving at a great speed.
     
    Last edited by a moderator: Mar 11, 2018
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  32. igoddard

    igoddard Active Member

    I plotted with red dots each location the flying entity appears in the two opening segments with minimal camera motion. These segments are run at half speed. To me, the paths look consistent with the slightly erratic path of a bird. There's also two points I note where the object seems to slow down, but it's all so blurred and grainy I can't be sure.

    [​IMG]

    Notable is that its brightness often dims down to almost invisible. That would seem to be consistent with wing flaps, changing the surface area exposed to the lens. However, when the camera locks onto it later it does not seem to fade out. So there are some notable differences with the before- and after-locked object.

    [​IMG]

    When that camera locks on in the rest of the footage you can’t detect any erratic motions or fading of its brightness. When the camera gets locked on, it looks more like a sphere-shaped object. But then IR only shows temperature, not necessarily mass shape. But really?! Putting any extraordinary belief into just another grainy pin-head sized UFO seems foolish. #3 underwhelms!

    Last year WaPo said this (bold added):
    So the three TTSA videos we've examined are the best of the best. Just wow!
     
    Last edited: Mar 12, 2018
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  33. Agent K

    Agent K Active Member

    I thought a balloon is more likely because a bird would appear warmer than the background.
    Also, I wonder how the WSO detected it in the first place. Did it show up on radar or on FLIR in wide field of view?
     
  34. Mick West

    Mick West Administrator Staff Member

    What value did you use for this?
     
  35. Agent K

    Agent K Active Member

    The WaPo article also said something that at least Leslie Kean and maybe Elizondo disputed:
    It suggested that Elizondo tricked the Pentagon into releasing the videos, but Leslie Kean told Open Minds UFO Radio that the memo she read didn't have any false pretense, though it may have been a different memo. Elizondo may have said this as well, but I don't remember. The point is to take the WaPo reporting with a grain of salt.
    That said, it makes sense that Elizondo would want to release the most unusual videos, and it's almost funny how disappointing they were, like literally "It's a bird, it's a plane."

    Edit: Elizondo did deny any false pretense in a recent interview. But he also said, "We got very clever at dual-using" like putting out requirements that could apply to studying ballistic missiles or "other objects."
     
    Last edited: Mar 12, 2018
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  36. Justin Shaw

    Justin Shaw New Member

    @Agent K I agree that if these are three of the best videos, it is not very convincing. Nice work @igoddard The apparent change in can also be attributed to camera trajectory. Can you extract the raw data from thos plots? Also, if anyone can extract aircraft attitude from the artificial horizon, I can add that to the simulation above and solve for x, y, z and v of the object.

    I added the camera position and found an error in the previous plot. Here is the new plot in absolute position from the initial range solution.

    @Mick West , I used 258 knots level flight. Could do better with attitude assuming coordinated turns.


    https://photos.app.goo.gl/A0niEc6ZAG84VKMn2
    upload_2018-3-12_8-27-33.
    Code:
    from numpy import *
    from pylab import *
    from scipy.interpolate import *
    
    #		 t sec	az deg
    az_data = array([
    	[12 + 10./30, -43],
    	[13 + 10./30, -44],
    	[13 + 20./30, -45],
    	[14 + 19./30, -46],
    	[15 + 13./30, -47],
    	[16 + 13./30, -48],
    	[18 +  0./30, -49],
    	[21 +  6./30, -50],
    	[23 +  6./30, -51],
    	[24 + 18./30, -52],
    	[26 +  6./30, -53],
    	[27 + 18./30, -54],
    	[29 +  6./30, -55],
    	[30 + 13./30, -56],
    	[31 + 19./30, -57],
    	[32 + 25./30, -58],
    	[33 +  0./30, -58]
    	])
    el_data = array([
    	[12 + 10./30, -26],
    	[13 + 19./30, -27],
    	[16 +  6./30, -28],
    	[18 + 25./30, -29],
    	[21 +  7./30, -30],
    	[23 + 13./30, -31],
    	[25 + 25./30, -32],
    	[28 +  1./30, -33],
    	[30 +  1./30, -34],
    	[32 +  7./30, -35],
    	[33 +  0./30, -35]
    	])
    rng_data = array([
    	[12 + 10./30, 4.4],
    	[13 + 10./30, 4.3],
    	[15 +  3./30, 4.2],
    	[17 +  4./30, 4.1],
    	[19 +  1./30, 4.0],
    	[20 + 29./30, 3.9],
    	[22 + 28./30, 3.8],
    	[24 + 28./30, 3.7],
    	[27 +  1./30, 3.6],
    	[29 + 13./30, 3.5],
    	[31 + 22./30, 3.4],
    	[33 +  0./30, 3.4],
    	])
    ts = data[:,0]
    ephem = interp1d(ts, data.T)
    azs = data[:,1]
    els = data[:,2]
    rngs = data[:,3]
    vs = data[:,4]
    az = interp1d(az_data[:,0], az_data[:,1])
    el = interp1d(el_data[:,0], el_data[:,1])
    rng = interp1d(rng_data[:,0], rng_data[:,1])
    
    def pos(t):
    	vel = array([258 * KTS, 0, 0])
    	return array([0, 0, 0])[newaxis] + vel[newaxis,:] * (t[:,newaxis] - az_data[0, 0])
    
    NMI = 1852.
    HOUR = 3600.
    DEG = pi / 180.
    KTS = NMI / HOUR
    FEET = FOOT = .3048
    
    rel_speed = (diff(rng_data[:,1] * NMI) / diff(rng_data[:,0])) / KTS
    
    t = arange(15, 30, .1)
    azs = az(t)
    els = el(t)
    rngs = rng(t)
    
    x = rngs * NMI * cos(azs * DEG) * cos(els * DEG)
    y = -rngs * NMI * sin(azs * DEG) * cos(els * DEG)
    z = rngs * NMI * sin(els * DEG)
    
    xyz = vstack([x, y, z]).T
    p = pos(t)
    
    ax = subplot(4, 1, 1)
    plot(az_data[:,0], az(az_data[:,0]))
    plot(t, -arctan2(y, x) / DEG)
    ylabel('Az [deg]')
    
    subplot(4, 1, 2, sharex=ax)
    ylabel('El [deg]')
    plot(el_data[:,0], el(el_data[:,0]))
    plot(t, arcsin(z / linalg.norm(xyz, axis=1)) / DEG)
    
    subplot(4, 1, 3, sharex=ax)
    ylabel('Range [nmi]')
    plot(rng_data[:,0], rng(rng_data[:,0]))
    plot(t, linalg.norm(xyz, axis=1) / NMI)
    
    subplot(4, 1, 4, sharex=ax)
    ylabel('Rel vel [kts]')
    xlabel('t [sec]')
    plot(rng_data[2:-1,0], rel_speed[1:-1])
    
    import matplotlib as mpl
    from mpl_toolkits.mplot3d import Axes3D
    fig = plt.figure()
    ax = fig.gca(projection='3d')
    
    ax.plot([0], [0], [0], 'bo')
    
    ax.plot(x / NMI, y / NMI, z / FEET, 'r-')
    ax.plot(x[:1]/NMI, y[:1] / NMI, z[:1] / FEET, 'ro')
    
    xlabel('x [nmi]')
    ylabel('y [nmi]')
    ax.set_zlabel('z [feet]')
    
    
    fig = plt.figure()
    ax = fig.gca(projection='3d')
    
    ax.plot((p[:,0])/NMI, (p[:,1]) / NMI, (p[:,2]) / FEET, 'b-')
    ax.plot((p[:1,0])/NMI, (p[:1,1]) / NMI, (p[:1,2]) / FEET, 'bo')
    
    ax.plot((x + p[:,0])/NMI, (y + p[:,1]) / NMI, (z + p[:,2]) / FEET, 'r-')
    ax.plot((x[:1] + p[:1,0])/NMI, (y[:1] + p[:1,1]) / NMI, (z[:1] + p[:1,2]) / FEET, 'ro')
    
    xlabel('x [nmi]')
    ylabel('y [nmi]')
    ax.set_zlabel('z [feet]')
    show()
    
     
    Last edited by a moderator: Mar 12, 2018
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  37. Mick West

    Mick West Administrator Staff Member

    Metabunk 2018-03-12 08-32-11.
    That number there varies between 252 and 259.
    The M number varies from 0.61 to 0.62, flipping at 254/255

    Those numbers are a bit confusing, as 254 is not 0.61 of the speed of sound. However:
    http://www.hochwarth.com/misc/AviationCalculator.html
    Metabunk 2018-03-12 08-39-16.

    Hence, the 254 number is CAS, Calibrated airspeed. It's not groundspeed, and it's not True Airspeed (TAS) which is actually 369 knots (which matches 0.61285*602, where 602 is the speed of sound in knots at 25,000 feet pressure altitude)

    The groundspeed depends on the windspeed at 25,000 feet. An additional complication would be how this differers from the airspeed at 13,000 feet.

    But how does your chart look with an aircraft ground speed of 369 knots?
     
    Last edited: Mar 12, 2018
  38. Mick West

    Mick West Administrator Staff Member

    Assuming a simple difference there of 369-258, or 111, that presumably reduces your calculated closing speed to ~69 knots?
     
  39. Kaen

    Kaen Member

    During the entire period when the ATFLIR is locked on the object, the object’s speed can be estimated on a moment by moment basis.

    At every moment during the locked-on period, the speed vector of the F18 can be projected onto the slant vector (the vector pointing towards the object). This gives the F18’s contribution to the closure speed:

    Vc,F18 = V x cos(left) x cos(down)

    Where V is the airspeed of the F18 in the ATFLIR display, ‘left’ is the angle to the left in the ATFLIR display, and ‘down’ is the vertical angle in the ATFLIR display.

    The object’s contribution to the closure speed is:

    Vc,obj = Vc – Vc,F18

    Where Vc is the closure speed in the ATFLIR display.

    If we assume that the object travels approximately along the same line as the F18 (plus or minus 20 degrees), but on a different altitude, the object’s real velocity can be estimated as:

    Vobj = Vc,obj / (cos(left) x cos(down))

    In this way I estimated the object’s speed at every second during two periods in the official GO FAST video, one period where the F18 is flying level (1:35-1:39) and one period where the F18 is in a stable banking position to the left (1:43-1:55).

    The results are below.
    (I also played a bit with the angle between the object’s line-of-motion and the F18’s line-of-motion, but until a deviation of plus or minus 20 degrees the results are basically the same.)

    Conclusion: The average estimated speed of the object is 80 knots, and it seems to be traveling at a constant speed with a standard deviation over the entire lock-on period of only 7 knots (which could be caused by measuring errors of the sensors involved).

    Note: If the real ground speed of the F18 is higher, the object’s speed is even lower…

    T left down RNG Vc V ALT Vc,F18 Vc,obj V,obj

    1:35 43 26 4,4 220 253 25000 166 54 82

    1:36 45 27 4,3 210 254 25000 160 50 79

    1:37 46 27 4,3 210 254 25000 157 53 85

    1:38 47 27 4,2 200 254 25000 154 46 75

    1:39 48 28 4,2 200 254 25000 150 50 85


    T left down RNG Vc V ALT Vc,F18 Vc,obj V,obj

    1:43 50 30 3,9 180 254 25010 141 39 69

    1:44 50 30 3,9 180 254 25010 141 39 69

    1:45 50 30 3,8 180 254 25000 141 39 69

    1:46 51 31 3,8 180 255 25010 138 42 79

    1:47 52 31 3,7 170 254 25000 134 36 68

    1:48 52 32 3,7 170 255 25010 133 37 71

    1:49 53 32 3,7 170 255 25000 130 40 78

    1:50 54 33 3,6 170 255 25010 126 44 90

    1:51 54 33 3,6 160 256 25010 126 34 69

    1:52 55 34 3,5 160 256 25010 122 38 80
     
  40. Mick West

    Mick West Administrator Staff Member

    See above. The true air speed is 369 knots, you might want to redo your post.